Refine
Year of publication
Document Type
- Doctoral Thesis (201)
- Journal article (155)
- Other (1)
- Report (1)
Keywords
- Ackerschmalwand (39)
- Arabidopsis thaliana (28)
- Abscisinsäure (14)
- Pflanzen (12)
- Arabidopsis (10)
- Mais (10)
- Schließzelle (10)
- Kutikula (9)
- Pseudomonas syringae (9)
- Schmalwand <Arabidopsis> (9)
- Signaltransduktion (9)
- Calcium (8)
- Oxylipine (8)
- Wurzel (8)
- gene expression (8)
- Genexpression (7)
- Jasmonate (7)
- Kaliumkanal (7)
- Tabak (7)
- optogenetics (7)
- ABA (6)
- Bakterien (6)
- Biologie (6)
- Elektrophysiologie (6)
- Gerste (6)
- Meeresschwämme (6)
- Molekularbiologie (6)
- Tomate (6)
- Vakuole (6)
- actinomycetes (6)
- arabidopsis thaliana (6)
- guard cell (6)
- stomata (6)
- Abwehrreaktion (5)
- Anionentranslokator (5)
- Ionenkanal (5)
- Jasmonsäure (5)
- Optogenetics (5)
- Phytoprostane (5)
- ROS (5)
- SLAC1 (5)
- Spaltöffnung (5)
- Transkriptionsfaktor (5)
- guard cells (5)
- jasmonates (5)
- marine sponges (5)
- membrane potential (5)
- metabolomics (5)
- salt stress (5)
- sponges (5)
- Agrobacterium tumefaciens (4)
- Aquaporin (4)
- Drosophila melanogaster (4)
- Genregulation (4)
- Glatter Krallenfrosch (4)
- Invertase (4)
- Knochen-Morphogenese-Proteine (4)
- Kutikularwachs (4)
- Nitratreduktase (4)
- Optogenetik (4)
- Plasmamembran (4)
- Saccharose (4)
- Salzstress (4)
- SnRK1 (4)
- Stofftransport <Biologie> (4)
- Venusfliegenfalle (4)
- Zea mays (4)
- abscisic acid (4)
- calcium (4)
- marine sponge (4)
- phytoprostanes (4)
- plant cuticle (4)
- potassium (4)
- signal transduction (4)
- tomato (4)
- wax (4)
- Abwehr (3)
- Adjuvans (3)
- Anionenkanal (3)
- Antikörper (3)
- BMP (3)
- Bacteria (3)
- Channelrhodopsin-2 (3)
- Chemische Ökologie (3)
- Cyanobacteria (3)
- Dionaea muscipula (3)
- Inhibitor (3)
- Lycopersicon esculentum (3)
- Membranpotential (3)
- Mensch (3)
- Mesophyll (3)
- Nicotiana tabacum (3)
- OST1 (3)
- Oxidativer Stress (3)
- Pappel (3)
- Pflanzenfressende Insekten (3)
- Pseudomonas (3)
- Regulation (3)
- Resistenz (3)
- Rezeptor (3)
- Schließzellen (3)
- Schwämme (3)
- Sekundärmetabolit (3)
- Stickstoffmonoxid (3)
- Stomata (3)
- Stress (3)
- Suberin (3)
- Symbiose (3)
- TRAF2 (3)
- TWEAK (3)
- Taufliege (3)
- Transforming Growth Factor (3)
- Trockenstress (3)
- Wachs (3)
- abiotic stress (3)
- anion channel (3)
- aquaporin (3)
- bZIP (3)
- biology (3)
- crystal structure (3)
- detoxification (3)
- photosynthesis (3)
- plants (3)
- pollen tube (3)
- protein purification (3)
- salt (3)
- secondary metabolites (3)
- sequence motif analysis (3)
- sodium (3)
- streptomyces (3)
- stress (3)
- sucrose (3)
- transcription factors (3)
- ALMT (2)
- Abscisic Acid (2)
- Abscisic acid (2)
- Ackerbohne (2)
- Actinomyceten (2)
- Actinomycetes (2)
- Adjuvant (2)
- Agrobacterium (2)
- Aldehyde (2)
- Apoplast (2)
- Apoptosis (2)
- Aquaporine (2)
- AtSUC4 (2)
- Biomembran (2)
- Blumeria graminis (2)
- Botanik (2)
- ChR2 (2)
- Channelrhodopsin (2)
- Cuticle (2)
- Cuticular waxes (2)
- DNA methylation (2)
- Endodermis (2)
- Epichloë (2)
- Epiphyten (2)
- Erysiphe graminis (2)
- Flavonoide (2)
- Fluoreszenzmikroskopie (2)
- Glucosetransport (2)
- Glucosinolate (2)
- Hitzestress (2)
- Induzierte Resistenz (2)
- Insekten (2)
- Interaktion (2)
- Isoprostane (2)
- Jasmonatbiosynthese (2)
- Jasmonates (2)
- K+ channels (2)
- Kalium (2)
- Licht (2)
- Lipid-Carrier-Proteine (2)
- Lipidstoffwechsel (2)
- Lipoxygenase (2)
- Lipoxygenase 6 (2)
- Lolium perenne (2)
- Lyme-Borreliose (2)
- Mehltau (2)
- Membrandomänen (2)
- Membranpotenzial (2)
- Membranproteine (2)
- Membrantransport (2)
- Metabolomics (2)
- Metagenom (2)
- Metagenomics (2)
- Microarray (2)
- NMR (2)
- NRPS (2)
- Nitrate Reductase (2)
- Oozyte (2)
- PAC (2)
- Patch-Clamp-Methode (2)
- Pathogens (2)
- Permeation (2)
- Pflanzenhormon (2)
- Pflanzenschutzmittel (2)
- Pflanzenwachstum (2)
- Pharmakokinetik (2)
- Phoenix dactylifera (2)
- Phyllosphäre (2)
- Phytohormone (2)
- Plant Protection (2)
- Plant cuticle (2)
- Pollen (2)
- Pollenschlauch (2)
- Porifera (2)
- Porin (2)
- Prostaglandin-ähnliche Verbindungen in Pflanzen (2)
- Prostaglandine (2)
- Proteinreinigung (2)
- Protonenpumpe (2)
- Protoplast (2)
- RES-Oxylipine (2)
- RS1 (2)
- Rhodopsin (2)
- Rizinus (2)
- SLAC/SLAH (2)
- Samenpflanzen (2)
- Schwamm (2)
- Sojabohne (2)
- Solanum lycopersicum (2)
- Sphingolipide (2)
- Sphingolipids (2)
- Sponges (2)
- Stomaschluss (2)
- Strahlenpilze (2)
- Streptomyces (2)
- Streptomyces axinellae (2)
- Stressreaktion (2)
- Symport (2)
- Transpiration <Pflanzen> (2)
- Transport (2)
- Ulcerative colitis (2)
- Wasserhaushalt (2)
- Wassertransport (2)
- Wurzelhalsgalle (2)
- Xylem (2)
- Zellkultur (2)
- ZmSUT1 (2)
- abscisic acid (ABA) (2)
- active ingredients (2)
- agrobacterium tumefaciens (2)
- alkaloids (2)
- anti-infective (2)
- anti-parasitic (2)
- anti-protease (2)
- anti-trypanosomal (2)
- apoptosis (2)
- aquaporins (2)
- atopic diseases (2)
- auxins (2)
- barley (2)
- bioactivity (2)
- biosynthesis (2)
- cAMP (2)
- cancer (2)
- chemical ecology (2)
- circadian rhythms (2)
- coreceptor (2)
- corn (2)
- cuticle (2)
- cysteine protease (2)
- cytotoxic (2)
- dereplication (2)
- drought stress (2)
- endophyte (2)
- epicuticular wax crystals (2)
- epikutikuläre Wachskristalle (2)
- feeding (2)
- flavonoids (2)
- fruit (2)
- fungi (2)
- gene-expression (2)
- herbivory (2)
- honeybee (2)
- hydraulic conductivity (2)
- in vitro (2)
- innate immunity (2)
- ion channel (2)
- ion channels (2)
- jasmonic acid (2)
- juvenile hormone (2)
- kidney (2)
- maize (2)
- metabolism (2)
- metabolites (2)
- metagenomics (2)
- mitochondria (2)
- model (2)
- oncogenes (2)
- optogenetic (2)
- oxylipins (2)
- pH (2)
- pharmacokinetics (2)
- phosphorylation (2)
- phyllosphere (2)
- phylogenetic analysis (2)
- physiology (2)
- plant (2)
- plant defence (2)
- plant defenses (2)
- potassium channel (2)
- programmed cell death (2)
- prostaglandin-like compounds in plants (2)
- protease inhibition (2)
- protein domains (2)
- protein kinase (2)
- proton pump (2)
- reactive electrophilic species (2)
- reaktive elektrophile Spezies (2)
- receptor (2)
- rhodopsin (2)
- root (2)
- root growth (2)
- roots (2)
- soil (2)
- soybean (2)
- tetromycin (2)
- thermotolerance (2)
- toxicity (2)
- transcription factor (2)
- transpiration (2)
- transport (2)
- triglycerides (2)
- vacuole (2)
- vertical transmission (2)
- voltage clamp (2)
- vulnerability curve (2)
- wood anatomy (2)
- (Signal transduction pathways) (1)
- - (1)
- . (1)
- 12-oxo-phytodienoic acid (1)
- 14-3-3 (1)
- 14-3-3 . calcium (1)
- 14-3-3s (1)
- 16S metabarcoding (1)
- 18D1 (1)
- 9-HOT (1)
- 9-Hydroxyoktadekatriensäure (1)
- A-D (1)
- A. thaliana (1)
- ABA receptors (1)
- ABA-GE (1)
- ABA-Konjugate (1)
- ABA-conjugates (1)
- ACC deaminase (1)
- ACL (1)
- ADHD (1)
- AIDS (1)
- AKT1 (1)
- AKT1-like (1)
- APOPLAST (1)
- ATR-FTIR (1)
- AZI1 (1)
- Abschirmung (1)
- Abwehrmechanismen (1)
- Acer platanoides (1)
- Acromesomelic dysplasias (1)
- Actinokineospora (1)
- Activin (1)
- Adapterproteine (1)
- Adenylatcyclase (1)
- Advanced Therapy Medicinal Product (1)
- Agonist (1)
- Aktionspotenzial (1)
- Aktivierungsenergie (1)
- Aktivsubstanzen (1)
- Aliphaten (1)
- Aliphatics (1)
- Alkekengi (1)
- Allendorf-Kapelle (1)
- Allendorf-chapell (1)
- Allendorfkapelle (1)
- Allerg (1)
- Allergie (1)
- Allorhizobium vitis (1)
- Alpha therapy (1)
- Alpha-Glucosidase (1)
- Altern (1)
- Alzheimer's disease (1)
- AmGr1 (1)
- AmGr2 (1)
- AmGr3 (1)
- Ameisen (1)
- American foulbrood (1)
- Amino acids (1)
- Aminosäuren (1)
- Analoga (1)
- Anion (1)
- Anion channel (1)
- Anionen (1)
- Anionenkanäle (1)
- Anoxie (1)
- Anthropogene Störung (1)
- Anthropogener Einfluss (1)
- Antibiotikum (1)
- Antibodies (1)
- Antigen (1)
- Antigen CD23 (1)
- Antigen CD40 (1)
- Antimicrobial activities (1)
- Antimicrobial proteins (1)
- Antimikrobielle Aktivitäten (1)
- Antimikrobieller Wirkstoff (1)
- Antioxidants (1)
- Antiport (1)
- Antisense (1)
- Ants (1)
- Aplysina aerophoba (1)
- Apoptose (1)
- Arabidopside (1)
- Arabidopsides (1)
- Arbeitsteilung (1)
- Arbuscular Mycorrhiza (1)
- Arbuskuläre Mykorrhiza (1)
- Arid biomes (1)
- Artenkombination (1)
- Arzneibuch (1)
- Arzneimittel für neuartige Therapien (1)
- Arzneipflanzen (1)
- Aspergillus medium (1)
- AtERDl6 (1)
- AtTMT1/2 (1)
- AtTORF-Ex-Kollektion (1)
- AtTPC1 (1)
- AtrbohD (1)
- Autoimmune diseases (1)
- Autoimmunity (1)
- Autökologie (1)
- AuxRE (1)
- Auxin (1)
- Auxin-regulated transcription (1)
- Auxine (1)
- Available soil water capacity (1)
- Azelainsäure (1)
- Azospirillum brasilense (1)
- B cells (1)
- BETA-Diversität (1)
- BETA-Multifunktionalität (1)
- BIAcore (1)
- BLUF (1)
- BMP antagonist (1)
- BMP signaling (1)
- BMPR1B (1)
- Baja California [(PNN) Mexico] (1)
- Bambi (1)
- Bauchspeicheldrüsenkrebs (1)
- Baumkrone (1)
- Baumphysiologie (1)
- Bestrahlung (1)
- Beta-1-Rezeptor (1)
- Bidirectional manipulation (1)
- Biene (1)
- Bienenwachs (1)
- Bilderzeugung (1)
- Bildgebendes Verfahren (1)
- Biochemie (1)
- Biochemische Analyse (1)
- Biodiversität (1)
- Biogenic (1)
- Bioinformatics (1)
- Bioinformatik (1)
- Biophysics (1)
- Biosensor (1)
- Biosynthese (1)
- Biosynthese-Genclustern (1)
- Biosynthesis of Jasmonates (1)
- Bioverfügbarkeit (1)
- Blatt (1)
- Blattknospen (1)
- Blattkäfer (1)
- Blaulicht (1)
- Blütenpflanzen (1)
- Bodenwasser (1)
- Bone Morphogenetic Proteins (1)
- Bone marrow transplantantation (1)
- Bone morphogenetic protein (1)
- Bone morphogenetic protein-2 (1)
- Borrelia (1)
- Brackwespen (1)
- Brain diseases (1)
- Brassica napus (1)
- Brassicaceae (1)
- Breeding system (1)
- Buche (1)
- Buchweizenkraut (1)
- Bunias orientalis (1)
- Büchold (1)
- C-elegans (1)
- CASPARY-STREIFEN (1)
- CD23 (1)
- CD27 (1)
- CD40 (1)
- CD70 (1)
- CIPK23 (1)
- CNG channel (1)
- CO2 (1)
- CO2 Reaktion (1)
- CO2 Response (1)
- CO2 gas exchange (1)
- CORONATINE INSENSITIVE 1 (1)
- CO\(_{2}\) signaling (1)
- CPK (1)
- CYR61 (1)
- Ca2+ signal (1)
- Ca2+-Signal (1)
- Ca2+-signal (1)
- Ca\(^{2+}\) indicator (1)
- Ca\(^{2+}\) signalling (1)
- Calcium Imaging (1)
- Calcium-Oszillationen (1)
- Calciumion (1)
- Calciumkanal (1)
- Camponotus rufipes (1)
- Cancer (1)
- Cancer of Pancreas (1)
- Candidate Phylum Poribacteria (1)
- Carpinus betulus (1)
- Casparian strip (1)
- Castor bean (1)
- Cation channel (1)
- Celaflor (1)
- Chain-length distribution (1)
- Channelrhodopsinen (1)
- Characterizing New Photoreceptors to Expand the Optogenetic Toolbox (1)
- Chemical Ecology (1)
- Chemiluminescence (1)
- Chemilumineszenz (1)
- Chemosensory neurons (1)
- Chirurgiegeschichte (1)
- Chlamydomonas reinhardii (1)
- Chlamydomonas reinhardtii (1)
- Chlorophyll fluorescence (1)
- Chloroplast (1)
- Chronobiologie (1)
- Chronobiology (1)
- Cirl (1)
- Cis-elements (1)
- Climate change (1)
- Climatic water balance (1)
- Complex medium (1)
- Cortex (1)
- Crown Gall (1)
- Cryptogein (1)
- Cuscuta (1)
- Cuscuta reflexa (1)
- Cuticular transpiration (1)
- Cuticular water permeabilities (1)
- Cutinase (1)
- Cvi-0 (1)
- Cyanobakterien (1)
- Cyclic electron transport (1)
- Cyclic peptides (1)
- Cyclics (1)
- Cyclo-AMP (1)
- Cyclo-GMP (1)
- Cystinknotenprotein (1)
- Cytokine (1)
- Cytokinin (1)
- Cytokinine (1)
- Cytokinins (1)
- Cytoplasma (1)
- Cytoplasmic Ca"+ (1)
- Cytotoxic T lymphocytes (1)
- DAF (1)
- DAN modulator proteins (1)
- DAN-Modulatorproteine (1)
- DC gate (1)
- DEVC (1)
- DIMBOA (1)
- DIRK method (1)
- DNA transcription (1)
- DNA-Methylierung (1)
- DNS (1)
- DRMs (1)
- Darm (1)
- Dattelpalme (1)
- Dauer formation (1)
- Deckenmalerei (1)
- Deep sequencing (1)
- Denaturierende Gradienten-Gelelektrophorese (1)
- Denaturing Gradient Gel Electrophoresis (1)
- Depolarisation (1)
- DiBAC4(3) (1)
- Diabetes (1)
- Dickkopf proteins (1)
- Differential scanning calorimetry (1)
- Differentielle Genexpression (1)
- Diffusion (1)
- Diffusion coefficient (1)
- Dionaea (1)
- Disease network (1)
- Drosophila (1)
- Drosophila melanogaster motoneuron (1)
- Drought stress (1)
- Drug discovery (1)
- Dual-PAM-100 (1)
- Dürreresistenz (1)
- Dürrestress (1)
- EF-TU (1)
- ENDODERMIS (1)
- ER-Export (1)
- ETR (1)
- Ecology (1)
- Efeu (1)
- Egypt (1)
- Einstichmessungen (1)
- Einzelzellgenomik (1)
- Embolism resistance (1)
- Endoplasmatisches Retikulum (1)
- Energy depletion (1)
- Entomology (1)
- Entzündung (1)
- Enyzme (1)
- Enzymatische Regulation (1)
- Enzymes (1)
- Eosinophiler Granulozyt (1)
- Epichloë spp. (1)
- Equisetum (1)
- Esterasen (1)
- Etablierungsstadium (1)
- Euglena gracilis (1)
- Eulen <Schmetterlinge> (1)
- European foulbrood (1)
- Evolution (1)
- Exodermis (1)
- Expansion microscopy (1)
- Expression (1)
- Extrazellulärraum (1)
- FGF signaling (1)
- FISH-CLEM (1)
- FT-IR-Spektroskopie (1)
- FTIR-Spektroskopie (1)
- FTIR-spectroscopy (1)
- FURA (1)
- Fabaceae (1)
- Factor receptor (1)
- Falle (1)
- Farne (1)
- FeS proteins (1)
- Fertilization in angiosperm (1)
- Fettsäure (1)
- Fettsäuren (1)
- Flagelline (1)
- Flash relaxation kinetics (1)
- Fluorescence mi (1)
- Fluoreszenz (1)
- Fluoreszmikroskopie (1)
- Fluorimetrie (1)
- Fn14 (1)
- Foraging behaviour (1)
- Forschungsstation Fabrikschleichach (1)
- Fortpflanzung (1)
- Fortpflanzungsmechanismen (1)
- Fraxinus excelsior (1)
- Fruchtbildung (1)
- Fruit (1)
- Fungus (1)
- Fura-2 (1)
- Furagieraktivität (1)
- G-Protein gekoppelte Rezeptor (1)
- GC-Wert (1)
- GC-value (1)
- GFP (1)
- GLR (1)
- GMP-Regeln (1)
- Gartenerde (1)
- Gaschromatographie-Massenspektrometrie (1)
- Gastrulation (1)
- Gaussia princeps Luziferase (1)
- Gefäßpflanzen (1)
- Geitonogamy (1)
- Gen shaker (1)
- Genaktivierung (1)
- Genanalyse (1)
- Genexpressionsanalysen (1)
- Genmutation (1)
- Genomics (1)
- Germination (1)
- Germination and differentiation (1)
- Gerstenkrankheit (1)
- Geschichte (1)
- Getreide (1)
- Gewebe (1)
- Glaukom (1)
- Gliederfüßer (1)
- Glucocorticosteroide (1)
- Glucose (1)
- Glucose uptake (1)
- Glucose/Saccharose Transport (1)
- Glucosetransportproteine (1)
- Glucosinolates (1)
- Glutamate (1)
- Glutamate-receptor (1)
- Glutamatrezeptor (1)
- Glutathione (1)
- Glycerin (1)
- Glykomodifizierung (1)
- Glykosylierung (1)
- Graft-versus-leukemia (1)
- Grebe dysplasia (1)
- Grenzflächenaktiver Stoff (1)
- GtACR1 (1)
- Guanylatcyclase (1)
- Guanylyl Cyclase (1)
- Guard Cell (1)
- Guard Cells (1)
- H+-atpase (1)
- HAK5-like (1)
- HIV (1)
- HIVDR (1)
- HKT transporter (1)
- HKT1 (1)
- HKT1-like (1)
- HPLC-MS (1)
- HPLC/UPLC methods (1)
- Heat stress (1)
- Hefe-Elicitor (1)
- Hegyi competition index (1)
- Heilpflanzen (1)
- Helianthus annuus (1)
- Hemiparasit (1)
- Herbicid (1)
- Herbivoren-Abwehr-Strategie (1)
- Herbivorie (1)
- Heterologe Expression (1)
- Hexokinase (1)
- High throughput screening (1)
- History of medicine (1)
- History of the medicine (1)
- Hitzeschock-Proteine (1)
- Holz (1)
- Holzbildung (1)
- Holzstrahlen (1)
- Homöostase (1)
- Honigbiene (1)
- Hordeum vulgare (1)
- Hormontransport (1)
- Human sodium iodide symporter (1)
- Hydrathülle (1)
- Hydraulic conductivity (1)
- Hydraulic plasticity (1)
- Hydraulische Leitfähigkeit (1)
- Hydroxylamin (1)
- Hyperpolarisierung (1)
- Hypoxia (1)
- Hypoxie (1)
- Hyrtios (1)
- IL-4 antagonists (1)
- IL8 (1)
- Illumina HiSeq (1)
- Immunactivation (1)
- Immunaktivierung (1)
- Immunologie (1)
- Immunolokalisation (1)
- Immunsystem (1)
- Impfstoff (1)
- In vitro (1)
- Inbreeding depression (1)
- Incompatible parasite-host interaction (1)
- Indirekte Abwehr (1)
- Indonylessigsäure <3-> (1)
- Inf-TRAP-Seq (1)
- Inflammatory bowel disease (1)
- Infliximab (1)
- Inkompatible Parasit-Wirt-Interaktion (1)
- Inoculum production (1)
- Inosite (1)
- Insects (1)
- Insekten-Pflanzen-Interaktionen (1)
- Interleukin (1)
- Interleukin 13 (1)
- Interleukin 4 (1)
- Interleukin 5 (1)
- Interleukin-4 (IL-4) (1)
- Interleukin-4 Antagonist (1)
- Invasion <Biologie> (1)
- Invasive (1)
- Invertase-Inhibitor (1)
- Invertaseinhibitor (1)
- Ionenkanäle (1)
- Ionenleitfähigkeit (1)
- Irradiation (1)
- Isoprostanes (1)
- Isothiocyanate (1)
- JA/JA-Ile transport protein JAT1 (1)
- JMT (1)
- Jaborandi (1)
- Janus kinase (1)
- Jasmonate info (1)
- Jasmonic acid (1)
- Jurkat T cells (1)
- KCO (1)
- Kaliumkanäle (1)
- Kaliumtransporter (1)
- Kannenpflanze (1)
- Kanäle (1)
- Karibisches Meer (1)
- Kationenkanal (1)
- Keimling (1)
- Keimlingsentwicklung (1)
- Keimung (1)
- Kellerassel (1)
- Kernproteine (1)
- Klappertopf (1)
- Klimawandel (1)
- Klimaänderung (1)
- Knochenhomöostase (1)
- Konidie (1)
- Krankheit (1)
- Künstliche Samenalterung (1)
- LC-MS (1)
- LCB (1)
- LC–MS/MS (1)
- LIGNIN (1)
- LMNA S143F (1)
- LRP5/6 (1)
- LRP6 (1)
- Lamin (1)
- Laminopathie (1)
- Larval development (1)
- Laser (1)
- Laser Microdissection (1)
- Laser Mikrodissektion (1)
- Lateral root development (1)
- Latrophilin (1)
- Laurdan (1)
- Leaching (1)
- Leaf (1)
- Leitfähigkeit (1)
- Lernen (1)
- LiDAR (1)
- Ligand (1)
- Ligand <Biochemie> (1)
- Ligand-Rezeptor-Interaktion (1)
- Lignin (1)
- Lipasen (1)
- Lipases (1)
- Lipid Metabolism (1)
- Lipid Transfer Protein (1)
- Lipid Transfer Proteine (1)
- Lipid polarization (1)
- Lipid-Peroxide (1)
- Lipide (1)
- Lipidomik (1)
- Lipidperoxidation (1)
- Lipids (1)
- Lipidtransferprotein (1)
- Lipidumbau (1)
- Lipophilic fluorescent dyes (1)
- Lipoprotein (1)
- Lipoxyg (1)
- Liquid (dis-) ordered phase (1)
- Luciferasen (1)
- Luftröhre (1)
- Lupeol synthase (1)
- Lupeolsynthase (1)
- Lyme disease (1)
- Lyme-Krankheit (1)
- Lymphocytes (1)
- Lymphotoxin (1)
- Lymphozyt (1)
- Lymphozyten (1)
- MAP Kinase (1)
- MAP kinase (1)
- MJE (1)
- MPK12 (1)
- MYB (1)
- MYC (1)
- Malvaviscus arboreus (1)
- Mariae Heimsuchung und Sankt Nikolaus (1)
- Mariae Himmelfahrt (1)
- Marin (1)
- Marine (1)
- Maus (1)
- Mechanisms (1)
- Medicago truncatula (1)
- Medicinal Plant (1)
- Medizingeschichte (1)
- Meerrettichkäfer (1)
- Mehrdimensionale NMR-Spektroskopie (1)
- Membran (1)
- Membrandepolarisierung (1)
- Membrane depolarisation (1)
- Membrane domains (1)
- Mesocestoides corti (1)
- Mesophyllvakuole (1)
- Metabolismus (1)
- Metabolit (1)
- Metabolomik (1)
- Metagenomomanalyse (1)
- Metapleural gland (1)
- Methyl jasmonate esterase (1)
- Methylglasmonat (1)
- Methylierung (1)
- Methyljasmonat (1)
- Methyljasmonat Esterase (1)
- Mexico [North America] (1)
- Micromonospora (1)
- Microscopy (1)
- Middle Age (1)
- Mikrobiologie (1)
- Mikrodissektion (1)
- Mikroorganismen (1)
- Mikroorganismus (1)
- Mikroskopie (1)
- Millisecond-timescale (1)
- Mitochondria (1)
- Mitochondrium (1)
- Mittelalter (1)
- Mitteleuropa (1)
- Modelle (1)
- Modifizierung (1)
- Molecular biophysics (1)
- Molecular neuroscience (1)
- Morgenländisches Zackenschötchen (1)
- Morphogenese (1)
- Mustererkennung (1)
- Mutante (1)
- Mykorrhiza (1)
- Myofibroblast differentiation (1)
- Myrosinase (1)
- NAD(P)H-dehydrogenase (1)
- NAD(P)H-plastoquinone-oxidoreductase (1)
- NADH-dehydrogenase (1)
- NADPH oxidase 2 (NOX2) (1)
- NDH-H (1)
- NDH-I (1)
- NDH-J (1)
- NDH-K (1)
- NFATc1 (1)
- NFKB (1)
- NFkB-Signalling (1)
- NHase (1)
- NMR fingerprint (1)
- NMR spectroscopy (1)
- NSG (1)
- NSG mice (1)
- NSG-UC (1)
- Nachweis (1)
- Nanoparticles (1)
- Naturstoff (1)
- Neisseria gonorrhoeae (1)
- Nekroptose (1)
- Nekrose (1)
- Nektar-Sekretion (1)
- Nektarium (1)
- Nematode Caenorhabditis-elegans (1)
- Neophyten (1)
- Neophyten <Botanik> (1)
- Nepenthes (1)
- Neurochemie (1)
- Neurologie (1)
- Neuronales visuelles System (1)
- Nicandra (1)
- Nichtwirtsresistenz (1)
- Nicotiana benthamiana (1)
- Nierenfunktion (1)
- Nitrate reductase (1)
- Nitration (1)
- Nitric Oxide (1)
- Nitric Oxide Synthase (1)
- Nitric oxide (1)
- Nitrilase (1)
- Nitrite (1)
- NpHR (1)
- NtAQP1 (1)
- Nuklearfaktor Kappa B (1)
- Nährstoffaufnahme (1)
- Nährstoffmangel (1)
- ODC (1)
- OPDA (1)
- Oberflächenplasmonresonanz (SPR) (1)
- Oberfranken (1)
- Olfr1393 (1)
- Oligomerisation (1)
- Oncogene (1)
- Oncolytic Virus (1)
- Onkogen (1)
- Onkolyse (1)
- Oozyten (1)
- Optical control (1)
- Oralsekret (1)
- Oregon Green-BAPTA (1)
- Ornithindecarboxylase (1)
- Orobanche crenata (1)
- Osmolarität (1)
- Oxidosqualene cyclase (1)
- Oxidosqualenzyklase (1)
- Oxophytodiensäure <12-> (1)
- Oxylipines (1)
- Oxylipins (1)
- O–I 1 fluorescence rise (1)
- P515 (1)
- PALM stoichiometry (1)
- PAMPS (1)
- PAR (1)
- PCD (1)
- PER (1)
- PKS (1)
- PKS I (1)
- PKS II (1)
- PLAT-Domain (1)
- PacBio sequencing (1)
- Paenibacterin (1)
- Pankreaskrebs (1)
- Parasit (1)
- Parkinson-Krankheit (1)
- Parkinsonismus (1)
- Parna´iba <Region> (1)
- Patch-Clamp (1)
- Pathogenabwehr (1)
- Pathogene Bakterien (1)
- Pathogener Mikroorganismus (1)
- Pathogeninteraktion (1)
- Pathologie (1)
- Pathology (1)
- Pax-5 (1)
- Performance (1)
- Permeability (1)
- Pesticide (1)
- Pestizide (1)
- Pflanze-Pathogen-Interaktion (1)
- Pflanzen-Insekten Interaktionen (1)
- Pflanzendarstellung (1)
- Pflanzengewebe (1)
- Pflanzengröße (1)
- Pflanzenhormone (1)
- Pflanzenhydraulik (1)
- Pflanzeninhaltsstoff (1)
- Pflanzenmalerei (1)
- Pflanzenphysiologie (1)
- Pflanzenwachs (1)
- Pflanzenzelle (1)
- Pflanzenzellkulturen (1)
- Pflanzenökologie (1)
- Pharmakotherapie (1)
- Pharmazie (1)
- Phenole (1)
- Pheromone (1)
- Phloem (1)
- Phophorylierung (1)
- Photoreceptor (1)
- Photorezeptor (1)
- Photosynthese (1)
- Photosystem I (1)
- Phototropine (1)
- Phototropins (1)
- Phyllosphere (1)
- Physalis (1)
- Physiologie (1)
- Physiologische Chemie (1)
- Phytoalexin (1)
- Phytoalexine (1)
- Phytoalexins (1)
- Phytochemie (1)
- Phytohormon (1)
- Phytopathogene Pilze (1)
- Phytopathologie (1)
- Phytophthora (1)
- Phytoprostanes (1)
- Phytosphingosine (1)
- Phytosterine (1)
- Pichia pastoris (1)
- Pilocarpin (1)
- Pilocarpus (1)
- Pilocarpus microphyllus (1)
- Pilzbefall (1)
- Pilze (1)
- Pilzkörper (1)
- Pimelinsäure (1)
- Pinus sylvestris L. (1)
- Piriformospora indica (1)
- Pitrakinra (1)
- Plant Biology (1)
- Plant Ecology (1)
- Plant Hormones (1)
- Plant antimicrobial proteins (1)
- Plant cell cultures (1)
- Plant fertilization (1)
- Plant growth promotion (1)
- Plant hydraulic (1)
- Plant immunity (1)
- Plant root endophyte (1)
- Plant signalling (1)
- Plant-Insect Interactions (1)
- Plasma membrane (1)
- Plastid DNA (1)
- Pollenkeimung (1)
- Pollenschlauch Calcium Anionen Kanal Kinase (1)
- Polygonum cuspidatum (1)
- Polyphasic fluorescence rise (1)
- Polypodium vulgare (1)
- Populus (1)
- Poribacteria (1)
- Positron Emission Tomography (1)
- Positronen-Emissions-Tomographie (1)
- Posttranslationale Änderung (1)
- Potassium channel (1)
- Powdery mildew fungus (1)
- Precipitation gradient (1)
- Prednisolon (1)
- Prednisolone (1)
- Premna (1)
- Primärmetabolite (1)
- Proliferation (1)
- Promotor <Genetik> (1)
- Promotor Regulation (1)
- Promotoraktivität (1)
- Protein Purification (1)
- Proteinbiochemie (1)
- Proteine (1)
- Proteinen mit antimikrobieller Wirkung (1)
- Proteinkinase (1)
- Proteinkinasen (1)
- Proteinmodifizierung (1)
- Protoplasten (1)
- Protoplasts (1)
- Pseudomonas syringae pv. tabaci (1)
- Pseudomonas syringae tomato (1)
- Pulvini (1)
- Pyrophosphatase (1)
- QTOF (1)
- QUAC (1)
- Quecksilber (1)
- Quercetin (1)
- Quercus petraea (1)
- R-GECO1 cytosolic Ca\(^{2+}\) reporter (1)
- R-type (1)
- R-type currents (1)
- RIP3 (1)
- RNA Integrität (1)
- RNA integrity (1)
- Raps (1)
- Reaktive Sauerstoffspezies (1)
- Receptor (1)
- Recombinant protein (1)
- Red sea (1)
- Reflexa Roxb (1)
- Regenbaum (1)
- Regenerative Medizin (1)
- Regulatory-cells (1)
- Reis (1)
- Rekombinantes Protein (1)
- Remorin (1)
- Renaturierung <Biochemie> (1)
- Resistances (1)
- Resistenzfaktor (1)
- Resorption (1)
- Respiratory chain (1)
- Retroviren (1)
- Rezeptorblocker (1)
- Rezeptorkinasen (1)
- Rheumatoid arthritis (1)
- Rhinanthus (1)
- Rhizodermis (1)
- Ricinus communis (1)
- Root (1)
- Root Nodule Symbiosis (1)
- Rorippa austriaca (1)
- Rose (1)
- Rossameise (1)
- Rothenfels (1)
- Rückfallfieber (1)
- Rüsselreflex (1)
- S-Typ (1)
- S-Typ Anionenkanal (1)
- S-Typ-Anionenkanäle (1)
- S-Type-Anionchannels (1)
- S-typ anionchannel (1)
- S-type (1)
- SGLT-1 (1)
- SGLT1 (1)
- SGLT2 inhibitor (1)
- STP (1)
- SUBERIN (1)
- SUT1 (1)
- SV/TPC1 (1)
- Saatgutbeizung (1)
- Saccharomyces cerevisiae (1)
- Saisonalität (1)
- Salicylhydroxamsäure (1)
- Salz (1)
- Salzresistenz (1)
- Samen (1)
- Samenschale (1)
- Schachtelhalm (1)
- Schachtelhalme (1)
- Schlacke (1)
- Schmalwand (1)
- Schneckenklee (1)
- Schwammsymbionten (1)
- Sclerotinia (1)
- Sclerotinia sclerotiorum (1)
- Sehen (1)
- Sekundärer Bote (1)
- Selective extraction (1)
- Senescence (1)
- Serendipita indica (1)
- Serine proteases (1)
- Shaker (1)
- Siberian spurge (1)
- Signaling (1)
- Signalkette (1)
- Signalling (1)
- Signalpeptide (1)
- Signalweg (1)
- Silver (1)
- Single chain (1)
- Single-cell genomics (1)
- Sink-Source-Relation (1)
- Sleeping Beauty (1)
- Smooth-muscle-cells (1)
- SnRK1-bZIP complex (1)
- Sodium-myoinositol cotransporter-1 (SMIT1) (1)
- Solanaceae (1)
- Solanazeen (1)
- Sonnenblume (1)
- Sonoran Desert (1)
- Spannungsklemmen-Fluorometrie (1)
- Spannungskontrollierter Ionenkanal (1)
- Spheciospongia vagabunda (1)
- Sphingobasen (LCB, LCB-P) (1)
- Sphingobases (1)
- Sphingolipid (1)
- Sphingolipidstoffwechsel (1)
- Spirochäten (1)
- Spodoptera (1)
- Spodoptera frugiperda (1)
- Sponge diseases (1)
- Spross (1)
- SsAQP1 (1)
- SsAQP2 (1)
- SthK-bPAC (1)
- Stickstoffoxide (1)
- Stickstoffoxidsynthase (1)
- Stoffwechsel (1)
- Stoffwechselweg (1)
- Stress-Syndrom (1)
- Struktur-Aktivitäts-B (1)
- Strukturbiologie (1)
- Styrylpyrone (1)
- Subtractive hybridisation (1)
- Subtraktive Hybridisierung (1)
- Sucrose (1)
- Sulforaphan (1)
- Superresolution microscopy (1)
- Suppression (1)
- Surgeon (1)
- Symbionten (1)
- Symbionts (1)
- Symbolik (1)
- Synechocystis 6803 (1)
- Synechocystis sp. PCC6803 (1)
- Synthasen (1)
- Synthese (1)
- Systemic acquired resistance (1)
- Systemisch erworbenen Resistenz (1)
- T-Lymphozyt (1)
- T-cells (1)
- T6P (1)
- TGA-Transkriptionsfaktoren (1)
- TGF (1)
- TGF-beta (1)
- TGF-β superfamily (1)
- TGFβ/BMP signaling (1)
- TH2 Immunantwort (1)
- TNF (1)
- TNF Superfamilie (1)
- TNFR2 (1)
- TOR (1)
- TPC1 channel (1)
- TPCA1 (1)
- TPK (1)
- TRAF (1)
- TRAF1 (1)
- TRAIL (1)
- TRAILR-Mutants (1)
- Tagesrhythmus (1)
- Tansania (1)
- Tanzania (1)
- Targeted Radiotherapy (1)
- Thaumatins (1)
- Thermotoleranz (1)
- Thioredoxin (1)
- Ti plasmids (1)
- Tilia cordata (1)
- Tissue Engineering (1)
- Tod (1)
- Todesrezeptor (1)
- Toxizitätstest (1)
- Trachea (1)
- Transcription factor (1)
- Transforming Growth Factor beta (1)
- Transkriptstabilität (1)
- Translokation (1)
- Transpiration barrier (1)
- Transporter (1)
- Tree physiology (1)
- Triglyceride (1)
- Tritrophische Interaktionen (1)
- Trockenheit (1)
- Tropischer Regenwald (1)
- Tropismen (1)
- Tropismus (1)
- Trypanosoma brucei (1)
- Tumor-necrosis-factor (1)
- Tumorentwicklung (1)
- Twisted gastrulation (1)
- UAV (1)
- Ultraviolett (1)
- Ungesättigte Fettsäuren (1)
- Ustilago zeae (1)
- V-ATPase (1)
- V-ATPasen (1)
- VA-Mykorrhiza (1)
- VCF (1)
- VOC <Ökologische Chemie> (1)
- VOC emissions (1)
- Vaccinia Virus (1)
- Vaccinia-Virus (1)
- Variovorax paradoxus (1)
- Vegetable juice (1)
- Vegetationsentwicklung (1)
- Verteidigung (1)
- Verticillium (1)
- Verticillium dahliae (1)
- Verticillium longisporum (1)
- Vertikale Übertragung (1)
- Verwundung (1)
- Very-long-chain aliphatic (1)
- Vicia (1)
- Vicia faba (1)
- Vielfalt (1)
- Vitis (1)
- Vitis vinifera (1)
- Volatiler oraganischer Verbindungen (1)
- Volatiole Compounds (1)
- WNT (1)
- WRKY (1)
- WURZEL (1)
- Wachstum (1)
- Waldökosystem (1)
- Wasser (1)
- Wasserfluss (1)
- Wasserpermeabilität (1)
- Water stress (1)
- Wechselwirkung (1)
- Weinrebe (1)
- Westliche Balsampappel (1)
- Williamsia sp. ARP1 (1)
- Wirt (1)
- Wirtsfindung (1)
- Wnt signaling cascade (1)
- Wnt signalling (1)
- Wnt-Proteine (1)
- Wuchsleistung (1)
- Wundarznei (1)
- Wurzel-Spross-Stresssignal (1)
- Wurzelhalsgallen (1)
- Wurzelknöllchen (1)
- Wurzelknöllchensymbiose (1)
- Wurzelsystem (1)
- Wurzelzellschichten (1)
- Würzburg (1)
- X-ray crystallography (1)
- X-ray diffraction (1)
- Xenobiotikum (1)
- Xenopus (1)
- Xenopus laevis oocytes (1)
- Xerostomia (1)
- Xylem vulnerability curve (1)
- Y-gastric bypass (1)
- Zea (1)
- Zellschichtspezifische Expression (1)
- Zelltod (1)
- Zentralzylinder (1)
- Zucker (1)
- Zucker-Signaling (1)
- Zuckerrübeneule (1)
- Zuckertransport (1)
- Zuckertransporter (1)
- Zusammensetzung (1)
- Zwei-Hefen-Hybrid-System (1)
- Zwiebel (1)
- abiotic stress tolerance of plants (1)
- abiotische Stresstoleranz von Pflanzen (1)
- abiotische stress (1)
- aboveground biomass (1)
- abscisic-acid activation (1)
- absorption (1)
- acquired thermotolerance (1)
- acquisition (1)
- actinobacteria (1)
- actinosporins (1)
- action potential (1)
- activation (1)
- acylcarnitine (1)
- adaption (1)
- adaptive conflict (1)
- aldehydes (1)
- alien (1)
- alignmen (1)
- aliphatic compounds (1)
- aliphatic glucosinolates (1)
- alkaloid detection methods (1)
- allene oxide synthase (1)
- amino acid analysis (1)
- amino acid transporter (1)
- amino-acid-metabolism (1)
- amplicon pyrosequencing (1)
- angiogenesis (1)
- animal models (1)
- anion channels (1)
- annotation (1)
- anoxia (1)
- antagonist (1)
- antagonists (1)
- anthropogenic disturbance (1)
- anti-microbial activit (1)
- anti-predator defence (1)
- anti-trypanosoma (1)
- antibodies (1)
- antibody production (1)
- antigen binding antibody fragment (Fab) (1)
- antioxidant (1)
- antioxidants (1)
- antiport (1)
- antisense (1)
- apical GLUT2 (1)
- apoplast (1)
- aqueous pathways (1)
- arabidopsis (1)
- arabidopsis-thaliana (1)
- artificial neural network (1)
- artificial rearing (1)
- asparaginase (1)
- asparagine (1)
- asparagine synthetase (1)
- aspergillus fumigatus (1)
- assembly (1)
- atmospheric chemistry (1)
- autotoxicity (1)
- auxin (1)
- azelaic acid (1)
- bPAC (1)
- bZIP transcription fators (1)
- bZIPs (1)
- bacteria (1)
- bacterial communities (1)
- bacterial community (1)
- bacterial genomics (1)
- bariatric surgery (1)
- basale Immunität (1)
- bee disease (1)
- behavior (1)
- beta diversity (1)
- beta-multifunctionality (1)
- beta1-adrenergic receptor (1)
- betaglycan (1)
- biliopancreatic diversion (1)
- binding analysis (1)
- bioactive (1)
- bioartificial tissue (1)
- bioartifizielles Rekonstruktionsgewebe (1)
- bioassays (1)
- bioavailibility (1)
- biofilms (1)
- biogenic volatile organic compounds (1)
- biological locomotion (1)
- biomass (1)
- biophysics (1)
- biosurfactants (1)
- biosynthetic gene clusters (1)
- biosynthetic glycosylation (1)
- biotic and abiotic stress (1)
- biotic stress (1)
- biotische stress (1)
- bipartite metabolism (1)
- bluelight (1)
- body weight (1)
- bone homeostasis (1)
- bone morphogenetic protein 2 (BMP2) (1)
- bone morphogenetic proteins (1)
- bone regeneration (1)
- brush border membrane (1)
- bryozoan bugula-neritina (1)
- buckwheat (1)
- buds (1)
- butenolide (1)
- cGMP (1)
- cIAP (1)
- caged glutamate (1)
- calcium absorption (1)
- calcium dependent membrane conductance (1)
- calcium oscillations (1)
- calcium signalling (1)
- calciumabhängige Membranleitfähigkeiten (1)
- canine cancer cell lines (1)
- canine cancer therapy (1)
- canine soft tissue sarcoma (CSTS) (1)
- capra hircus (1)
- cardiomyocytes (1)
- carnivorus plants (1)
- carrier (1)
- caterpillars (1)
- cathepsin (1)
- cathepsin-L (1)
- cell binding assay (1)
- cell compartmentation (1)
- cell culture (1)
- cell cycle and cell division (1)
- cell death (1)
- cell membranes (1)
- cell metabolism (1)
- cell-type specific (1)
- cell-wall invertases (1)
- cellular binding studies (1)
- channelrhodopsin (1)
- channelrhodopsins (1)
- channels (1)
- chemical glycosylation (1)
- chemische Ökologie (1)
- chemotherapy (1)
- chlamydomonas reinhardtii (1)
- chlamyopsin (1)
- chlorella (1)
- chlorophyll fluorescence (1)
- chlorophyll fluorescence imaging (1)
- chondrodysplasia (1)
- circadian rhythm (1)
- circular dichroism spectra (1)
- cis-element modules (1)
- class II TGA factors (1)
- climatological water deficit (1)
- clinical practice guidelines (1)
- co-cultivation (1)
- cold stress (1)
- community structure (1)
- compounds (1)
- computational cell biology (1)
- conductance (1)
- conidial differentiation (1)
- contact lens (1)
- cool-season grass species (1)
- cotransporter (1)
- cotransporter SGLT1 (1)
- covalent coupling (1)
- cpYFP cytosolic pH reporter (1)
- cristae (1)
- crown gall (1)
- crown galls (1)
- cultivation (1)
- cuticular permeability (1)
- cuticular transpiration (1)
- cuticular uptake (1)
- cuticular wax (1)
- cuticular waxes (1)
- cutin (1)
- cyanobacteria (1)
- cyanobacterium (1)
- cyclic GMP (1)
- cyclic compounds (1)
- cyclic dipeptide (1)
- cyclin-dependent kinases (1)
- cystin knot protein (1)
- cytokinins (1)
- cytosolic pH (1)
- de novo sequenced genomes (1)
- defence (1)
- defence response (1)
- dehydration (1)
- denaturing gradient gel electrophoresis (1)
- density (1)
- depolarization (1)
- desert (1)
- desert soil (1)
- diazepinomicin (1)
- diazidisches Motiv (1)
- differential coverage binning (1)
- differentiation (1)
- diffusive component (1)
- dihydrosphingosine-1-phosphate lyase (1)
- dionaea muscipula (1)
- direct PCR (1)
- discovery (1)
- disease resistance (1)
- divergence times (1)
- dodder (1)
- dominance (1)
- double electrode voltage clamp (1)
- doxorubicin (1)
- draft genome (1)
- drosophila melanogaster (1)
- drug discovery (1)
- drug metabolism (1)
- drugs (1)
- du Pan dysplasia (1)
- duodenal jejunal bypass (1)
- duplicate genes (1)
- eATP (1)
- earlywood (1)
- ecophysiology (1)
- effectors (1)
- electrochromic absorbance shift (1)
- electron density (1)
- electrophysiology (1)
- elektrische Signale (1)
- elicitors (1)
- embolism resistance (1)
- embryology (1)
- empagliflozin (1)
- endoplasmatic reticulum (1)
- enemy hypothesis (1)
- energy conservation (1)
- energy deprivation (1)
- energy dissipation (1)
- energy metabolism (1)
- energy signaling (1)
- enzymes (1)
- eosinophil (1)
- epigenetics (1)
- epiphytes (1)
- epithelial cells (1)
- escherichia coli (1)
- evolution (1)
- excretory-secretory (1)
- exocytosis (1)
- exodermis (1)
- experimental vegetation (1)
- experimentelle Vegetation (1)
- expression (1)
- extended phenotype (1)
- extrafloral nectaries (1)
- extraflorale Nektarien (1)
- extrazelluläre Invertasen (1)
- farm forestry (1)
- farmland woodlots (1)
- fatty acid (1)
- fatty acids (1)
- fermentation (1)
- ferns (1)
- fibre length (1)
- fine root biomass (1)
- fine root necromass (1)
- flagellin (1)
- flg22 (1)
- flow path (1)
- flowering plants (1)
- fluorescence (1)
- fluorescence microscopy (1)
- fluorescent microscopy (1)
- fluorometry (1)
- food intake (1)
- foragers (1)
- foraging (1)
- foraging activity (1)
- fractal analysis (1)
- functional absorption cross section of PS II (1)
- functional studies (1)
- fungal spores (1)
- gamma (1)
- gaschromatography-mass spectrometry (1)
- gastrointestinal mucositis (1)
- gene (1)
- gene activation (1)
- gene expression profiling (1)
- gene regulation (1)
- gene stability (1)
- genetically modified plants (1)
- genome analysis (1)
- genome assembly (1)
- genomic analysis (1)
- genomic databases (1)
- gezielte Radiotherapie (1)
- glands (1)
- glaucoma (1)
- glossy11 (1)
- glucagon like peptide-1 (1)
- glucose (1)
- glucose handling (1)
- glucose lowering agent (1)
- glucose metabolism (1)
- glucose transport (1)
- glucose/sucrose transport (1)
- glycerol (1)
- glycoengineering (1)
- glycophyte Arabidopsis (1)
- glycoprotein (1)
- grass endophytes (1)
- grasslands (1)
- grebe (1)
- green fluorescence protein (GFP) (1)
- growth (1)
- growth and differentiation factor 5 (1)
- growth factor beta (1)
- growth rate (1)
- growth ring width (1)
- guanylyl cyclase (1)
- guanylyl cyclase (GC) (1)
- gustatory receptors (Grs) (1)
- gut hormones (1)
- halophyte Thellungiella/Eutrema (1)
- heart (1)
- heat shock response (1)
- heat stress (1)
- hemiparasite (1)
- hemolymph lipids (1)
- herbivore defense strategies (1)
- heterologous expression (1)
- high performance liquid chromatography (1)
- high resolution visualisation (1)
- high throughput screening (1)
- higher plants (1)
- honeybee taste perception (1)
- hormone flow modelling (1)
- horses (1)
- horsetail (1)
- human diseases (1)
- human interleukin-4 (1)
- humaner Natrium-Iodid-Symporter (1)
- hybrid assembly (1)
- hydration (1)
- hydraulic architecture (1)
- hydraulic efficiency (1)
- hydraulic variability (1)
- hydroxylamine (1)
- hyperexpression techniques (1)
- hyperglycemia (1)
- hyperpolarisation (1)
- hyperpolarization (1)
- iLID (1)
- imaging (1)
- imaging PAM (1)
- immunity response (1)
- immunolocalisation (1)
- immunomodulatory (1)
- in-vitro (1)
- incompatible interaction (1)
- increases bone-formation (1)
- incretin secretion (1)
- indirect defense (1)
- indirect plant defence (1)
- indirekte Verteidigung (1)
- indole-glucosinolates (1)
- induced metabolites (1)
- infection rates (1)
- inflammation (1)
- inflated fruiting calyx (1)
- insect (1)
- insect-plant-interaction (1)
- intact plants (1)
- interaction (1)
- interleukin-13 (1)
- interleukin-4 (1)
- interleukin-5 signaling (1)
- intestinal glucose (1)
- intestinal mucositis (1)
- intraguild predation (1)
- intrauterine growth (1)
- invasive (1)
- invertase (1)
- invertase inhibitor (1)
- iodides (1)
- ion signaling (1)
- ion transport (1)
- isolation (1)
- isoprene (1)
- isoprostanes (1)
- isothiocyanates (1)
- jasmonic acid biosynthesis (1)
- jasmonoyl-isoleucine (1)
- kidney disease (1)
- klinische Studie (1)
- kutikuläre Aufnahme (1)
- lamin (1)
- laminopathy (1)
- latewood (1)
- latitude (1)
- leaching (1)
- leaf (1)
- leaf beetle (1)
- leaf wax analysis (1)
- leaves (1)
- lebende Pflanzen (1)
- lichen (1)
- lichtgesteuerte Manipulation (1)
- ligand (1)
- ligand binding (1)
- ligand-receptor complex (1)
- ligand-receptor promiscuity (1)
- light-driven metabolism (1)
- light-induced dimerization (1)
- light-sensitive anion channel (1)
- lightinduced manipulation (1)
- lignan (1)
- linkage analysis (1)
- lipid peroxidation (1)
- lipid remodeling (1)
- lipid signaling (1)
- lipid transfer proteins (1)
- lipidomics (1)
- lipochitinoligosaccharides (1)
- lipoproteins (1)
- live-cell imaging (1)
- livestock (1)
- living plants (1)
- localization (1)
- locomotor activity (1)
- long-chain base (1)
- lox6 (1)
- luciferase (1)
- luminal Ca2+ sensing sites (1)
- luminale Ca2+-Sensorstellen (1)
- luminescence (1)
- malaria parasites (1)
- male sterility (1)
- marine (1)
- marine Synechococcus strains (1)
- marine bacteria (1)
- marine microalgae (1)
- marine natural products (1)
- marker genes (1)
- mass spectrometry (1)
- mechanisms (1)
- medicinal plant (1)
- medicinal plants (1)
- medicine (1)
- membrane anchor (1)
- membrane depolarization (1)
- membrane protein (1)
- membrane proteins (1)
- membrane remodeling (1)
- mercury (1)
- meristems (1)
- mesophyll (1)
- mesophyll cells (1)
- mesophyll vacuole (1)
- messenger-RNA (1)
- messenger-RNA translation (1)
- metabolic flux analysis (1)
- metabolic profiling (1)
- metabolomic (1)
- metabolomic changes (1)
- method comparison (1)
- methyl jasmonate (1)
- mice (1)
- microarray (1)
- microbial communities (1)
- microbial rhodopsin (1)
- microelectrodes (1)
- microorganism (1)
- mineral nutrient (1)
- minimum (1)
- missense (1)
- mitochondrial activity (1)
- models (1)
- molecular engineering (1)
- molecular structure (1)
- morphological adaptions (1)
- multiple linear regression (1)
- multiple myeloma (1)
- multivariate analysis (1)
- mustard oil bomb (1)
- mutagenesis (1)
- mycotoxins (1)
- männliche Sterilität (1)
- natural products (1)
- ndhH gene (1)
- necromass/biomass ratio (1)
- necrotic cell death (1)
- nectar (1)
- nectar secretion (1)
- nectaries (1)
- needle surface waxes (1)
- nektar (1)
- nektarien (1)
- neuer anti-infektiver Substanzen (1)
- neurochemistry (1)
- neurology (1)
- neuronal silencing (1)
- neuronal visual system (1)
- neutralizing antibody (1)
- next generation sequencing (1)
- nitrate reductase (1)
- nitric oxide (1)
- nitrogen status (1)
- nittric (1)
- non-host resistance (1)
- non-indigenous (1)
- nonribosomal peptide synthetase (1)
- nucleus (1)
- nurse bees (1)
- nursing (1)
- nutrient deficiency (1)
- nutrient uptake (1)
- nutrition (1)
- oberflächenaktive Stoffe (1)
- oil palm (1)
- olfactory bioassay (1)
- olfactory receptor (1)
- oncolytic virus (1)
- onion (1)
- onkolytische Viren (1)
- oocytes (1)
- opsins (1)
- oral mucositis (1)
- organic (1)
- osteoblasts (1)
- osteoporosis (1)
- oxidative NO-Bildung (1)
- oxidative NO-formation (1)
- oxidative and pH dependent regulation (1)
- oxidative stress (1)
- oxidative und pH-abhängige Regulation (1)
- oxide DAF (1)
- oxidized lipids (1)
- ozone (1)
- pH-Wert (1)
- package (1)
- paediatric research (1)
- parasite biology (1)
- parasitic plants (1)
- parasitoid (1)
- parkinsonism (1)
- particle bombardment (1)
- patch-clamp (1)
- patchiness (1)
- pathogen vector (1)
- pathogens (1)
- pbl (1)
- pea (1)
- peltula patellata (1)
- peptide engineering (1)
- peptide-based interleukin-5 inhibitor (1)
- perennial ryegrass (1)
- permeability (1)
- permeation (1)
- pesicicles (1)
- pesticides (1)
- pflanze (1)
- pflanzliche Elektrophysiologie (1)
- pflanzliche Kutikula (1)
- pflanzliche Pathogenresistenz (1)
- pflanzliche Sterole (1)
- pflanzliche Vaccine (1)
- phage display (1)
- pharmacophore map (1)
- pharmacy (1)
- phenolic compounds (1)
- phenolic constituents (1)
- phenolics (1)
- phenology (1)
- phenols (1)
- phenotypic plasticity (1)
- phosphoproteomics (1)
- photoaktiviert (1)
- photoinhibition (1)
- photoprotection (1)
- photoreceptors (1)
- photosynthetic electron transport (1)
- photosystem II (1)
- phylogenetic (1)
- phylogenetic trees (1)
- phylogenetics (1)
- phylogenomics (1)
- phytochemicals (1)
- phytochemistry (1)
- phytohormones (1)
- phytoprostane (1)
- pilocarpine (1)
- pimelic acid (1)
- pit membrane diameter (1)
- placidium (1)
- plakortide E. (1)
- plakortis halichondroides (1)
- plan sciences (1)
- plant cells (1)
- plant communities (1)
- plant decorations (1)
- plant defense (1)
- plant fresh/dry weight (1)
- plant genomics (1)
- plant growth and development (1)
- plant immunity (1)
- plant pathogen resistance (1)
- plant photoassimilate partitioning (1)
- plant signaling (1)
- plant size (1)
- plant sphingolipid metabolism (1)
- plant-animal interaction (1)
- plant-derived vaccines (1)
- plant-pathogen-interaction (1)
- plant-plant interaction (1)
- plants response (1)
- plant–microbe interaction (1)
- plant–pathogen interaction (1)
- plasma membrane (1)
- pollen germination (1)
- pollen tube calcium anion channel kinase (1)
- pollen tubes (1)
- polyamines (1)
- polyketide synthase gene (1)
- polymerization (1)
- polyvinyl chloride (1)
- pore (1)
- porin (1)
- postmenopausal osteoporosis (1)
- postmortales Humangewebe (1)
- postmortem human tissue (1)
- posttranscriptional regulation (1)
- potassium carrier (1)
- potassium channels (1)
- powdery mildew (1)
- powdery mildew desease (1)
- presteady-state (1)
- presteady-state Ströme (1)
- prevention (1)
- primary metabolites (1)
- proboscis extension reflex (1)
- proboscis extension response (PER) (1)
- programmierter Zelltod (1)
- promoter activity (1)
- promoter regulation (1)
- prostaglandins (1)
- protease inhibitor (1)
- protein (1)
- protein interaction (1)
- protein secondary structure (1)
- protein structure (1)
- protein translocation (1)
- protein-1 CDMP1 gene (1)
- protein-protein interactions (1)
- protein-protein recognition (1)
- proteins (1)
- proteomic (1)
- proteomic analysis (1)
- proteomics (1)
- proteomics analysis (1)
- proton efflux (1)
- protoplast (1)
- protoplast transformation (1)
- protoplasten (1)
- protoplasts (1)
- pseudomonas syringae (1)
- psora decipiens (1)
- pulvini (1)
- quantitative trait locus (1)
- quercetin (1)
- quinoa (1)
- rainfall gradient (1)
- random forest (1)
- ranscription factors (1)
- rat hippocampal neurons (1)
- rat model (1)
- rat small-intestine (1)
- rates (1)
- ray solution scattering (1)
- reaction centre (1)
- reactivation (1)
- reactive electrophile oxylipins (1)
- reactive oxygen species (ROS) (1)
- recent origin (1)
- receptor kinases (1)
- receptor type III (1)
- recj exonuclease (1)
- redox homeostasis (1)
- regulator genes (1)
- regurgitation (1)
- relapsing fever (1)
- repeated dose (1)
- resistance (1)
- resveratrol biosynthesis (1)
- reveals (1)
- rheumatoid-arthritis (1)
- rhizobacteria (1)
- rhodesain (1)
- ribosomal RNA (1)
- ribosomal RNA genes (1)
- rice (1)
- root infection systems (1)
- root morphology (1)
- root pathogens (1)
- root-to-shoot stress signal (1)
- rootsystem (1)
- rough woodlouse (1)
- s-phase (1)
- sRNA (1)
- saccharmyces cerevisiae (1)
- safety-efficiency trade-off (1)
- salicylic acid (1)
- salinity stress (1)
- scFv (1)
- schutz (1)
- sclerostin (1)
- screening tools (1)
- seasonality (1)
- secondary metabolomics (1)
- seed coat (1)
- seed dispersal strategy (1)
- seed protein concentration (1)
- seed treatment (1)
- seedling establishment (1)
- seedlings (1)
- selection (1)
- sequence analysis (1)
- sequestration (1)
- shock response (1)
- signal inhibition (1)
- signal specification (1)
- single cell (1)
- single-cell genomics (1)
- single-stranded-DNA (1)
- slowly-binding reversible inhibitor (1)
- small-angle scattering (1)
- sodium channel (1)
- sodium uptake (1)
- sodium/glucose cotransporters (SGLT) (1)
- soil crust (1)
- soil-borne microorganisms (1)
- spacer sequences (1)
- species composition (1)
- specificity (1)
- sphingolipid (1)
- sphingomonads (1)
- sponge (1)
- sponge holicolona-simulans (1)
- sponge microbiome (1)
- sponge-associated actinomyetes (1)
- staphilococci (1)
- staurosporine (1)
- stomatal closure (1)
- stress signaling cascade (1)
- stress tolerance (1)
- striga (1)
- structural biology (1)
- structure (1)
- structure analysis (1)
- structured illumination microscope (1)
- styrylpyrones (1)
- subcutaneous animal model (1)
- suberin (1)
- successional stage (1)
- sugar absorption (1)
- sugar beet (1)
- sugar responsiveness (1)
- sugar signaling (1)
- sugar transport (1)
- sugar transport protein (1)
- sulforaphane (1)
- superfamily (1)
- support vector machine (1)
- surface potential recording (1)
- surfactants (1)
- symbionts (1)
- symbiosis (1)
- symbiotic bacteria (1)
- symbolism (1)
- symport (1)
- synechocystis (1)
- synthetic D-glucose analogy (1)
- syringae (1)
- systemic acquired resistance (1)
- systemic resistance (1)
- systemisch erworbene Resistenz (1)
- systemische Resistenz (1)
- tannins (1)
- targeting (1)
- task allocation (1)
- taxonomy (1)
- temperature (1)
- terpenes (1)
- thaliana (1)
- tobacco (1)
- tool (1)
- topology (1)
- toxicity testing (1)
- transcription factor function (1)
- transcriptional profiling (1)
- transformation (1)
- transiente Transformation (1)
- transition temperature (1)
- transporter (1)
- transporters (1)
- tree architecture (1)
- tree growth (1)
- triacylglycerols (1)
- triterpenoids (1)
- tritrophic interactions (1)
- tropisms (1)
- trypanosoma brucei (1)
- tryptophan (1)
- tumor cell (1)
- tumor development (1)
- two-component (1)
- two-component system (1)
- two-hybrid system (1)
- tyloses (1)
- type 2 diabetes (1)
- ultrastructure (1)
- ultraviolet (1)
- ultraviolet radiation (1)
- ultraviolette Strahlung (1)
- undernourishment (1)
- unfolded protein response (1)
- unsaturated Fatty Acids (1)
- vacuolar calcium sensor (1)
- vacuolar membrane (1)
- vacuolar proton-ATPase (1)
- valinomycin (1)
- vertical and radial variation (1)
- vertikale Weitergabe (1)
- very long-chain aliphatic compounds (1)
- very-long-chain aldehydes (1)
- vessel lumen diameter (1)
- vessel tapering (1)
- volatile (1)
- volatile organic compounds (1)
- volatiles (1)
- voltage clamp fluorometry (1)
- voltage dependent (1)
- voltage gating (1)
- volvox carteri (1)
- von Willebrand type C domain (1)
- wasserhaushalt (1)
- water (1)
- water availability (1)
- water flow (1)
- water relation (1)
- water relations (1)
- water transport root (1)
- waterpermeability (1)
- wax biosynthesis (1)
- wax composition (1)
- waxes (1)
- web server (1)
- weed dodder (1)
- whole genome sequencing (1)
- whole-genome duplication (1)
- windpipe (1)
- wood density (1)
- wood formation (1)
- wood production (1)
- wood rays (1)
- xenobiotic metabolism (1)
- xerostomia (1)
- xylem (1)
- xylem loading (1)
- yeast-elicitor (1)
- zelluläre Bindungsstudien (1)
- zyklische Peptide (1)
- Ökologie (1)
- Ökophysiologie (1)
- Österreichische Sumpfkresse (1)
- ß-D-Glucosidase (1)
- ß-D-glucosidase (1)
Institute
- Julius-von-Sachs-Institut für Biowissenschaften (358) (remove)
Sonstige beteiligte Institutionen
- Albert-Ludwigs-Universität Freiburg (1)
- Fraunhofer IGB Stuttgart (1)
- GEOMAR Helmholtz-Zentrum für Ozeanforschung Kiel (1)
- Goethe-Universität Frankfurt (1)
- IZKF (Interdisziplinäres Zentrum für Klinische Forschung), Universität Würzburg (1)
- IZKF Laboratory for Microarray Applications, University Hospital of Wuerzburg, Wuerzburg, Germany (1)
- Julius-von-Sachs-Institut für Biowissenschaften Lehrstuhl für Botanik II - Ökophysiologie und Vegetationsökologie (1)
- Leuphana Universität Lüneburg (1)
- Technische Universität Dresden (1)
- Technische Universität München (1)
To fire action-potential-like electrical signals, the vacuole membrane requires the two-pore channel TPC1, formerly called SV channel. The TPC1/SV channel functions as a depolarization-stimulated, non-selective cation channel that is inhibited by luminal Ca\(^{2+}\). In our search for species-dependent functional TPC1 channel variants with different luminal Ca\(^{2+}\) sensitivity, we found in total three acidic residues present in Ca\(^{2+}\) sensor sites 2 and 3 of the Ca\(^{2+}\)-sensitive AtTPC1 channel from Arabidopsis thaliana that were neutral in its Vicia faba ortholog and also in those of many other Fabaceae. When expressed in the Arabidopsis AtTPC1-loss-of-function background, wild-type VfTPC1 was hypersensitive to vacuole depolarization and only weakly sensitive to blocking luminal Ca\(^{2+}\). When AtTPC1 was mutated for these VfTPC1-homologous polymorphic residues, two neutral substitutions in Ca\(^{2+}\) sensor site 3 alone were already sufficient for the Arabidopsis At-VfTPC1 channel mutant to gain VfTPC1-like voltage and luminal Ca\(^{2+}\) sensitivity that together rendered vacuoles hyperexcitable. Thus, natural TPC1 channel variants exist in plant families which may fine-tune vacuole excitability and adapt it to environmental settings of the particular ecological niche.
Interleukin-4 (IL-4) plays a key role in atopic diseases. It coordinates T-helper cell differentiation to subtype 2, thereby directing defense toward humoral immunity. Together with Interleukin-13, IL-4 further induces immunoglobulin class switch to IgE. Antibodies of this type activate mast cells and basophilic and eosinophilic granulocytes, which release pro-inflammatory mediators accounting for the typical symptoms of atopic diseases. IL-4 and IL-13 are thus major targets for pharmaceutical intervention strategies to treat atopic diseases. Besides neutralizing antibodies against IL-4, IL-13, or its receptors, IL-4 antagonists can present valuable alternatives. Pitrakinra, an Escherichia coli-derived IL-4 antagonist, has been evaluated in clinical trials for asthma treatment in the past; however, deficits such as short serum lifetime and potential immunogenicity among others stopped further development. To overcome such deficits, PEGylation of therapeutically important proteins has been used to increase the lifetime and proteolytic stability. As an alternative, glycoengineering is an emerging strategy used to improve pharmacokinetics of protein therapeutics. In this study, we have established different strategies to attach glycan moieties to defined positions in IL-4. Different chemical attachment strategies employing thiol chemistry were used to attach a glucose molecule at amino acid position 121, thereby converting IL-4 into a highly effective antagonist. To enhance the proteolytic stability of this IL-4 antagonist, additional glycan structures were introduced by glycoengineering utilizing eucaryotic expression. IL-4 antagonists with a combination of chemical and biosynthetic glycoengineering could be useful as therapeutic alternatives to IL-4 neutralizing antibodies already used to treat atopic diseases.
Key message
Mobile laser scanning and geometrical analysis revealed relationships between tree geometry and seed dispersal mechanism, latitude of origin, as well as growth.
Abstract
The structure and dynamics of a forest are defined by the architecture and growth patterns of its individual trees. In turn, tree architecture and growth result from the interplay between the genetic building plans and environmental factors. We set out to investigate whether (1) latitudinal adaptations of the crown shape occur due to characteristic solar elevation angles at a species’ origin, (2) architectural differences in trees are related to seed dispersal strategies, and (3) tree architecture relates to tree growth performance. We used mobile laser scanning (MLS) to scan 473 trees and generated three-dimensional data of each tree. Tree architectural complexity was then characterized by fractal analysis using the box-dimension approach along with a topological measure of the top heaviness of a tree. The tree species studied originated from various latitudinal ranges, but were grown in the same environmental settings in the arboretum. We found that trees originating from higher latitudes had significantly less top-heavy geometries than those from lower latitudes. Therefore, to a certain degree, the crown shape of tree species seems to be determined by their original habitat. We also found that tree species with wind-dispersed seeds had a higher structural complexity than those with animal-dispersed seeds (p < 0.001). Furthermore, tree architectural complexity was positively related to the growth performance of the trees (p < 0.001). We conclude that the use of 3D data from MLS in combination with geometrical analysis, including fractal analysis, is a promising tool to investigate tree architecture.
Climate change is increasing the frequency and intensity of warming and drought periods around the globe, currently representing a threat to many plant species. Understanding the resistance and resilience of plants to climate change is, therefore, urgently needed. As date palm (Phoenix dactylifera) evolved adaptation mechanisms to a xeric environment and can tolerate large diurnal and seasonal temperature fluctuations, we studied the protein expression changes in leaves, volatile organic compound emissions, and photosynthesis in response to variable growth temperatures and soil water deprivation. Plants were grown under controlled environmental conditions of simulated Saudi Arabian summer and winter climates challenged with drought stress. We show that date palm is able to counteract the harsh conditions of the Arabian Peninsula by adjusting the abundances of proteins related to the photosynthetic machinery, abiotic stress and secondary metabolism. Under summer climate and water deprivation, these adjustments included efficient protein expression response mediated by heat shock proteins and the antioxidant system to counteract reactive oxygen species formation. Proteins related to secondary metabolism were downregulated, except for the P. dactylifera isoprene synthase (PdIspS), which was strongly upregulated in response to summer climate and drought. This study reports, for the first time, the identification and functional characterization of the gene encoding for PdIspS, allowing future analysis of isoprene functions in date palm under extreme environments. Overall, the current study shows that reprogramming of the leaf protein profiles confers the date palm heat- and drought tolerance. We conclude that the protein plasticity of date palm is an important mechanism of molecular adaptation to environmental fluctuations.
The carbohydrate D-glucose is the main source of energy in living organisms. In contrast to animals, as well as most fungi, bacteria, and archaea, plants are capable to synthesize a surplus of sugars characterizing them as autothrophic organisms. Thus, plants are de facto the source of all food on earth, either directly or indirectly via feed to livestock. Glucose is stored as polymeric glucan, in animals as glycogen and in plants as starch. Despite serving a general source for metabolic energy and energy storage, glucose is the main building block for cellulose synthesis and represents the metabolic starting point of carboxylate- and amino acid synthesis. Finally yet importantly, glucose functions as signalling molecule conveying the plant metabolic status for adjustment of growth, development, and survival. Therefore, cell-to-cell and long-distance transport of photoassimilates/sugars throughout the plant body require the fine-tuned activity of sugar transporters facilitating the transport across membranes. The functional plant counterparts of the animal sodium/glucose transporters (SGLTs) are represented by the proton-coupled sugar transport proteins (STPs) of the plant monosaccharide transporter(-like) family (MST). In the framework of this special issue on “Glucose Transporters in Health and Disease,” this review gives an overview of the function and structure of plant STPs in comparison to the respective knowledge obtained with the animal Na+-coupled glucose transporters (SGLTs).
Young grapevines (Vitis vinifera) suffer and eventually can die from the crown gall disease caused by the plant pathogen Allorhizobium vitis (Rhizobiaceae). Virulent members of A. vitis harbor a tumor-inducing plasmid and induce formation of crown galls due to the oncogenes encoded on the transfer DNA. The expression of oncogenes in transformed host cells induces unregulated cell proliferation and metabolic and physiological changes. The crown gall produces opines uncommon to plants, which provide an important nutrient source for A. vitis harboring opine catabolism enzymes. Crown galls host a distinct bacterial community, and the mechanisms establishing a crown gall–specific bacterial community are currently unknown. Thus, we were interested in whether genes homologous to those of the tumor-inducing plasmid coexist in the genomes of the microbial species coexisting in crown galls. We isolated 8 bacterial strains from grapevine crown galls, sequenced their genomes, and tested their virulence and opine utilization ability in bioassays. In addition, the 8 genome sequences were compared with 34 published bacterial genomes, including closely related plant-associated bacteria not from crown galls. Homologous genes for virulence and opine anabolism were only present in the virulent Rhizobiaceae. In contrast, homologs of the opine catabolism genes were present in all strains including the nonvirulent members of the Rhizobiaceae and non-Rhizobiaceae. Gene neighborhood and sequence identity of the opine degradation cluster of virulent and nonvirulent strains together with the results of the opine utilization assay support the important role of opine utilization for cocolonization in crown galls, thereby shaping the crown gall community.
Modern lifestyle is often at odds with endogenously driven rhythmicity, which can lead to circadian disruption and metabolic syndrome. One signature for circadian disruption is a reduced or altered metabolite cycling in the circulating tissue reflecting the current metabolic status. Drosophila is a well-established model in chronobiology, but day-time dependent variations of transport metabolites in the fly circulation are poorly characterized. Here, we sampled fly hemolymph throughout the day and analyzed diacylglycerols (DGs), phosphoethanolamines (PEs) and phosphocholines (PCs) using LC-MS. In wild-type flies kept on sugar-only medium under a light-dark cycle, all transport lipid species showed a synchronized bimodal oscillation pattern with maxima at the beginning and end of the light phase which were impaired in period01 clock mutants. In wild-type flies under constant dark conditions, the oscillation became monophasic with a maximum in the middle of the subjective day. In strong support of clock-driven oscillations, levels of the targeted lipids peaked once in the middle of the light phase under time-restricted feeding independent of the time of food intake. When wild-type flies were reared on full standard medium, the rhythmic alterations of hemolymph lipid levels were greatly attenuated. Our data suggest that the circadian clock aligns daily oscillations of DGs, PEs, and PCs in the hemolymph to the anabolic siesta phase, with a strong influence of light on phase and modality.
In the scope of climate warming and the increase in frequency and intensity of severe heat waves in Central Europe, identification of temperate tree species that are suited to cope with these environmental changes is gaining increasing importance. A number of tree physiological characteristics are associated with drought-stress resistance and survival following severe heat, but recent studies have shown the importance of plant hydraulic and anatomical traits for predicting drought-induced tree mortality, such as vessel diameter, and their potential to predict species distribution in a changing climate.
A compilation of large global datasets is required to determine traits related to drought-induced embolism and test whether embolism resistance can be determined solely by anatomical traits. However, most measurements of plant hydraulic traits are labour-intense and prone to measurement artefacts. A fast, accurate and widely applicable technique is necessary for estimating xylem embolism resistance (e.g., water potential at 50% loss of conductivity, P50), in order to improve forecasts of future forest changes. These traits and their combination must have evolved following the selective pressure of the environmental conditions in which each species occurs. Describing these environmental-trait relationships can be useful to assess potential responses to environmental change and mitigation strategies for tree species, as future warmer temperatures may be compounded by drier conditions.
Maintaining the balance between CO2 uptake and transpiration is important for plants and depends on tightly controlled turgor changes caused by the activity of various anion and cation channels. These channels are part of signaling cascades triggered, for example, by phytohormones such as ABA (abscisic acid) and JA (jasmonate), both of which act during drought stress in guard cells. In addition, JA is known to be involved in the plant's response to pathogen attack or wounding.
GORK (guard cell outward rectifying K+ channel) is the only known outward rectifying K+ channel in guard cells and therefore responsible for K+ efflux during stomatal closure.
In the course of this work it could be demonstrated by stomatal aperture assays, that GORK is an essential part of JA-induced stomatal closure. This is true for both triggers, leaf wounding as well as direct MeJA (methyl jasmonate) application. Patch clamp experiments on guard cell protoplasts backed this finding by revealing GORK K+ outward currents as a target of JA signaling in guard cells. As cytosolic Ca2+ signals are known to be involved in both ABA as well as JA signaling, the interaction of GORK with Ca2+-dependent kinases was examined consequently. An antagonistic regulation of GORK by
CIPK5-CBL1/9 complexes and ABI2 was identified by DEVC (double electrode voltage clamp) and protein-protein interaction experiments and backed up by in vitro kinase assays. Patch-clamp recordings on guard cell protoplasts of cipk5-2 kinase loss-of-function mutant revealed the importance of CIPK5 for JA-triggered stomatal closure via activation of GORK. The interaction of different CDPKs (Ca2+-dependent protein kinases) with GORK was also investigated.
Besides Ca2+ signaling also ROS (reactive oxygen species) production is essential in ABA and MeJA signaling. In DEVC experiments a reversible effect of ROS on GORK channel activity could be demonstrated, which could be one piece in the explanation of those ROS effects in ABA and MeJA signaling.
The slowly activating vacuolar SV/TPC1 channel is ubiquitously expressed in plants and provides a large cation conductance in the vacuolar membrane. Thereby, monovalent (K+, Na+) and in principle also divalent cations, such as Ca2+, can pass through the channel. The SV/TPC1 channel is activated upon membrane depolarization and cytosolic Ca2+ but inhibited by luminal calcium. With respect to the latter, two luminal Ca2+ binding sites (site 1 Asp240/Asp454/Glu528, site 2 Glu239/Asp240/Glu457) were identified to coordinate luminal Ca2+. In this work, the characteristics of the SV/TPC1 channels in terms of regulation and function were further elucidated, focusing on the TPC1s of Arabidopsis thaliana and Vicia faba. For electrophysiological analysis of the role of distinct pore residues for channel gating and luminal Ca2+ sensing, TPC1 channel variants were generated by site-directed mutagenesis and transiently expressed as eGFP/eYFP-fusion constructs in Arabidopsis thaliana mesophyll protoplasts of the TPC1 loss-of-function mutant attpc1-2.
1. As visualized by confocal fluorescence laser-scanning microscopy, all AtTPC1 (WT, E605A/Q, D606N, D607N, E605A/D606N, E605Q/D606N/D607N, E457N/E605A/D606N) and VfTPC1 channel variants (WT, N458E/A607E/ N608D) were correctly targeted to the vacuole membrane.
2. Patch-clamp studies revealed that removal of one of the negative charges at position Glu605 or Asp606 was already sufficient to promote voltage-dependent channel activation with higher voltage sensitivity. The combined neutralization of these residues (E605A/D606N), however, was required to additionally reduce the luminal Ca2+ sensitivity of the AtTPC1 channel, leading to hyperactive AtTPC1 channels. Thus, the residues Glu605/Asp606 are functionally coupled with the voltage sensor of AtTPC1 channel, thereby modulating channel gating, and form a novel luminal Ca2+ sensing site 3 in AtTPC1 at the luminal entrance of the ion transport pathway.
3. Interestingly, this novel luminal Ca2+ sensing site 3 (Glu605/Asp606) and Glu457 from the luminal Ca2+ sensing site 2 of the luminal Ca2+-sensitive AtTPC1 channel were neutralized by either asparagine or alanine in the TPC1 channel from Vicia faba and many other Fabaceae. Moreover, the VfTPC1 was validated to be a hyperactive TPC1 channel with higher tolerance to luminal Ca2+ loads which was in contrast to the AtTPC1 channel features. As a result, VfTPC1 but not AtTPC1 conferred the hyperexcitability of vacuoles. When AtTPC1 was mutated for the three VfTPC1-homologous polymorphic site residues, the AtTPC1 triple mutant (E457N/E605A/D606N) gained VfTPC1-like characteristics. However, when VfTPC1 was mutated for the three AtTPC1-homologous polymorphic site residues, the VfTPC1 triple mutant (N458E/A607E/N608D) still sustained VfTPC1-WT-like features. These findings indicate that the hyperactivity of VfTPC1 is achieved in part by the loss of negatively charged amino acids at positions that - as part of the luminal Ca2+ sensing sites 2 and 3 – are homologous to AtTPC1-Glu457/Glu605/Asp606 and are likely stabilized by other unknown residues or domains.
4.The luminal polymorphic pore residues (Glu605/Asp606 in AtTPC1) apparently do not contribute to the unitary conductance of TPC1. Under symmetrical K+ conditions, a single channel conductance of about 80 pS was determined for AtTPC1 wild type and the AtTPC1 double mutant E605A/D606A. This is in line with the three-fold higher unitary conductance of VfTPC1 (232 pS), which harbors neutral luminal pore residues at the homologous sites to AtTPC1.
In conclusion, by studying TPC1 channel from Arabidopsis thaliana and Vicia faba, the present thesis provides evidence that the natural TPC1 channel variants exhibit differences in voltage gating, luminal Ca2+ sensitivity and luminal Ca2+ binding sites.
Xylem embolism resistance has been identified as a key trait with a causal relation to drought-induced tree mortality, but not much is known about its intra-specific trait variability (ITV) in dependence on environmental variation. We measured xylem safety and efficiency in 300 European beech (Fagus sylvatica L.) trees across 30 sites in Central Europe, covering a precipitation reduction from 886 to 522 mm year−1. A broad range of variables that might affect embolism resistance in mature trees, including climatic and soil water availability, competition, and branch age, were examined. The average P50 value varied by up to 1 MPa between sites. Neither climatic aridity nor structural variables had a significant influence on P50. However, P50 was less negative for trees with a higher soil water storage capacity, and positively related to branch age, while specific conductivity (Ks) was not significantly associated with either of these variables. The greatest part of the ITV for xylem safety and efficiency was attributed to random variability within populations. We conclude that the influence of site water availability on P50 and Ks is low in European beech, and that the high degree of within-population variability for P50, partly due to variation in branch age, hampers the identification of a clear environmental signal.
Bone morphogenetic proteins (BMPs) are involved in various aspects of cell-cell communication in complex life forms. They act as morphogens, help differentiate different cell types from different progenitor cells in development, and are involved in many instances of intercellular communication, from forming a body axis to healing bone fractures, from sugar metabolism to angiogenesis. If the same protein or protein family carries out many functions, there is a demand to regulate and fine-tune their biological activities, and BMPs are highly regulated to generate cell- and context-dependent outcomes.
Not all such instances can be explained yet. Growth/differentiation factor (GDF)5 (or BMP14) synergizes with BMP2 on chondrogenic ATDC5 cells, but antagonizes BMP2 on myoblastic C2C12 cells. Known regulators of BMP2/GDF5 signal transduction failed to explain this context-dependent difference, so a microarray was performed to identify new, cell-specific regulatory components. One identified candidate, the fibroblast growth factor receptor (FGFR)2, was analyzed as a potential new co-receptor to BMP ligands such as GDF5: It was shown that FGFR2 directly binds BMP2, GDF5, and other BMP ligands in vitro, and FGFR2 was able to positively influence BMP2/GDF5-mediated signaling outcome in cell-based assays. This effect was independent of FGFR2s kinase activity, and independent of the downstream mediators SMAD1/5/8, p42/p44, Akt, and p38. The elevated colocalization of BMP receptor type IA and FGFR2 in the presence of BMP2 or GDF5 suggests a signaling complex containing both receptors, akin to other known co-receptors of BMP ligands such as repulsive guidance molecules.
This unexpected direct interaction between FGF receptor and BMP ligands potentially opens a new category of BMP signal transduction regulation, as FGFR2 is the second receptor tyrosine kinase to be identified as BMP co-receptor, and more may follow. The integration of cell surface interactions between members of the FGF and BMP family especially may widen the knowledge of such cellular communication mechanisms which involve both growth factor families, including morphogen gradients and osteogenesis, and may in consequence help to improve treatment options in osteochodnral diseases.
Calcium ion (Ca2+) and protons (H+) are both regarded as second messengers, participating in plant growth and stress mechanisms. However, H+ signals in plant physiology are less well investigated compared to Ca2+ signals. If interconnections between these two second messengers exist remains to be uncovered because appropriate imaging tools to monitor Ca2+ and H+ simultaneously in the same cell as well as accurate bioinformatics analysis remain to be developed. To overcome this problem and unravel the role and possible interconnection of Ca2+ and H+ in plants, a new biosensor named CapHensor was developed and optimized to visualize intracellular Ca2+ and H+ changes simultaneously and ratiometrically in the same cell. The CapHensor consisted of an optimized green fluorescent pH sensor (PRpHluorin) and an established red fluorescent Ca2+ sensor (R-GECO1) that were combined in one construct via a P2A sequence. A P2A self-cleavage site between the two sensors allowed to express equal amounts but spatially separated sensors, which enabled artifact-free and ratiometric imaging of cellular Ca2+ and pH side-by-side. The function of the CapHensor was verified in pollen tubes, since they possess standing Ca2+ and pH gradients. We found better imaging quality and the signal-to-noise ratio to be enhanced in live-cell imaging when two R-GECO1 proteins were fused in tandem within the CapHensor construct. To guarantee exclusive subcellular localization and avoid mixed signals from different compartments, Nuclear Export Sequence (NES) and Nuclear Localization Sequence (NLS) were used to target PRpHluorin and R-GECO1 to distinct compartments. After optimization and verification its function, CapHensor was successfully expressed in different cell types to investigate the role of Ca2+ and H+ signals to control polar growth of pollen tube, stomatal movement or leaf defense signaling. Results obtained in the past indicated both Ca2+ gradients and pH gradients in pollen tubes play roles in polar growth. However, the role and temporal relationship between the growth process and changes in Ca2+ and pH have not been conclusively resolved. Using CapHensor, I found cytosolic acidification at the tip could promote and alkalization to suppress growth velocity in N. tabacum pollen tubes, indicating that cytosolic H+ concentrations ([H+]cyt) play an important role in regulation pollen tubes growth despite the accompanied changes in cytosolic Ca2+ concentrations ([Ca2+]cyt). Moreover, growth correlated much better with the tip [H+]cyt regime than with the course of the tip [Ca2+]cyt regime. However, surprisingly, tip-focused [Ca2+]cyt andII [H+]cyt oscillations both lagged behind growth oscillations approximately 33 s and 18 s, respectively, asking for a re-evaluation of the role that tip [Ca2+]cyt may play in pollen tube growth. Live-cell CapHensor imaging combined with electrophysiology uncovered that oscillatory membrane depolarization correlated better with tip [H+]cyt oscillations than with tip [Ca2+]cyt oscillations, indicative for a prominent role of [H+]cyt to also control electrogenic membrane transport. Using CapHensor, reading out cellular movement at the same time enabled to provide a precise temporal and spatial resolution of ion signaling events, pointing out a prominent role of [H+]cyt in pollen tube tip growth. For leaf cells, a special CapHensor construct design had to be developed, containing additional NES localization sequences to avoid overlapping of fluorescense signals from the nucleus and the cytosol. Once this was achieved, the role of Ca2+ and pH changes in guard cells, another typical single-cell system was investigated. Cytosolic pH changes have been described in stomatal movement, but the physiological role of pH and the interaction with changing Ca2+ signals were still unexplored. Combining CapHensor with the here developed technique to monitor stomatal movement in parallel, the role of Ca2+ and H+ in stomatal movement was studied in detail and novel aspects were identified. The phytohormone ABA and the bacterial elicitor flagellin (flg22) are typical abiotic and biotic stresses, respectively, to trigger stomatal closure. What kind of Ca2+ and H+ signals by ABA and flg22 are set-off in guard cells and what their temporal relationship and role for stomatal movement is were unknown. Similar [Ca2+]cyt increases were observed upon ABA and flg22 triggered stomatal closure, but [H+]cyt dynamics differed fundamentally. ABA triggered pronounced cytosolic alkalization preceded the [Ca2+]cyt responses significantly by 57 s while stomata started to close ca. 205 s after phytohormone application. With flg22, stomatal closure was accompanied only with a mild cytosolic alkalization but the [Ca2+]cyt response was much more pronounced compared to the ABA effects. Where the cytosolic alkalization originates from was unclear but the vacuole was speculated to contribute in the past. In this thesis, vacuolar pH changes were visualized by the dye BCECF over time, basically displaying exactly the opposite course of the concentration shift in the vacuole than observed in the cytosol. This is indicative for the vacuolar pH dynamics to be coupled strongly to the cytosolic pH changes. In stomatal closure signalling, reactive oxygen species (ROS) were proposed to play a major role, however, only very high concentration of H2O2 (> 200 µM), which resulted in the loss of membrane integrity, induced stomatal closure. Unexpectedly, physiological concentrations of ROS led to cytosolic acidificationIII which was associated with stomatal opening, but not stomatal closure. To study the role of [H+]cyt to steer stomatal movement in detail, extracellular and intracellular pH variations were evoked in N. tabacum guard cells and their behaviour was followed. The results demonstrated cytosolic acidification stimulated stomatal opening while cytosolic alkalization triggered stomatal closure accompanied by [Ca2+]cyt elevations. This demonstrated pH regulation to be an important aspect in stomatal movement and to feed-back on the Ca2+-dynamics. It was remarkable that cytosolic alkalization but not [Ca2+]cyt increase seemed to play a crucial role in stomatal closure, because more pronounced cytosolic alkalization, evoked stronger stomatal closure despite similar [Ca2+]cyt increases. Increases in [Ca2+]cyt, which are discussed as an early stomatal closure signal in the past, could not trigger stomatal closure alone in my experiments, even when extremely strong [Ca2+]cyt signals were triggered. Regarding the interaction between the two second messengers, [Ca2+]cyt and [H+]cyt were negatively correlated most of the times, which was different from pollen tubes showing positive correlation of [Ca2+]cyt and [H+]cyt regimes. [Ca2+]cyt elevations were always associated with a cytosolic alkalization and this relationship could be blocked by the presence of vanadate, a plasma membrane H+-pump blocker, indicating plasma membrane H+-ATPases to contribute to the negative correlation of [Ca2+]cyt and [H+]cyt. To compare with guard cells, cytosolic and nuclear versions of CapHensor were expressed in N. benthamiana mesophyll cells, a multicellular system I investigated. Mesophyll cell responses to the same stimuli as tested in guard cells demonstrated that ABA and H2O2 did not induce any [Ca2+]cyt and [H+]cyt changes while flg22 induced an increase in [Ca2+]cyt and [H+]cyt, which is different from the response in guard cells. I could thus unequivocally demonstrate that guard cells and mesophyll cells do respond differently with [Ca2+]cyt and [H+]cyt changes to the same stimuli, a concept that has been proposed before, but never demonstrated in such detail for plants. Spontaneous Ca2+ oscillations have been observed for a long time in guard cells, but the function or cause is still poorly understood. Two populations of oscillatory guard cells were identified according to their [Ca2+]cyt and [H+]cyt phase relationship in my study. In approximately half of the oscillatory cells, [H+]cyt oscillations preceded [Ca2+]cyt oscillations whereas [Ca2+]cyt was the leading signal in the other half of the guard cells population. Strikingly, natural [H+]cyt oscillations were dampened by ABA but not by flg22. This effect could be well explained by dampening of vacuolar H+ oscillations in the presence of ABA, but not through flg22. Vacuolar pH contributes to spontaneous [H+]cyt oscillations and ABA but not flg22 can block the interdependence of naturalIV [Ca2+]cyt and [H+]cyt signals. To study the role of [Ca2+]cyt oscillations in stomatal movement, solutions containing high and low KCl concentrations were applied aiming to trigger [Ca2+]cyt oscillations. The triggering of [Ca2+]cyt oscillations by this method was established two decades ago leading to the dogma that [Ca2+]cyt increases are the crucial signal for stomatal closure. However, I found stomatal movement by this method was mainly due to osmotic effects rather than [Ca2+]cyt increases. Fortunately, through this methodology, I found a strong correlation between cytosolic pH and the transport of potassium across the plasma membrane and vacuole existed. The plasma membrane H+-ATPases and H+-coupled K+ transporters were identified as the cause of [H+]cyt changes, both very important aspects in stomata physiology that were not visualized experimentally before. Na+ transport is also important for stomatal regulation and leaves generally since salt can be transported from the root to the shoot. Unlike well-described Ca2+- dependent mechanisms in roots, how leaves process salt stress is not at all understood. I applied salt on protoplasts from leaves, mesophyll cells and guard cells and combined live-cell imaging with Vm recordings to understand the transport and signaling for leaf cells to cope with salt stress. In both, mesophyll and guard cells, NaCl did not trigger Ca2+-signals as described for roots but rather triggered Ca2+ peaks when washing salt out. However, membrane depolarization and pronounced alkalinization were very reliably triggered by NaCl, which could presumably act as a signal for detoxification of high salt concentrations. In line with this, I found the vacuolar cation/H+ antiporter NHX1 to play a role in sodium transport, [H+]cyt homeostasis and the control of membrane potential. Overexpression of AtNHX1 enabled to diminish [H+]cyt changes and resulted in a smaller depolarization responses druing NaCl stress. My results thus demonstrated in contrast to roots, leaf cells do not use Ca2+-dependent signalling cascades to deal with salt stress. I could show Na+ and K+ induced [H+]cyt and Vm responses and Cl- transport to only have a minor impact. Summing all my results up briefly, I uncovered pH signals to play important roles to control pollen tube growth, stomatal movement and leaf detoxification upon salt. My results strongly suggested pH changes might be a more important signal than previously thought to steer diverse processes in plants. Using CapHensor in combination with electrophysiology and bioinformatics tools, I discovered distinct interconnections between [Ca2+]cyt and [H+]cyt in different cell types and distinct [Ca2+]cyt and [H+]cyt signals are initiated through diverse stimuli and environmental cues. The CapHensor will be very useful in the future to further investigate the coordinated role of Ca2+ and pH changes in controlling plant physiology.
Sphingolipid long-chain bases (LCBs) are the building blocks of the biosynthesis of sphingolipids. They
are defined as structural elements of the plant cell membrane and play an important role
determining the fate of the cells. Complex ceramides represent a substantial fraction of total
sphingolipids which form a major part of eukaryotic membranes. At the same time, LCBs are well
known signaling molecules of cellular processes in eukaryotes and are involved in signal transduction
pathways in plants. High levels of LCBS have been shown to be associated with the induction of
programmed cell death as well as pathogen-derived toxin-induced cell death. Indeed, several studies
confirmed the regulatory function of sphingobases in plant programmed cell death (PCD):
(i) Spontaneous PCD and altered cell death reaction caused by mutated related genes of sphingobase
metabolism. (ii) Cell death conditions increases levels of LCBs. (iii) PCD due to interfered sphingolipid
metabolism provoked by toxins produced from necrotrophic pathogens, such as Fumonisin B1 (FB1).
Therefore, to prevent cell death and control cell death reaction, the regulation of levels of free LCBs
can be crucial.
The results of the present study challenged the comprehension of sphingobases and sphingolipid
levels during PCD. We provided detailed analysis of sphingolipids levels that revealed correlations of
certain sphingolipid species with cell death. Moreover, the investigation of sphingolipid biosynthesis
allowed us to understand the flux after the accumulation of high LCB levels. However, further
analysis of degradation products or sphingolipid mutant lines, would be required to fully understand
how high levels of sphingobases are being treated by the plant.
Optogenetics is a powerful technique that utilizes light to precisely regulate physiological activities of neurons and other cell types. Specifically, light-sensitive ion channels, pumps or enzymes are expressed in cells to enable their regulation by illumination, thus allowing for precise control of biochemical signaling pathways. The first part of my study involved the construction, optimization, and characterization of two optogenetic tools, KCR1 and NCR1. Elena Govorunova et al. discovered a lightgated potassium channel, KCR1, in the protozoan Hyphochytrium catenoides. Traditional potassium ion channels are classified as either ligand-gated or voltage-gated and possess conserved pore-forming domains and K+ -selective filters. However, KCR1 is unique in that it does not contain the signature sequence of previously known K+ channels and is a channelrhodopsin. We synthesized the KCR1 plasmid according to the published sequence and expressed it in Xenopus oocytes. Due to the original KCR1 current being too small, I optimized it into KCR1 2.0 to improve its performance by fusing LR (signal peptide LucyRho, enhances expression) at the N-terminal and T (trafficking signal peptide) and E (ER export signal peptide) at the C-terminal. Additionally, I investigated the light sensitivity, action spectrum, and kinetics of KCR1 2.0 in Xenopus oocytes. The potassium permeability of KCR1 2.0, PK/Pna 24, makes KCR1 2.0 a powerful hyperpolarizing tool that can be used to inhibit neuronal firing in animals. Inspired by KCR1, we used the KCR1 sequence as a template for gene sequence alignment with the sequences in H. catenoides. We found that NCR1 and KCR1 have similar gene sequences. NCR1 was characterized by us as a light-gated sodium channel. This NCR1 was also characterized and published by Govorunova et al. very recently, with the name HcCCR. Due to the original NCR1 current being too small, I optimized it into NCR1 2.0 to improve its performance by fusing LR at the N-terminal and T and E at the C-terminal, which significantly improved the expression level and greatly increased the current amplitude of NCR1. Full-length NCR1 2.0 contains 432 amino acids. To test whether the number of amino acids changes the characteristics of NCR1 2.0, we designed NCR1 2.0 (330), NCR1 2.0 (283), and NCR1 2.0 (273) by retaining the number of amino acids at 330, 280, and 273 in NCR1 2.0, respectively. As the number of amino acids decreased, the current in NCR1 2.0 increased. I also investigated the light sensitivity, action spectrum, and kinetics of NCR1 2.0 (273) in the Xenopus Abstract 2 oocytes. We performed four point mutations at amino acid positions 133 and 116 of NCR1 2.0 and analyzed the reversal potentials of the mutants. The mutations were as follows: NCR1 2.0 (273 D116H), NCR1 2.0 (273 D116E), NCR1 2.0 (283 V133H), and NCR1 2.0 (283 D116Q). The second part of this study focuses on light-induced water transport using optogenetic tools. We explored the use of optogenetic tools to regulate water flow by changing the osmolarity in oocytes. Water flux through AQP1 is driven by the osmotic gradient that results from concentration differences of small molecules or ions. Therefore, we seek to regulate ion concentrations, using optogenetic tools to regulate the flux of water noninvasively. To achieve this, I applied the light-gated cation channels XXM 2.0 and NCR1 2.0 to regulate the concentration of Na+ , while K + channel KCR1 2.0 was used to regulate K + concentration. As Na+ flows into the Xenopus oocytes, the membrane potential of the oocytes becomes positive, and Clcan influx through the light-gated anion channel GtACR1. By combining these optogenetic tools to regulate NaCl or KCl concentrations, I can change the osmolarity inside the oocytes, thus regulating the flux of water. I co-expressed AQP1 with optogenetic tools in the oocytes to accelerate water flux. Overall, I designed three combinations (1: AQP1, XXM 2.0 and GtACR1. 2: AQP1, NCR1 2.0 and GtACR1. 3: AQP1, KCR1 2.0 and GtACR1) to regulate the flow of water in oocytes. The shrinking or swelling of the oocytes can only be achieved when AQP1, light-gated cation channels (XXM 2.0/NCR1 2.0/KCR1 2.0), and light-gated anion channels (GtACR1) are expressed together. The illumination after expression of either or both alone does not result in changes in oocyte morphology. In sum, I demonstrated a novel strategy to manipulate water movement into and out of Xenopus oocytes, non-invasively through illumination. These findings provide a new avenue to interfere with water homeostasis as a means to study related biological phenomena across cell types and organisms.
Xylem hydraulic safety and efficiency are key traits determining tree fitness in a warmer and drier world. While numerous plant hydraulic studies have focused on branches, our understanding of root hydraulic functioning remains limited, although roots control water uptake, influence stomatal regulation and have commonly been considered as the most vulnerable organ along the hydraulic pathway.
We investigated 11 traits related to xylem safety and efficiency along the hydraulic pathway in four temperate broad-leaved tree species.
Continuous vessel tapering from coarse roots to stems and branches caused considerable reduction in hydraulic efficiency. Wood density was always lowest in roots, but did not decline linearly along the flow path. In contrast, xylem embolism resistance (P50) did not differ significantly between roots and branches, except for one species. The limited variation in xylem safety between organs did not adequately reflect the corresponding reductions in vessel diameter (by ~70%) and hydraulic efficiency (by ~85%). Although we did not observe any trade-off between xylem safety and specific conductivity, vessel diameter, vessel lumen fraction and wood density were related to embolism resistance, both across and partly within organs.
We conclude that coarse roots are not highly vulnerable to xylem embolism as commonly believed, indicating that hydraulic failure during soil drying might be restricted to fine roots.
In contrast to the well described molecular basis for S-type anion currents, the genes underlying R-type anion currents were unknown until 2010. Meyer S. and colleagues (2010) showed that, localized in the guard cell plasma membrane, AtALMT12 is an R-type anion channel involved in stomatal closure. However, knocking out AtALMT12 did not fully shut down R-type currents; the almt12 loss-of-function mutant has residual R-type-like currents indicating that ALMT12 is not the only gene encoding Arabidopsis thaliana R-type channels (Meyer S. et al., 2010). This PhD thesis is focussed on understanding the properties, regulation and molecular nature of the R-type channels in Arabidopsis thaliana plants. To fulfil these aims, the patch clamp technique was used to characterize electrical features of R-type currents in various conditions such as the presence/absence of ATP, variation in cytosolic calcium concentration or the presence of cytosolic chloride. Electrophysiological study revealed many similarities between the features of Arabidopsis thaliana R-type currents (Col0) and residual R-type currents (the almt12 loss-of-function mutant). Strong voltage dependency, channel activity in the same voltage range, position of maximal recorded current and blockage by cytosolic ATP all pointed to a shared phylogenetic origin of the channels underlying these R-type currents. Expression patterns of the ALMT family members for Col0 and the almt12 mutant revealed ALMT13 and AMT14 as potential candidates of the R-type channels. Electrical characterization of Col0, almt12 and the two double loss-of-function mutants (almt12/almt13 and almt12/almt14) strongly suggest that ALMT13 mediates the calcium-dependent R-type current component that is directly regulated by cytosolic calcium. Additionally, similarly to ALMT12, ALMT14 could participate as a calcium-independent R-type anion channel. Differences in response to the cytosolic calcium concentration between ALMT12, ALMT13 and ALMT14 suggest their possible involvement in different signalling pathways leading to stomatal closure. Moreover, a study performed for the two Arabidopsis thaliana ecotypes Col0 and WS showed drastically increased ALMT13 expression for WS, which is related to R-type current properties. The WS ecotype has calcium-dependent R-type current behaviour, while it is calcium-independent in Col0. Furthermore, this plant line showed lower peak current densities compared to Col0 and almt mutants. These facts strongly suggest interaction between ALMT12 and ALMT13, with ALMT13 as a repressor of the ALMT12. Acquired patch clamp data revealed sulphate-dependent increases in ALMT13 current. This could be caused by changes in absolute open probability and/or permeability for sulphate and possibly chloride and links ALMT13 with sulphate-mediated stomatal closure under drought stress. It was then confirmed that ATP affects R-type currents. In contrast to Vicia faba, ATP was identified as a negative regulator of the Arabidopsis thaliana R-type anion channels. The effect of ATP is ambiguous but there is a high probability that it is a result of direct block and phosphorylation. However, the phosphorylation site and place of ATP binding needs further investigation.
The story of the ALMT family, as examined in this thesis, sheds light on the complexity of the stomatal closure process.
Epidermal fragments enriched in guard cells (GCs) were isolated from the halophyte quinoa (Chenopodium quinoa Wild.) species, and the response at the proteome level was studied after salinity treatment of 300 mM NaCl for 3 weeks. In total, 2147 proteins were identified, of which 36% were differentially expressed in response to salinity stress in GCs. Up and downregulated proteins included signaling molecules, enzyme modulators, transcription factors and oxidoreductases. The most abundant proteins induced by salt treatment were desiccation-responsive protein 29B (50-fold), osmotin-like protein OSML13 (13-fold), polycystin-1, lipoxygenase, alpha-toxin, and triacylglycerol lipase (PLAT) domain-containing protein 3-like (eight-fold), and dehydrin early responsive to dehydration (ERD14) (eight-fold). Ten proteins related to the gene ontology term “response to ABA” were upregulated in quinoa GC; this included aspartic protease, phospholipase D and plastid-lipid-associated protein. Additionally, seven proteins in the sucrose–starch pathway were upregulated in the GC in response to salinity stress, and accumulation of tryptophan synthase and L-methionine synthase (enzymes involved in the amino acid biosynthesis) was observed. Exogenous application of sucrose and tryptophan, L-methionine resulted in reduction in stomatal aperture and conductance, which could be advantageous for plants under salt stress. Eight aspartic proteinase proteins were highly upregulated in GCs of quinoa, and exogenous application of pepstatin A (an inhibitor of aspartic proteinase) was accompanied by higher oxidative stress and extremely low stomatal aperture and conductance, suggesting a possible role of aspartic proteinase in mitigating oxidative stress induced by saline conditions.
Soil salinity is a major environmental constraint affecting crop growth and threatening global food security. Plants adapt to salinity by optimizing the performance of stomata. Stomata are formed by two guard cells (GCs) that are morphologically and functionally distinct from the other leaf cells. These microscopic sphincters inserted into the wax-covered epidermis of the shoot balance CO\(_2\) intake for photosynthetic carbon gain and concomitant water loss. In order to better understand the molecular mechanisms underlying stomatal function under saline conditions, we used proteomics approach to study isolated GCs from the salt-tolerant sugar beet species. Of the 2088 proteins identified in sugar beet GCs, 82 were differentially regulated by salt treatment. According to bioinformatics analysis (GO enrichment analysis and protein classification), these proteins were involved in lipid metabolism, cell wall modification, ATP biosynthesis, and signaling. Among the significant differentially abundant proteins, several proteins classified as “stress proteins” were upregulated, including non-specific lipid transfer protein, chaperone proteins, heat shock proteins, inorganic pyrophosphatase 2, responsible for energized vacuole membrane for ion transportation. Moreover, several antioxidant enzymes (peroxide, superoxidase dismutase) were highly upregulated. Furthermore, cell wall proteins detected in GCs provided some evidence that GC walls were more flexible in response to salt stress. Proteins such as L-ascorbate oxidase that were constitutively high under both control and high salinity conditions may contribute to the ability of sugar beet GCs to adapt to salinity by mitigating salinity-induced oxidative stress.
Embryo implantation requires a hospitable uterine environment. A key metabolic change that occurs during the peri-implantation period, and throughout early pregnancy, is the rise in endometrial glycogen content. Glycogen accumulation requires prior cellular uptake of glucose. Here we show that both human and murine endometrial epithelial cells express the high affinity Na\(^+\)-coupled glucose carrier SGLT1. Ussing chamber experiments revealed electrogenic glucose transport across the endometrium in wild type (\(Slc5a1^{+/+}\)) but not in SGLT1 defcient (\(Slc5a1^{−/−}\)) mice. Endometrial glycogen content, litter size and weight of offspring at birth were signifcantly lower in \(Slc5a1^{−/−}\) mice. In humans, \(SLC5A1\) expression was upregulated upon decidualization of primary endometrial stromal cells. Endometrial \(SLC5A1\) expression during the implantation window was attenuated in patients with recurrent pregnancy loss when compared with control subjects. Our fndings reveal a novel mechanism establishing adequate endometrial glycogen stores for pregnancy. Disruption of this histiotrophic pathway leads to adverse pregnancy outcome.
Farmland tree cultivation is considered an important option for enhancing wood production. In South India, the native leaf-deciduous tree species Melia dubia is popular for short-rotation plantations. Across a rainfall gradient from 420 to 2170 mm year\(^{–1}\), we studied 186 farmland woodlots between one and nine years in age. The objectives were to identify the main factors controlling aboveground biomass (AGB) and growth rates. A power-law growth model predicts an average stand-level AGB of 93.8 Mg ha\(^{–1}\) for nine-year-old woodlots. The resulting average annual AGB increment over the length of the rotation cycle is 10.4 Mg ha\(^{–1}\) year\(^{–1}\), which falls within the range reported for other tropical tree plantations. When expressing the parameters of the growth model as functions of management, climate and soil variables, it explains 65% of the variance in AGB. The results indicate that water availability is the main driver of the growth of M. dubia. Compared to the effects of water availability, the effects of soil nutrients are 26% to 60% smaller. We conclude that because of its high biomass accumulation rates in farm forestry, M. dubia is a promising candidate for short-rotation plantations in South India and beyond.
To reach their target site, systemic pesticides must enter the plant from a spray droplet applied in the field. The uptake of an active ingredient (AI) takes place via the barrier-forming cuticular membrane, which is the outermost layer of the plant, separating it from the surrounding environment. Formulations are usually used which, in addition to the AI, also contain stabilizers and adjuvants. Adjuvants can either have surface-active properties or they act directly as barrier-modifying agents. The latter are grouped in the class of accelerating adjuvants, whereby individual variants may also have surface-active properties. The uptake of a pesticide from a spray droplet depends essentially on its permeability through the cuticular barrier. Permeability defines a combined parameter, which is the product of AI mobility and AI solubility within the cuticle. In recent decades, several tools have been developed that allowed the determination of individual parameters of organic compound penetration across the cuticular membrane. Nevertheless, earlier studies showed that mainly cuticular waxes are the barrier-determining component of the cuticular membrane and additionally, it was shown that mainly the very-long-chain aliphatic compounds (VLCAs) are responsible for establishing an effective barrier. However, the barrier-determining role of the individual VLCAs, being classified according to their respective functional groups, is still unknown.
Therefore, the following objectives were pursued and achieved in this work: (1) A new ATR-FTIR-based approach was developed to measure the temperature-dependent real-time diffusion kinetics of organic models for active ingredients (AIs) in paraffin wax, exclusively consisting of very-long chain alkanes. (2) The developed ATR-FTIR approach was applied to determine the diffusion kinetics of self-accelerating adjuvants in cuticular model waxes of different VLCA composition. At the same time, wax-specific changes were recorded in the respective IR spectra, which provided information about the respective wax modification. (3) The ATR-FTIR method was used to characterize the diffusion kinetics, as well as to determine the wax-specific sorption capacities for an AI-modeling organic compound and water in cuticular model waxes after adjuvant treatment. Regarding the individual chemical compositions and structures, conclusions were drawn about the adjuvant-specific modes of action (MoA).
In the first chapter, the ATR-FTIR based approach to determine organic compound diffusion kinetics in paraffin wax was successfully established. The diffusion kinetics of the AI modelling organic compounds heptyl parabene (HPB) and 4-cyanophenol (CNP) were recorded, comprising different lipophilicities and molecular volumes typical for AIs used in pesticide formulations. Derived diffusion coefficients ranged within 10-15 m2 s-1, thus being thoroughly higher than those obtained from previous experiments using an approach solely investigating desorption kinetics in reconstituted cuticular waxes. An ln-linear dependence between the diffusion coefficients and the applied diffusion temperature was demonstrated for the first time in cuticular model wax, from which activation energies were derived. The determined activation energies were 66.2 ± 7.4 kJ mol-1 and 56.4 ± 9.8 kJ mol-1, being in the expected range of already well-founded activation energies required for organic compound diffusion across cuticular membranes, which again confirmed the significant contribution of waxes to the cuticular barrier. Deviations from the assumed Fickian diffusion were attributed to co-occurring water diffusion and apparatus-specific properties.
In the second and third chapter, mainly the diffusion kinetics of accelerating adjuvants in the cuticular model waxes candelilla wax and carnauba wax were investigated, and simultaneously recorded changes in the wax-specific portion of the IR spectrum were interpreted as indications of plasticization. For this purpose, the oil derivative methyl oleate, as well as the organophosphate ester TEHP and three non-ionic monodisperse alcohol ethoxylates (AEs) C12E2, C12E4 and C12E6 were selected. Strong dependence of diffusion on the respective principal components of the mainly aliphatic waxes was demonstrated. The diffusion kinetics of the investigated adjuvants were faster in the n-alkane dominated candelilla wax than in the alkyl ester dominated carnauba wax. Furthermore, the equilibrium absorptions, indicating equilibrium concentrations, were also higher in candelilla wax than in carnauba wax. It was concluded that alkyl ester dominated waxes feature higher resistance to diffusion of accelerating adjuvants than alkane dominated waxes with shorter average chain lengths due to their structural integrity. This was also found either concerning candelilla/policosanol (n-alcohol) or candelilla/rice bran wax (alkyl-esters) blends: with increasing alcohol concentration, the barrier function was decreased, whereas it was increased with increasing alkyl ester concentration. However, due to the high variability of the individual diffusion curves, only a trend could be assumed here, but significant differences were not shown. The variability itself was described in terms of fluctuating crystalline arrangements and partial phase separation of the respective wax mixtures, which had inevitable effects on the adjuvant diffusion. However, diffusion kinetics also strongly depended on the studied adjuvants. Significantly slower methyl oleate diffusion accompanied by a less pronounced reduction in orthorhombic crystallinity was found in carnauba wax than in candelilla wax, whereas TEHP diffusion was significantly less dependent on the respective wax structure and therefore induced considerable plasticization in both waxes. Of particular interest was the AE diffusion into both waxes. Differences in diffusion kinetics were also found here between candelilla blends and carnauba wax. However, these depended equally on the degree of ethoxylation of the respective AEs. The lipophilic C12E2 showed approximately Fickian diffusion kinetics in both waxes, accompanied by a drastic reduction in orthorhombic crystallinity, especially in candelilla wax, whereas the more hydrophilic C12E6 showed significantly retarded diffusion kinetics associated with a smaller effect on orthorhombic crystallinity. The individual diffusion kinetics of the investigated adjuvants sometimes showed drastic deviations from the Fickian diffusion model, indicating a self-accelerating effect. Hence, adjuvant diffusion kinetics were accompanied by a distinct initial lag phase, indicating a critical concentration in the wax necessary for effective penetration, leading to sigmoidal rather than to exponential diffusion kinetics.
The last chapter dealt with the adjuvant-affected diffusion of the AI modelling CNP in candelilla and carnauba wax. Using ATR-FTIR, diffusion kinetics were recorded after adjuvant treatment, all of which were fully explicable based on the Fickian model, with high diffusion coefficients ranging from 10-14 to 10-13 m2 s-1. It is obvious that the diffusion coefficients presented in this work consistently demonstrated plasticization induced accelerated CNP mobilities. Furthermore, CNP equilibrium concentrations were derived, from which partition- and permeability coefficients could be determined. Significant differences between diffusion coefficients (mobility) and partition coefficients (solubility) were found on the one hand depending on the respective waxes, and on the other hand depending on treatment with respective adjuvants. Mobility was higher in candelilla wax than in carnauba wax only after methyl oleate treatment. Treatment with TEHP and AEs resulted in higher CNP mobility in the more polar alkyl ester dominated carnauba wax. The partition coefficients, on the other hand, were significantly lower after methyl oleate treatment in both candelilla and carnauba wax as followed by TEHP or AE treatment. Models were designed for the CNP penetration mode considering the respective adjuvants in both investigated waxes. Co-penetrating water, which is the main ingredient of spray formulations applied in the field, was likely the reason for the drastic differences in adjuvant efficacy. Especially the investigated AEs favored an enormous water uptake in both waxes with increasing ethoxylation level. Surprisingly, this effect was also found for the lipophilic TEHP in both waxes. This led to the assumption that the AI permeability is not exclusively determined by adjuvant induced plasticization, but also depends on a “secondary plasticization”, induced by adjuvant-attracted co-penetrating water, consequently leading to swelling and drastic destabilization of the crystalline wax structure.
The successful establishment of the presented ATR-FTIR method represents a milestone for the study of adjuvant and AI diffusion kinetics in cuticular waxes. In particular, the simultaneously detectable wax modification and, moreover, the determinable water uptake form a perfect basis to establish the ATR-FTIR system as a universal screening tool for wax-adjuvants-AI-water interaction in crop protection science.
Small bacterial regulatory RNAs (sRNAs) have been implicated in the regulation of numerous metabolic pathways. In most of these studies, sRNA-dependent regulation of mRNAs or proteins of enzymes in metabolic pathways has been predicted to affect the metabolism of these bacteria. However, only in a very few cases has the role in metabolism been demonstrated. Here, we performed a combined transcriptome and metabolome analysis to define the regulon of the sibling sRNAs NgncR_162 and NgncR_163 (NgncR_162/163) and their impact on the metabolism of Neisseria gonorrhoeae. These sRNAs have been reported to control genes of the citric acid and methylcitric acid cycles by posttranscriptional negative regulation. By transcriptome analysis, we now expand the NgncR_162/163 regulon by several new members and provide evidence that the sibling sRNAs act as both negative and positive regulators of target gene expression. Newly identified NgncR_162/163 targets are mostly involved in transport processes, especially in the uptake of glycine, phenylalanine, and branched-chain amino acids. NgncR_162/163 also play key roles in the control of serine-glycine metabolism and, hence, probably affect biosyntheses of nucleotides, vitamins, and other amino acids via the supply of one-carbon (C\(_1\)) units. Indeed, these roles were confirmed by metabolomics and metabolic flux analysis, which revealed a bipartite metabolic network with glucose degradation for the supply of anabolic pathways and the usage of amino acids via the citric acid cycle for energy metabolism. Thus, by combined deep RNA sequencing (RNA-seq) and metabolomics, we significantly extended the regulon of NgncR_162/163 and demonstrated the role of NgncR_162/163 in the regulation of central metabolic pathways of the gonococcus.
The discovery, heterologous expression, and characterization of channelrhodopsin-2 (ChR2) – a light-sensitive cation channel found in the green alga Chlamydomonas reinhardtii – led to the success of optogenetics as a powerful technology, first in neuroscience. ChR2 was employed to induce action potentials by blue light in genetically modified nerve cells. In optogenetics, exogenous photoreceptors are expressed in cells to manipulate cellular activity. These photoreceptors were in the beginning mainly microbial opsins. During nearly two decades, many microbial opsins and their mutants were explored for their application in neuroscience. Until now, however, the application of optogenetics to plant studies is limited to very few reports. Several optogenetic strategies for plant research were demonstrated, in which most attempts are based on non-opsin optogenetic tools. Opsins need retinal (vitamin A) as a cofactor to generate the functional protein, the rhodopsin. As most animals have eyes that contain animal rhodopsins, they also have the enzyme - a 15, 15'-Dioxygenase - for retinal production from food-supplied provitamin A (beta-carotene). However, higher plants lack a similar enzyme, making it difficult to express functional rhodopsins successfully in plants. But plant chloroplasts contain plenty of beta-carotene. I introduced a gene, coding for a 15, 15'-Dioxygenase with a chloroplast target peptide, to tobacco plants. This enzyme converts a molecule of β-carotene into two of all-trans-retinal. After expressing this enzyme in plants, the concentration of all-trans-retinal was increased greatly. The increased retinal concentration led to increased expression of several microbial opsins, tested in model higher plants. Unfortunately, most opsins were observed intracellularly and not in the plasma membrane. To improve their localization in the plasma membrane, some reported signal peptides were fused to the N- or C-terminal end of opsins. Finally, I helped to identify three microbial opsins -- GtACR1 (a light-gated anion channel), ChR2 (a light-gated cation channel), PPR (a light-gated proton pump) which express and work well in the plasma membrane of plants. The transgene plants were grown under red light to prevent activation of the expressed opsins. Upon illumination with blue or green light, the activation of these opsins then induced the expected change of the membrane potential, dramatically changing the phenotype of plants with activated rhodopsins.
This study is the first which shows the potential of microbial opsins for optogenetic research in higher plants, using the ubq10 promoter for ubiquitous expression. I expect this to be just the beginning, as many different opsins and tissue-specific promoters for selective expression now can be tested for their usefulness. It is further to be expected that the here established method will help investigators to exploit more optogenetic tools and explore the secrets, kept in the plant kingdom.
Plants do not have neurons but operate transmembrane ion channels and can get electrical excited by physical and chemical clues. Among them the Venus flytrap is characterized by its peculiar hapto-electric signaling. When insects collide with trigger hairs emerging the trap inner surface, the mechanical stimulus within the mechanosensory organ is translated into a calcium signal and an action potential (AP). Here we asked how the Ca\(^{2+}\) wave and AP is initiated in the trigger hair and how it is feed into systemic trap calcium-electrical networks. When Dionaea muscipula trigger hairs matures and develop hapto-electric excitability the mechanosensitive anion channel DmMSL10/FLYC1 and voltage dependent SKOR type Shaker K\(^{+}\) channel are expressed in the sheering stress sensitive podium. The podium of the trigger hair is interface to the flytrap’s prey capture and processing networks. In the excitable state touch stimulation of the trigger hair evokes a rise in the podium Ca2+ first and before the calcium signal together with an action potential travel all over the trap surface. In search for podium ion channels and pumps mediating touch induced Ca\(^{2+}\) transients, we, in mature trigger hairs firing fast Ca\(^{2+}\) signals and APs, found OSCA1.7 and GLR3.6 type Ca\(^{2+}\) channels and ACA2/10 Ca\(^{2+}\) pumps specifically expressed in the podium. Like trigger hair stimulation, glutamate application to the trap directly evoked a propagating Ca\(^{2+}\) and electrical event. Given that anesthetics affect K\(^+\) channels and glutamate receptors in the animal system we exposed flytraps to an ether atmosphere. As result propagation of touch and glutamate induced Ca\(^{2+}\) and AP long-distance signaling got suppressed, while the trap completely recovered excitability when ether was replaced by fresh air. In line with ether targeting a calcium channel addressing a Ca\(^{2+}\) activated anion channel the AP amplitude declined before the electrical signal ceased completely. Ether in the mechanosensory organ did neither prevent the touch induction of a calcium signal nor this post stimulus decay. This finding indicates that ether prevents the touch activated, glr3.6 expressing base of the trigger hair to excite the capture organ.
Honeybees (Apis mellifera) need their fine sense of taste to evaluate nectar and pollen sources. Gustatory receptors (Grs) translate taste signals into electrical responses. In vivo experiments have demonstrated collective responses of the whole Gr-set. We here disentangle the contributions of all three honeybee sugar receptors (AmGr1-3), combining CRISPR/Cas9 mediated genetic knock-out, electrophysiology and behaviour. We show an expanded sugar spectrum of the AmGr1 receptor. Mutants lacking AmGr1 have a reduced response to sucrose and glucose but not to fructose. AmGr2 solely acts as co-receptor of AmGr1 but not of AmGr3, as we show by electrophysiology and using bimolecular fluorescence complementation. Our results show for the first time that AmGr2 is indeed a functional receptor on its own. Intriguingly, AmGr2 mutants still display a wildtype-like sugar taste. AmGr3 is a specific fructose receptor and is not modulated by a co-receptor. Eliminating AmGr3 while preserving AmGr1 and AmGr2 abolishes the perception of fructose but not of sucrose. Our comprehensive study on the functions of AmGr1, AmGr2 and AmGr3 in honeybees is the first to combine investigations on sugar perception at the receptor level and simultaneously in vivo. We show that honeybees rely on two gustatory receptors to sense all relevant sugars.
The negative impact of juvenile undernourishment on adult behavior has been well reported for vertebrates, but relatively little is known about invertebrates. In honeybees, nutrition has long been known to affect task performance and timing of behavioral transitions. Whether and how a dietary restriction during larval development affects the task performance of adult honeybees is largely unknown. We raised honeybees in-vitro, varying the amount of a standardized diet (150 µl, 160 µl, 180 µl in total). Emerging adults were marked and inserted into established colonies. Behavioral performance of nurse bees and foragers was investigated and physiological factors known to be involved in the regulation of social organization were quantified. Surprisingly, adult honeybees raised under different feeding regimes did not differ in any of the behaviors observed. No differences were observed in physiological parameters apart from weight. Honeybees were lighter when undernourished (150 µl), while they were heavier under the overfed treatment (180 µl) compared to the control group raised under a normal diet (160 µl). These data suggest that dietary restrictions during larval development do not affect task performance or physiology in this social insect despite producing clear effects on adult weight. We speculate that possible effects of larval undernourishment might be compensated during the early period of adult life.
Sphingolipid long-chain bases (LCBs) are building blocks for membrane-localized sphingolipids, and are involved in signal transduction pathways in plants. Elevated LCB levels are associated with the induction of programmed cell death and pathogen-derived toxin-induced cell death. Therefore, levels of free LCBs can determine survival of plant cells. To elucidate the contribution of metabolic pathways regulating high LCB levels, we applied the deuterium-labeled LCB D-erythro-sphinganine-d7 (D7-d18:0), the first LCB in sphingolipid biosynthesis, to Arabidopsis leaves and quantified labeled LCBs, LCB phosphates (LCB-Ps), and 14 abundant ceramide (Cer) species over time. We show that LCB D7-d18:0 is rapidly converted into the LCBs d18:0P, t18:0, and t18:0P. Deuterium-labeled ceramides were less abundant, but increased over time, with the highest levels detected for Cer(d18:0/16:0), Cer(d18:0/24:0), Cer(t18:0/16:0), and Cer(t18:0/22:0). A more than 50-fold increase of LCB-P levels after leaf incubation in LCB D7-d18:0 indicated that degradation of LCBs via LCB-Ps is important, and we hypothesized that LCB-P degradation could be a rate-limiting step to reduce high levels of LCBs. To functionally test this hypothesis, we constructed a transgenic line with dihydrosphingosine-1-phosphate lyase 1 (DPL1) under control of an inducible promotor. Higher expression of DPL1 significantly reduced elevated LCB-P and LCB levels induced by Fumonisin B1, and rendered plants more resistant against this fungal toxin. Taken together, we provide quantitative data on the contribution of major enzymatic pathways to reduce high LCB levels, which can trigger cell death. Specifically, we provide functional evidence that DPL1 can be a rate-limiting step in regulating high LCB levels.
Pivotal barrier properties of the hydrophobic plant cuticle covering aerial plant surfaces depend on its physicochemical composition. Among plant species and organs, compounds of this boundary layer between the plant interior and the environment vary considerably but cuticle-related studies comparing different organs from the same plant species are still scarce. Thus, this study focused on the cuticle profiles of Physalis peruviana, Physalis ixocarpa, Alkekengi officinarum, and Nicandra physalodes species. Inflated fruiting calyces enveloping fruits make Physalis, Alkekengi, and Nicandra highly recognizable genera among the Solanoideae subfamily. Although the inflation of fruiting calyces is well discussed in the literature still little is known about their post-floral functionalities. Cuticular composition, surface structure, and barrier function were examined and compared in fully expanded amphistomatous leaves, ripe astomatous fruits, and fully inflated hypostomatous fruiting calyces. Species- and organ-specific abundances of non-glandular and glandular trichomes revealed high structural diversity, covering not only abaxial and adaxial leaf surfaces but also fruiting calyx surfaces, whereas fruits were glabrous. Cuticular waxes, which limit non-stomatal transpiration, ranged from <1 μg cm\(^{−2}\) on P. peruviana fruiting calyces and N. physalodes fruits to 22 μg cm\(^{−2}\) on P. peruviana fruits. Very-long-chain aliphatic compounds, notably n-alkanes, iso-, and anteiso-branched alkanes, alkanols, alkanoic acids, and alkyl esters, dominated the cuticular wax coverages (≥86%). Diversity of cuticular wax patterns rose from leaves to fruiting calyces and peaked in fruits. The polymeric cutin matrix providing the structural framework for cuticular waxes was determined to range from 81 μg cm\(^{−2}\) for N. physalodes to 571 μg cm\(^{−2}\) for A. officinarum fruits. Cuticular transpiration barriers were highly efficient, with water permeabilities being ≤5 × 10\(^{−5}\) m s\(^{−1}\). Only the cuticular water permeability of N. physalodes fruits was 10 × 10\(^{−5}\) m s\(^{−1}\) leading to their early desiccation and fruits that easily split, whereas P. peruviana, P. ixocarpa, and A. officinarum bore fleshy fruits for extended periods after maturation. Regarding the functional significance, fruiting calyces establish a physicochemical shield that reduces water loss and enables fruit maturation within a protective microclimate, and promotes different seed dispersal strategies among plant species investigated.
For the treatment of large bone defects, the commonly used technique of autologous bone grafting presents several drawbacks and limitations. With the discovery of the bone-inducing capabilities of bone morphogenetic protein 2 (BMP2), several delivery techniques were developed and translated to clinical applications. Implantation of scaffolds containing adsorbed BMP2 showed promising results. However, off-label use of this protein-scaffold combination caused severe complications due to an uncontrolled release of the growth factor, which has to be applied in supraphysiological doses in order to induce bone formation. Here, we propose an alternative strategy that focuses on the covalent immobilization of an engineered BMP2 variant to biocompatible scaffolds. The new BMP2 variant harbors an artificial amino acid with a specific functional group, allowing a site-directed covalent scaffold functionalization. The introduced artificial amino acid does not alter BMP2′s bioactivity in vitro. When applied in vivo, the covalently coupled BMP2 variant induces the formation of bone tissue characterized by a structurally different morphology compared to that induced by the same scaffold containing ab-/adsorbed wild-type BMP2. Our results clearly show that this innovative technique comprises translational potential for the development of novel osteoinductive materials, improving safety for patients and reducing costs.
The evolution of the internal water transport system was a prerequisite for high plant productivity. In times of climate change, understanding the dependency of juvenile growth on xylem hydraulic physiology is therefore of high importance. Here, we explored various wood anatomical, hydraulic, and leaf morphological traits related to hydraulic safety and efficiency in three temperate broadleaved tree species (Acer pseudoplatanus, Betula pendula, and Sorbus aucuparia). We took advantage of a severe natural heat wave that resulted in different climatic growing conditions for even-aged plants from the same seed source growing inside a greenhouse and outside. Inside the greenhouse, the daily maximum vapour pressure deficit was on average 36% higher than outside during the growing seasons. Because of the higher atmospheric moisture stress, the biomass production differed up to 5.6-fold between both groups. Except for one species, a high productivity was associated with a high hydraulic efficiency caused by large xylem vessels and a large, supported leaf area. Although no safety-efficiency trade-off was observed, productivity was significantly related to P\(_{50}\) in two of the tree species but without revealing any clear pattern. A considerable plasticity in given traits was observed between both groups, with safety-related traits being more static while efficiency-related traits revealed a higher intra-specific plasticity. This was associated with other wood anatomical and leaf morphological adjustments. We confirm that a high hydraulic efficiency seems to be a prerequisite for a high biomass production, while our controversial results on the growth–xylem safety relationship confirm that safety-efficiency traits are decoupled and that their relationship with juvenile growth and water regime is species-specific.
The light-gated cation channel Channelrhodopsin-2 was discovered and characterized in 2003. Already in 2005/2006 five independent groups demonstrated that heterologous expression of Channelrhodopsin-2 is a highly useful and simply applicable method for depolarizing and thereby activating nerve cells. The application of Channelrhodopsin-2 revolutionized neuroscience research and the method was then called optogenetics. In recent years more and more light-sensitive proteins were successfully introduced as “optogenetic tools”, not only in neuroscience. Optogenetic tools for neuronal excitation are well developed with many different cation-conducting wildtype and mutated channelrhodopsins, whereas for inhibition of neurons in the beginning (2007) only hyperpolarizing ion pumps were available. The later discovered light-activated anion channels (anion channelrhodopsins) can be useful hyperpolarizers, but only at low cytoplasmic anion concentration. For this thesis, I optimized CsR, a proton-pumping rhodopsin from Coccomyxa subellipsoidea, which naturally shows a robust expression in Xenopus laevis oocytes and plant leaves. I improved the expression and therefore the photocurrent of CsR about two-fold by N-terminal modification to the improved version CsR2.0, without altering the proton pump function and the action spectrum. A light pulse hyperpolarised the mesophyll cells of CsR2.0-expressing transgenic tobacco plants (N. tabacum) by up to 20 mV from the resting membrane potential of -150 to -200 mV. The robust heterologous expression makes CsR2.0 a promising optogenetic tool for hyperpolarization in other organisms as well. A single R83H point-mutation converted CsR2.0 into a light-activated (passive) proton channel with a reversal potential close to the Nernst potential for intra-/extra-cellular H+ concentration. This light-gated proton channel is expected to become a further useful optogenetic tool, e.g. for analysis of pH-regulation in cells or the intercellular space. Ion pumps as optogenetic tools require high expression levels and high light intensity for efficient pump currents, whereas long-term illumination may cause unwanted heating effects. Although anion channelrhodopsins are effective hyperpolarizing tools in some cases, their effect on neuronal activity is dependent on the cytoplasmic chloride concentration which can vary among neurons. In nerve cells, increased conductance for potassium terminates the action potential and K+ conductance underlies the resting membrane potential in excitable cells. Therefore, several groups attempted to synthesize artificial light-gated potassium channels but 2 all of these published innovations showed serious drawbacks, ranging from poor expression over lacking reversibility to poor temporal precision. A highly potassium selective light-sensitive silencer of action potentials is needed. To achieve this, I engineered a light-activated potassium channel by the genetic fusion of a photoactivated adenylyl cyclase, bPAC, and a cAMP-gated potassium channel, SthK. Illumination activates bPAC to produce cAMP and the elevated cAMP level opens SthK. The slow diffusion and degradation of cAMP makes this construct a very light-sensitive, long-lasting inhibitor. I have successfully developed four variants with EC50 to cAMP ranging from 7 over 10, 21, to 29 μM. Together with the original fusion construct (EC50 to cAMP is 3 μm), there are five different light- (or cAMP-) sensitive potassium channels for researchersto choose, depending on their cell type and light intensity needs.
Stomata are pores in the leaf surface, formed by pairs of guard cells. The guard cells modulate the aperture of stomata, to balance uptake of CO2 and loss of water vapor to the atmosphere. During drought, the phytohormone abscisic acid (ABA) provokes stomatal closure, via a signaling chain with both Ca2+-dependent and Ca2+-independent branches. Both branches are likely to activate SLAC1-type (Slow Anion Channel Associated 1) anion channels that are essential for initiating the closure of stomata. However, the importance of the Ca2+-dependent signaling branch is still debated, as the core ABA signaling pathway only possesses Ca2+-independent components. Therefore, the aim of this thesis was to address the role of the Ca2+-dependent branch in the ABA signaling pathway of guard cells.
In the first part of the thesis, the relation between ABA-induced Ca2+ signals and stomatal closure was studied, with guard cells that express the genetically encoded Ca2+-indicator R-GECO1-mTurquoise. Ejection of ABA into the guard cell wall rapidly induced stomatal closure, however, only in ¾ of the guard cells ABA evoked a cytosolic Ca2+ signal. A small subset of stomata (¼ of the experiments) closed without Ca2+ signals, showing that the Ca2+ signals are not essential for ABA-induced stomatal closure. However, stomata in which ABA evoked Ca2+ signals closed faster as those in which no Ca2+ signals were detected. Apparently, ABA-induced Ca2+ signals enhance the velocity of stomatal closure. In addition to ABA, hyperpolarizing voltage pulses could also trigger Ca2+ signals in wild type guard cells, which in turn activated S-type anion channels. However, these voltage pulses failed to elicit S-type anion currents in the slac1/slah3 guard cells, suggesting that SLAC1 and SLAH3 contribute to Ca2+-activated conductance. Taken together, our data indicate that ABA-induced Ca2+ signals enhance the activity of S-type anion channels, which accelerates stomatal closure.
The second part of the thesis deals with the signaling pathway downstream of the Ca2+ signals. Two types of Ca2+-dependent protein kinase modules (CPKs and CBL/CIPKs) have been implicated in guard cells. We focused on the protein kinase CIPK23 (CBL-Interacting Protein Kinase 23), which is activated by the Ca2+-dependent protein CBL1 or 9 (Calcineurin B-Like protein 1 or 9) via interacting with the NAF domain of CIPK23. The CBL1/9-CIPK23 complex has been shown to affect stomatal movements, but the underlying molecular mechanisms remain largely unknown. We addressed this topic by using an estrogen-induced expression system, which specifically enhances the expression of wild type CIPK23, a phosphomimic CIPK23T190D and a kinase dead CIPK23K60N in guard cells. Our data show that guard cells expressing CIPK23T190D promoted stomatal opening, while CIPK23K60N enhanced ABA-induced stomatal closure, suggesting that CIPK23 is a negative regulator of stomatal closure. Electrophysiological measurements revealed that the inward K+ channel currents were similar in guard cells that expressed CIPK23, CIPK23T190D or CIPK23K60N, indicating that CIPK23-mediated inward K+ channel AKT1 does not contribute to stomatal movements. Expression of CIPK23K60N, or loss of CIPK23 in guard cells enhanced S-type anion activity, while the active CIPK23T190D inhibited the activity of these anion channels. These results are in line with the detected changes in stomatal movements and thus indicate that CIPK23 regulates stomatal movements by inhibiting S-type anion channels. CIPK23 thus serves as a brake to control anion channel activity. Overall, our findings demonstrate that CIPK23-mediated stomatal movements do not depend on CIPK23-AKT1 module, instead, it is achieved by regulating S-type anion channels SLAC1 and SLAH3.
In sum, the data presented in this thesis give new insights into the Ca2+-dependent branch of ABA signaling, which may help to put forward new strategies to breed plants with enhanced drought stress tolerance, and in turn boost agricultural productivity in the future.
Rhodopsin-cyclases for photocontrol of cGMP/cAMP and 2.3 Å structure of the adenylyl cyclase domain
(2018)
The cyclic nucleotides cAMP and cGMP are important second messengers that orchestrate fundamental cellular responses. Here, we present the characterization of the rhodopsinguanylyl cyclase from Catenaria anguillulae (CaRhGC), which produces cGMP in response to green light with a light to dark activity ratio > 1000. After light excitation the putative signaling state forms with tau = 31 ms and decays with tau = 570 ms. Mutations (up to 6) within the nucleotide binding site generate rhodopsin-adenylyl cyclases (CaRhACs) of which the double mutated YFP-CaRhAC (E497K/C566D) is the most suitable for rapid cAMP production in neurons. Furthermore, the crystal structure of the ligand-bound AC domain (2.25 angstrom) reveals detailed information about the nucleotide binding mode within this recently discovered class of enzyme rhodopsin. Both YFP-CaRhGC and YFP-CaRhAC are favorable optogenetic tools for non-invasive, cell-selective, and spatio-temporally precise modulation of cAMP/cGMP with light.
The recently observed consistent loss of β-diversity across ecosystems indicates increasingly homogeneous communities in patches of landscapes, mainly caused by increasing land-use intensity. Biodiversity is related to numerous ecosystem functions and stability. Therefore, decreasing β-diversity is also expected to reduce multifunctionality. To assess the impact of homogenization and to develop guidelines to reverse its potentially negative effects, we combine expertise from forest science, ecology, remote sensing, chemical ecology and statistics in a collaborative and experimental β-diversity approach. Specifically, we will address the question whether the Enhancement of Structural Beta Complexity (ESBC) in forests by silviculture or natural disturbances will increase biodiversity and multifunctionality in formerly homogeneously structured production forests. Our approach will identify potential mechanisms behind observed homogenization-diversity-relationships and show how these translate into effects on multifunctionality. At eleven forest sites throughout Germany, we selected two districts as two types of small ‘forest landscapes’. In one of these two districts, we established ESBC treatments (nine differently treated 50x50 m patches with a focus on canopy cover and deadwood features). In the second, the control district, we will establish nine patches without ESBC. By a comprehensive sampling, we will monitor 18 taxonomic groups and measure 21 ecosystem functions, including key functions in temperate forests, on all patches. The statistical framework will allow a comprehensive biodiversity assessment by quantifying the different aspects of multitrophic biodiversity (taxonomical, functional and phylogenetic diversity) on different levels of biodiversity (α-, β-, γ-diversity). To combine overall diversity, we will apply the concept of multidiversity across the 18 taxa. We will use and develop new approaches for quantification and partitioning of multifunctionality at α- and β- scales. Overall, our study will herald a new research avenue, namely by experimentally describing the link between β-diversity and multifunctionality. Furthermore, we will help to develop guidelines for improved silvicultural concepts and concepts for management of natural disturbances in temperate forests reversing past homogenization effects.
In vitro rearing of honeybee larvae is an established method that enables exact control and monitoring of developmental factors and allows controlled application of pesticides or pathogens. However, only a few studies have investigated how the rearing method itself affects the behavior of the resulting adult honeybees. We raised honeybees in vitro according to a standardized protocol: marking the emerging honeybees individually and inserting them into established colonies. Subsequently, we investigated the behavioral performance of nurse bees and foragers and quantified the physiological factors underlying the social organization. Adult honeybees raised in vitro differed from naturally reared honeybees in their probability of performing social tasks. Further, in vitro-reared bees foraged for a shorter duration in their life and performed fewer foraging trips. Nursing behavior appeared to be unaffected by rearing condition. Weight was also unaffected by rearing condition. Interestingly, juvenile hormone titers, which normally increase strongly around the time when a honeybee becomes a forager, were significantly lower in three- and four-week-old in vitro bees. The effects of the rearing environment on individual sucrose responsiveness and lipid levels were rather minor. These data suggest that larval rearing conditions can affect the task performance and physiology of adult bees despite equal weight, pointing to an important role of the colony environment for these factors. Our observations of behavior and metabolic pathways offer important novel insight into how the rearing environment affects adult honeybees.
The plant hormone jasmonoyl-isoleucine (JA-Ile) is an important regulator of plant growth and defense in response to various biotic and abiotic stress cues. Under our experimental conditions, JA-Ile levels increased approximately seven-fold in NaCl-treated Arabidopsis thaliana roots. Although these levels were around 1000-fold lower than in wounded leaves, genes of the JA-Ile signaling pathway were induced by a factor of 100 or more. Induction was severely compromised in plants lacking the JA-Ile receptor CORONATINE INSENSITIVE 1 or enzymes required for JA-Ile biosynthesis. To explain efficient gene expression at very low JA-Ile levels, we hypothesized that salt-induced expression of the JA/JA-Ile transporter JAT1/AtABCG16 would lead to increased nuclear levels of JA-Ile. However, mutant plants with different jat1 alleles were similar to wild-type ones with respect to salt-induced gene expression. The mechanism that allows COI1-dependent gene expression at very low JA-Ile levels remains to be elucidated.
Pflanzen müssen sich während der Samenkeimung und Keimlingsentwicklung über eingelagerte Speicherstoffe heterotroph versorgen, bis sie, nach Etablierung ihres Photosyntheseapparats, einen autotrophen Lebensstil führen können.
Diese Arbeit geht von der Hypothese aus, dass der evolutionär konservierten zentral-metabolischen Kinase Snf1-RELATED PROTEIN KINASE 1 (SnRK1) eine besondere Rolle bei der Mobilisierung von Speicherstoffen während der Keimlingsentwicklung zukommt. Während die Bedeutung von SnRK1 als zentraler Regulator katabolischer Prozesse unter Energiemangel- und Stresssituationen bereits gezeigt wurde, war die Funktion von SnRK1 im Zusammenhang mit der Samenkeimung weitgehend ungeklärt. In dieser Arbeit konnte erstmals gezeigt werden, dass SnRK1 in Arabidopsis die Mobilisierung und Degradation von Speicherstoffen, insbesondere von Triacylglyceride (TAGs), Samenspeicherproteinen und Aminosäuren, steuert. Sowohl Studien zur Lokalisation von SnRK1:GFP-Fusionsproteinen als auch Kinaseaktivitätsassays unterstützen eine mögliche Funktion von SnRK1 während der Keimlingsentwicklung. Eine induzierbare snrk1-knockdown Mutante zeigt neben einem eingeschränkten Wurzel- und Hypokotylwachstum auch keine Ausbildung eines Photosyntheseapparats, was die zentrale Rolle der SnRK1 in diesem frühen Entwicklungsstadium untermauert. Durch Fütterungsexperimente mit Glukose konnte der Phänotyp einer snrk1 -Mutante in Keimlingen gerettet werden. Dies zeigt, dass der metabolische Block durch externe Gabe von Kohlenhydraten umgangen werden kann. Die zentrale Funktion von SnRK1 ist folgich der Abbau von Speicherstoffen und keine allgemeine Deregulation des pflanzlichen Stoffwechsels. Durch massenspektrometrische Untersuchungen von Keimlingen des Wildtyps und der snrk1-Mutante konnte gezeigt werden, dass TAGs in der Mutante in der spä- ten Keimlingsentwicklung ab Tag 4 langsamer abgebaut werden als im Wildtyp. Ebenso werden Samenspeicherproteine in der Mutante langsamer degradiert, wodurch die Verfügbarkeit von freien Aminosäuren in geringer ist. Entgegen der allgemeinen Annahme konnte gezeigt werden, dass während der Keimlingsentwicklung zumindest in Arabidopsis, einer ölhaltigen Pflanze, zunächst Kohlenhydrate in Form von Saccharose abgebaut werden, bevor die Degradation von TAGs und Aminosäuren beginnt. Diese Abbauprodukte können dann der Glukoneogenese zugeführt werden um daraus Glukose herzustellen. Mittels Transkriptom-Analysen konnten zentrale SnRK1-abhängige Gene in der Speicherstoffmobilisierung von TAG, beispielsweise PEROXISOMAL NAD-MALATE DEHYDROGENASE 2 (PMDH2) und ACYL-CoA-OXIDASE 4 (ACX4), und Aminosäuren identifiziert werden. Somit wurde ein Mechanismus der SnRK1-abhängigen Genregulation während der Samenkeimung in Arabidopsis gefunden. Bei der Degradation von Aminosäuren wird die cytosolische PYRUVATE ORTHOPHOSPHATE DIKINASE (cyPPDK), ein Schlüsselenzym beim Abbau bestimmter Aminosäuren und bei der Glukoneogenese, SnRK1-abhängig transkriptionell reguliert. Durch Koregulation konnte der Transkriptionsfaktor bZIP63 (BASIC LEUCINE ZIPPER 63) gefunden werden, dessen Transkription ebenfalls SnRK1-abhängig reguliert wird. Außerdem konnte die Transkription von cyPPDK in bzip63-Mutanten nur noch sehr schwach induziert werden. In Protoplasten konnte der cyPPDK-Promotor durch Aktivierungsexperimente mit bZIP63 und SnRK1α1 induziert werden. Durch Mutationskartierung und Chromatin-Immunopräzipitation (ChIP)PCR konnte mehrfach eine direkte Bindung von bZIP63 an den cyPPDK-Promotor nachgewiesen werden. Zusammenfassend ergibt sich ein mechanistisches Arbeitsmodell, in dem bZIP63 durch SnRK1 phosphoryliert wird und durch Bindung an regulatorische G-Box cis-Elemente im cyPPDK- Promotor dessen Transkription anschaltet. Infolgedessen werden Aminosäuren abgebaut und wird über die Glukoneogenese Glukose aufgebaut. Dieser Mechanismus ist essentiell für die Übergangsphase zwischen heterotropher und autotropher Lebensweise, und trägt dazu bei, die im Samen vorhandenen Ressourcen dem Keimling zum idealen Zeitpunkt zugänglich zu machen. Darüber hinaus werden Gene im Abbau von verzweigtkettigen Aminosäuren ebenfalls durch bZIP63 reguliert. Dabei wird dem Keimling Energie in Form von Adenosin-Triphosphat (ATP) zur Verfügung gestellt.
Zusammengefasst zeigen die Ergebnisse dieser Arbeit, dass die Mobilisierung von Speicherstoffen auch während der Keimlingsentwicklung direkt von SnRK1 abhängig ist. Die umfangreichen Datensätze der RNA-Seq-Analysen bieten zudem die Möglichkeit, weitere SnRK1-abhängige Gene der Speichermobilisierung zu identifizieren und somit einem besseren Verständnis der Keimlingsentwicklung beizutragen. Aufgrund der zentralen Bedeutung der SnRK1-Kinase in diesem entscheidenden Entwicklungsschritt ist davon auszugehen, dass diese Erkenntnisse mittelfristig auch für bessere Keimungsraten und somit bessere Erträge in der Landwirtschaft genutzt werden können.
Plant transpiration is a key element in the hydrological cycle. Widely used methods for its assessment comprise sap flux techniques for whole-plant transpiration and porometry for leaf stomatal conductance. Recently emerging approaches based on surface temperatures and a wide range of machine learning techniques offer new possibilities to quantify transpiration. The focus of this study was to predict sap flux and leaf stomatal conductance based on drone-recorded and meteorological data and compare these predictions with in-situ measured transpiration. To build the prediction models, we applied classical statistical approaches and machine learning algorithms. The field work was conducted in an oil palm agroforest in lowland Sumatra. Random forest predictions yielded the highest congruence with measured sap flux (r\(^2\) = 0.87 for trees and r\(^2\) = 0.58 for palms) and confidence intervals for intercept and slope of a Passing-Bablok regression suggest interchangeability of the methods. Differences in model performance are indicated when predicting different tree species. Predictions for stomatal conductance were less congruent for all prediction methods, likely due to spatial and temporal offsets of the measurements. Overall, the applied drone and modelling scheme predicts whole-plant transpiration with high accuracy. We conclude that there is large potential in machine learning approaches for ecological applications such as predicting transpiration.
A part of the plant kingdom consists of a variety of carnivorous plants. Some trap their prey
using sticky leaves, others have pitfall traps where prey cannot escape once it has fallen inside.
A rare trap type is the snap-trap: it appears only twice in the plant kingdom, in the genera
Aldrovanda and Dionaea. Even Charles Darwin himself described Dionaea muscipula, the
Venus flytrap, with the following words “This plant, commonly called Venus' fly-trap, from the
rapidity and force of its movements, is one of the most wonderful in the world”. For a long
time now, the mechanisms of Dionaea’s prey recognition, capture and utilization are of
interest for scientists and have been studied intensively.
Dionaea presents itself with traps wide-open, ready to catch insects upon contact. For this,
the insect has to touch the trigger hairs of the opened trap twice within about 20-30 seconds.
Once the prey is trapped, the trap lobes close tight, forming a hermetically sealed “green
stomach”.
Until lately, there was only limited knowledge about the molecular and hormonal mechanisms
which lead to prey capture and excretion of digestive fluids. It is known that the digestion
process is very water-consuming; therefore, the interplay of digestion-inducing and digestion inhibiting
substances was to be analyzed in this work, to elucidate the fine-tuning of the
digestive pathway. Special attention was given to the impact of phytohormones on mRNA
transcript levels of digestion-related proteins after various stimuli as well as their effect on
Dionaea’s physiological responses.
Jasmonic acid (JA) and its isoleucine-conjugated form, JA-Ile, are an important signal in the
jasmonate pathway. In the majority of non-carnivorous plants, jasmonates are critical for the
defense against herbivory and pathogens. In Dionaea, this defense mechanism has been
restructured towards offensive prey catching. One question in this work was how the
frequency of trigger hair bendings is related to the formation of jasmonates and the induction
of the digestion process. Upon contact of a prey with the trigger hairs in the inside of the trap,
the trap closes and jasmonates are produced biosynthetically. JA-Ile interacts with the COI1-
receptor, thereby activating the digestion pathway which leads to the secretion of digestive
fluid and production of transporters needed to take up prey-derived nutrients. In this work it
could be shown that the number of trigger hair bendings is positively correlated with the level
and duration of transcriptional induction of several digestive enzymes/hydrolases.
Abscisic acid (ABA) acts, along with many other functions, as the plant “drought stress
hormone”. It is synthesized either by roots as the primary sensor for water shortage or by
guard cells in the leaves. ABA affects a network of several thousand genes whose regulation
prepares the plant for drought and initiates protective measurements. It was known from
previous work that the application of ABA for 48 hours increased the required amount of
trigger hair bendings to achieve trap closure. As the digestion process is very water-intensive,
the question arose how exactly the interplay between the jasmonate- and the ABA-pathway
is organized, and if ABA could stop the running digestion process once it had been activated.
In the present work it could be shown that the application of ABA on intact traps prior to
mechanically stimulating the trigger hairs (mechanostimulation) already significantly reduced
the transcription of digestive enzymes for an incubation time as short as 4 h, showing that
already short-term exposure to ABA counteracts the effects of jasmonates when it comes to
initiating the digestion process, but does not inhibit trap closure. Incubation for 24 and 48
hours with 100 μM active ABA had no effect on trap reopening, only very high levels of 200
μM of active ABA inhibited trap reopening but also led to tissue necrosis. As the application
of ABA could reduce the transcription of digestive hydrolases, it is likely that Dionaea can stop
the digestion process, if corresponding external stimuli are received.
Another factor, which only emerged later, was the effect of the wounding-induced systemic
jasmonate burst. As efficient as ABA was in inhibiting marker hydrolase expression after
mechanostimulation in intact plants, the application of ABA on truncated traps was not able
to inhibit mechanostimulation-induced marker hydrolase expression. One reason might be
that the ABA-signal is perceived in the roots, and therefore truncated traps were not able to
react to it. Another reason might be that the wounding desensitized the tissue for the ABAsignal.
Further research is required at this point.
Inhibitors of the jasmonate pathway were also used to assess their effect on the regulation of
Dionaea´s hunting cycle. Coronatine-O-methyloxime proved to be a potent inhibitor of
mechanostimulation-induced expression of digestive enzymes, thus confirming the key
regulatory role of jasmonates for Dionaea´s prey consumption mechanism.
In a parallel project, the generation of in vitro cultures from sterilized seeds and single plant
parts proved successful, which may be important for stock-keeping of future transgenic lines.
Protoplasts were generated from leaf blade tissue and transiently transformed, expressing the
reporter protein YFP after 24 h of incubation. In the future this might be the starting point for
the generation of transgenic lines or the functional testing of DNA constructs.
Optogenetics became successful in neuroscience with Channelrhodopsin-2 (ChR2), a light-gated cation channel from the green alga Chlamydomonas reinhardtii, as an easy applicable tool. The success of ChR2 inspired the development of various photosensory proteins as powerful actuators for optogenetic manipulation of biological activity. However, the current optogenetic toolbox is still not perfect and further improvements are desirable. In my thesis, I engineered and characterized several different optogenetic tools with new features.
(i) Although ChR2 is the most often used optogenetic actuator, its single-channel conductance and its Ca2+ permeability are relatively low. ChR2 variants with increased Ca2+ conductance were described recently but a further increase seemed possible. In addition, the H+ conductance of ChR2 may lead to cellular acidification and unintended pH-related side effects upon prolonged illumination. Through rational design, I developed several improved ChR2 variants with larger photocurrent, higher cation selectivity, and lower H+ conductance.
(ii) The light-activated inward chloride pump NpHR is a widely used optogenetic tool for neural silencing. However, pronounced inactivation upon long time illumination constrains its application for long-lasting neural inhibition. I found that the deprotonation of the Schiff base underlies the inactivation of NpHR. Through systematically exploring optimized illumination schemes, I found illumination with blue light alone could profoundly increase the temporal stability of the NpHR-mediated photocurrent. A combination of green and violet light eliminates the inactivation effect, similar to blue light, but leading to a higher photocurrent and therefore better light-induced inhibition.
(iii) Photoactivated adenylyl cyclases (PACs) were shown to be useful for light-manipulation of cellular cAMP levels. I developed a convenient in-vitro assay for soluble PACs that allows their reliable characterization. Comparison of different PACs revealed that bPAC from Beggiatoa is the best optogenetic tool for cAMP manipulation, due to its high efficiency and small size. However, a residual activity of bPAC in the dark is unwanted and the cytosolic localization prevents subcellular precise cAMP manipulation. I therefore introduced point mutations into bPAC to reduce its dark activity. Interestingly, I found that membrane targeting of bPAC with different linkers can remarkably alter its activity, in addition to its localization. Taken together, a set of PACs with different activity and subcellular localization were engineered for selection based on the intended usage. The membrane-bound PM-bPAC 2.0 with reduced dark activity is well-tolerated by hippocampal neurons and reliably evokes a transient photocurrent, when co-expression with a CNG channel.
(iv) Bidirectional manipulation of cell activity with light of different wavelengths is of great importance in dissecting neural networks in the brain. Selection of optimal tool pairs is the first and most important step for dual-color optogenetics. Through N- and C-terminal modifications, an improved ChR variant (i.e. vf-Chrimson 2.0) was engineered and selected as the red light-controlled actuator for excitation. Detailed comparison of three two-component potassium channels, composed of bPAC and the cAMP-activated potassium channel SthK, revealed the superior properties of SthK-bP. Combining vf-Chrimson 2.0 and improved SthK-bP “SthK(TV418)-bP” could reliably induce depolarization by red light and hyperpolarization by blue light. A residual tiny crosstalk between vf-Chrimson 2.0 and SthK(TV418)-bP, when applying blue light, can be minimized to a negligible level by applying light pulses or simply lowering the blue
light intensity.
While much research has addressed the aboveground response of trees to climate warming and related water shortage, not much is known about the drought sensitivity of the fine root system, in particular of mature trees. This study investigates the response of topsoil (0–10 cm) fine root biomass (FRB), necromass (FRN), and fine root morphology of five temperate broadleaf tree species (Acer platanoides L., Carpinus betulus L., Fraxinus excelsior L., Quercus petraea (Matt.) Liebl., Tilia cordata Mill.) to a reduction in water availability, combining a precipitation gradient study (nine study sites; mean annual precipitation (MAP): 920–530 mm year\(^{−1}\)) with the comparison of a moist period (average spring conditions) and an exceptionally dry period in the summer of the subsequent year. The extent of the root necromass/biomass (N/B) ratio increase was used as a measure of the species’ belowground sensitivity to water deficits. We hypothesized that the N/B ratio increases with long-term (precipitation gradient) and short-term reductions (moist vs. dry period) of water availability, while FRB changes only a little. In four of the five species (exception: A. platanoides), FRB did not change with a reduction in MAP, whereas FRN and N/B ratio increased toward the dry sites under ample water supply (exception: Q. petraea). Q. petraea was also the only species not to reduce root tip frequency after summer drought. Different slopes of the N/B ratio-MAP relation similarly point at a lower belowground drought sensitivity of Q. petraea than of the other species. After summer drought, all species lost the MAP dependence of the N/B ratio. Thus, fine root mortality increased more at the moister than the drier sites, suggesting a generally lower belowground drought sensitivity of the drier stands. We conclude that the five species differ in their belowground drought response. Q. petraea follows the most conservative soil exploration strategy with a generally smaller FRB and more drought-tolerant fine roots, as it maintains relatively constant FRB, FRN, and morphology across spatial and temporal dimensions of soil water deficits.
Studying how cambial age and axial height affects wood anatomical traits may improve our understanding of xylem hydraulics, heartwood formation and axial growth. Radial strips were collected from six different heights (0–11.3 m) along the main trunk of three Manchurian catalpa (Catalpa bungei) trees, yielding 88 samples. In total, thirteen wood anatomical vessel and fiber traits were observed usinglight microscopy (LM) and scanning electron microscopy (SEM), and linear models were used to analyse the combined effect of axial height, cambial age and their interaction. Vessel diameter differed by about one order of magnitude between early- and latewood, and increased significantly with both cambial age and axial height in latewood, while it was positively affected by cambial age and independent of height in earlywood. Vertical position further had a positive effect on earlywood vessel density, and negative effects on fibre wall thickness, wall thickness to diameter ratio and length. Cambial age had positive effects on the pit membrane diameter and vessel element length, while the annual diameter growth decreased with both cambial age and axial position. In contrast, early- and latewood fiber diameter were unaffected by both cambial age and axial height. We further observed an increasing amount of tyloses from sapwood to heartwood, accompanied by an increase of warty layers and amorphous deposits on cell walls, bordered pit membranes and pit apertures. This study highlights the significant effects of cambial age and vertical position on xylem anatomical traits, and confirms earlier work that cautions to take into account xylem spatial position when interpreting wood anatomical structures, and thus, xylem hydraulic functioning.
Protein purification is the vital basis to study the function, structure and interaction of proteins. Widely used methods are affinity chromatography-based purifications, which require different chromatography columns and harsh conditions, such as acidic pH and/or adding imidazole or high salt concentration, to elute and collect the purified proteins. Here we established an easy and fast purification method for soluble proteins under mild conditions, based on the light-induced protein dimerization system improved light-induced dimer (iLID), which regulates protein binding and release with light. We utilize the biological membrane, which can be easily separated by centrifugation, as the port to anchor the target proteins. In Xenopus laevis oocyte and Escherichia coli, the blue light-sensitive part of iLID, AsLOV2-SsrA, was targeted to the plasma membrane by different membrane anchors. The other part of iLID, SspB, was fused with the protein of interest (POI) and expressed in the cytosol. The SspB-POI can be captured to the membrane fraction through light-induced binding to AsLOV2-SsrA and then released purely to fresh buffer in the dark after simple centrifugation and washing. This method, named mem-iLID, is very flexible in scale and economic. We demonstrate the quickly obtained yield of two pure and fully functional enzymes: a DNA polymerase and a light-activated adenylyl cyclase. Furthermore, we also designed a new SspB mutant for better dissociation and less interference with the POI, which could potentially facilitate other optogenetic manipulations of protein–protein interaction.
Cytosolic calcium signals are evoked by a large variety of biotic and abiotic stimuli and play an important role in cellular and long distance signalling in plants. While the function of the plasma membrane in cytosolic Ca\(^{2+}\) signalling has been intensively studied, the role of the vacuolar membrane remains elusive.
A newly developed vacuolar voltage clamp technique was used in combination with live-cell imaging, to study the role of the vacuolar membrane in Ca\(^{2+}\) and pH homeostasis of bulging root hair cells of Arabidopsis.
Depolarisation of the vacuolar membrane caused a rapid increase in the Ca\(^{2+}\) concentration and alkalised the cytosol, while hyperpolarisation led to the opposite responses.
The relationship between the vacuolar membrane potential, the cytosolic pH and Ca2+ concentration suggests that a vacuolar H\(^{+}\)/Ca\(^{2+}\) exchange mechanism plays a central role in cytosolic Ca2+ homeostasis. Mathematical modelling further suggests that the voltage-dependent vacuolar Ca\(^{2+}\) homeostat could contribute to calcium signalling when coupled to a recently discovered K\(^{+}\) channel-dependent module for electrical excitability of the vacuolar membrane.
Plant stress signalling involves bursts of reactive oxygen species (ROS), which can be mimicked by the application of acute pulses of ozone. Such ozone-pulses inhibit photosynthesis and trigger stomatal closure in a few minutes, but the signalling that underlies these responses remains largely unknown.
We measured changes in Arabidopsis thaliana gas exchange after treatment with acute pulses of ozone and set up a system for simultaneous measurement of membrane potential and cytosolic calcium with the fluorescent reporter R-GECO1.
We show that within 1 min, prior to stomatal closure, O\(_{3}\) triggered a drop in whole-plant CO\(_{2}\) uptake. Within this early phase, O\(_{3}\) pulses (200–1000 ppb) elicited simultaneous membrane depolarization and cytosolic calcium increase, whereas these pulses had no long-term effect on either stomatal conductance or photosynthesis. In contrast, pulses of 5000 ppb O\(_{3}\) induced cell death, systemic Ca\(^{2+}\) signals and an irreversible drop in stomatal conductance and photosynthetic capacity.
We conclude that mesophyll cells respond to ozone in a few seconds by distinct pattern of plasma membrane depolarizations accompanied by an increase in the cytosolic calcium ion (Ca\(^{2+}\)) level. These responses became systemic only at very high ozone concentrations. Thus, plants have rapid mechanism to sense and discriminate the strength of ozone signals.
Guard cells control the aperture of plant stomata, which are crucial for global fluxes of CO\(_2\) and water. In turn, guard cell anion channels are seen as key players for stomatal closure, but is activation of these channels sufficient to limit plant water loss? To answer this open question, we used an optogenetic approach based on the light-gated anion channelrhodopsin 1 (GtACR1). In tobacco guard cells that express GtACR1, blue- and green-light pulses elicit Cl\(^-\) and NO\(_3\)\(^-\) currents of -1 to -2 nA. The anion currents depolarize the plasma membrane by 60 to 80 mV, which causes opening of voltage-gated K+ channels and the extrusion of K+. As a result, continuous stimulation with green light leads to loss of guard cell turgor and closure of stomata at conditions that provoke stomatal opening in wild type. GtACR1 optogenetics thus provides unequivocal evidence that opening of anion channels is sufficient to close stomata.
Soil salinity is an increasingly global problem which hampers plant growth and crop yield. Plant productivity depends on optimal water-use efficiency and photosynthetic capacity balanced by stomatal conductance. Whether and how stomatal behavior contributes to salt sensitivity or tolerance is currently unknown. This work identifies guard cell-specific signaling networks exerted by a salt-sensitive and salt-tolerant plant under ionic and osmotic stress conditions accompanied by increasing NaCl loads.
We challenged soil-grown Arabidopsis thaliana and Thellungiella salsuginea plants with short- and long-term salinity stress and monitored genome-wide gene expression and signals of guard cells that determine their function.
Arabidopsis plants suffered from both salt regimes and showed reduced stomatal conductance while Thellungiella displayed no obvious stress symptoms. The salt-dependent gene expression changes of guard cells supported the ability of the halophyte to maintain high potassium to sodium ratios and to attenuate the abscisic acid (ABA) signaling pathway which the glycophyte kept activated despite fading ABA concentrations.
Our study shows that salinity stress and even the different tolerances are manifested on a single cell level. Halophytic guard cells are less sensitive than glycophytic guard cells, providing opportunities to manipulate stomatal behavior and improve plant productivity.
Background
While leaves are far more accessible for analysing plant defences, roots are hidden in the soil, leading to difficulties in studying soil-borne interactions. Inoculation strategies for infecting model plants with model root pathogens are described in the literature, but it remains demanding to obtain a methodological overview. To address this challenge, this study uses the model root pathogen Verticillium longisporum on Arabidopsis thaliana host plants and provides recommendations for selecting appropriate infection systems to investigate how plants cope with root pathogens.
Results
A novel root infection system is introduced, while two existing ones are precisely described and optimized. Step-by-step protocols are presented and accompanied by pathogenicity tests, transcriptional analyses of indole-glucosinolate marker genes and independent confirmations using reporter constructs. Advantages and disadvantages of each infection system are assessed. Overall, the results validate the importance of indole-glucosinolates as secondary metabolites that limit the Verticillium propagation in its host plant.
Conclusion
Detailed assistances on studying host defence strategies and responses against V. longisporum is provided. Furthermore, other soil-borne microorganisms (e.g., V. dahliae) or model plants, such as economically important oilseed rape and tomato, can be introduced in the infection systems described. Hence, these proven manuals can support finding a root infection system for your specific research questions to further decipher root-microbe interactions.