@phdthesis{vonMeyer2021,
  author    = {von Meyer, Katharina},
  title     = {Molecular characterization of defensin-like proteins in the fertilization process of \(Nicotiana\) \(tabacum\)},
  doi       = {10.25972/OPUS-19214},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-192141},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2021},
  abstract  = {Flowering plants or angiosperms have developed a fertilization mechanism that involves a female egg and central cell, as well as two male sperm cells. A male gametophyte carries the two non-mobile sperm cells, as they need to be delivered to the female gametophyte, the embryo sac. This transport is initiated by a pollen grain that is transmitted onto the stigma of the angiosperm flower. Here it hydrates, germinates, and forms a pollen tube, which navigates through the female plant tissue towards the ovary. The pollen tube grows into an ovule through the funiculus and into one of the two synergid cells. There, growth arrests and the pollen tube bursts, releasing the two sperm cells. One of the sperm cells fuses with the egg cell, giving rise to the embryo, the other one fuses with the central cell, developing into the endosperm, which nourishes the embryo during its development. After a successful fertilization, each ovule develops into a seed and a fruit is formed. This usually consists of several fertilized ovules. The directional growth of the pollen tube through the maternal tissues towards the ovule, as well as sperm cell release, requires a complex communication between the male and the female gametophyte to achieve reproductive success. Over the last years many studies have been performed, contributing to the understanding of cell-cell communication events between the two gametophytes, nevertheless still many aspects remain to be elucidated. This work focused on two topics: i.) Analysis of biological processes affected by pollination and fertilization in the Nicotiana tabacum flower and identification of cysteine rich proteins (CRPs) expressed via isolating and sequencing RNA from the tissue and analyzing the resulting data. ii.) Identification of the defensin-like protein (DEFL) responsible for pollen tube attraction towards the ovule in tobacco. First, tissue samples of pollen tubes and mature ovules were taken at different stages of the fertilization process (unpollinated ovules, after pollination, and after fertilization of the flower). RNA was then isolated and a transcriptome was created. The resulting reads were assembled and transcriptome data analysis was performed. Results showed that pollen tubes and mature ovules differ severely from each other, only sharing about 23 \% of the transcripts, indicating that different biological processes are dominant in the two gametophytes. A MapMan analysis revealed that in the pollen tube the most relevant biological processes are related to the cell wall, signaling, and transport, which supports the fact that the pollen tube grows fast to reach the ovule. On the other hand, in the ovule the values of highest significance were obtained for processes related to protein synthesis and regulation. Upon comparing the transcripts in the ovule before and after pollination, as well as after fertilization, it showed that pollination of the flower causes a bigger alteration in the ovule on the transcriptomic level compared to the step from pollination to fertilization. A total of 953 CRPs were identified in Nicotiana tabacum, including 116 DEFLs. Among those, the peptide responsible for pollen tube attraction towards the ovule should be found. Based on in-silico analysis four candidate peptides were chosen for further analysis, two of which had increased expression levels upon pollination and fertilization and the other two displayed an opposite expression. Quantitative real time PCR experiments were performed for the candidates, confirming the in-silico data in vivo. The candidate transcripts were then expressed in a cell free system and applied to pollen tubes in order to test their effect on the growing cells. Positive controls were used, where pollen tubes grew towards freshly dissected ovules. The four candidates did not provoke a pollen tube attraction towards the peptide, leaving open the chance to work on the 112 remaining DEFLs in the future.},
  subject      = {Samenpflanzen},
  language  = {en}
}
@phdthesis{Lange2021,
  author    = {Lange, Manuel},
  title     = {Mutanten im RES-Oxylipin Signalweg von \(Arabidopsis\) \(thaliana\)},
  doi       = {10.25972/OPUS-16608},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-166085},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2021},
  abstract  = {Reaktive elektrophile Spezies-Oxylipine (RES-Oxylipine) finden sich in Pflanzen- und Tierzellen und zeichnen sich durch eine f{\"u}r sie typische Anordnung von Atomen aus: einer α,β unges{\"a}ttigten Carbonyl Gruppe. In Pflanzenzellen geh{\"o}ren unter anderem 2-(E)-Hexenal und die Vorstufe der Jasmons{\"a}ure 12-Oxophytodiens{\"a}ure (OPDA) zu den RES-Oxylipinen, in Tierzellen z.B. Prostaglandin A1 (PGA). RES-Oxylipine {\"u}ben Signalfunktionen aus, wie dies in Pflanzenzellen funktioniert ist jedoch noch nicht bekannt. Ziel dieser Arbeit ist dabei einen m{\"o}glichen RES-Oxylipin Signalweg aufzukl{\"a}ren und die beteiligten Gene zu identifizieren. Es konnte aber gezeigt werden, dass die Expressionsrate von bestimmten Genen wie z.B. GST6 durch RES-Oxylipine spezifisch induziert wird. Zur Untersuchung des RES-Oxylipin Signalweges wurde der GST6 Promotor vor das Luciferase-Gen fusioniert, um so ein RES-Oxylipin spezifisches Reportersystem zu erhalten. Die Ethylmethansulfonat mutagenisierten Linien wurden auf ge{\"a}nderte Luciferase-Aktivit{\"a}t hin untersucht. Dabei wurden drei Mutanten isoliert, die in dieser Arbeit n{\"a}her untersucht wurden. Eine zeigte basal erh{\"o}hte Luciferase-Aktivit{\"a}t (constitutive overexpresser 3 = coe3) und die anderen beiden erniedrigte Luciferase-Aktivit{\"a}t nach PGA Gabe (non responsive 1 und 2 = nr1 und nr2). In dieser Arbeit konnte gezeigt werden, dass die Ph{\"a}notypen in allen 3 Mutanten rezessiv vererbt werden und die Mutanten nicht zueinander allel sind. Zudem war die ver{\"a}nderte Luciferase-Aktivit{\"a}t nicht durch ge{\"a}nderte Phytohormonspiegel oder durch Mutationen im GST6 Promotor erkl{\"a}rbar. Auf die Gabe von RES, wie Benzylisothiocyanat oder Sulforaphan, sowie auf endogene RES-Oxylipine, wie OPDA und Hexenal, reagierten die Mutanten auf {\"a}hnliche Weise, wie nach PGA Gabe. Weiterf{\"u}hrende Untersuchungen zeigten, dass sich die drei Mutanten stark voneinander unterschieden. Das Transkriptom kontrollbehandelter coe3 Pflanzen unterschied sich stark von dem der GST6::LUC Pflanzen. Die Mutante war trockenstressresistenter zudem war sie sensibler gegen{\"u}ber NaCl, was jedoch nicht von einer ver{\"a}nderten Reaktion auf Abscisins{\"a}ure herr{\"u}hrte. Des Weiteren war der Chlorophyllabbau bei dunkel inkubierten Bl{\"a}ttern geringer. Bei der Lokalisierung der Mutation, die noch nicht abgeschlossen ist, konnten Chromosom 2 und 5 als die wahrscheinlichsten Kandidaten ermittelt werden. Weitere Analysen sind n{\"o}tig um den Bereich weiter eingrenzen zu k{\"o}nnen. Die Mutante nr1, die sich durch verminderte Reaktion auf RES-Oxylipine auszeichnete, zeigte einen kleineren Wuchs und ein deutlich verz{\"o}gertes Bl{\"u}hen. Außerdem wies die Mutante erh{\"o}hte Argininspiegel in ihren Bl{\"a}ttern auf. Das Transkriptom unterschied sich sowohl bei kontrollbehandelten, als auch bei PGA behandelten nr1 Pflanzen massiv von denen der gleichbehandelten Kontrollen. Auch die nr1 schien trockenstressresistenter zu sein, sie war im Gegensatz zur coe3 aber robuster gegen{\"u}ber h{\"o}heren Konzentrationen an NaCl. Mit Hilfe eines „Next Generation Genome-Mappings" war es m{\"o}glich die Mutation am Ende von Chromosom 3 zu lokalisieren und auf f{\"u}nf m{\"o}gliche Gene einzugrenzen. Weitere Untersuchungen m{\"u}ssen nun kl{\"a}ren, welches dieser Gene urs{\"a}chlich f{\"u}r den Ph{\"a}notyp der ge{\"a}nderten Luciferase-Aktivit{\"a}t ist. Die zweite Mutante mit einer reduzierten Reaktion auf RES-Oxylipine war die nr2. {\"U}berraschender Weise unterschied sich das Transkriptom kontrollbehandelter nr2 Pflanzen deutlich st{\"a}rker von dem der gleichbehandelten GST6::LUC Pflanzen, als das nach PGA Gabe der Fall war. Sie reagierte nur mit sehr schwacher Luciferase-Aktivit{\"a}t auf Verwundung und war zudem deutlich sensibler gegen{\"u}ber Trockenheit. F{\"u}r eine zuk{\"u}nftige Lokalisation der urs{\"a}chlichen Mutation wurden entsprechende Kreuzungen durchgef{\"u}hrt aus deren Samen jederzeit mit einer Selektionierung begonnen werden kann. Mit dieser Arbeit konnte ein erster großer Schritt in Richtung Identifikation der, f{\"u}r die ge{\"a}nderte Luciferase-Aktivit{\"a}t, verantwortlichen Mutation gemacht werden, sowie erste Reaktionen der Mutanten auf abiotische Stressfaktoren untersucht werden. Somit ist man der Entdeckung von Signaltransduktionsfaktoren, die RES-Oxylipinabh{\"a}ngig reguliert werden, einen wichtigen Schritt n{\"a}her gekommen.},
  subject      = {Arabidopsis thaliana},
  language  = {de}
}
@phdthesis{Thomas2021,
  author    = {Thomas, Sarah Katharina},
  title     = {Design of novel IL-4 antagonists employing site-specific chemical and biosynthetic glycosylation},
  doi       = {10.25972/OPUS-17517},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-175172},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2021},
  abstract  = {The cytokines interleukin 4 (IL-4) and IL-13 are important mediators in the humoral immune response and play a crucial role in the pathogenesis of chronic inflammatory diseases, such as asthma, allergies, and atopic dermatitis. Hence, IL-4 and IL-13 are key targets for treatment of such atopic diseases. For cell signalling IL-4 can use two transmembrane receptor assemblies, the type I receptor consisting of receptors IL-4R and γc, and type II receptor consisting of receptors IL-4R and IL-13R1. The type II receptor is also the functional receptor of IL-13, receptor sharing being the molecular basis for the partially overlapping effects of IL-4 and IL-13. Since both cytokines require the IL-4R receptor for signal transduction, this allows the dual inhibition of both IL-4 and IL-13 by specifically blocking the receptor IL-4R. This study describes the design and synthesis of novel antagonistic variants of human IL-4. Chemical modification was used to target positions localized in IL-4 binding sites for γc and IL-13R1 but outside of the binding epitope for IL-4R. In contrast to existing studies, which used synthetic chemical compounds like polyethylene glycol for modification of IL-4, we employed glycan molecules as a natural alternative. Since glycosylation can improve important pharmacological parameters of protein therapeutics, such as immunogenicity and serum half-life, the introduced glycan molecules thus would not only confer a steric hindrance based inhibitory effect but simultaneously might improve the pharmacokinetic profile of the IL-4 antagonist. For chemical conjugation of glycan molecules, IL-4 variants containing additional cysteine residues were produced employing prokaryotic, as well as eukaryotic expression systems. The thiol-groups of the engineered cysteines thereby allow highly specific modification. Different strategies were developed enabling site-directed coupling of amine- or thiol- functionalized monosaccharides to introduced cysteine residues in IL-4. A linker-based coupling procedure and an approach requiring phenylselenyl bromide activation of IL-4 thiol-groups were hampered by several drawbacks, limiting their feasibility. Surprisingly, a third strategy, which involved refolding of IL-4 cysteine variants in the presence of thiol- glycans, readily allowed synthesis of IL-4 glycoconjugates in form of mixed disulphides in milligram amount. This approach, therefore, has the potential for large-scale synthesis of IL-4 antagonists with highly defined glycosylation. Obtaining a homogenous glycoconjugate with exactly defined glycan pattern would allow using the attached glycan structures for fine-tuning of pharmacokinetic properties of the IL-4 antagonist, such as absorption and metabolic stability. The IL-4 glycoconjugates generated in this work proved to be highly effective antagonists inhibiting IL-4 and/or IL-13 dependent responses in cell-based experiments and in in vitro binding studies. Glycoengineered IL-4 antagonists thus present valuable alternatives to IL-4 inhibitors used for treatment of atopic diseases such as the neutralizing anti-IL-4R antibody Dupilumab.},
  subject      = {Glykosylierung},
  language  = {en}
}
@phdthesis{BergmannBueno2021,
  author    = {Bergmann Bueno, Amauri},
  title     = {Ecophysiological adaptations of cuticular water permeability of plants to hot arid biomes},
  doi       = {10.25972/OPUS-16783},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-167832},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2021},
  abstract  = {Arid environments cover almost one-third of the land over the world. Plant life in hot arid regions is prone to the water shortage and associated high temperatures. Drought-stressed plants close the stomata to reduce water loss. Under such conditions, the remaining water loss exclusively happens across the plant cuticle. The cuticular water permeability equals the minimum and inevitable water loss from the epidermal cells to the atmosphere under maximally stomatal closure. Thus, low cuticular water permeability is primordial for plant survival and viability under limited water source. The assumption that non-succulent xerophytes retard water loss due to the secretion of a heavier cuticle is often found in the literature. Intuitively, this seems to be plausible, but few studies have been conducted to evaluate the cuticular permeability of xerophilous plants. In chapter one, we investigated whether the cuticular permeability of Quercus coccifera L. grown in the aridest Mediterranean-subtype climate is indeed lower than that of individuals grown under temperate climate conditions. Also, the cuticular wax chemical compositions of plants grown in both habitats were qualitatively and quantitatively analysed by gas-chromatography. In few words, our findings showed that although the cuticular wax deposition increased in plants under Mediterranean climate, the cuticular permeability remained unaltered, regardless of habitat. The associated high temperatures in arid regions can drastically increase the cuticular water permeability. Thereby, the thermal stability of the cuticular transpirational barrier is decisive for safeguarding non-succulent xerophytes against desiccation. The successful adaptation of plants to hot deserts might be based on finding different solutions to cope with water and heat stresses. Water-saver plants close the stomata before the leaf water potential drastically changes in order to prevent damage, whereas water-spender plants reduce the leaf water potential by opening the stomata, which allow them to extract water from the deep soil to compensate the high water loss by stomatal transpiration. In chapter two, we compare the thermal stability of the cuticular transpiration barrier of the desert water-saver Phoenix dactylifera L. and the water-spender Citrullus colocynthis (L.) Schrad. In short, the temperature-dependent increase of the cuticular permeability of P. dactylifera was linear over the whole temperature range (25-50°C), while that of C. colocynthis was biphasic with a steep increase at temperatures ≥ 40°C. This drastic increase of cuticular permeability indicates a thermally induced breakdown of the C. colocynthis cuticular transpiration barrier, which does not occur in P. dactylifera. We further discussed how the specific chemical composition of the cutin and cuticular waxes might contribute to the pronounced thermal resistance of the P. dactylifera cuticular transpiration barrier. A multitude of morpho and physiological modifications, including photosynthetic thermal tolerance and traits related to water balance, led to the successful plant colonisation of hot arid regions over the globe. High evaporative demand and elevated temperatures very often go along together, thereby constraining the plant life in arid environments. In chapter 3, we surveyed cuticular permeability, leaf thermal tolerance, and cuticular wax chemical composition of 14 non-succulent plant species native from some of the hottest and driest biomes in South-America, Europe, and Asia. Our findings showed that xerophilous flowering plants present high variability for cuticular permeability and leaf thermal tolerance, but both physiological features could not be associated with the species original habitat. We also provide substantial evidence that non-succulent xerophytes with more efficient cuticular transpirational barrier have higher leaf thermal tolerance, which might indicate a potential coevolution of these features in hot arid biomes. We further discussed the efficiency of the cuticular transpiration barrier in function to the cuticular wax chemical composition in the general discussion section.},
  subject      = {Plant cuticle},
  language  = {en}
}
@phdthesis{Mueller2021,
  author    = {M{\"u}ller, Heike Milada},
  title     = {Anpassung an Trocken- und Salzstress: Untersuchungen an Modellpflanzen und Extremophilen},
  doi       = {10.25972/OPUS-17900},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-179005},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2021},
  abstract  = {Die wahrscheinlich gr{\"o}ßten Probleme des 21. Jahrhunderts sind der Klimawandel und die Sicherstellung der Nahrungsmittelversorgung f{\"u}r eine steigende Zahl an Menschen. Durch die Zunahme von extremen Wetterbedingungen wie Trockenheit und Hitze wird der Anbau konventioneller, wenig toleranter Nutzpflanzen erschwert und die dadurch notwendige, steigende Bew{\"a}sserung der Fl{\"a}chen f{\"u}hrt dar{\"u}ber hinaus zu einer zus{\"a}tzlichen Versalzung der B{\"o}den mit f{\"u}r Pflanzen toxischen Natrium- und Chlorid-Ionen. Kenntnisse {\"u}ber Anpassungsstrategien salztoleranter Pflanzen an Salzstress, aber auch detailliertes Wissen {\"u}ber die Steuerung der Transpiration und damit des Wasserverlusts von Pflanzen sind daher wichtig, um auch k{\"u}nftig ertragreiche Landwirtschaft betreiben zu k{\"o}nnen. In dieser Arbeit habe ich verschiedene Aspekte der pflanzlichen Stressphysiologie bearbeitet, die im Folgenden getrennt voneinander zusammengefasst werden. I. Funktionelle Unterschiede der PYR/PYL-Rezeptoren von Schließzellen Entscheidend f{\"u}r den Wasserstatus von Pflanzen ist die Kontrolle des Wasserverlusts durch Spalt{\"o}ffnungen (Stomata), die von einem Paar Schließzellen gebildet werden. Externe Faktoren wie Licht, Luftfeuchtigkeit und CO2, sowie interne Faktoren wie das Phytohormon Abszisins{\"a}ure (ABA) regulieren {\"u}ber Signalkaskaden die Stomaweite und dadurch den Wasserverlust. Die zugrunde liegenden Signalkaskaden {\"u}berlappen teilweise. Vor allem der Stomaschluss durch erh{\"o}htes CO2 und ABA weisen viele Gemeinsamkeiten auf und die Identifizierung des Konvergenzpunktes beider Signale ist immer noch aktueller Gegenstand der Forschung. Von besonderem Interesse sind dabei die in Schließzellen exprimierten ABA-Rezeptoren der PYR/PYL-Familie. Denn obwohl bislang nicht nachgewiesen werden konnte, dass CO2 zu einem Anstieg des ABA-Gehalts von Schließzellen f{\"u}hrt deuten einige Studien darauf hin, dass die ABA-Rezeptoren selbst am CO2-Signalweg beteiligt sind. Durch Untersuchungen der Stomareaktion von Arabidopsis ABA-Rezeptormutanten konnte ich in dieser Arbeit zeigen, dass die in Schließzellen exprimierten ABA-Rezeptoren der PYR/PYL-Familie funktionale Unterschiede aufweisen. F{\"u}nffach-Verlustmutanten der ABA-Rezeptoren PYR1, PYL2, 4, 5 und 8 (12458) waren in ihrem ABA-induzierten Stomaschluss beeintr{\"a}chtigt und nur die Komplementation mit PYL2 und in geringerem Maße PYR1 konnte die ABA-Sensitivit{\"a}t wiederherstellen. Die Stomata von 12458-Verlustmutanten waren außerdem insensitiv gegen{\"u}ber erh{\"o}htem CO2, was auf eine Beteiligung der ABA-Rezeptoren am CO2-induzierten Stomaschluss hindeutet und diese Sensitivit{\"a}t konnte nur durch die Komplementation mit PYL4 oder PYL5, nicht aber mit PYL2 wiederhergestellt werden. Somit konnten in dieser Arbeit erstmals funktionelle Unterschiede der PYR/PYLs beim Stoma-Schluss nachgewiesen werden. Alle externen und internen Stomaschluss-Signale haben außerdem Einfluss auf die Genexpression der Schließzellen und f{\"u}hren zu individuellen expressionellen Adaptionen. In vorangegangenen Microarray Studien konnte gezeigt werden, dass jeder Stimulus auch die Expression eines distinkten Sets an ABA-Rezeptoren beeinflusst. Im Rahmen dieser Arbeit konnte ich außerdem zeigen, dass die Expression der ABA-Rezeptoren bereits auf kleine {\"A}nderungen der ABA-Konzentration der Schließzellen reagiert und dass diese sich außerdem in ihrer Sensitivit{\"a}t gegen{\"u}ber ABA unterschieden. Geringe {\"A}nderungen der ABA-Konzentration von Schließzellen haben demnach Auswirkungen auf deren Rezeptor-zusammensetzung. Dar{\"u}ber hinaus konnte ich zeigen, dass die Rezeptoren die Expression unterschiedlicher nachgeschalteter Gene beeinflussen, was darauf hindeutet, dass Anpassungen des Rezeptorpools durch geringe {\"A}nderungen des ABA-Gehalts von Schließzellen schlussendlich auf genexpressioneller Ebene zur l{\"a}ngerfristigen Adaption an externe Bedingungen f{\"u}hren und die Rezeptoren auch hier funktional verschieden sind. II. Stomat{\"a}re Besonderheiten der toleranten Dattelpalme (Phoenix dactylifera) Dattelpalmen kommen nat{\"u}rlicherweise an besonders trockenen und heißen Standorten vor, an denen es aufgrund der harschen Bedingungen nur sehr wenigen Pflanzen m{\"o}glich ist {\"u}berhaupt zu wachsen. Ein naheliegender Grund f{\"u}r die herausragende Toleranz dieser Art gegen{\"u}ber wasserlimitierenden Bedingungen ist eine Anpassung der stomat{\"a}ren Regulation zu Gunsten des Wasserhaushalts. In dieser Arbeit konnte ich durch vergleichende Untersuchungen der lichtabh{\"a}ngigen Transpiration sowie dem ABA-induzierten Stomaschluss grundlegende Unterschiede in der Stomaphysiologie der Dattelpalmen und der eher sensitiven Modellpflanze Arabidopsis thaliana nachweisen. Blattgaswechselmessungen zeigten, dass Dattelpalmen in der Lage sind die Spalt{\"o}ffnungen bei niedrigen Lichtintensit{\"a}ten, bei denen Arabidopsis bereits deutlich ge{\"o}ffnete Stomata aufwies, geschlossen zu halten. Der bedeutendste Unterschied in der Stomaphysiologie von Dattelpalmen und Arabidopsis lag aber im ABA-induzierten Stomaschluss. W{\"a}hrend {\"u}ber die Petiole verabreichtes ABA bei Arabidopsis innerhalb von 15 Minuten zu einem vollst{\"a}ndigen Stomaschluss f{\"u}hrte, konnte ich in dieser Arbeit zeigen, dass der ABA-induzierte Stomaschluss der Datteln nitratabh{\"a}ngig ist. ABA allein f{\"u}hrte nur zu einem sehr langsamen Stomaschluss der innerhalb einer Stunde nicht vollst{\"a}ndig abgeschlossen war. Nur in Gegenwart von Nitrat f{\"u}hrte die ABA-Gabe in den Transpirationsstrom der Fiederbl{\"a}tter der Datteln zu einem schnellen und vollst{\"a}ndigen Stomaschluss. In Arabidopsis wird der in Schließzellen vorkommende Anionenkanal AtSLAC1 durch eine {\"u}ber den ABA-Signalweg vermittelte Phosphorylierung aktiviert, was schlussendlich zur Aktivierung spannungsabh{\"a}ngiger Kationenkan{\"a}le und zum Ausstrom von Kalium aus den Schließzellen f{\"u}hrt. Es konnte gezeigt werden, dass die Nitratabh{\"a}ngigkeit der ABA-Antwort der Schließzellen von Dattelpalmen auf Eigenschaften von PdSLAC1 zur{\"u}ckzuf{\"u}hren ist und dieser Kanal nur in Anwesenheit von extrazellul{\"a}rem Nitrat aktivierbar ist. Mittlerweile konnte, unter anderem basierend auf diesen Ergebnissen, eine Tandem-Aminos{\"a}uresequenz identifiziert werden, die die SLAC-Homologe monokotyler Pflanzen wie der Dattelpalme von der dikotyler Pflanzen unterscheidet und zumindest teilweise f{\"u}r die nitratabh{\"a}ngige Aktivierung des Stomaschlusses vieler monokotyler verantwortlich ist. III. Die Salztoleranz von Phoenix dactylifera und Chenopodium quinoa Sowohl Dattelpalmen als auch C. quinoa weisen, verglichen mit den meisten anderen Pflanzen, eine hohe Toleranz gegen{\"u}ber NaCl-haltigen B{\"o}den auf. In dieser Arbeit habe ich die Salztoleranz beider Arten untersucht, um so Strategien zu identifizieren, die diesen Pflanzen diese gesteigerte Toleranz erm{\"o}glichen. Dattelpalmen k{\"o}nnen nat{\"u}rlicherweise auf salzigen B{\"o}den wachsen. Makroskopisch weisen diese Pflanzen aber keine Anpassungen wie bspw. Salzdr{\"u}sen auf und bislang ist unklar wie Dattelpalmen mit dem NaCl aus dem Boden umgehen. In dieser Arbeit konnte ich zeigen, dass der Natriumgehalt der Fiederbl{\"a}tter der Datteln durch eine sechsw{\"o}chige Bew{\"a}sserung mit 600mM NaCl, was ungef{\"a}hr der Konzentration von Meerwasser entspricht, nicht zunimmt. Demnach sind Datteln so genannte „Exkluder", also Pflanzen, die eine {\"u}berm{\"a}ßige Natriumaufnahme in photosynthetisch aktives Gewebe vermeiden. Der Natriumgehalt der Wurzeln dagegen nahm unter Salzstress aber zu. Diese Zunahme war allerdings in unterschiedlichen Bereichen der Wurzeln verschieden stark. Flammenphotometrische Messungen ergaben einen vom Wurzelansatz ausgehenden graduellen Anstieg des Natriumgehalts, der an der Wurzelspitze am h{\"o}chsten war. Dar{\"u}ber hinaus konnte eine Induktion von PdSOS1, einem putativen Na+/H+-Antiporter in diesen unteren, natriumhaltigen Bereichen nachgewiesen werden. Eine hohe SOS1-Aktivit{\"a}t gilt bereits in anderen toleranten Arten als Schl{\"u}sselmerkmal f{\"u}r deren Toleranz und die gesteigerte Expression von PdSOS1 deutet auf eine erh{\"o}hte Natrium-Exportrate aus der Wurzel zur{\"u}ck in den Boden in diesen unteren Bereichen hin, was schlussendlich den Ausschluss von Natrium vermitteln k{\"o}nnte. In sensitiven Arten f{\"u}hrt Salzstress h{\"a}ufig zu einer Abnahme der Kaliumkonzentration des Gewebes. Interessanterweise war dies weder f{\"u}r das Blatt- noch das Wurzelgewebe der Dattelpalmen der Fall. Der Kaliumgehalt beider Gewebe blieb trotz der Bew{\"a}sserung der Pflanzen mit Salzwasser konstant. Auf expressioneller Ebene konnte ich dar{\"u}ber hinaus zeigen, dass PdHAK5, ein putativer hochaffiner Kaliumtransporter, der unter Kontrollbedingungen {\"u}berwiegend in den oberen Wurzelabschnitten exprimiert wurde, durch den Salzstress dort reprimiert wurde. PdKT, ebenfalls ein putatives Kalium-Transportprotein dagegen, wurde nicht durch die Salzbehandlung beeinflusst, was zusammengenommen darauf hindeutet, dass das Aufrechterhalten des Kaliumgehalts bei Salzstress durch die differentielle Regulation verschiedener Kaliumaufnahmesysteme gew{\"a}hrleistet wird. Der effiziente Ausschluss von Natrium zusammen mit dem hohen K+/Na+-Verh{\"a}ltnis k{\"o}nnten demnach Schl{\"u}sselmerkmale f{\"u}r die hohe Salztoleranz von Phoenix dactylifera darstellen. Quinoa ist, {\"a}hnlich wie die Dattelpalme, eine salztolerante Nutzpflanze. Im Gegensatz zu Dattelpalmen weist Quinoa allerdings besondere Strukturen auf der Epidermis auf, die so genannten epidermalen Blasenhaare (englisch: epidermal bladder cells, EBCs). Die Funktion dieser ballonartig vergr{\"o}ßerten Zellen als externe Salzspeicher wird seit l{\"a}ngerem diskutiert. Flammenphotometrische Messungen des Natriumgehalts von Quinoa unter Salzstressbedingungen ergaben, dass Quinoa anders als Dattelpalmen, Natrium in die oberirdischen, photosynthetisch aktiven Organe aufnimmt. Auch die Zunahme des Natriumgehalts der EBCs konnte ich nachweisen. Junge Bl{\"a}tter haben eine hohe Dichte an intakten EBCs, was deren Funktion als externe Salzspeicher besonders zum Schutz dieser jungen Bl{\"a}tter nahelegt. mRNA-Sequenzierungen ergaben dar{\"u}ber hinaus, dass die EBCs bereits unter Kontrollbedingungen viele in grundlegende Stoffwechselprozesse involvierte Gene sowie membranst{\"a}ndige Transportproteine differentiell exprimieren. Diese Unterschiede im Transkriptom der EBCs zum Blattgewebe zeigen, dass katabole Stoffwechselwege nur eine untergeordnete Rolle in den hochspezialisierten EBCs spielen und deren Stoffwechsel auf dem Import energiereicher Zucker und Aminos{\"a}uren basiert. Mittels qPCR-Messungen und RNA-Sequenzierungen konnte ich die gewebespezifische Expression verschiedener Transportproteine nachweisen, die eine gerichtete Aufnahme von Natrium in EBCs erm{\"o}glichen k{\"o}nnten. Besonders die differentielle Expression eines Natriumkanals der HKT1-Familie deutet auf dessen Beteiligung an der Natriumbeladung der EBCs hin. CqHKT1.2 wurde ausschließlich in EBCs exprimiert und die elektrophysiologische Charakterisierung dieses Transportproteins ergab eine spannungsabh{\"a}ngige Natriumleitf{\"a}higkeit. Dieser Natriumkanal kann demnach die Natriumaufnahme bei Membranspannungen nahe dem Ruhepotential in die EBCs vermitteln und die Deaktivierung des CqHKT1.2 bei depolarisierenden Membranspannungen kann dar{\"u}ber hinaus einen Efflux von Na+ aus den EBCs verhindern. Auch das Expressionsmuster eines putativen Na+/H+-Antiporters (CqSOS1) der nur sehr gering in EBCs aber deutlich h{\"o}her in Blattgewebe exprimiert wurde, deutet auf eine indirekte Beteiligung dieses SOS1 an der Beladung der EBCs hin. Bereits charakterisierte SOS1-Proteine anderer Pflanzen zeigten unter physiologischen Bedingungen eine Natriumexport-Aktivit{\"a}t. CqSOS1 k{\"o}nnte demnach den Export von Natrium aus Mesophyll- und Epidermiszellen der Bl{\"a}tter in den Apoplasten vermitteln, welches dann {\"u}ber CqHKT1.2 in die EBCs aufgenommen wird. Trotz der Natriumaufnahme in die oberirdischen Teile und die EBCs f{\"u}hrte die Salzbehandlung {\"a}hnlich wie bei den Datteln nicht zu einer Abnahme des bemerkenswert hohen Kaliumgehalts. Mittels qPCR-Untersuchungen konnte ich die Expression verschiedener HAK-Orthologe nachweisen, deren Aktivit{\"a}t die Aufrechterhaltung des Kaliumgehalts unter Salzstress vermitteln k{\"o}nnten. Fr{\"u}here Studien konnten zeigen, dass Salzstress bei Quinoa wie bei vielen salztoleranten Arten zu einem Anstieg der Konzentration von kompatiblen gel{\"o}sten Substanzen und besonders von Prolin f{\"u}hrt. In dieser Arbeit konnte ich die hohe Expression eines Prolintransporters in EBCs nachweisen, was eher auf einen importbasierten Anstieg der Prolinkonzentration als auf die Synthese innerhalb der EBCs schließen l{\"a}sst. Zusammengefasst ergaben der Anstieg des Natriumgehalts der EBCs in Verbindung mit den Ergebnissen der RNA-Sequenzierung und den erg{\"a}nzenden qPCR Messungen, dass die EBCs von Quinoa bereits unter Kontrollbedingen f{\"u}r die Aufnahme von {\"u}bersch{\"u}ssigen Ionen unter Salzstress spezialisierte Zellen sind, deren Spezialisierung auf dem Import von energiereichreichen Zucken und anderen Substanzen basiert.},
  subject      = {Botanik},
  language  = {de}
}
@phdthesis{ScheideNoeth2021,
  author    = {Scheide-N{\"o}th, Jan-Philipp},
  title     = {Activation of the Interleukin-5 receptor and its inhibition by cyclic peptides},
  doi       = {10.25972/OPUS-18250},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-182504},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2021},
  abstract  = {The cytokine interleukin-5 (IL-5) is part of the TH2-mediated immune response. As a key regulator of eosinophilic granulocytes (eosinophils), IL-5 controls multiple aspects of eosinophil life. Eosinophils play a pathogenic role in the onset and progression of atopic diseases as well as hypereosinophilic syndrome (HES). Here, cytotoxic proteins and pro-inflammatory mediators stored in intracellular vesicles termed granula are released upon activation thereby causing local inflammation to fight the pathogen. However, if such inflammation persists, tissue damage and organ failure can occur. Due to the close relationship between eosinophils and IL-5 this cytokine has become a major pharmaceutical target for the treatment of atopic diseases or HES. As observed with other cytokines, IL-5 signals by assembling a heterodimeric receptor complex at the cell surface in a stepwise mechanism. In the first step IL-5 binds to its receptor IL-5Rα (CD125). This membrane-located complex then recruits the so-called common beta chain βc (CD131) into a ternary ligand receptor complex, which leads to activation of intracellular signaling cascades. Based on this mechanism various strategies targeting either IL-5 or IL-5Rα have been developed allowing to specifically abrogate IL-5 signaling. In addition to the classical approach of employing neutralizing antibodies against IL 5/IL-5Rα or antagonistic IL-5 variants, two groups comprising small 18 to 30mer peptides have been discovered, that bind to and block IL-5Rα from binding its activating ligand IL-5. Structure-function studies have provided detailed insights into the architecture and interaction of IL-5IL-5Rα and βc. However, structural information for the ternary IL-5 complex as well as IL-5 inhibiting peptides is still lacking. In this thesis three areas were investigated. Firstly, to obtain insights into the second receptor activation step, i.e. formation of the ternary ligand-receptor complex IL-5•IL-5Rα•βc, a high-yield production for the extracellular domain of βc was established to facilitate structure determination of the ternary ligand receptor assembly by either X-ray crystallography or cryo-electron microscopy. In a second project structure analysis of the ectodomain of IL-5Rα in its unbound conformation was attempted. Data on IL-5Rα in its ligand-free state would provide important information as to whether the wrench-like shaped ectodomain of IL-5Rα adopts a fixed preformed conformation or whether it is flexible to adapt to its ligand binding partner upon interaction. While crystallization of free IL-5Rα failed, as the crystals obtained did not diffract X rays to high resolution, functional analysis strongly points towards a selection fit binding mechanism for IL-5Rα instead of a rigid and fixed IL-5Rα structure. Hence IL-5 possibly binds to a partially open architecture, which then closes to the known wrench-like architecture. The latter is then stabilized by interactions within the D1-D2 interface resulting in the tight binding of IL-5. In a third project X-ray structure analysis of a complex of the IL-5 inhibitory peptide AF17121 bound to the ectodomain of IL-5Rα was performed. This novel structure shows how the small cyclic 18mer peptide tightly binds into the wrench-like cleft formed by domains D1 and D2 of IL-5Rα. Due to the partial overlap of its binding site at IL-5Rα with the epitope for IL-5 binding, the peptide blocks IL-5 from access to key residues for binding explaining how the small peptide can effectively compete with the rather large ligand IL-5. While AF17121 and IL-5 seemingly bind to the same site at IL-5Rα, functional studies however showed that recognition and binding of both ligands differ. With the structure for the peptide-receptor complex at hand, peptide design and engineering could be performed to generate AF17121 analogies with enhanced receptor affinity. Several promising positions in the peptide AF17121 could be identified, which could improve inhibition capacity and might serve as a starting point for AF17121-based peptidomimetics that can yield either superior peptide based IL-5 antagonists or small-molecule-based pharmacophores for future therapies of atopic diseases or the hypereosinophilic syndrome.},
  subject      = {Interleukin 5},
  language  = {en}
}
@phdthesis{Kucka2021,
  author    = {Kucka, Kirstin Michaela},
  title     = {Charakterisierung eines neuen Tumor Nekrose Faktor (TNF) Rezeptor 2 (TNFR2) Agonisten: Der heteromere, membranst{\"a}ndige Ligand Lymphotoxin α\(_2\)β},
  doi       = {10.25972/OPUS-24982},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-249824},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2021},
  abstract  = {Seit mehr als zwei Jahrzehnten ist bekannt, dass nicht nur der Tumor Nekrose Faktor-α (=TNF-α) sondern auch Lymphotoxin-α (=LTα) in Form von Trimeren an TNFR1 und TNFR2 binden kann. Durch diese F{\"a}higkeit an beide Rezeptoren zu binden, haben diese zwei Liganden eine essentielle Rolle in der Entwicklung und dem Verlauf von Autoimmunerkrankungen. Bereits mit Beginn der 1990er Jahren wurde gezeigt, dass LTα nicht nur in Form von Homotrimeren vorliegt, sondern auch mit dem verwandten TNF-Superfamilie Liganden Lymphotoxin β (=LTβ) Heterotrimere bilden kann. Hierbei lagern sich LTα und LTβ in Form von LTα2β und LTαβ2 zusammen. Die initialen Experimente mit diesen Heterotrimeren zeigten bereits Unterschiede von LTα2β und LTαβ2. W{\"a}hrend LTα2β wie LTα an den TNFR1 bindet, kann LTαβ2 weder an TNFR1 noch TNFR2 binden und interagiert mit einem eigenen Rezeptor namens Lymphotoxin β Rezeptor (=LTβR). Da bereits zwei Liganden (TNF und LTα) f{\"u}r TNFR1 und TNFR2 bekannt waren, wurde LTα2β bis heute nicht weiter charakterisiert. LTαβ2 hingegen war lange Zeit der einzige bekannte Ligand f{\"u}r den LTβR, weshalb die LTαβ2-LTβR-Interaktion ausf{\"u}hrlich untersucht wurde. Diese Arbeit fokusiert sich auf die Charakterisierung von LTα2β. Hierf{\"u}r wurde die einzige bekannte Eigenschaft aus den 90er Jahren von LTα2β n{\"a}mlich die Bindung an TNFR1 aufgegriffen und um die Rezeptoren TNFR2 und LTβR erweitert. Diese Arbeit zeigt, dass LTα2β nicht nur an den TNFR1, sondern auch an TNFR2 und schwach an LTβR bindet. Trotz der asymmetrischen Bindestellen kann membrangebundenes LTα2β TNFR1 und TNFR2 nicht nur binden, sondern ist auch in der Lage diese zu aktivieren. Diese Arbeit gibt erste Einblicke in die Komplexizit{\"a}t dieses Heterotrimers indem gezeigt wird, dass LTα2β sowohl in seiner l{\"o}slichen als auch in seiner membrangebundenen Form den TNFR1 aktivieren kann, w{\"a}hrend der TNFR2 nur durch das membranst{\"a}ndige LTα2β aktiviert wird. Aufgrund der aktivierenden Eigenschaften von membranst{\"a}ndigem LTα2β und LTαβ2 auf die murine (=mu) Panc02-Zelllinie wird ein ersten Ausblick auf m{\"o}gliche weitergehende Experimente in mausbasierten Modellen gegeben. Die erzielten Ergebnisse zeigen, dass mit membranst{\"a}ndigem LTα2β ein neuer TNFR2 Agonist gefunden wurde.},
  subject      = {Ligand},
  language  = {de}
}
@article{KarimiFreundWageretal.2021,
  author    = {Karimi, Sohail M. and Freund, Matthias and Wager, Brittney M. and Knoblauch, Michael and Fromm, J{\"o}rg and M. Mueller, Heike and Ache, Peter and Krischke, Markus and Mueller, Martin J. and M{\"u}ller, Tobias and Dittrich, Marcus and Geilfus, Christoph-Martin and Alfaran, Ahmed H. and Hedrich, Rainer and Deeken, Rosalia},
  title     = {Under salt stress guard cells rewire ion transport and abscisic acid signaling},
  series = {New Phytologist},
  volume    = {231},
  journal   = {New Phytologist},
  number    = {3},
  doi       = {10.1111/nph.17376},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-259635},
  pages     = {1040-1055},
  year      = {2021},
  abstract  = {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.},
  language  = {en}
}
@phdthesis{Kumari2021,
  author    = {Kumari, Khushbu},
  title     = {The role of lipid transfer proteins (LTPs) during the fertilization process in Arabidopsis thaliana},
  doi       = {10.25972/OPUS-19961},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-199613},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2021},
  abstract  = {Double fertilization is a defining characteristic of flowering plants (angiosperms). As the sperm cells of higher plants are non-motile, they need to be transported to the female gametophyte via the growing pollen tube. The pollen-tube journey through the female tissues represents a highly complex process. To provide for successful reproduction it demands intricate communication between the cells of the two haploid gametophytes - the polar growing pollen tube (carrying the two non-motile sperm cells) and the ovule (hosting the egg cell/synergid cells). The polar growth of the pollen tube towards the female gamete is guided by different signaling molecules, including sugars, amino acids and peptides. Some of these belong to the family of lipid transfer proteins (LTPs), which are secreted cysteine-rich peptides. Depending on the plant species several lines of evidence have also suggested potential roles for LTPs during pollen germination or pollen-tube guidance. Although Arabidopsis thaliana has 49 annotated genes for LTPs, several of which are involved in plant immunity and cell-to-cell communication, the role of most members of this family during fertilization is unknown. The aim of this project was therefore to systematically identify LTPs which play a role in the fertilization process in A. thaliana, particularly during pollen tube guidance. To identify candidate proteins, the expression profile of LTPs in reproductive tissue was investigated. This was accomplished by in-silico bioinformatic analysis using different expression databases. Following confirmion of these results by qRT-PCR analysis, seven Type-I nsLTPs (LTP1, LTP2, LTP3, LTP4, LTP5, LTP6 and LTP12) were found to be exclusively expressed in pistils. Except for LTP12, all other pistil expressed LTPs were transcriptionally induced upon pollination. Using reporter-based transcriptional and translational fusions the temporal and spatial expression patterns together with protein localizations for LTP2, 3, 4, 5, 6, and 12 were determined in planta. Stable transgenic plants carrying PromLTP::GUS constructs of the six different LTP candidates showed that most of LTPs were expressed in the stigma/stylar region and were induced upon pollination. With respect to protein localization on the cellular level, they split into two categories: LTP2, LTP5 and LTP6 were localized in the cell wall, while LTP3, LTP4 and LTP12 were specifically targeted to the plasma membrane. For the functional characterization of the candidate LTPs, several T-DNA insertion mutant plant lines were investigated for phenotypes affecting the fertilization process. Pollen development and quality as well as their in-vitro germination rate did not differ between the different single ltp mutant lines and wildtype plants. Moreover, in-vivo cross pollination experiments revealed that tube growth and fertilization rate of the mutant plants were similar to wildtype plants. Altogether, no discernible phenotype was evident in other floral and vegetative parts between different single ltp mutant lines and wildtype plants. As there was no distinguishable phenotype observed for single ltp-ko plants, double knock out plants of the two highly homologous genes LTP2 (expressed in the female stigma, style and transmitting tract) and LTP5 (expressed in the stigma, style, pollen pollen-tube and transmitting tract) were generated using the EPCCRISPR-Cas9 genome editing technique. Two ltp2ltp5 mutant transgenic-lines (\#P31-P2 and \#P31-P3) with frameshift mutations in both the genes could be established. Further experiments showed, that the CRISPR/Cas9-mediated knock-out of LTP2/LTP5 resulted in significantly reduced fertilization success. Cell biological analyses revealed that the ltp2ltp5 double mutant was impaired in pollen tube guidance towards the ovules and that this phenotype correlated with aberrant callose depositions in the micropylar region during ovule development. Detailed analysis of in-vivo pollen-tube growth and reciprocal cross pollination assay suggested that, the severely compromised fertility was not caused by any defect in development of the pollen grains, but was due to the abnormal callose deposition in the embryo sac primarily concentrated at the synergid cell near the micropylar end. Aberrant callose deposition in ltp2ltp5 ovules pose a complete blockage for the growing pollen tube to change its polarity to enter the funiculus indicating funicular and micropylar defects in pollen tube guidance causing fertilization failure. Our finding suggests that female gametophyte expressed LTP2 and LTP5 play a crucial role in mediating pollen tube guidance process and ultimately having an effect on the fertilization success. In line with the existence of a N-terminal signal peptide, secreted LTPs might represent a well-suited mobile signal carrier in the plant's extracellular matrix. Previous reports suggested that, LTPs could act as chemoattractant peptide, imparting competence to the growing pollen tube, but the molecular mechanism is still obscure. The results obtained in this thesis further provide strong evidence, that LTP2/5 together regulate callose homeostasis and testable models are discussed. Future work is now required to elucidate the detailed molecular link between these LTPs and their potential interacting partners or receptors expressed in pollen and synergid cells, which should provide deeper insight into their functional role as regulatory molecules in the pollen tube guidance mechanism.},
  subject      = {Fertilization in angiosperm},
  language  = {en}
}
@phdthesis{Seufert2021,
  author    = {Seufert, Pascal},
  title     = {Chemical and physical structure of the barrier against water transpiration of leaves: Contribution of different wax compounds},
  doi       = {10.25972/OPUS-20896},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-208963},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2021},
  abstract  = {The cuticle is constituted of the biopolymer cutin and intra- and epicuticular waxes. In some cases, it has epicuticular wax crystals, protruding from the epicuticular wax film. One of the most important tasks is protection against desiccation. Many investigations were conducted to find the transport limiting component of the cuticle. It is evidentially confirmed that the waxes form this barrier. These waxes are multifactorial blends made of very-long-chain aliphatic (VLCA) compounds and triterpenoids (TRP). The VLCAs were proposed to constitute the transpiration barrier to water. However, experimental confirmation was lacking so far. The present study focuses on the development of a method to selectively extract TRPs from the cuticle and the impact of the removal on the transpiration barrier. The plants deployed in this study exhibited several features. They had no epicuticular crystals on their surfaces, were astomatous, had a rather durable and possibly isolatable cuticle. A broad range of wax compositions was covered from plants with no TRP content and low wax load like Hedera helix and Zamioculcas zamiifolia to plants with high TRP content and high wax load like Nerium oleander. The selective extraction was conducted using a sequence of solvents. TRPs were extracted almost exhaustively from CMs with the first MeOH extract. Only a minor amount of shorter chained VLCAs was obtained. The remaining waxes, consisting mostly of VLCAs and some remnant TRPs, were removed with the following TCM extract. After the extractions, the water permeance of native cuticular membranes (CM), MeOH extracted (M) and dewaxed cuticular discs (MX) was investigated gravimetrically. Compared to the water permeance of CMs, Ms showed no or only a small increase in water conductance. MXs, however, always showed strongly increased values. The knowledge about the wax compounds constituting the transport-limiting properties is vital for different projects. For various issues, it would be favourable to have a standardized wax mixture as an initial point of research. It could be used to develop screening procedures to investigate the impact of adjuvants on cuticular waxes or the influence of wax constituents on the properties of cuticular waxes. This work concentrated on the development of an artificial wax mixture, which mimics the physical properties of a plant leaf wax sufficiently. As target wax, the leaf wax of Schefflera elegantissima was chosen. The wax of this plant species consisted almost exclusively of VLCAs, had a rather simple composition regarding compound classes and chain length distribution and CMs could be isolated. Artificial binary, ternary and quaternary waxes corresponding to the conditions within the plant wax were investigated using differential scanning calorimetry (DSC), X-ray diffraction (XRD) techniques and Fourier-transform infrared (FTIR) spectroscopy. Phase diagrams were mapped out for a series of binary, ternary and quaternary wax mixtures. FTIR experiments were conducted using, ternary and a quaternary artificial wax blends. The blends were chosen to represent the conditions within the wax of the adaxial CM plant wax. The FTIR experiments exhibited an increasing resemblance of the artificial wax to the plant wax (adaxial CM wax) with an increasing number of compounds in the artificial wax. The same trend was found for DSC thermograms. Thermograms of ternary and quaternary blends exhibited more overlapping peaks and occurred in a temperature range more similar to the range of the whole leaf plant wax. The XRD spectrum at room temperature showed good conformity with the quaternary blend. The current work illustrates a method for selective extraction of TRPs from isolated CMs. It gives direct experimental proof of the association of the water permeance barrier with the VLCA rather than to the TRPs. Furthermore, the possibility to mimic cuticular waxes using commercially available wax compounds is investigated. The results show promising feasibility for its viability, enabling it to perform as a standardized initial point for further research (e.g. to examine the influence of different constituents on waxes), revealing valuable knowledge about the structure and the chemistry-function relationship of cuticular waxes.},
  subject      = {Kutikula},
  language  = {en}
}
@article{SchilcherHilsmannRauscheretal.2021,
  author    = {Schilcher, Felix and Hilsmann, Lioba and Rauscher, Lisa and Değirmenci, Laura and Krischke, Markus and Krischke, Beate and Ankenbrand, Markus and Rutschmann, Benjamin and Mueller, Martin J. and Steffan-Dewenter, Ingolf and Scheiner, Ricarda},
  title     = {In vitro rearing changes social task performance and physiology in honeybees},
  series = {Insects},
  volume    = {13},
  journal   = {Insects},
  number    = {1},
  issn      = {2075-4450},
  doi       = {10.3390/insects13010004},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-252305},
  year      = {2021},
  abstract  = {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.},
  language  = {en}
}
@article{RoellRameshaLinketal.2021,
  author    = {R{\"o}ll, Alexander and Ramesha, Mundre N. and Link, Roman M. and Hertel, Dietrich and Schuldt, Bernhard and Patil, Shekhargouda L. and H{\"o}lscher, Dirk},
  title     = {Water availability controls the biomass increment of Melia dubia in South India},
  series = {Forests},
  volume    = {12},
  journal   = {Forests},
  number    = {12},
  issn      = {1999-4907},
  doi       = {10.3390/f12121675},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-250150},
  year      = {2021},
  abstract  = {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.},
  language  = {en}
}
@article{TangYangNageletal.2021,
  author    = {Tang, Ruijing and Yang, Shang and Nagel, Georg and Gao, Shiqiang},
  title     = {mem-iLID, a fast and economic protein purification method},
  series = {Bioscience Reports},
  volume    = {41},
  journal   = {Bioscience Reports},
  number    = {7},
  doi       = {10.1042/BSR20210800},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-261420},
  year      = {2021},
  abstract  = {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.},
  language  = {en}
}
@phdthesis{Duan2021,
  author    = {Duan, Xiaodong},
  title     = {Development of new channelrhodopsin versions with enhanced plasma membrane targeting and high calcium/sodium conductance},
  doi       = {10.25972/OPUS-18839},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-188397},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2021},
  abstract  = {The technique to manipulate cells or living animals by illumination after gene transfer of light-sensitive proteins is called optogenetics. Successful optogenetics started with the use of the light-gated cation channel channelrhodopsin-2 (ChR2). After early demonstrations of the power of ChR2, further light-sensitive ion channels and ion pumps were recruited to the optogenetic toolbox. Furthermore, mutations and chimera of ChR2 improved its versatility. However, there is still a need for improved optogenetic tools, e.g. with higher permeability for calcium or better expression in the plasma membrane. In this thesis, my work focuses on the design of highly functional channelrhodopsins with enhanced Na+ and Ca2+ conductance. First, I tested different N-terminal signal peptides to improve the plasma membrane targeting of Channelrhodopsins. We found that a N-terminal peptide, named LR, could improve the plasma membrane targeting of many rhodopsins. Modification with LR contributed to three to ten-fold larger photocurrents (than that of the original version) of multiple channelrhodopsins, like ChR2 from C. reinhardtii (CrChR2), PsChR, Chrimson, CheRiff, CeChR, ACRs, and the light-activated pump rhodopsins KR2, Jaw, HR. Second, by introducing point mutation, I could further improve the light sensitivity and photocurrent of different channelrhodopsins. For instance, ChR2-XXM 2.0, ChR2-XXL 2.0 and PsChR D139H 2.0 exhibited hundred times larger photocurrents than wild type ChR2 and they show high light sensitivity. Also, the Ca2+ permeable channelrhodopsins PsCatCh 2.0f and PsCatCh 2.0e show very large photocurrents and fast kinetics. In addition, I also characterized a novel bi-stable CeChR (from the acidophilic green alga Chlamydomonas eustigma) with a much longer closing time. Third, I analysed the ion selectivity of different ChRs, which provides a basis for rational selection of channelrhodopsins for different experimental purposes. I demonstrate that ChR2, Chronos, Chrimson, CheRiff and CeChR are highly proton conductive, compared with wild type PsChR. Interestingly, Chronos has the lowest potassium conductance among these channelrhodopsins. Furthermore, I found that mutation of an aspartate in TM4 of ChR2 (D156) and PsChR (D139) to histidine obviously increased both the sodium and calcium permeability while proton conductance was reduced. PsChR D139H 2.0 has the largest sodium conductance of any published channelrhodopsin variants. Additionally, I generated PsCatCh 2.0e which exhibits a ten-fold larger calcium current than the previously reported Ca2+ transporting CrChR2 mutant CatCh. In summary, my research work 1.) described strategies for improving plasma membrane trafficking efficiency of opsins; 2.) yielded channelrhodopsins with fast kinetics or high light sensitivity; 3.) provided optogenetic tools with improved calcium and sodium conductance. We could also improve the performance of channelrhodopsins with distinct action spectra, which will facilitate two-color neural excitation, both in-vitro and in-vivo.},
  subject      = {Optogenetik},
  language  = {en}
}
@phdthesis{LindenbergverhSchubert2021,
  author    = {Lindenberg [verh. Schubert], Annekathrin},
  title     = {Timing of sensory preferences in \(Camponotus\) Ants},
  doi       = {10.25972/OPUS-16094},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-160948},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2021},
  abstract  = {Ants belong to the most successful insects living on our planet earth. One criterion of their tremendous success is the division of labor among workers that can be related to age (age¬- or temporal polyethism) and/ or body size (size-related polymorphism). Young ants care for the queen and brood in the nest interior and switch to foraging tasks in the outside environment with ongoing age. This highly flexible interior-exterior transition probably allows the ant workers to properly match the colony needs and is one of the most impressive behaviors a single worker undergoes during its life. As environmental stimuli are changing with this transition, workers are required to perform a new behavioral repertoire. This requires significant adaptions in sensory and higher¬-order integration centers in the brain, like the mushroom bodies. Furthermore, foragers need proper time measuring mechanisms to cope with daily environmental changes and to adapt their own mode of life. Therefore, they possess a functional endogenous clock that generates rhythms with a period length of approximately 24 hours. The species-rich genus of Camponotus ants constitute a rewarding model to study how behavioral duties of division of labor were performed and modulated within the colony and how synaptic plasticity in the brain is processed, as they can divide their labor to both, age and body size, simultaneously. In my PhD thesis, I started to investigate the behavioral repertoire (like foraging and locomotor activity) of two sympatric Camponotus species, C. mus and C. rufipes workers under natural and under controlled conditions. Furthermore, I focused on the division of labor in C. rufipes workers and started to examine structural and ultrastructural changes of neuronal architectures in the brain that are accompanied by the interior-exterior transition of C. rufipes ants. In the first part of my thesis, I started to analyze the temporal organization of task allocation throughout the life of single C. rufipes workers. Constant video-tracking of individually labeled workers for up to 11 weeks, revealed an age-related division of labor of interior and exterior workers. After emergence, young individuals are tended to by older ones within the first 48 hours of their lives before they themselves start nurturing larvae and pupae. Around 52\% switch to foraging duties at an age of 14-20 days. The workers that switched to foraging tasks are mainly media-sized workers and seem to be more specialized than nurses. Variations in proportion and the age of switching workers between and within different subcolonies indicate how highly flexible and plastic the age-related division of labor occurs in this ant species. Most of the observed workers were engaged in foraging tasks exclusively during nighttime. As the experiments were conducted in the laboratory, they are completely lacking environmental stimuli of the ants´ natural habitat. I therefore asked in a second study, how workers of the two closely related Camponotus species, C. rufipes and C. mus, adapt their daily activity patterns (foraging and locomotor activity) under natural (in Uruguay, South America) and controlled (in the laboratory) conditions to changing thermal conditions. Monitoring the foraging activity of both Camponotus species in a field experiment revealed, that C. mus workers are exclusively diurnal, whereas C. rufipes foragers are predominantly nocturnal. However, some nests showed an elevated daytime activity, which could be an adaption to seasonally cold night temperatures. To further investigate the impact of temperature and light on the differing foraging activity patterns in the field, workers of both Camponotus species were artificially exposed to different thermal regimes in the laboratory, simulating local winter and summer conditions. Here again, C. mus workers display solely diurnal locomotor activity, whereas workers of C. rufipes shifted their locomotor activity from diurnal under thermal winter conditions to nocturnal under thermal summer conditions. Hence, the combination of both, field work and laboratory studies, shows that daily activity is mostly shaped by thermal conditions and that temperature cycles are not just limiting foraging activity but can be used as zeitgeber to schedule the outside activities of the nests. Once an individual worker switches from indoor duties to exterior foraging tasks, it is confronted with an entirely new set of sensory information. To cope with changes of the environmental conditions and to facilitate the behavioral switch, workers need a highly flexible and plastic neuronal system. Hence, my thesis further focuses on the underlying neuronal adaptations of the visual system, including the optic lobes as the primary visual neuropil and the mushroom bodies as secondary visual brain neuropil, that are accompanied with the behavioral switch from nursing to foraging. The optic lobes as well as the mushroom bodies of light-deprived workers show an `experience-independent´ volume increase during the first two weeks of adulthood. An additional light exposure for 4 days induces an `experience-dependent´ decrease of synaptic complexes in the mushroom body collar, followed by an increase after extended light exposure for 14 days. I therefore conclude, that the plasticity of the central visual system represents important components for the optimal timing of the interior-exterior transitions and flexibility of the age-related division of labor. These remarkable structural changes of synaptic complexes suggest an active involvement of the mushroom body neuropil in the lifetime plasticity that promotes the interior-exterior transition of Camponotus rufipes ants. Beside these investigations of neuronal plasticity of synaptic complexes in the mushroom bodies on a structural level, I further started to examine mushroom body synaptic structures at the ultrastructural level. Until recently, the detection of synaptic components in projection neuron axonal boutons were below resolution using classical Transmission Electron Microscopy. Therefore, I started to implement Electron Tomography to increase the synaptic resolution to understand architectural changes in neuronal plasticity process. By acquiring double tilt series and consecutive computation of the acquired tilt information, I am now able to resolve individual clear-core and dense-core vesicles within the projection neuron cytoplasm of C. rufipes ants. I additionally was able to reveal single postsynaptic Kenyon cell dendritic spines (~62) that surround one individual projection neuron bouton. With this, I could reveal first insights into the complex neuronal architecture of single projection neuron boutons in the olfactory mushroom body lip region. The high resolution images of synaptic architectures at the ultrastructural level, received with Electron Tomography would promote the understanding of architectural changes in neuronal plasticity. In my PhD thesis, I demonstrate that the temporal organization within Camponotus colonies involves the perfect timing of different tasks. Temperature seems to be the most scheduling abiotic factors of foraging and locomotor activity. The ants do not only need to adapt their behavioral repertoire in accordance to the interior-exterior switch, also the parts in the peripheral and central that process visual information need to adapt to the new sensory environment.},
  subject      = {Rossameise},
  language  = {en}
}
@phdthesis{Tang2021,
  author    = {Tang, Ruijing},
  title     = {Optogenetic Methods to Regulate Water Transport and Purify Proteins},
  doi       = {10.25972/OPUS-23173},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-231736},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2021},
  abstract  = {Water transport through the water channels, aquaporins (AQPs), is involved in epithelial fluid secretion and absorption, cell migration, brain edema, adipocyte metabolism, and other physiological or pathological functions. Modulation of AQP function has therapeutic potential in edema, cancer, obesity, brain injury, glaucoma, etc. The function of AQPs is in response to the osmotic gradient that is formed by the concentration differences of ions or small molecules. In terms of brain edema, it is a pathophysiological condition, resulting from dysfunction of the plasma membrane that causes a disorder of intracellular ion homeostasis and thus increases intracellular fluid content. Optogenetics can be used to regulate ion transport easily by light with temporal and spatial precision. Therefore, if we control the cell ion influx, boosting the water transport through AQPs, this will help to investigate the pathological mechanisms in e.g. brain edema. To this end, I investigated the possibility for optogenetic manipulating water transport in Xenopus oocytes. The main ions in Xenopus oocyte cytoplasm are ~10 mM Na+, ~50 mM Cl- and ~100 mM K+, similar to the mammalian cell physiological condition. Three light-gated channels, ChR2-XXM 2.0 (light-gated cation channel), GtACR1 (light-gated anion channel) and SthK-bPAC (light-gated potassium channel), were used in my study to regulate ion transport by light and thus manipulate the osmotic gradient and water transport. To increase water flow, I also used coexpression of AQP1. When expressing ChR2-XXM 2.0 and GtACR1 together, mainly Na+ influx was triggered by ChR2-XXM2.0 under blue light illumination, which then made the membrane potential more positive and facilitated Cl- influx by GtACR1. Due to this inward movement of Na+ and Cl-, the osmotic gradient was formed to trigger water influx through AQP1. Large amounts of water uptake can speedily increase the oocyte volume until membrane rupture. Next, when co-expressing GtACR1 and SthK-bPAC, water efflux will be triggered with blue light because of the light-gated KCl efflux and then oocyte shrinking could be observed. I also developed an optogenetic protein purification method based on a light-induced protein interactive system. Currently, the most common protein purification method is based on affinity chromatography, which requires different chromatography columns and harsh conditions, such as acidic pH 4.5 - 6 and/or adding imidazole or high salt concentration, to elute and collect the purified proteins. The change in conditions could influence the activity of target proteins. So, an easy and flexible protein purification method based on the photo-induced protein interactive system iLID was designed, which regulates protein binding with light in mild conditions and does not require a change of solution composition. For expression in E. coli, the blue light-sensitive part of iLID, the LOV2 domain, was fused with a membrane anchor and expressed in the plasma membrane, and the other binding partner, SspB, was fused with the protein of interest (POI), expressed in the cytosol. The plasma membrane fraction and the soluble cytosolic fraction of E. coli can be easily separated by centrifugation. The SspB-POI can be then captured to the membrane fraction by light stimulation and released to clean buffer in the dark after washing. This method does not require any specific column and functions in mild conditions, which are very flexible at scale and will facilitate extensive protein engineering and purification of proteins, sensitive to changed buffer conditions.},
  language  = {en}
}
@phdthesis{Voss2021,
  author    = {Voß, Lena Johanna},
  title     = {{\"A}nderungen der Membranspannung und der Osmolarit{\"a}t als Ausl{\"o}ser f{\"u}r Calciumsignale in Pflanzen - Studien an Schließzellen von Nicotiana tabacum und Polypodium vulgare},
  doi       = {10.25972/OPUS-21963},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-219639},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2021},
  abstract  = {Stomata sind kleine Poren in der Blattoberfl{\"a}che, die Pflanzen eine Anpassung ihres Wasserhaushalts an sich {\"a}ndernde Umweltbedingungen erm{\"o}glichen. Die {\"O}ffnungsweite der Stomata wird durch den Turgordruck der Schließzellen bestimmt, der wiederum durch Ionenfl{\"u}sse {\"u}ber die Membranen der Zelle reguliert wird. Ein Netzwerk von Signaltransduktionswegen sorgt daf{\"u}r, dass Pflanzen die Stomabewegungen an die Umgebungsbedingungen anpassen k{\"o}nnen. Viele molekulare Komponenten dieser Signaltransduktionketten in Schließzellen von Angiospermen sind inzwischen bekannt und Calcium spielt darin als Signalmolek{\"u}l eine wichtige Rolle. Weitgehend unbekannt sind dagegen die Mechanismen, die zur Erzeugung von transienten Erh{\"o}hungen der Calciumkonzentration f{\"u}hren. Auch die molekularen Grundlagen der Regulierung der Stomaweite in Nicht-Angiospermen-Arten sind bisher nur wenig verstanden. Um zur Aufkl{\"a}rung dieser Fragestellungen beizutragen, wurden in dieser Arbeit Mechanismen zur Erh{\"o}hungen der cytosolischen Calciumkonzentration sowie elektrophysiologische Eigenschaften von Schließzellen untersucht. Der Fokus lag hierbei insbesondere auf der Visualisierung cytosolischer Calciumsignale in Schließzellen. Im ersten Teil der Arbeit wurde durch die Applikation hyperpolarisierender Spannungspulse mittels TEVC (Two Electrode Voltage Clamp) gezielt eine Erh{\"o}hung der cytosolischen Calciumkonzentration in einzelnen Schließzellen von Nicotiana tabacum ausgel{\"o}st. Um die Dynamik der cytosolischen Calciumkonzentration dabei zeitlich und r{\"a}umlich hoch aufgel{\"o}st zu visualisieren, wurde simultan zu den elektrophysiologischen Messungen ein Spinning-Disc-System f{\"u}r konfokale Aufnahmen eingesetzt. W{\"a}hrend der Applikation hyperpolarisierender Spannungspulse wurde eine transiente Vergr{\"o}ßerung des cytosolischen Volumens beobachtet. Diese l{\"a}sst sich durch einen osmotisch getriebenen Wasserfluss erkl{\"a}ren, der durch die Ver{\"a}nderung der Ionenkonzentration im Cytosol verursacht wird. Diese wiederum wird durch die spannungsabh{\"a}ngige Aktivierung einw{\"a}rtsgleichrichtender Kaliumkan{\"a}le in der Plasmamembran der Schließzellen und durch den Kompensationsstrom der eingestochenen Mikroelektrode hervorgerufen. Mit Hilfe des calciumsensitiven Farbstoffs Fura-2 konnte gezeigt werden, dass die Erh{\"o}hung der freien cytosolischen Calciumkonzentration w{\"a}hrend der Applikation hyperpolarisierender Spannungspulse durch zwei Mechanismen verursacht wird. Der erste Mechanismus ist die Aktivierung hyperpolarisationsaktivierter, calciumpermeabler Kan{\"a}le (HACCs) in der Plasmamembran, die schon 1998 von Grabov \& Blatt beschrieben wurde. Zus{\"a}tzlich zu diesem Mechanismus der Calciumfreisetzung, konnte ein zweiter bislang unbekannter Mechanismus aufgedeckt werden, bei dem Calcium aus intrazellul{\"a}ren Speichern in das Cytosol freigesetzt wird. Dieser Mechanismus h{\"a}ngt mit der oben beschriebenen Vergr{\"o}ßerung des cytosolischen Volumens zusammen und ist wahrscheinlich durch die {\"A}nderungen der mechanischen Spannung der Membran bzw. der Osmolarit{\"a}t innerhalb der Zelle bedingt. Diese k{\"o}nnten zu einer Aktivierung mechanosensitiver, calciumpermeabler Kan{\"a}le f{\"u}hren. Der zweite Teil der Arbeit besch{\"a}ftigt sich mit den molekularen Grundlagen der Regulierung von Stomata in Nicht-Angiospermen. In Schließzellen von Polypodium vulgare konnten durch die Anwendung der TEVC-Technik {\"a}hnliche spannungsabh{\"a}ngige Str{\"o}me {\"u}ber die Plasmamembran gemessen werden wie in Angiospermen. Ebenso wurden durch die Applikation hyperpolarisierender Spannungspulse an Schließzellen von Polypodium und Asplenium Erh{\"o}hungen der cytosolischen Calciumkonzentration ausgel{\"o}st, die auf die Existenz spannungsabh{\"a}ngiger, calciumpermeabler Kan{\"a}le in der Plasmamembran hinweisen. Die Diffusion von Fluoreszenzfarbstoffen in die Nachbarschließzellen nach der iontophoretischen Beladung in Polypodium, Asplenium, Ceratopteris und Selaginella zeigte, dass in diesen Arten eine symplastische Verbindung zwischen benachbarten Schließzellen besteht, die an Schließzellen von Angiospermen bisher nicht beobachtet werden konnte. Anhand elektronenmikroskopischer Aufnahmen von Polypodium glycyrrhiza Schließzellen konnte gezeigt werden, dass diese Verbindung wahrscheinlich durch Plasmodesmata zwischen benachbarten Schließzellen gebildet wird. Durch die Analyse der Calciumdynamik in benachbarten Schließzellen nach hyperpolarisierenden Spannungspulsen stellte sich heraus, dass die Calciumhom{\"o}ostase trotz symplastischer Verbindung in beiden Schließzellen unabh{\"a}ngig voneinander reguliert zu werden scheint. Im Rahmen der Untersuchungen an Farnschließzellen wurde desweiteren eine Methode zur Applikation von ABA etabliert, die es erlaubt mithilfe von Mikroelektroden das Phytohormon iontophoretisch in den Apoplasten zu laden. Im Gegensatz zu den Schließzellen von Nicotiana tabacum, die auf eine so durchgef{\"u}hrte ABA-Applikation mit dem Stomaschluss reagierten, wurde in Polypodium vulgare auf diese Weise kein Stomaschluss ausgel{\"o}st. Da die ABA-Antwort der Farnstomata aber auch von anderen Faktoren wie Wachstumsbedingungen abh{\"a}ngig ist (H{\~o}rak et al., 2017), kann eine ABA-Responsivit{\"a}t in dieser Farnart trotzdem nicht vollkommen ausgeschlossen werden. Die Freisetzung von Calcium aus intrazellul{\"a}ren Speichern, wie sie in dieser Arbeit gezeigt wurde, k{\"o}nnte eine wichtige Rolle bei der Regulierung der Stomaweite spielen. Zur Aufkl{\"a}rung dieser Fragestellung w{\"a}re die Identifizierung der Kan{\"a}le, die an der osmotisch/mechanisch induzierten Calciumfreisetzung aus internen Speichern beteiligt sind, von großem Interesse. Weiterf{\"u}hrende Studien an Schließzellen von Farnen k{\"o}nnten die physiologische Bedeutung der aus Angiospermen bekannten Ionenkan{\"a}le f{\"u}r die Stomabewegungen in evolution{\"a}r {\"a}lteren Landpflanzen aufkl{\"a}ren und so maßgeblich zum Verst{\"a}ndnis der Evolution der Regulierunsgmechanismen von Stomata beitragen. Außerdem stellt sich die Frage, welche Rolle die hier gezeigte symplastische Verbindung der Nachbarschließzellen durch Plasmodesmata f{\"u}r die Funktion der Stomata spielt.},
  subject      = {Schließzelle},
  language  = {de}
}
@article{ZhouDingDuanetal.2021,
  author    = {Zhou, Yang and Ding, Meiqi and Duan, Xiaodong and Konrad, Kai R. and Nagel, Georg and Gao, Shiqiang},
  title     = {Extending the Anion Channelrhodopsin-Based Toolbox for Plant Optogenetics},
  series = {Membranes},
  volume    = {11},
  journal   = {Membranes},
  number    = {4},
  issn      = {2077-0375},
  doi       = {10.3390/membranes11040287},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-236617},
  year      = {2021},
  abstract  = {Optogenetics was developed in the field of neuroscience and is most commonly using light-sensitive rhodopsins to control the neural activities. Lately, we have expanded this technique into plant science by co-expression of a chloroplast-targeted β-carotene dioxygenase and an improved anion channelrhodopsin GtACR1 from the green alga Guillardia theta. The growth of Nicotiana tabacum pollen tube can then be manipulated by localized green light illumination. To extend the application of analogous optogenetic tools in the pollen tube system, we engineered another two ACRs, GtACR2, and ZipACR, which have different action spectra, light sensitivity and kinetic features, and characterized them in Xenopus laevis oocytes, Nicotiana benthamiana leaves and N. tabacum pollen tubes. We found that the similar molecular engineering method used to improve GtACR1 also enhanced GtACR2 and ZipACR performance in Xenopus laevis oocytes. The ZipACR1 performed in N. benthamiana mesophyll cells and N. tabacum pollen tubes with faster kinetics and reduced light sensitivity, allowing for optogenetic control of anion fluxes with better temporal resolution. The reduced light sensitivity would potentially facilitate future application in plants, grown under low ambient white light, combined with an optogenetic manipulation triggered by stronger green light.},
  language  = {en}
}
@article{TianNagelGao2021,
  author    = {Tian, Yuehui and Nagel, Georg and Gao, Shiqiang},
  title     = {An engineered membrane-bound guanylyl cyclase with light-switchable activity},
  series = {BMC Biology},
  volume    = {19},
  journal   = {BMC Biology},
  number    = {1},
  doi       = {10.1186/s12915-021-00978-6},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-259181},
  pages     = {54},
  year      = {2021},
  abstract  = {Background Microbial rhodopsins vary in their chemical properties, from light sensitive ion transport to different enzymatic activities. Recently, a novel family of two-component Cyclase (rhod)opsins (2c-Cyclop) from the green algae Chlamydomonas reinhardtii and Volvox carteri was characterized, revealing a light-inhibited guanylyl cyclase (GC) activity. More genes similar to 2c-Cyclop exist in algal genomes, but their molecular and physiological functions remained uncharacterized. Results Chlamyopsin-5 (Cop5) from C. reinhardtii is related to Cr2c-Cyclop1 (Cop6) and can be expressed in Xenopus laevis oocytes, but shows no GC activity. Here, we exchanged parts of Cop5 with the corresponding ones of Cr2c-Cyclop1. When exchanging the opsin part of Cr2c-Cyclop1 with that of Cop5, we obtained a bi-stable guanylyl cyclase (switch-Cyclop1) whose activity can be switched by short light flashes. The GC activity of switch-Cyclop1 is increased for hours by a short 380 nm illumination and switched off (20-fold decreased) by blue or green light. switch-Cyclop1 is very light-sensitive and can half-maximally be activated by ~ 150 photons/nm2 of 380 nm (~ 73 J/m2) or inhibited by ~ 40 photons/nm\(^2\) of 473 nm (~ 18 J/m\(^2\)). Conclusions This engineered guanylyl cyclase is the first light-switchable enzyme for cGMP level regulation. Light-regulated cGMP production with high light-sensitivity is a promising technique for the non-invasive investigation of the effects of cGMP signaling in many different tissues.},
  language  = {en}
}
@article{LiPradaDaminelietal.2021,
  author    = {Li, Kunkun and Prada, Juan and Damineli, Daniel S. C. and Liese, Anja and Romeis, Tina and Dandekar, Thomas and Feij{\´o}, Jos{\´e} A. and Hedrich, Rainer and Konrad, Kai Robert},
  title     = {An optimized genetically encoded dual reporter for simultaneous ratio imaging of Ca\(^{2+}\) and H\(^{+}\) reveals new insights into ion signaling in plants},
  series = {New Phytologist},
  volume    = {230},
  journal   = {New Phytologist},
  number    = {6},
  doi       = {10.1111/nph.17202},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-239847},
  pages     = {2292 -- 2310},
  year      = {2021},
  abstract  = {Whereas the role of calcium ions (Ca\(^{2+}\)) in plant signaling is well studied, the physiological significance of pH-changes remains largely undefined. Here we developed CapHensor, an optimized dual-reporter for simultaneous Ca\(^{2+}\) and pH ratio-imaging and studied signaling events in pollen tubes (PTs), guard cells (GCs), and mesophyll cells (MCs). Monitoring spatio-temporal relationships between membrane voltage, Ca\(^{2+}\)- and pH-dynamics revealed interconnections previously not described. In tobacco PTs, we demonstrated Ca\(^{2+}\)-dynamics lag behind pH-dynamics during oscillatory growth, and pH correlates more with growth than Ca\(^{2+}\). In GCs, we demonstrated abscisic acid (ABA) to initiate stomatal closure via rapid cytosolic alkalization followed by Ca2+ elevation. Preventing the alkalization blocked GC ABA-responses and even opened stomata in the presence of ABA, disclosing an important pH-dependent GC signaling node. In MCs, a flg22-induced membrane depolarization preceded Ca2+-increases and cytosolic acidification by c. 2 min, suggesting a Ca\(^{2+}\)/pH-independent early pathogen signaling step. Imaging Ca2+ and pH resolved similar cytosol and nuclear signals and demonstrated flg22, but not ABA and hydrogen peroxide to initiate rapid membrane voltage-, Ca\(^{2+}\)- and pH-responses. We propose close interrelation in Ca\(^{2+}\)- and pH-signaling that is cell type- and stimulus-specific and the pH having crucial roles in regulating PT growth and stomata movement.},
  language  = {en}
}
@article{NuhkatBroscheStoezleFeixetal.2021,
  author    = {Nuhkat, Maris and Brosch{\´e}, Mikael and Stoezle-Feix, Sonja and Dietrich, Petra and Hedrich, Rainer and Roelfsema, M. Rob G. and Kollist, Hannes},
  title     = {Rapid depolarization and cytosolic calcium increase go hand-in-hand in mesophyll cells' ozone response},
  series = {New Phytologist},
  volume    = {232},
  journal   = {New Phytologist},
  number    = {4},
  doi       = {10.1111/nph.17711},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-259646},
  pages     = {1692-1702},
  year      = {2021},
  abstract  = {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.},
  language  = {en}
}
@article{DindasDreyerHuangetal.2021,
  author    = {Dindas, Julian and Dreyer, Ingo and Huang, Shouguang and Hedrich, Rainer and Roelfsema, M. Rob G.},
  title     = {A voltage-dependent Ca\(^{2+}\) homeostat operates in the plant vacuolar membrane},
  series = {New Phytologist},
  volume    = {230},
  journal   = {New Phytologist},
  number    = {4},
  doi       = {10.1111/nph.17272},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-259627},
  pages     = {1449-1460},
  year      = {2021},
  abstract  = {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.},
  language  = {en}
}
@article{Froeschel2021,
  author    = {Fr{\"o}schel, Christian},
  title     = {In-depth evaluation of root infection systems using the vascular fungus Verticillium longisporum as soil-borne model pathogen},
  series = {Plant Methods},
  volume    = {17},
  journal   = {Plant Methods},
  doi       = {10.1186/s13007-021-00758-x},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-260807},
  year      = {2021},
  abstract  = {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.},
  language  = {en}
}
@article{RasouliKianiPouyaShabalaetal.2021,
  author    = {Rasouli, Fatemeh and Kiani-Pouya, Ali and Shabala, Lana and Li, Leiting and Tahir, Ayesha and Yu, Min and Hedrich, Rainer and Chen, Zhonghua and Wilson, Richard and Zhang, Heng and Shabala, Sergey},
  title     = {Salinity effects on guard cell proteome in Chenopodium quinoa},
  series = {International Journal of Molecular Sciences},
  volume    = {22},
  journal   = {International Journal of Molecular Sciences},
  number    = {1},
  issn      = {1422-0067},
  doi       = {10.3390/ijms22010428},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-285625},
  year      = {2021},
  abstract  = {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.},
  language  = {en}
}
@article{HuangDingRoelfsemaetal.2021,
  author    = {Huang, Shouguang and Ding, Meiqi and Roelfsema, M. Rob G. and Dreyer, Ingo and Scherzer, S{\"o}nke and Al-Rasheid, Khaled A. S and Gao, Shiqiang and Nagel, Georg and Hedrich, Rainer and Konrad, Kai R.},
  title     = {Optogenetic control of the guard cell membrane potential and stomatal movement by the light-gated anion channel GtACR1},
  series = {Science Advances},
  volume    = {7},
  journal   = {Science Advances},
  number    = {28},
  doi       = {10.1126/sciadv.abg4619},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-260925},
  year      = {2021},
  abstract  = {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.},
  language  = {en}
}
@article{SchieferleTappeKorteetal.2021,
  author    = {Schieferle, Sebastian and Tappe, Beeke and Korte, Pamela and Mueller, Martin J. and Berger, Susanne},
  title     = {Pathogens and Elicitors Induce Local and Systemic Changes in Triacylglycerol Metabolism in Roots and in Leaves of Arabidopsis thaliana},
  series = {Biology},
  volume    = {10},
  journal   = {Biology},
  number    = {9},
  issn      = {2079-7737},
  doi       = {10.3390/biology10090920},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-246198},
  year      = {2021},
  abstract  = {Simple Summary Abiotic and biotic stress conditions result in profound changes in plant lipid metabolism. Vegetable oil consists of triacylglycerols, which are important energy and carbon storage compounds in seeds of various plant species. These compounds are also present in vegetative tissue, and levels have been reported to increase with different abiotic stresses in leaves. This work shows that triacylglycerols accumulate in roots and in distal, non-treated leaves upon treatment with a fungal pathogen or lipopolysaccharide (a common bacterial-derived elicitor in animals and plants). Treatment of leaves with a bacterial pathogen or a bacterial effector molecule results in triacylglycerol accumulation in leaves, but not systemically in roots. These results suggest that elicitor molecules are sufficient to induce an increase in triacylglycerol levels, and that unidirectional long-distance signaling from roots to leaves is involved in pathogen and elicitor-induced triacylglycerol accumulation. Abstract Interaction of plants with the environment affects lipid metabolism. Changes in the pattern of phospholipids have been reported in response to abiotic stress, particularly accumulation of triacylglycerols, but less is known about the alteration of lipid metabolism in response to biotic stress and leaves have been more intensively studied than roots. This work investigates the levels of lipids in roots as well as leaves of Arabidopsis thaliana in response to pathogens and elicitor molecules by UPLC-TOF-MS. Triacylglycerol levels increased in roots and systemically in leaves upon treatment of roots with the fungus Verticillium longisporum. Upon spray infection of leaves with the bacterial pathogen Pseudomonas syringae, triacylglycerols accumulated locally in leaves but not in roots. Treatment of roots with a bacterial lipopolysaccharide elicitor induced a strong triacylglycerol accumulation in roots and leaves. Induction of the expression of the bacterial effector AVRRPM1 resulted in a dramatic increase of triacylglycerol levels in leaves, indicating that elicitor molecules are sufficient to induce accumulation of triacylglycerols. These results give insight into local and systemic changes to lipid metabolism in roots and leaves in response to biotic stresses.},
  language  = {en}
}
@article{GhirardoNosenkoKreuzwieseretal.2021,
  author    = {Ghirardo, Andrea and Nosenko, Tetyana and Kreuzwieser, J{\"u}rgen and Winkler, J. Barbro and Kruse, J{\"o}rg and Albert, Andreas and Merl-Pham, Juliane and Lux, Thomas and Ache, Peter and Zimmer, Ina and Alfarraj, Saleh and Mayer, Klaus F. X. and Hedrich, Rainer and Rennenberg, Heinz and Schnitzler, J{\"o}rg-Peter},
  title     = {Protein expression plasticity contributes to heat and drought tolerance of date palm},
  series = {Oecologia},
  volume    = {197},
  journal   = {Oecologia},
  number    = {4},
  issn      = {0029-8549},
  doi       = {10.1007/s00442-021-04907-w},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-308075},
  pages     = {903-919},
  year      = {2021},
  abstract  = {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.},
  language  = {en}
}
@article{DorjiSchuldtNeudametal.2021,
  author    = {Dorji, Yonten and Schuldt, Bernhard and Neudam, Liane and Dorji, Rinzin and Middleby, Kali and Isasa, Emilie and K{\"o}rber, Klaus and Ammer, Christian and Annigh{\"o}fer, Peter and Seidel, Dominik},
  title     = {Three-dimensional quantification of tree architecture from mobile laser scanning and geometry analysis},
  series = {Trees},
  volume    = {35},
  journal   = {Trees},
  number    = {4},
  issn      = {0931-1890},
  doi       = {10.1007/s00468-021-02124-9},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-307501},
  pages     = {1385-1398},
  year      = {2021},
  abstract  = {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.},
  language  = {en}
}