@article{BlaettnerDasPaprotkaetal.2016, author = {Bl{\"a}ttner, Sebastian and Das, Sudip and Paprotka, Kerstin and Eilers, Ursula and Krischke, Markus and Kretschmer, Dorothee and Remmele, Christian W. and Dittrich, Marcus and M{\"u}ller, Tobias and Schuelein-Voelk, Christina and Hertlein, Tobias and Mueller, Martin J. and Huettel, Bruno and Reinhardt, Richard and Ohlsen, Knut and Rudel, Thomas and Fraunholz, Martin J.}, title = {Staphylococcus aureus Exploits a Non-ribosomal Cyclic Dipeptide to Modulate Survival within Epithelial Cells and Phagocytes}, series = {PLoS Pathogens}, volume = {12}, journal = {PLoS Pathogens}, number = {9}, doi = {10.1371/journal.ppat.1005857}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-180380}, year = {2016}, abstract = {Community-acquired (CA) Staphylococcus aureus cause various diseases even in healthy individuals. Enhanced virulence of CA-strains is partly attributed to increased production of toxins such as phenol-soluble modulins (PSM). The pathogen is internalized efficiently by mammalian host cells and intracellular S. aureus has recently been shown to contribute to disease. Upon internalization, cytotoxic S. aureus strains can disrupt phagosomal membranes and kill host cells in a PSM-dependent manner. However, PSM are not sufficient for these processes. Here we screened for factors required for intracellular S. aureus virulence. We infected escape reporter host cells with strains from an established transposon mutant library and detected phagosomal escape rates using automated microscopy. We thereby, among other factors, identified a non-ribosomal peptide synthetase (NRPS) to be required for efficient phagosomal escape and intracellular survival of S. aureus as well as induction of host cell death. By genetic complementation as well as supplementation with the synthetic NRPS product, the cyclic dipeptide phevalin, wild-type phenotypes were restored. We further demonstrate that the NRPS is contributing to virulence in a mouse pneumonia model. Together, our data illustrate a hitherto unrecognized function of the S. aureus NRPS and its dipeptide product during S. aureus infection.}, language = {en} } @article{WalperWeisteMuelleretal.2016, author = {Walper, Elisabeth and Weiste, Christoph and Mueller, Martin J. and Hamberg, Mats and Dr{\"o}ge-Laser, Wolfgang}, title = {Screen Identifying Arabidopsis Transcription Factors Involved in the Response to 9-Lipoxygenase-Derived Oxylipins}, series = {PLoS One}, volume = {11}, journal = {PLoS One}, number = {4}, doi = {10.1371/journal.pone.0153216}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-146857}, pages = {e0153216}, year = {2016}, abstract = {13-Lipoxygenase-derived oxylipins, such as jasmonates act as potent signaling molecules in plants. Although experimental evidence supports the impact of oxylipins generated by the 9-Lipoxygenase (9-LOX) pathway in root development and pathogen defense, their signaling function in plants remains largely elusive. Based on the root growth inhibiting properties of the 9-LOX-oxylipin 9-HOT (9-hydroxy-10,12,15-octadecatrienoic acid), we established a screening approach aiming at identifying transcription factors (TFs) involved in signaling and/or metabolism of this oxylipin. Making use of the AtTORF-Ex (Arabidopsis thaliana Transcription Factor Open Reading Frame Expression) collection of plant lines overexpressing TF genes, we screened for those TFs which restore root growth on 9-HOT. Out of 6,000 lines, eight TFs were recovered at least three times and were therefore selected for detailed analysis. Overexpression of the basic leucine Zipper (bZIP) TF TGA5 and its target, the monoxygenase CYP81D11 reduced the effect of added 9-HOT, presumably due to activation of a detoxification pathway. The highly related ETHYLENE RESPONSE FACTORs ERF106 and ERF107 induce a broad detoxification response towards 9-LOX-oxylipins and xenobiotic compounds. From a set of 18 related group S-bZIP factors isolated in the screen, bZIP11 is known to participate in auxin-mediated root growth and may connect oxylipins to root meristem function. The TF candidates isolated in this screen provide starting points for further attempts to dissect putative signaling pathways involving 9-LOX-derived oxylipins.}, language = {en} } @article{StotzMuellerZoelleretal.2013, author = {Stotz, Henrik U. and Mueller, Stefan and Zoeller, Maria and Mueller, Martin J. and Berger, Susanne}, title = {TGA transcription factors and jasmonate-independent COI1 signalling regulate specific plant responses to reactive oxylipins}, series = {Journal of Experimental Botany}, volume = {64}, journal = {Journal of Experimental Botany}, number = {4}, doi = {10.1093/jxb/ers389}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-132318}, pages = {963-975}, year = {2013}, abstract = {Jasmonates and phytoprostanes are oxylipins that regulate stress responses and diverse physiological and developmental processes. 12-Oxo-phytodienoic acid (OPDA) and phytoprostanes are structurally related electrophilic cyclopentenones, which activate similar gene expression profiles that are for the most part different from the action of the cyclopentanone jasmonic acid (JA) and its biologically active amino acid conjugates. Whereas JA-isoleucine signals through binding to COI1, the bZIP transcription factors TGA2, TGA5, and TGA6 are involved in regulation of gene expression in response to phytoprostanes. Here root growth inhibition and target gene expression were compared after treatment with JA, OPDA, or phytoprostanes in mutants of the COI1/MYC2 pathway and in different TGA factor mutants. Inhibition of root growth by phytoprostanes was dependent on COI1 but independent of jasmonate biosynthesis. In contrast, phytoprostane-responsive gene expression was strongly dependent on TGA2, TGA5, and TGA6, but not dependent on COI1, MYC2, TGA1, and TGA4. Different mutant and overexpressing lines were used to determine individual contributions of TGA factors to cyclopentenone-responsive gene expression. Whereas OPDA-induced expression of the cytochrome P450 gene CYP81D11 was primarily regulated by TGA2 and TGA5, the glutathione S-transferase gene GST25 and the OPDA reductase gene OPR1 were regulated by TGA5 and TGA6, but less so by TGA2. These results support the model that phytoprostanes and OPDA regulate differently (i) growth responses, which are COI1 dependent but jasmonate independent; and (ii) lipid stress responses, which are strongly dependent on TGA2, TGA5, and TGA6. Identification of molecular components in cyclopentenone signalling provides an insight into novel oxylipin signal transduction pathways.}, language = {en} } @article{WallerMuellerPedrotti2013, author = {Waller, Frank and Mueller, Martin J. and Pedrotti, Lorenzo}, title = {Piriformospora indica Root Colonization Triggers Local and Systemic Root Responses and Inhibits Secondary Colonization of Distal Roots}, series = {PLoS ONE}, journal = {PLoS ONE}, doi = {10.1371/journal.pone.0069352}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-96493}, year = {2013}, abstract = {Piriformospora indica is a basidiomycete fungus colonizing roots of a wide range of higher plants, including crop plants and the model plant Arabidopsis thaliana. Previous studies have shown that P. indica improves growth, and enhances systemic pathogen resistance in leaves of host plants. To investigate systemic effects within the root system, we established a hydroponic split-root cultivation system for Arabidopsis. Using quantitative real-time PCR, we show that initial P. indica colonization triggers a local, transient response of several defense-related transcripts, of which some were also induced in shoots and in distal, non-colonized roots of the same plant. Systemic effects on distal roots included the inhibition of secondary P. indica colonization. Faster and stronger induction of defense-related transcripts during secondary inoculation revealed that a P. indica pretreatment triggers root-wide priming of defense responses, which could cause the observed reduction of secondary colonization levels. Secondary P. indica colonization also induced defense responses in distant, already colonized parts of the root. Endophytic fungi therefore trigger a spatially specific response in directly colonized and in systemic root tissues of host plants.}, language = {en} } @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} } @article{KraussVikukYoungetal.2020, author = {Krauss, Jochen and Vikuk, Veronika and Young, Carolyn A. and Krischke, Markus and Mueller, Martin J. and Baerenfaller, Katja}, title = {Epichlo{\"e} endophyte infection rates and alkaloid content in commercially available grass seed mixtures in Europe}, series = {Microorganisms}, volume = {8}, journal = {Microorganisms}, number = {4}, issn = {2076-2607}, doi = {10.3390/microorganisms8040498}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-203323}, pages = {498}, year = {2020}, abstract = {Fungal endophytes of the genus Epichlo{\"e} live symbiotically in cool season grass species and can produce alkaloids toxic to insects and vertebrates, yet reports of intoxication of grazing animals have been rare in Europe in contrast to overseas. However, due to the beneficial resistance traits observed in Epichlo{\"e} infected grasses, the inclusion of Epichlo{\"e} in seed mixtures might become increasingly advantageous. Despite the toxicity of fungal alkaloids, European seed mixtures are rarely tested for Epichlo{\"e} infection and their infection status is unknown for consumers. In this study, we tested 24 commercially available seed mixtures for their infection rates with Epichlo{\"e} endophytes and measured the concentrations of the alkaloids ergovaline, lolitrem B, paxilline, and peramine. We detected Epichlo{\"e} infections in six seed mixtures, and four contained vertebrate and insect toxic alkaloids typical for Epichlo{\"e} festucae var. lolii infecting Lolium perenne. As Epichlo{\"e} infected seed mixtures can harm livestock, when infected grasses become dominant in the seeded grasslands, we recommend seed producers to test and communicate Epichlo{\"e} infection status or avoiding Epichlo{\"e} infected seed mixtures.}, language = {en} } @article{ElmaidomyMohammedHassanetal.2019, author = {Elmaidomy, Abeer H. and Mohammed, Rabab and Hassan, Hossam M. and Owis, Asmaa I. and Rateb, Mostafa E. and Khanfar, Mohammad A. and Krischke, Markus and Mueller, Martin J. and Abdelmohsen, Usama Ramadan}, title = {Metabolomic profiling and cytotoxic tetrahydrofurofuran lignans investigations from Premna odorata Blanco}, series = {Metabolites}, volume = {9}, journal = {Metabolites}, number = {10}, issn = {2218-1989}, doi = {10.3390/metabo9100223}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-193187}, pages = {223}, year = {2019}, abstract = {Metabolomic profiling of different Premna odorata Blanco (Lamiaceae) organs, bark, wood, young stems, flowers, and fruits dereplicated 20, 20, 10, 20, and 20 compounds, respectively, using LC-HRESIMS. The identified metabolites (1-34) belonged to different chemical classes, including iridoids, flavones, phenyl ethanoids, and lignans. A phytochemical investigation of P. odorata bark afforded one new tetrahydrofurofuran lignan, 4β-hydroxyasarinin 35, along with fourteen known compounds. The structure of the new compound was confirmed using extensive 1D and 2D NMR, and HRESIMS analyses. A cytotoxic investigation of compounds 35-38 against the HL-60, HT-29, and MCF-7 cancer cell lines, using the MTT assay showed that compound 35 had cytotoxic effects against HL-60 and MCF-7 with IC50 values of 2.7 and 4.2 µg/mL, respectively. A pharmacophore map of compounds 35 showed two hydrogen bond acceptor (HBA) aligning the phenoxy oxygen atoms of benzodioxole moieties, two aromatic ring features vectored on the two phenyl rings, one hydrogen bond donor (HBD) feature aligning the central hydroxyl group and thirteen exclusion spheres which limit the boundaries of sterically inaccessible regions of the target's active site.}, language = {en} } @article{SchilcherHilsmannAnkenbrandetal.2022, author = {Schilcher, Felix and Hilsmann, Lioba and Ankenbrand, Markus J. and Krischke, Markus and Mueller, Martin J. and Steffan-Dewenter, Ingolf and Scheiner, Ricarda}, title = {Honeybees are buffered against undernourishment during larval stages}, series = {Frontiers in Insect Science}, volume = {2}, journal = {Frontiers in Insect Science}, issn = {2673-8600}, doi = {10.3389/finsc.2022.951317}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-304646}, year = {2022}, abstract = {The negative impact of juvenile undernourishment on adult behavior has been well reported for vertebrates, but relatively little is known about invertebrates. In honeybees, nutrition has long been known to affect task performance and timing of behavioral transitions. Whether and how a dietary restriction during larval development affects the task performance of adult honeybees is largely unknown. We raised honeybees in-vitro, varying the amount of a standardized diet (150 µl, 160 µl, 180 µl in total). Emerging adults were marked and inserted into established colonies. Behavioral performance of nurse bees and foragers was investigated and physiological factors known to be involved in the regulation of social organization were quantified. Surprisingly, adult honeybees raised under different feeding regimes did not differ in any of the behaviors observed. No differences were observed in physiological parameters apart from weight. Honeybees were lighter when undernourished (150 µl), while they were heavier under the overfed treatment (180 µl) compared to the control group raised under a normal diet (160 µl). These data suggest that dietary restrictions during larval development do not affect task performance or physiology in this social insect despite producing clear effects on adult weight. We speculate that possible effects of larval undernourishment might be compensated during the early period of adult life.}, 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{KraussVikukYoungetal.2020, author = {Krauss, Jochen and Vikuk, Veronika and Young, Carolyn A. and Krischke, Markus and Mueller, Martin J. and Baerenfaller, Katja}, title = {Correction: Krauss, J., et al. Epichlo{\"e} endophyte infection rates and alkaloid content in commercially available grass seed mixtures in Europe. Microorganisms 2020, 8, 498}, series = {Microorganisms}, volume = {8}, journal = {Microorganisms}, number = {10}, issn = {2076-2607}, doi = {10.3390/microorganisms8101616}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-216254}, year = {2020}, abstract = {No abstract available.}, language = {en} } @article{ThurowKrischkeMuelleretal.2020, author = {Thurow, Corinna and Krischke, Markus and Mueller, Martin J. and Gatz, Christiane}, title = {Induction of jasmonoyl-isoleucine (JA-Ile)-dependent JASMONATE ZIM-DOMAIN (JAZ) genes in NaCl-treated Arabidopsis thaliana roots can occur at very low JA-Ile levels and in the absence of the JA/JA-Ile transporter JAT1/AtABCG16}, series = {Plants}, volume = {9}, journal = {Plants}, number = {12}, issn = {2223-7747}, doi = {10.3390/plants9121635}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-219382}, year = {2020}, abstract = {The plant hormone jasmonoyl-isoleucine (JA-Ile) is an important regulator of plant growth and defense in response to various biotic and abiotic stress cues. Under our experimental conditions, JA-Ile levels increased approximately seven-fold in NaCl-treated Arabidopsis thaliana roots. Although these levels were around 1000-fold lower than in wounded leaves, genes of the JA-Ile signaling pathway were induced by a factor of 100 or more. Induction was severely compromised in plants lacking the JA-Ile receptor CORONATINE INSENSITIVE 1 or enzymes required for JA-Ile biosynthesis. To explain efficient gene expression at very low JA-Ile levels, we hypothesized that salt-induced expression of the JA/JA-Ile transporter JAT1/AtABCG16 would lead to increased nuclear levels of JA-Ile. However, mutant plants with different jat1 alleles were similar to wild-type ones with respect to salt-induced gene expression. The mechanism that allows COI1-dependent gene expression at very low JA-Ile levels remains to be elucidated.}, language = {en} } @article{YoussifHaggagElshamyetal.2019, author = {Youssif, Khayrya A. and Haggag, Eman G. and Elshamy, Ali M. and Rabeh, Mohamed A. and Gabr, Nagwan M. and Seleem, Amany and Salem, M. Alaraby and Hussein, Ahmed S. and Krischke, Markus and Mueller, Martin J. and Ramadan Abdelmohsen, Usama}, title = {Anti-Alzheimer potential, metabolomic profiling and molecular docking of green synthesized silver nanoparticles of Lampranthus coccineus and Malephora lutea aqueous extracts}, series = {PLoS ONE}, volume = {14}, journal = {PLoS ONE}, number = {11}, doi = {10.1371/journal.pone.0223781}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-202696}, pages = {e0223781}, year = {2019}, abstract = {The green synthesis of silver nanoparticles (SNPs) using plant extracts is an eco-friendly method. It is a single step and offers several advantages such as time reducing, cost-effective and environmental non-toxic. Silver nanoparticles are a type of Noble metal nanoparticles and it has tremendous applications in the field of diagnostics, therapeutics, antimicrobial activity, anticancer and neurodegenerative diseases. In the present work, the aqueous extracts of aerial parts of Lampranthus coccineus and Malephora lutea F. Aizoaceae were successfully used for the synthesis of silver nanoparticles. The formation of silver nanoparticles was early detected by a color change from pale yellow to reddish-brown color and was further confirmed by transmission electron microscope (TEM), UV-visible spectroscopy, Fourier transform infrared (FTIR) spectroscopy, dynamic light scattering (DLS), X-ray diffraction (XRD), and energy-dispersive X-ray diffraction (EDX). The TEM analysis of showed spherical nanoparticles with a mean size between 12.86 nm and 28.19 nm and the UV- visible spectroscopy showed λ\(_{max}\) of 417 nm, which confirms the presence of nanoparticles. The neuroprotective potential of SNPs was evaluated by assessing the antioxidant and cholinesterase inhibitory activity. Metabolomic profiling was performed on methanolic extracts of L. coccineus and M. lutea and resulted in the identification of 12 compounds, then docking was performed to investigate the possible interaction between the identified compounds and human acetylcholinesterase, butyrylcholinesterase, and glutathione transferase receptor, which are associated with the progress of Alzheimer's disease. Overall our SNPs highlighted its promising potential in terms of anticholinesterase and antioxidant activity as plant-based anti-Alzheimer drug and against oxidative stress.}, language = {en} } @article{SegererHadamekZundleretal.2016, author = {Segerer, Gabriela and Hadamek, Kerstin and Zundler, Matthias and Fekete, Agnes and Seifried, Annegrit and Mueller, Martin J. and Koentgen, Frank and Gessler, Manfred and Jeanclos, Elisabeth and Gohla, Antje}, title = {An essential developmental function for murine phosphoglycolate phosphatase in safeguarding cell proliferation}, series = {Scientific Reports}, volume = {6}, journal = {Scientific Reports}, doi = {10.1038/srep35160}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-181094}, year = {2016}, abstract = {Mammalian phosphoglycolate phosphatase (PGP) is thought to target phosphoglycolate, a 2-deoxyribose fragment derived from the repair of oxidative DNA lesions. However, the physiological role of this activity and the biological function of the DNA damage product phosphoglycolate is unknown. We now show that knockin replacement of murine Pgp with its phosphatase-inactive Pgp\(^{D34N}\) mutant is embryonically lethal due to intrauterine growth arrest and developmental delay in midgestation. PGP inactivation attenuated triosephosphate isomerase activity, increased triglyceride levels at the expense of the cellular phosphatidylcholine content, and inhibited cell proliferation. These effects were prevented under hypoxic conditions or by blocking phosphoglycolate release from damaged DNA. Thus, PGP is essential to sustain cell proliferation in the presence of oxygen. Collectively, our findings reveal a previously unknown mechanism coupling a DNA damage repair product to the control of intermediary metabolism and cell proliferation.}, language = {en} } @article{VikukFuchsKrischkeetal.2020, author = {Vikuk, Veronika and Fuchs, Benjamin and Krischke, Markus and Mueller, Martin J. and Rueb, Selina and Krauss, Jochen}, title = {Alkaloid Concentrations of Lolium perenne Infected with Epichlo{\"e} festucae var. lolii with Different Detection Methods—A Re-Evaluation of Intoxication Risk in Germany?}, series = {Journal of Fungi}, volume = {6}, journal = {Journal of Fungi}, number = {3}, issn = {2309-608X}, doi = {10.3390/jof6030177}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-213171}, year = {2020}, abstract = {Mycotoxins in agriculturally used plants can cause intoxication in animals and can lead to severe financial losses for farmers. The endophytic fungus Epichlo{\"e} festucae var. lolii living symbiotically within the cool season grass species Lolium perenne can produce vertebrate and invertebrate toxic alkaloids. Hence, an exact quantitation of alkaloid concentrations is essential to determine intoxication risk for animals. Many studies use different methods to detect alkaloid concentrations, which complicates the comparability. In this study, we showed that alkaloid concentrations of individual plants exceeded toxicity thresholds on real world grasslands in Germany, but not on the population level. Alkaloid concentrations on five German grasslands with high alkaloid levels peaked in summer but were also below toxicity thresholds on population level. Furthermore, we showed that alkaloid concentrations follow the same seasonal trend, regardless of whether plant fresh or dry weight was used, in the field and in a common garden study. However, alkaloid concentrations were around three times higher when detected with dry weight. Finally, we showed that alkaloid concentrations can additionally be biased to different alkaloid detection methods. We highlight that toxicity risks should be analyzed using plant dry weight, but concentration trends of fresh weight are reliable.}, language = {en} } @article{AbdelhafezFawzyFahimetal.2018, author = {Abdelhafez, Omnia Hesham and Fawzy, Michael Atef and Fahim, John Refaat and Desoukey, Samar Yehia and Krischke, Markus and Mueller, Martin J. and Abdelmohsen, Usama Ramadan}, title = {Hepatoprotective potential of Malvaviscus arboreus against carbon tetrachloride-induced liver injury in rats}, series = {PLoS ONE}, volume = {13}, journal = {PLoS ONE}, number = {8}, doi = {10.1371/journal.pone.0202362}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-177243}, pages = {e0202362}, year = {2018}, abstract = {Malvaviscus arboreus Cav. is a medicinal plant belonging to family Malvaceae with both ethnomedical and culinary value; however, its phytochemical and biological profiles have been scarcely studied. Accordingly, this work was designed to explore the chemical composition and the hepatoprotective potential of M. arboreus against carbon tetrachloride (CCl\(_4\))-induced hepatotoxicity. The total extract of the aerial parts and its derived fractions (petroleum ether, dichloromethane, ethyl acetate, and aqueous) were orally administered to rats for six consecutive days, followed by injection of CCl\(_4\) (1:1 v/v, in olive oil, 1.5 ml/kg, i.p.) on the next day. Results showed that the ethyl acetate and dichloromethane fractions significantly alleviated liver injury in rats as indicated by the reduced levels of alanine transaminase (ALT), aspartate transaminase (AST), alkaline phosphatase (ALP), total bilirubin (TB), and malondialdehyde (MDA), along with enhancement of the total antioxidant capacities of their livers, with the maximum effects were recorded by the ethyl acetate fraction. Moreover, the protective actions of both fractions were comparable to those of silymarin (100 mg/kg), and have been also substantiated by histopathological evaluations. On the other hand, liquid chromatography-high resolution electrospray ionization mass spectrometry (LC‒HR‒ESI‒MS) metabolomic profiling of the crude extract of M. arboreus aerial parts showed the presence of a variety of phytochemicals, mostly phenolics, whereas the detailed chemical analysis of the most active fraction (i.e. ethyl acetate) resulted in the isolation and identification of six compounds for the first time in the genus, comprising four phenolic acids; β-resorcylic, caffeic, protocatechuic, and 4-hydroxyphenylacetic acids, in addition to two flavonoids; trifolin and astragalin. Such phenolic principles, together with their probable synergistic antioxidant and liver-protecting properties, seem to contribute to the observed hepatoprotective potential of M. arboreus.}, language = {en} } @article{OsmanStigloherMuelleretal.2020, author = {Osman, Mohamed and Stigloher, Christian and Mueller, Martin J. and Waller, Frank}, title = {An improved growth medium for enhanced inoculum production of the plant growth-promoting fungus Serendipita indica}, series = {Plant Methods}, volume = {16}, journal = {Plant Methods}, doi = {10.1186/s13007-020-00584-7}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-229186}, year = {2020}, abstract = {Background The plant endophytic fungus Serendipita indica colonizes roots of a wide range of plant species and can enhance growth and stress resistance of these plants. Due to its ease of axenic cultivation and its broad host plant range including the model plant Arabidopsis thaliana and numerous crop plants, it is widely used as a model fungus to study beneficial fungus-root interactions. In addition, it was suggested to be utilized for commercial applications, e.g. to enhance yield in barley and other species. To produce inoculum, S. indica is mostly cultivated in a complex Hill-Kafer medium (CM medium), however, growth in this medium is slow, and yield of chlamydospores, which are often used for plant root inoculation, is relatively low. Results We tested and optimized a simple vegetable juice-based medium for an enhanced yield of fungal inoculum. The described vegetable juice (VJ) medium is based on commercially available vegetable juice and is easy to prepare. VJ medium was superior to the currently used CM medium with respect to biomass production in liquid medium and hyphal growth on agar plates. Using solid VJ medium supplemented with sucrose (VJS), a high amount of chlamydospores developed already after 8 days of cultivation, producing significantly more spores than on CM medium. Use of VJ medium is not restricted to S. indica, as it also supported growth of two pathogenic fungi often used in plant pathology experiments: the ascomycete Fusarium graminearum, the causal agent of Fusarium head blight disease on wheat and barley, and Verticillium longisporum, the causal agent of verticillium wilt. Conclusions The described VJ medium is recommended for streamlined and efficient production of inoculum for the plant endophytic fungus Serendipita indica and might prove superior for the propagation of other fungi for research purposes.}, language = {en} } @article{SchaeblerAmatobiHornetal.2020, author = {Sch{\"a}bler, Stefan and Amatobi, Kelechi M. and Horn, Melanie and Rieger, Dirk and Helfrich‑F{\"o}rster, Charlotte and Mueller, Martin J. and Wegener, Christian and Fekete, Agnes}, title = {Loss of function in the Drosophila clock gene period results in altered intermediary lipid metabolism and increased susceptibility to starvation}, series = {Cellular and Molecular Life Sciences}, volume = {77}, journal = {Cellular and Molecular Life Sciences}, issn = {1420-682X}, doi = {10.1007/s00018-019-03441-6}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-232432}, pages = {4939-4956}, year = {2020}, abstract = {The fruit fly Drosophila is a prime model in circadian research, but still little is known about its circadian regulation of metabolism. Daily rhythmicity in levels of several metabolites has been found, but knowledge about hydrophobic metabolites is limited. We here compared metabolite levels including lipids between period\(^{01}\) (per\(^{01}\)) clock mutants and Canton-S wildtype (WT\(_{CS}\)) flies in an isogenic and non-isogenic background using LC-MS. In the non-isogenic background, metabo-lites with differing levels comprised essential amino acids, kynurenines, pterinates, glycero(phospho)lipids, and fatty acid esters. Notably, detectable diacylglycerols (DAG) and acylcarnitines (AC), involved in lipid metabolism, showed lower levels in per\(^{01}\) mutants. Most of these differences disappeared in the isogenic background, yet the level differences for AC as well as DAG were consistent for fly bodies. AC levels were dependent on the time of day in WTCS in phase with food consumption under LD conditions, while DAGs showed weak daily oscillations. Two short-chain ACs continued to cycle even in constant darkness. per\(^{01}\) mutants in LD showed no or very weak diel AC oscillations out of phase with feeding activity. The low levels of DAGs and ACs in per\(^{01}\) did not correlate with lower total food consumption, body mass or weight. Clock mutant flies showed higher sensitivity to starvation independent of their background-dependent activity level. Our results suggest that neither feeding, energy storage nor mobilisation is significantly affected in per\(^{01}\) mutants, but point towards impaired mitochondrial activity, supported by upregulation of the mitochondrial stress marker 4EBP in the clock mutants}, language = {en} } @article{FerberGerhardsSaueretal.2020, author = {Ferber, Elena and Gerhards, Julian and Sauer, Miriam and Krischke, Markus and Dittrich, Marcus T. and M{\"u}ller, Tobias and Berger, Susanne and Fekete, Agnes and Mueller, Martin J.}, title = {Chemical Priming by Isothiocyanates Protects Against Intoxication by Products of the Mustard Oil Bomb}, series = {Frontiers in Plant Science}, volume = {11}, journal = {Frontiers in Plant Science}, issn = {1664-462X}, doi = {10.3389/fpls.2020.00887}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-207104}, year = {2020}, abstract = {In Brassicaceae, tissue damage triggers the mustard oil bomb i.e., activates the degradation of glucosinolates by myrosinases leading to a rapid accumulation of isothiocyanates at the site of damage. Isothiocyanates are reactive electrophilic species (RES) known to covalently bind to thiols in proteins and glutathione, a process that is not only toxic to herbivores and microbes but can also cause cell death of healthy plant tissues. Previously, it has been shown that subtoxic isothiocyanate concentrations can induce transcriptional reprogramming in intact plant cells. Glutathione depletion by RES leading to breakdown of the redox potential has been proposed as a central and common RES signal transduction mechanism. Using transcriptome analyses, we show that after exposure of Arabidopsis seedlings (grown in liquid culture) to subtoxic concentrations of sulforaphane hundreds of genes were regulated without depletion of the cellular glutathione pool. Heat shock genes were among the most highly up-regulated genes and this response was found to be dependent on the canonical heat shock factors A1 (HSFA1). HSFA1-deficient plants were more sensitive to isothiocyanates than wild type plants. Moreover, pretreatment of Arabidopsis seedlings with subtoxic concentrations of isothiocyanates increased resistance against exposure to toxic levels of isothiocyanates and, hence, may reduce the autotoxicity of the mustard oil bomb by inducing cell protection mechanisms.}, language = {en} } @article{LambourGlenzForneretal.2022, author = {Lambour, Benjamin and Glenz, Ren{\´e} and Forner, Carmen and Krischke, Markus and Mueller, Martin J. and Fekete, Agnes and Waller, Frank}, title = {Sphingolipid long-chain base phosphate degradation can be a rate-limiting step in long-chain base homeostasis}, series = {Frontiers in Plant Science}, volume = {13}, journal = {Frontiers in Plant Science}, issn = {1664-462X}, doi = {10.3389/fpls.2022.911073}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-277679}, year = {2022}, abstract = {Sphingolipid long-chain bases (LCBs) are building blocks for membrane-localized sphingolipids, and are involved in signal transduction pathways in plants. Elevated LCB levels are associated with the induction of programmed cell death and pathogen-derived toxin-induced cell death. Therefore, levels of free LCBs can determine survival of plant cells. To elucidate the contribution of metabolic pathways regulating high LCB levels, we applied the deuterium-labeled LCB D-erythro-sphinganine-d7 (D7-d18:0), the first LCB in sphingolipid biosynthesis, to Arabidopsis leaves and quantified labeled LCBs, LCB phosphates (LCB-Ps), and 14 abundant ceramide (Cer) species over time. We show that LCB D7-d18:0 is rapidly converted into the LCBs d18:0P, t18:0, and t18:0P. Deuterium-labeled ceramides were less abundant, but increased over time, with the highest levels detected for Cer(d18:0/16:0), Cer(d18:0/24:0), Cer(t18:0/16:0), and Cer(t18:0/22:0). A more than 50-fold increase of LCB-P levels after leaf incubation in LCB D7-d18:0 indicated that degradation of LCBs via LCB-Ps is important, and we hypothesized that LCB-P degradation could be a rate-limiting step to reduce high levels of LCBs. To functionally test this hypothesis, we constructed a transgenic line with dihydrosphingosine-1-phosphate lyase 1 (DPL1) under control of an inducible promotor. Higher expression of DPL1 significantly reduced elevated LCB-P and LCB levels induced by Fumonisin B1, and rendered plants more resistant against this fungal toxin. Taken together, we provide quantitative data on the contribution of major enzymatic pathways to reduce high LCB levels, which can trigger cell death. Specifically, we provide functional evidence that DPL1 can be a rate-limiting step in regulating high LCB levels.}, 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{AmatobiOzbekUnalSchaebleretal.2023, author = {Amatobi, Kelechi M. and Ozbek-Unal, Ayten Gizem and Sch{\"a}bler, Stefan and Deppisch, Peter and Helfrich-F{\"o}rster, Charlotte and Mueller, Martin J. and Wegener, Christian and Fekete, Agnes}, title = {The circadian clock is required for rhythmic lipid transport in Drosophila in interaction with diet and photic condition}, series = {Journal of Lipid Research}, volume = {64}, journal = {Journal of Lipid Research}, number = {10}, doi = {10.1016/j.jlr.2023.100417}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-349961}, pages = {100417}, year = {2023}, abstract = {Modern lifestyle is often at odds with endogenously driven rhythmicity, which can lead to circadian disruption and metabolic syndrome. One signature for circadian disruption is a reduced or altered metabolite cycling in the circulating tissue reflecting the current metabolic status. Drosophila is a well-established model in chronobiology, but day-time dependent variations of transport metabolites in the fly circulation are poorly characterized. Here, we sampled fly hemolymph throughout the day and analyzed diacylglycerols (DGs), phosphoethanolamines (PEs) and phosphocholines (PCs) using LC-MS. In wild-type flies kept on sugar-only medium under a light-dark cycle, all transport lipid species showed a synchronized bimodal oscillation pattern with maxima at the beginning and end of the light phase which were impaired in period01 clock mutants. In wild-type flies under constant dark conditions, the oscillation became monophasic with a maximum in the middle of the subjective day. In strong support of clock-driven oscillations, levels of the targeted lipids peaked once in the middle of the light phase under time-restricted feeding independent of the time of food intake. When wild-type flies were reared on full standard medium, the rhythmic alterations of hemolymph lipid levels were greatly attenuated. Our data suggest that the circadian clock aligns daily oscillations of DGs, PEs, and PCs in the hemolymph to the anabolic siesta phase, with a strong influence of light on phase and modality.}, language = {en} }