@article{CarpanetoKoepsellBambergetal.2010, author = {Carpaneto, Armando and Koepsell, Hermann and Bamberg, Ernst and Hedrich, Rainer and Geiger, Dietmar}, title = {Sucrose- and H+-Dependent Charge Movements Associated with the Gating of Sucrose Transporter ZmSUT1}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-68538}, year = {2010}, abstract = {Background: In contrast to man the majority of higher plants use sucrose as mobile carbohydrate. Accordingly protondriven sucrose transporters are crucial for cell-to-cell and long-distance distribution within the plant body. Generally very negative plant membrane potentials and the ability to accumulate sucrose quantities of more than 1 M document that plants must have evolved transporters with unique structural and functional features. Methodology/Principal Findings: To unravel the functional properties of one specific high capacity plasma membrane sucrose transporter in detail, we expressed the sucrose/H+ co-transporter from maize ZmSUT1 in Xenopus oocytes. Application of sucrose in an acidic pH environment elicited inward proton currents. Interestingly the sucrose-dependent H+ transport was associated with a decrease in membrane capacitance (Cm). In addition to sucrose Cm was modulated by the membrane potential and external protons. In order to explore the molecular mechanism underlying these Cm changes, presteady-state currents (Ipre) of ZmSUT1 transport were analyzed. Decay of Ipre could be best fitted by double exponentials. When plotted against the voltage the charge Q, associated to Ipre, was dependent on sucrose and protons. The mathematical derivative of the charge Q versus voltage was well in line with the observed Cm changes. Based on these parameters a turnover rate of 500 molecules sucrose/s was calculated. In contrast to gating currents of voltage dependentpotassium channels the analysis of ZmSUT1-derived presteady-state currents in the absence of sucrose (I =Q/t) was sufficient to predict ZmSUT1 transport-associated currents. Conclusions: Taken together our results indicate that in the absence of sucrose, 'trapped' protons move back and forth between an outer and an inner site within the transmembrane domains of ZmSUT1. This movement of protons in the electric field of the membrane gives rise to the presteady-state currents and in turn to Cm changes. Upon application of external sucrose, protons can pass the membrane turning presteady-state into transport currents.}, language = {en} } @article{DreyerGomezPorrasRianoPachonetal.2012, author = {Dreyer, Ingo and Gomez-Porras, Judith Lucia and Ria{\~n}o-Pach{\´o}n, Diego Mauricio and Hedrich, Rainer and Geiger, Dietmar}, title = {Molecular Evolution of Slow and Quick Anion Channels (SLACs and QUACs/ALMTs)}, series = {Frontiers in Plant Science}, volume = {3}, journal = {Frontiers in Plant Science}, issn = {1664-462X}, doi = {10.3389/fpls.2012.00263}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-189345}, pages = {263}, year = {2012}, abstract = {Electrophysiological analyses conducted about 25 years ago detected two types of anion channels in the plasma membrane of guard cells. One type of channel responds slowly to changes in membrane voltage while the other responds quickly. Consequently, they were named SLAC, for SLow Anion Channel, and QUAC, for QUick Anion Channel. Recently, genes SLAC1 and QUAC1/ALMT12, underlying the two different anion current components, could be identified in the model plant Arabidopsis thaliana. Expression of the gene products in Xenopus oocytes confirmed the quick and slow current kinetics. In this study we provide an overview on our current knowledge on slow and quick anion channels in plants and analyze the molecular evolution of ALMT/QUAC-like and SLAC-like channels. We discovered fingerprints that allow screening databases for these channel types and were able to identify 192 (177 non-redundant) SLAC-like and 422 (402 non-redundant) ALMT/QUAC-like proteins in the fully sequenced genomes of 32 plant species. Phylogenetic analyses provided new insights into the molecular evolution of these channel types. We also combined sequence alignment and clustering with predictions of protein features, leading to the identification of known conserved phosphorylation sites in SLAC1-like channels along with potential sites that have not been yet experimentally confirmed. Using a similar strategy to analyze the hydropathicity of ALMT/QUAC-like channels, we propose a modified topology with additional transmembrane regions that integrates structure and function of these membrane proteins. Our results suggest that cross-referencing phylogenetic analyses with position-specific protein properties and functional data could be a very powerful tool for genome research approaches in general.}, language = {en} } @article{BlachutzikDemirKreuzeretal.2012, author = {Blachutzik, J{\"o}rg O. and Demir, Faith and Kreuzer, Ines and Hedrich, Rainer and Harms, Gregory S.}, title = {Methods of staining and visualization of sphingolipid enriched and non-enriched plasma membrane regions of Arabidopsis thaliana with fluorescent dyes and lipid analogues}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-75433}, year = {2012}, abstract = {Background: Sterols and Sphingolipids form lipid clusters in the plasma membranes of cell types throughout the animal and plant kingdoms. These lipid domains provide a medium for protein signaling complexes at the plasma membrane and are also observed to be principal regions of membrane contact at the inception of infection. We visualized different specific fluorescent lipophilic stains of the both sphingolipid enriched and non-sphingolipid enriched regions in the plasma membranes of live protoplasts of Arabidopsis thaliana. Results: Lipid staining protocols for several fluorescent lipid analogues in plants are presented. The most emphasis was placed on successful protocols for the single and dual staining of sphingolipid enriched regions and exclusion of sphingolipid enriched regions on the plasma membrane of Arabidopsis thaliana protoplasts. A secondary focus was placed to ensure that these staining protocols presented still maintain cell viability. Furthermore, the protocols were successfully tested with the spectrally sensitive dye Laurdan. Conclusion: Almost all existing staining procedures of the plasma membrane with fluorescent lipid analogues are specified for animal cells and tissues. In order to develop lipid staining protocols for plants, procedures were established with critical steps for the plasma membrane staining of Arabidopsis leaf tissue and protoplasts. The success of the plasma membrane staining protocols was additionally verified by measurements of lipid dynamics by the fluorescence recovery after photobleaching technique and by the observation of new phenomena such as time dependent lipid polarization events in living protoplasts, for which a putative physiological relevance is suggested.}, subject = {Arabidopsis thaliana}, language = {de} } @article{DeekenGohlkeScholzetal.2013, author = {Deeken, Rosalia and Gohlke, Jochen and Scholz, Claus-Juergen and Kneitz, Susanne and Weber, Dana and Fuchs, Joerg and Hedrich, Rainer}, title = {DNA Methylation Mediated Control of Gene Expression Is Critical for Development of Crown Gall Tumors}, series = {PLoS Genetics}, journal = {PLoS Genetics}, doi = {10.1371/journal.pgen.1003267}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-96318}, year = {2013}, abstract = {Crown gall tumors develop after integration of the T-DNA of virulent Agrobacterium tumefaciens strains into the plant genome. Expression of the T-DNA-encoded oncogenes triggers proliferation and differentiation of transformed plant cells. Crown gall development is known to be accompanied by global changes in transcription, metabolite levels, and physiological processes. High levels of abscisic acid (ABA) in crown galls regulate expression of drought stress responsive genes and mediate drought stress acclimation, which is essential for wild-type-like tumor growth. An impact of epigenetic processes such as DNA methylation on crown gall development has been suggested; however, it has not yet been investigated comprehensively. In this study, the methylation pattern of Arabidopsis thaliana crown galls was analyzed on a genome-wide scale as well as at the single gene level. Bisulfite sequencing analysis revealed that the oncogenes Ipt, IaaH, and IaaM were unmethylated in crown galls. Nevertheless, the oncogenes were susceptible to siRNA-mediated methylation, which inhibited their expression and subsequently crown gall growth. Genome arrays, hybridized with methylated DNA obtained by immunoprecipitation, revealed a globally hypermethylated crown gall genome, while promoters were rather hypomethylated. Mutants with reduced non-CG methylation developed larger tumors than the wild-type controls, indicating that hypermethylation inhibits plant tumor growth. The differential methylation pattern of crown galls and the stem tissue from which they originate correlated with transcriptional changes. Genes known to be transcriptionally inhibited by ABA and methylated in crown galls became promoter methylated upon treatment of A. thaliana with ABA. This suggests that the high ABA levels in crown galls may mediate DNA methylation and regulate expression of genes involved in drought stress protection. In summary, our studies provide evidence that epigenetic processes regulate gene expression, physiological processes, and the development of crown gall tumors.}, language = {en} } @article{KreuzwieserScheererKruseetal.2014, author = {Kreuzwieser, J{\"u}rgen and Scheerer, Ursel and Kruse, J{\"o}rg and Burzlaff, Tim and Honsel, Anne and Alfarraj, Saleh and Georgiev, Palmen and Schnitzler, J{\"o}rg-Peter and Ghirardo, Andrea and Kreuzer, Ines and Hedrich, Rainer and Rennenberg, Heinz}, title = {The Venus flytrap attracts insects by the release of volatile organic compounds}, series = {Journal of Experimental Botany}, volume = {65}, journal = {Journal of Experimental Botany}, number = {2}, doi = {10.1093/jxb/ert455}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-121161}, pages = {755-66}, year = {2014}, abstract = {Does Dionaea muscipula, the Venus flytrap, use a particular mechanism to attract animal prey? This question was raised by Charles Darwin 140 years ago, but it remains unanswered. This study tested the hypothesis that Dionaea releases volatile organic compounds (VOCs) to allure prey insects. For this purpose, olfactory choice bioassays were performed to elucidate if Dionaea attracts Drosophila melanogaster. The VOCs emitted by the plant were further analysed by GC-MS and proton transfer reaction-mass spectrometry (PTR-MS). The bioassays documented that Drosophila was strongly attracted by the carnivorous plant. Over 60 VOCs, including terpenes, benzenoids, and aliphatics, were emitted by Dionaea, predominantly in the light. This work further tested whether attraction of animal prey is affected by the nutritional status of the plant. For this purpose, Dionaea plants were fed with insect biomass to improve plant N status. However, although such feeding altered the VOC emission pattern by reducing terpene release, the attraction of Drosophila was not affected. From these results it is concluded that Dionaea attracts insects on the basis of food smell mimicry because the scent released has strong similarity to the bouquet of fruits and plant flowers. Such a volatile blend is emitted to attract insects searching for food to visit the deadly capture organ of the Venus flytrap.}, language = {en} } @article{PlanesNinolesRubioetal.2015, author = {Planes, Maria D. and Ni{\~n}oles, Regina and Rubio, Lourdes and Bissoli, Gaetano and Bueso, Eduardo and Garc{\´i}a-S{\´a}nchez, Mar{\´i}a J. and Alejandro, Santiago and Gonzalez-Guzm{\´a}n, Miguel and Hedrich, Rainer and Rodriguez, Pedro L. and Fern{\´a}ndez, Jos{\´e} A. and Serrano, Ram{\´o}n}, title = {A mechanism of growth inhibition by abscisic acid in germinating seeds of Arabidopsis thaliana based on inhibition of plasma membrane \(H^+\)-ATPase and decreased cytosolic pH, \(K^+\), and anions}, series = {Journal of Experimental Botany}, volume = {66}, journal = {Journal of Experimental Botany}, number = {3}, doi = {10.1093/jxb/eru442}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-121221}, pages = {813-25}, year = {2015}, abstract = {The stress hormone abscisic acid (ABA) induces expression of defence genes in many organs, modulates ion homeostasis and metabolism in guard cells, and inhibits germination and seedling growth. Concerning the latter effect, several mutants of Arabidopsis thaliana with improved capability for \(H^+\) efflux (wat1-1D, overexpression of AKT1 and ost2-1D) are less sensitive to inhibition by ABA than the wild type. This suggested that ABA could inhibit \(H^+\) efflux (\(H^+\)-ATPase) and induce cytosolic acidification as a mechanism of growth inhibition. Measurements to test this hypothesis could not be done in germinating seeds and we used roots as the most convenient system. ABA inhibited the root plasma-membrane H+-ATPase measured in vitro (ATP hydrolysis by isolated vesicles) and in vivo (\(H^+\) efflux from seedling roots). This inhibition involved the core ABA signalling elements: PYR/PYL/RCAR ABA receptors, ABA-inhibited protein phosphatases (HAB1), and ABA-activated protein kinases (SnRK2.2 and SnRK2.3). Electrophysiological measurements in root epidermal cells indicated that ABA, acting through the PYR/PYL/RCAR receptors, induced membrane hyperpolarization (due to \(K^+\) efflux through the GORK channel) and cytosolic acidification. This acidification was not observed in the wat1-1D mutant. The mechanism of inhibition of the \(H^+\)-ATPase by ABA and its effects on cytosolic pH and membrane potential in roots were different from those in guard cells. ABA did not affect the in vivo phosphorylation level of the known activating site (penultimate threonine) of (\(H^+\)-ATPase in roots, and SnRK2.2 phosphorylated in vitro the C-terminal regulatory domain of (\(H^+\)-ATPase while the guard-cell kinase SnRK2.6/OST1 did not.}, language = {en} } @article{BoehmScherzerKroletal.2016, author = {B{\"o}hm, Jennifer and Scherzer, S{\"o}nke and Krol, Elzbieta and Kreuzer, Ines and von Meyer, Katharina and Lorey, Christian and Mueller, Thomas D. and Shabala, Lana and Monte, Isabel and Salano, Roberto and Al-Rasheid, Khaled A. S. and Rennenberg, Heinz and Shabala, Sergey and Neher, Erwin and Hedrich, Rainer}, title = {The Venus Flytrap Dionaea muscipula Counts Prey-Induced Action Potentials to Induce Sodium Uptake}, series = {Current Biology}, volume = {26}, journal = {Current Biology}, number = {3}, doi = {10.1016/j.cub.2015.11.057}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-128054}, pages = {286-295}, year = {2016}, abstract = {Carnivorous plants, such as the Venus flytrap (Dionaea muscipula), depend on an animal diet when grown in nutrient-poor soils. When an insect visits the trap and tilts the mechanosensors on the inner surface, action potentials (APs) are fired. After a moving object elicits two APs, the trap snaps shut, encaging the victim. Panicking preys repeatedly touch the trigger hairs over the subsequent hours, leading to a hermetically closed trap, which via the gland-based endocrine system is flooded by a prey-decomposing acidic enzyme cocktail. Here, we asked the question as to how many times trigger hairs have to be stimulated (e.g., now many APs are required) for the flytrap to recognize an encaged object as potential food, thus making it worthwhile activating the glands. By applying a series of trigger-hair stimulations, we found that the touch hormone jasmonic acid (JA) signaling pathway is activated after the second stimulus, while more than three APs are required to trigger an expression of genes encoding prey-degrading hydrolases, and that this expression is proportional to the number of mechanical stimulations. A decomposing animal contains a sodium load, and we have found that these sodium ions enter the capture organ via glands. We identified a flytrap sodium channel DmHKT1 as responsible for this sodium acquisition, with the number of transcripts expressed being dependent on the number of mechano-electric stimulations. Hence, the number of APs a victim triggers while trying to break out of the trap identifies the moving prey as a struggling Na+-rich animal and nutrition for the plant.}, subject = {Venusfliegenfalle}, language = {en} } @article{BoehmScherzerKroletal.2016, author = {B{\"o}hm, Jennifer and Scherzer, S{\"o}nke and Krol, Elzbieta and Kreuzer, Ines and von Meyer, Katharina and Lorey, Christian and Mueller, Thomas D. and Shabala, Lana and Monte, Isabel and Solano, Roberto and Al-Rasheid, Khaled A. S. and Rennenberg, Heinz and Shabala, Sergey and Neher, Erwin and Hedrich, Rainer}, title = {The Venus flytrap Dionaea muscipula counts prey-induced action potentials to induce sodium uptake}, series = {Current Biology}, volume = {26}, journal = {Current Biology}, number = {3}, doi = {10.1016/j.cub.2015.11.057}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-190870}, pages = {286-295}, year = {2016}, abstract = {Carnivorous plants, such as the Venus flytrap (Dionaea muscipula), depend on an animal diet when grown in nutrient-poor soils. When an insect visits the trap and tilts the mechanosensors on the inner surface, action potentials (APs) are fired. After a moving object elicits two APs, the trap snaps shut, encaging the victim. Panicking preys repeatedly touch the trigger hairs over the subsequent hours, leading to a hermetically closed trap, which via the gland-based endocrine system is flooded by a prey-decomposing acidic enzyme cocktail. Here, we asked the question as to how many times trigger hairs have to be stimulated (e.g., now many APs are required) for the flytrap to recognize an encaged object as potential food, thus making it worthwhile activating the glands. By applying a series of trigger-hair stimulations, we found that the touch hormone jasmonic acid (JA) signaling pathway is activated after the second stimulus, while more than three APs are required to trigger an expression of genes encoding prey-degrading hydrolases, and that this expression is proportional to the number of mechanical stimulations. A decomposing animal contains a sodium load, and we have found that these sodium ions enter the capture organ via glands. We identified a flytrap sodium channel DmHKT1 as responsible for this sodium acquisition, with the number of transcripts expressed being dependent on the number of mechano-electric stimulations. Hence, the number of APs a victim triggers while trying to break out of the trap identifies the moving prey as a struggling Na\(^+\)-rich animal and nutrition for the plant.}, language = {en} } @article{BemmBeckerLarischetal.2016, author = {Bemm, Felix and Becker, Dirk and Larisch, Christina and Kreuzer, Ines and Escalante-Perez, Maria and Schulze, Waltraud X. and Ankenbrand, Markus and Van de Weyer, Anna-Lena and Krol, Elzbieta and Al-Rasheid, Khaled A. and Mith{\"o}fer, Axel and Weber, Andreas P. and Schultz, J{\"o}rg and Hedrich, Rainer}, title = {Venus flytrap carnivorous lifestyle builds on herbivore defense strategies}, series = {Genome Research}, volume = {26}, journal = {Genome Research}, number = {6}, doi = {10.1101/gr.202200.115}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-188799}, pages = {812-825}, year = {2016}, abstract = {Although the concept of botanical carnivory has been known since Darwin's time, the molecular mechanisms that allow animal feeding remain unknown, primarily due to a complete lack of genomic information. Here, we show that the transcriptomic landscape of the Dionaea trap is dramatically shifted toward signal transduction and nutrient transport upon insect feeding, with touch hormone signaling and protein secretion prevailing. At the same time, a massive induction of general defense responses is accompanied by the repression of cell death-related genes/processes. We hypothesize that the carnivory syndrome of Dionaea evolved by exaptation of ancient defense pathways, replacing cell death with nutrient acquisition.}, language = {en} } @article{SchusterBurghardtAlfarhanetal.2016, author = {Schuster, Ann-Christin and Burghardt, Markus and Alfarhan, Ahmed and Bueno, Amauri and Hedrich, Rainer and Leide, Jana and Thomas, Jacob and Riederer, Markus}, title = {Effectiveness of cuticular transpiration barriers in a desert plant at controlling water loss at high temperatures}, series = {AoB Plants}, volume = {8}, journal = {AoB Plants}, doi = {10.1093/aobpla/plw027}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-160963}, pages = {plw027}, year = {2016}, abstract = {Maintaining the integrity of the cuticular transpiration barrier even at elevated temperatures is of vital importance especially for hot-desert plants. Currently, the temperature dependence of the leaf cuticular water permeability and its relationship with the chemistry of the cuticles are not known for a single desert plant. This study investigates whether (i) the cuticular permeability of a desert plant is lower than that of species from non-desert habitats, (ii) the temperature-dependent increase of permeability is less pronounced than in those species and (iii) whether the susceptibility of the cuticular permeability barrier to high temperatures is related to the amounts or properties of the cutin or the cuticular waxes. We test these questions with Rhazya stricta using the minimum leaf water vapour conductance (gmin) as a proxy for cuticular water permeability. gmin of R. stricta (5.41 × 10\(^{-5}\) m s\(^{-1}\) at 25 °C) is in the upper range of all existing data for woody species from various non-desert habitats. At the same time, in R. stricta, the effect of temperature (15-50 °C) on gmin (2.4-fold) is lower than in all other species (up to 12-fold). Rhazya stricta is also special since the temperature dependence of gmin does not become steeper above a certain transition temperature. For identifying the chemical and physical foundation of this phenomenon, the amounts and the compositions of cuticular waxes and cutin were determined. The leaf cuticular wax (251.4 μg cm\(^{-2}\)) is mainly composed of pentacyclic triterpenoids (85.2\% of total wax) while long-chain aliphatics contribute only 3.4\%. In comparison with many other species, the triterpenoid-to-cutin ratio of R. stricta (0.63) is high. We propose that the triterpenoids deposited within the cutin matrix restrict the thermal expansion of the polymer and, thus, prevent thermal damage to the highly ordered aliphatic wax barrier even at high temperatures.}, language = {en} } @article{HuerterFortCottazetal.2018, author = {H{\"u}rter, Anna-Lena and Fort, S{\´e}bastian and Cottaz, Sylvain and Hedrich, Rainer and Geiger, Dietmar and Roelfsema, M. Rob G.}, title = {Mycorrhizal lipochitinoligosaccharides (LCOs) depolarize root hairs of Medicago truncatula}, series = {PLoS ONE}, volume = {13}, journal = {PLoS ONE}, number = {5}, doi = {10.1371/journal.pone.0198126}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-176841}, pages = {e0198126}, year = {2018}, abstract = {Arbuscular Mycorrhiza and Root Nodule Symbiosis are symbiotic interactions with a high benefit for plant growth and crop production. Thus, it is of great interest to understand the developmental process of these symbioses in detail. We analysed very early symbiotic responses of Medicago truncatula root hair cells, by stimulation with lipochitinoligosaccharides specific for the induction of nodules (Nod-LCOs), or the interaction with mycorrhiza (Myc-LCOs). Intracellular micro electrodes were used, in combination with Ca\(^{2+}\) sensitive reporter dyes, to study the relations between cytosolic Ca\(^{2+}\) signals and membrane potential changes. We found that sulfated Myc- as well as Nod-LCOs initiate a membrane depolarization, which depends on the chemical composition of these signaling molecules, as well as the genotype of the plants that were studied. A successive application of sulfated Myc-LCOs and Nod-LCOs resulted only in a single transient depolarization, indicating that Myc-LCOs can repress plasma membrane responses to Nod-LCOs. In contrast to current models, the Nod-LCO-induced depolarization precedes changes in the cytosolic Ca\(^{2+}\) level of root hair cells. The Nod-LCO induced membrane depolarization thus is most likely independent of cytosolic Ca\(^{2+}\) signals and nuclear Ca\(^{2+}\) spiking.}, language = {en} } @article{LiuMaierhoferRybaketal.2019, author = {Liu, Yi and Maierhofer, Tobias and Rybak, Katarzyna and Sklenar, Jan and Breakspear, Andy and Johnston, Matthew G. and Fliegmann, Judith and Huang, Shouguang and Roelfsema, M. Rob G. and Felix, Georg and Faulkner, Christine and Menke, Frank L.H. and Geiger, Dietmar and Hedrich, Rainer and Robatzek, Silke}, title = {Anion channel SLAH3 is a regulatory target of chitin receptor-associated kinase PBL27 in microbial stomatal closure}, series = {eLife}, volume = {8}, journal = {eLife}, doi = {10.7554/eLife.44474}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-202631}, pages = {e44474}, year = {2019}, abstract = {In plants, antimicrobial immune responses involve the cellular release of anions and are responsible for the closure of stomatal pores. Detection of microbe-associated molecular patterns (MAMPs) by pattern recognition receptors (PRRs) induces currents mediated via slow-type (S-type) anion channels by a yet not understood mechanism. Here, we show that stomatal closure to fungal chitin is conferred by the major PRRs for chitin recognition, LYK5 and CERK1, the receptor-like cytoplasmic kinase PBL27, and the SLAH3 anion channel. PBL27 has the capacity to phosphorylate SLAH3, of which S127 and S189 are required to activate SLAH3. Full activation of the channel entails CERK1, depending on PBL27. Importantly, both S127 and S189 residues of SLAH3 are required for chitin-induced stomatal closure and anti-fungal immunity at the whole leaf level. Our results demonstrate a short signal transduction module from MAMP recognition to anion channel activation, and independent of ABA-induced SLAH3 activation.}, language = {en} } @article{JaślanDreyerLuetal.2019, author = {Jaślan, Dawid and Dreyer, Ingo and Lu, Jinping and O'Malley, Ronan and Dindas, Julian and Marten, Irene and Hedrich, Rainer}, title = {Voltage-dependent gating of SV channel TPC1 confers vacuole excitability}, series = {Nature Communications}, volume = {10}, journal = {Nature Communications}, doi = {10.1038/s41467-019-10599-x}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-202029}, pages = {2659}, year = {2019}, abstract = {In contrast to the plasma membrane, the vacuole membrane has not yet been associated with electrical excitation of plants. Here, we show that mesophyll vacuoles from Arabidopsis sense and control the membrane potential essentially via the K\(^+\)-permeable TPC1 and TPK channels. Electrical stimuli elicit transient depolarization of the vacuole membrane that can last for seconds. Electrical excitability is suppressed by increased vacuolar Ca\(^{2+}\) levels. In comparison to wild type, vacuoles from the fou2 mutant, harboring TPC1 channels insensitive to luminal Ca\(^{2+}\), can be excited fully by even weak electrical stimuli. The TPC1-loss-of-function mutant tpc1-2 does not respond to electrical stimulation at all, and the loss of TPK1/TPK3-mediated K\(^{+}\) transport affects the duration of TPC1-dependent membrane depolarization. In combination with mathematical modeling, these results show that the vacuolar K\(^+\)-conducting TPC1 and TPK1/TPK3 channels act in concert to provide for Ca\(^{2+}\)- and voltage-induced electrical excitability to the central organelle of plant cells.}, language = {en} } @article{RasouliKianiPouyaLietal.2020, author = {Rasouli, Fatemeh and Kiani-Pouya, Ali and Li, Leiting and Zhang, Heng and Chen, Zhonghua and Hedrich, Rainer and Wilson, Richard and Shabala, Sergey}, title = {Sugar beet (Beta vulgaris) guard cells responses to salinity stress: a proteomic analysis}, series = {International Journal of Molecular Sciences}, volume = {21}, journal = {International Journal of Molecular Sciences}, number = {7}, issn = {1422-0067}, doi = {10.3390/ijms21072331}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-285765}, year = {2020}, abstract = {Soil salinity is a major environmental constraint affecting crop growth and threatening global food security. Plants adapt to salinity by optimizing the performance of stomata. Stomata are formed by two guard cells (GCs) that are morphologically and functionally distinct from the other leaf cells. These microscopic sphincters inserted into the wax-covered epidermis of the shoot balance CO\(_2\) intake for photosynthetic carbon gain and concomitant water loss. In order to better understand the molecular mechanisms underlying stomatal function under saline conditions, we used proteomics approach to study isolated GCs from the salt-tolerant sugar beet species. Of the 2088 proteins identified in sugar beet GCs, 82 were differentially regulated by salt treatment. According to bioinformatics analysis (GO enrichment analysis and protein classification), these proteins were involved in lipid metabolism, cell wall modification, ATP biosynthesis, and signaling. Among the significant differentially abundant proteins, several proteins classified as "stress proteins" were upregulated, including non-specific lipid transfer protein, chaperone proteins, heat shock proteins, inorganic pyrophosphatase 2, responsible for energized vacuole membrane for ion transportation. Moreover, several antioxidant enzymes (peroxide, superoxidase dismutase) were highly upregulated. Furthermore, cell wall proteins detected in GCs provided some evidence that GC walls were more flexible in response to salt stress. Proteins such as L-ascorbate oxidase that were constitutively high under both control and high salinity conditions may contribute to the ability of sugar beet GCs to adapt to salinity by mitigating salinity-induced oxidative stress.}, 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{DuMaYanez‐Serranoetal.2021, author = {Du, Baoguo and Ma, Yuhua and Y{\´a}{\~n}ez-Serrano, Ana Maria and Arab, Leila and Fasbender, Lukas and Alfarraj, Saleh and Albasher, Gadah and Hedrich, Rainer and White, Philip J. and Werner, Christiane and Rennenberg, Heinz}, title = {Physiological responses of date palm (Phoenix dactylifera) seedlings to seawater and flooding}, series = {New Phytologist}, volume = {229}, journal = {New Phytologist}, number = {6}, doi = {10.1111/nph.17123}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-228226}, pages = {3318 -- 3329}, year = {2021}, abstract = {In their natural environment along coast lines, date palms are exposed to seawater inundation and, hence, combined stress by salinity and flooding. To elucidate the consequences of this combined stress on foliar gas exchange and metabolite abundances in leaves and roots, date palm seedlings were exposed to flooding with seawater and its major constituents under controlled conditions. Seawater flooding significantly reduced CO\(_{2}\) assimilation, transpiration and stomatal conductance, but did not affect isoprene emission. A similar effect was observed upon NaCl exposure. By contrast, flooding with distilled water or MgSO\(_{4}\) did not affect CO\(_{2}\)/H\(_{2}\)O gas exchange or stomatal conductance significantly, indicating that neither flooding itself, nor seawater sulfate, contributed greatly to stomatal closure. Seawater exposure increased Na and Cl contents in leaves and roots, but did not affect sulfate contents significantly. Metabolite analyses revealed reduced abundances of foliar compatible solutes, such as sugars and sugar alcohols, whereas nitrogen compounds accumulated in roots. Reduced transpiration upon seawater exposure may contribute to controlling the movement of toxic ions to leaves and, therefore, can be seen as a mechanism to cope with salinity. The present results indicate that date palm seedlings are tolerant towards seawater exposure to some extent, and highly tolerant to flooding.}, 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{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} }