TY - JOUR A1 - Schuster, Ann-Christin A1 - Burghardt, Markus A1 - Alfarhan, Ahmed A1 - Bueno, Amauri A1 - Hedrich, Rainer A1 - Leide, Jana A1 - Thomas, Jacob A1 - Riederer, Markus T1 - Effectiveness of cuticular transpiration barriers in a desert plant at controlling water loss at high temperatures JF - AoB Plants N2 - 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. KW - conductance KW - triterpenoids KW - aliphatic compounds KW - cuticular transpiration KW - cuticular wax KW - cutin KW - desert KW - minimum KW - plant cuticle KW - temperature KW - transition temperature Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-160963 VL - 8 ER - TY - JOUR A1 - Scherzer, Sönke A1 - Huang, Shouguang A1 - Iosip, Anda A1 - Kreuzer, Ines A1 - Yokawa, Ken A1 - Al-Rasheid, Khaled A. S. A1 - Heckmann, Manfred A1 - Hedrich, Rainer T1 - Ether anesthetics prevents touch-induced trigger hair calcium-electrical signals excite the Venus flytrap JF - Scientific reports N2 - Plants do not have neurons but operate transmembrane ion channels and can get electrical excited by physical and chemical clues. Among them the Venus flytrap is characterized by its peculiar hapto-electric signaling. When insects collide with trigger hairs emerging the trap inner surface, the mechanical stimulus within the mechanosensory organ is translated into a calcium signal and an action potential (AP). Here we asked how the Ca\(^{2+}\) wave and AP is initiated in the trigger hair and how it is feed into systemic trap calcium-electrical networks. When Dionaea muscipula trigger hairs matures and develop hapto-electric excitability the mechanosensitive anion channel DmMSL10/FLYC1 and voltage dependent SKOR type Shaker K\(^{+}\) channel are expressed in the sheering stress sensitive podium. The podium of the trigger hair is interface to the flytrap’s prey capture and processing networks. In the excitable state touch stimulation of the trigger hair evokes a rise in the podium Ca2+ first and before the calcium signal together with an action potential travel all over the trap surface. In search for podium ion channels and pumps mediating touch induced Ca\(^{2+}\) transients, we, in mature trigger hairs firing fast Ca\(^{2+}\) signals and APs, found OSCA1.7 and GLR3.6 type Ca\(^{2+}\) channels and ACA2/10 Ca\(^{2+}\) pumps specifically expressed in the podium. Like trigger hair stimulation, glutamate application to the trap directly evoked a propagating Ca\(^{2+}\) and electrical event. Given that anesthetics affect K\(^+\) channels and glutamate receptors in the animal system we exposed flytraps to an ether atmosphere. As result propagation of touch and glutamate induced Ca\(^{2+}\) and AP long-distance signaling got suppressed, while the trap completely recovered excitability when ether was replaced by fresh air. In line with ether targeting a calcium channel addressing a Ca\(^{2+}\) activated anion channel the AP amplitude declined before the electrical signal ceased completely. Ether in the mechanosensory organ did neither prevent the touch induction of a calcium signal nor this post stimulus decay. This finding indicates that ether prevents the touch activated, glr3.6 expressing base of the trigger hair to excite the capture organ. KW - biophysics KW - drug discovery KW - physiology KW - plan sciences Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-300411 VL - 12 ER - TY - JOUR A1 - Rasouli, Fatemeh A1 - Kiani-Pouya, Ali A1 - Shabala, Lana A1 - Li, Leiting A1 - Tahir, Ayesha A1 - Yu, Min A1 - Hedrich, Rainer A1 - Chen, Zhonghua A1 - Wilson, Richard A1 - Zhang, Heng A1 - Shabala, Sergey T1 - Salinity effects on guard cell proteome in Chenopodium quinoa JF - International Journal of Molecular Sciences N2 - 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. KW - quinoa KW - guard cell KW - stomata KW - salt stress KW - proteomics analysis Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-285625 SN - 1422-0067 VL - 22 IS - 1 ER - TY - JOUR A1 - Rasouli, Fatemeh A1 - Kiani-Pouya, Ali A1 - Li, Leiting A1 - Zhang, Heng A1 - Chen, Zhonghua A1 - Hedrich, Rainer A1 - Wilson, Richard A1 - Shabala, Sergey T1 - Sugar beet (Beta vulgaris) guard cells responses to salinity stress: a proteomic analysis JF - International Journal of Molecular Sciences N2 - 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. KW - guard cells KW - stomata KW - sugar beet KW - salt stress KW - proteomic Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-285765 SN - 1422-0067 VL - 21 IS - 7 ER - TY - JOUR A1 - Planes, Maria D. A1 - Niñoles, Regina A1 - Rubio, Lourdes A1 - Bissoli, Gaetano A1 - Bueso, Eduardo A1 - García-Sánchez, María J. A1 - Alejandro, Santiago A1 - Gonzalez-Guzmán, Miguel A1 - Hedrich, Rainer A1 - Rodriguez, Pedro L. A1 - Fernández, José A. A1 - Serrano, Ramón T1 - 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 JF - Journal of Experimental Botany N2 - 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. KW - ABA receptors KW - cytosolic pH KW - ion channels KW - microelectrodes KW - protein kinase KW - proton efflux Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-121221 VL - 66 IS - 3 ER - TY - JOUR A1 - Nuhkat, Maris A1 - Brosché, Mikael A1 - Stoezle-Feix, Sonja A1 - Dietrich, Petra A1 - Hedrich, Rainer A1 - Roelfsema, M. Rob G. A1 - Kollist, Hannes T1 - Rapid depolarization and cytosolic calcium increase go hand-in-hand in mesophyll cells' ozone response JF - New Phytologist N2 - 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. KW - reactive oxygen species (ROS) KW - Arabidopsis thaliana KW - Ca\(^{2+}\) indicator KW - Ca\(^{2+}\) signalling KW - membrane depolarization KW - mesophyll KW - ozone Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-259646 VL - 232 IS - 4 ER - TY - JOUR A1 - Liu, Yi A1 - Maierhofer, Tobias A1 - Rybak, Katarzyna A1 - Sklenar, Jan A1 - Breakspear, Andy A1 - Johnston, Matthew G. A1 - Fliegmann, Judith A1 - Huang, Shouguang A1 - Roelfsema, M. Rob G. A1 - Felix, Georg A1 - Faulkner, Christine A1 - Menke, Frank L.H. A1 - Geiger, Dietmar A1 - Hedrich, Rainer A1 - Robatzek, Silke T1 - Anion channel SLAH3 is a regulatory target of chitin receptor-associated kinase PBL27 in microbial stomatal closure JF - eLife N2 - 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. KW - plants Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-202631 VL - 8 ER - TY - JOUR A1 - Li, Kunkun A1 - Prada, Juan A1 - Damineli, Daniel S. C. A1 - Liese, Anja A1 - Romeis, Tina A1 - Dandekar, Thomas A1 - Feijó, José A. A1 - Hedrich, Rainer A1 - Konrad, Kai Robert T1 - An optimized genetically encoded dual reporter for simultaneous ratio imaging of Ca\(^{2+}\) and H\(^{+}\) reveals new insights into ion signaling in plants JF - New Phytologist N2 - 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. KW - abscisic acid (ABA) KW - calcium KW - flg22 KW - guard cells KW - imaging KW - ion signaling KW - pH KW - pollen tube Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-239847 VL - 230 IS - 6 SP - 2292 EP - 2310 ER - TY - JOUR A1 - Kreuzwieser, Jürgen A1 - Scheerer, Ursel A1 - Kruse, Jörg A1 - Burzlaff, Tim A1 - Honsel, Anne A1 - Alfarraj, Saleh A1 - Georgiev, Palmen A1 - Schnitzler, Jörg-Peter A1 - Ghirardo, Andrea A1 - Kreuzer, Ines A1 - Hedrich, Rainer A1 - Rennenberg, Heinz T1 - The Venus flytrap attracts insects by the release of volatile organic compounds JF - Journal of Experimental Botany N2 - 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. KW - carnivorus plants KW - dionaea muscipula KW - drosophila melanogaster KW - VOC emissions KW - nitrogen status KW - olfactory bioassay KW - plant-animal interaction Y1 - 2014 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-121161 VL - 65 IS - 2 ER - TY - JOUR A1 - Karimi, Sohail M. A1 - Freund, Matthias A1 - Wager, Brittney M. A1 - Knoblauch, Michael A1 - Fromm, Jörg A1 - M. Mueller, Heike A1 - Ache, Peter A1 - Krischke, Markus A1 - Mueller, Martin J. A1 - Müller, Tobias A1 - Dittrich, Marcus A1 - Geilfus, Christoph-Martin A1 - Alfaran, Ahmed H. A1 - Hedrich, Rainer A1 - Deeken, Rosalia T1 - Under salt stress guard cells rewire ion transport and abscisic acid signaling JF - New Phytologist N2 - 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. KW - soil KW - stomata KW - abscisic acid (ABA) KW - glycophyte Arabidopsis KW - guard cell KW - halophyte Thellungiella/Eutrema KW - ion transport KW - salt stress Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-259635 VL - 231 IS - 3 ER -