@article{BazihizinaBoehmMessereretal.2022,
  author    = {Bazihizina, Nadia and B{\"o}hm, Jennifer and Messerer, Maxim and Stigloher, Christian and M{\"u}ller, Heike M. and Cuin, Tracey Ann and Maierhofer, Tobias and Cabot, Joan and Mayer, Klaus F. X. and Fella, Christian and Huang, Shouguang and Al-Rasheid, Khaled A. S. and Alquraishi, Saleh and Breadmore, Michael and Mancuso, Stefano and Shabala, Sergey and Ache, Peter and Zhang, Heng and Zhu, Jian-Kang and Hedrich, Rainer and Scherzer, S{\"o}nke},
  title     = {Stalk cell polar ion transport provide for bladder-based salinity tolerance in Chenopodium quinoa},
  series = {New Phytologist},
  volume    = {235},
  journal   = {New Phytologist},
  number    = {5},
  doi       = {10.1111/nph.18205},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-287222},
  pages     = {1822 -- 1835},
  year      = {2022},
  abstract  = {Chenopodium quinoa uses epidermal bladder cells (EBCs) to sequester excess salt. Each EBC complex consists of a leaf epidermal cell, a stalk cell, and the bladder. Under salt stress, sodium (Na\(^{+}\)), chloride (Cl\(^{-}\)), potassium (K\(^{+}\)) and various metabolites are shuttled from the leaf lamina to the bladders. Stalk cells operate as both a selectivity filter and a flux controller. In line with the nature of a transfer cell, advanced transmission electron tomography, electrophysiology, and fluorescent tracer flux studies revealed the stalk cell's polar organization and bladder-directed solute flow. RNA sequencing and cluster analysis revealed the gene expression profiles of the stalk cells. Among the stalk cell enriched genes, ion channels and carriers as well as sugar transporters were most pronounced. Based on their electrophysiological fingerprint and thermodynamic considerations, a model for stalk cell transcellular transport was derived.},
  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{GrausLiRathjeetal.2023,
  author    = {Graus, Dorothea and Li, Kunkun and Rathje, Jan M. and Ding, Meiqi and Krischke, Markus and M{\"u}ller, Martin J. and Cuin, Tracey Ann and Al-Rasheid, Khaled A. S. and Scherzer, S{\"o}nke and Marten, Irene and Konrad, Kai R. and Hedrich, Rainer},
  title     = {Tobacco leaf tissue rapidly detoxifies direct salt loads without activation of calcium and SOS signaling},
  series = {New Phytologist},
  volume    = {237},
  journal   = {New Phytologist},
  number    = {1},
  doi       = {10.1111/nph.18501},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-312152},
  pages     = {217 -- 231},
  year      = {2023},
  abstract  = {Salt stress is a major abiotic stress, responsible for declining agricultural productivity. Roots are regarded as hubs for salt detoxification, however, leaf salt concentrations may exceed those of roots. How mature leaves manage acute sodium chloride (NaCl) stress is mostly unknown. To analyze the mechanisms for NaCl redistribution in leaves, salt was infiltrated into intact tobacco leaves. It initiated pronounced osmotically-driven leaf movements. Leaf downward movement caused by hydro-passive turgor loss reached a maximum within 2 h. Salt-driven cellular water release was accompanied by a transient change in membrane depolarization but not an increase in cytosolic calcium ion (Ca\(^{2+}\)) level. Nonetheless, only half an hour later, the leaves had completely regained turgor. This recovery phase was characterized by an increase in mesophyll cell plasma membrane hydrogen ion (H\(^{+}\)) pumping, a salt uptake-dependent cytosolic alkalization, and a return of the apoplast osmolality to pre-stress levels. Although, transcript numbers of abscisic acid- and Salt Overly Sensitive pathway elements remained unchanged, salt adaptation depended on the vacuolar H\(^{+}\)/Na\(^{+}\)-exchanger NHX1. Altogether, tobacco leaves can detoxify sodium ions (Na\(^{+}\)) rapidly even under massive salt loads, based on pre-established posttranslational settings and NHX1 cation/H+ antiport activity. Unlike roots, signaling and processing of salt stress in tobacco leaves does not depend on Ca\(^{2+}\) signaling.},
  language  = {en}
}
@article{HuangDingRoelfsemaetal.2021,
  author    = {Huang, Shouguang and Ding, Meiqi and Roelfsema, M. Rob G. and Dreyer, Ingo and Scherzer, S{\"o}nke and Al-Rasheid, Khaled A. S and Gao, Shiqiang and Nagel, Georg and Hedrich, Rainer and Konrad, Kai R.},
  title     = {Optogenetic control of the guard cell membrane potential and stomatal movement by the light-gated anion channel GtACR1},
  series = {Science Advances},
  volume    = {7},
  journal   = {Science Advances},
  number    = {28},
  doi       = {10.1126/sciadv.abg4619},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-260925},
  year      = {2021},
  abstract  = {Guard cells control the aperture of plant stomata, which are crucial for global fluxes of CO\(_2\) and water. In turn, guard cell anion channels are seen as key players for stomatal closure, but is activation of these channels sufficient to limit plant water loss? To answer this open question, we used an optogenetic approach based on the light-gated anion channelrhodopsin 1 (GtACR1). In tobacco guard cells that express GtACR1, blue- and green-light pulses elicit Cl\(^-\) and NO\(_3\)\(^-\) currents of -1 to -2 nA. The anion currents depolarize the plasma membrane by 60 to 80 mV, which causes opening of voltage-gated K+ channels and the extrusion of K+. As a result, continuous stimulation with green light leads to loss of guard cell turgor and closure of stomata at conditions that provoke stomatal opening in wild type. GtACR1 optogenetics thus provides unequivocal evidence that opening of anion channels is sufficient to close stomata.},
  language  = {en}
}
@phdthesis{Scherzer2012,
  author    = {Scherzer, S{\"o}nke},
  title     = {Biophysikalische Analyse und Rekonstitution des schnellen ABA-Signaltransduktionsweges aus Arabidopsis thaliana},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-76199},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2012},
  abstract  = {In dieser Arbeit sollte zun{\"a}chst die Frage gekl{\"a}rt werden, ob es sich bei SLAC1 um den S-typ Anionenkanal handelt, oder ob SLAC1 nur ein essentieller Bestandteil des Anionenkanals ist. Zur funktionellen Charakterisierung des per se inaktiven SLAC1 Proteins, wurde mit der Suche nach SLAC1-aktivierenden Interaktionspartnern begonnen. Zu diesem Zweck bediente man sich der Methode der bimolekularen Fluoreszenz Komplementation (BiFC) im heterologen Expressionssystem der Xenopus Oozyten. Da bereits die Abh{\"a}ngigkeit der Anionenstr{\"o}me in Schließzellen von De- und Phosphorylierungsereignissen bekannt war, galt Ca2+-abh{\"a}ngigen Kinasen der CPK Familie, ABA-aktivierten Kinasen der SnRK Familie und Phosphatasen des PP2C Typs eine besondere Aufmerksamkeit. Mitglieder dieser Familien wurden bereits mit der Regulation des Stomaschlusses in Verbindung gebracht. Bei diesen Experimenten zeigte sich, dass SnRK2.6 (OST1) und mehrere CPKs deutlich mit SLAC1 physikalisch interagierten. Als Folge dieser Interaktion in Oozyten konnten schließlich nach Koexpression von SLAC1 zusammen mit den interagierenden Kinasen typische S-Typ Anionenstr{\"o}me detektiert werden, wie man sie aus Patch-Clamp Experimenten an isolierten Schließzellprotoplasten kannte. Hierbei bewirkten die Kinasen OST1 und CPK23 die gr{\"o}ßte Anionenkanalaktivierung. Dieses Ergebnis wird durch die BIFC-Experimente gest{\"u}tzt, da OST1 und CPK23 die st{\"a}rkste Interaktion zu SLAC1 zeigten. Die elektrophysiologische Charakterisierung der SLAC1-Str{\"o}me im heterologen Expressionssystem der Xenopus Oozyten in Kombination mit in vivo Patch-Clamp Untersuchungen wies SLAC1 eindeutig als den lange gesuchten S-Typ Anionenkanal in Arabidopsis Schließzellen aus. Somit ist die direkte S-Typ Anionenkanalaktivierung durch OST1 auf dem Kalzium- unabh{\"a}ngigen und durch CPKs auf dem Ca2+-abh{\"a}ngigen ABA-Signaltransduktionsweg gelungen. Bei der Spezifizierung der einzelnen Kalzium-Abh{\"a}ngigkeiten dieser Kinasen in Oozyten und in in vitro Kinase Assays konnten weiterhin unterschiedliche Affinit{\"a}ten der CPKs zu Kalzium festgestellt werden. So vermittelten die schwach Kalzium-abh{\"a}ngigen CPK6 und CPK23 bereits ohne einen Anstieg der zytosolischen Kalziumkonzentratiom {\"u}ber das Ruheniveau hinaus schon die Anionenkanalaktivierung. Die stark Kalzium-abh{\"a}ngigen CPK3 und CPK21 hingegen, werden erst aktiv wenn die ABA vermittelte Signaltransduktion zu einem Anstieg der Kalziumkonzentration f{\"u}hrt. Da somit die Kinasen OST1, CPK6 und CPK23 ohne dieses Kalziumsignal aktiv sind, ben{\"o}tigen diese einen {\"u}bergeordneten Regulationsmechanismus. In den BIFC-Experimenten konnte eine deutliche Interaktion der Phosphatasen ABI1 und 2 zu den SLAC1 aktivierenden Kinasen beobachtet werden. Dass diese Interaktion zu einem Ausbleiben der Anionenkanalaktivierung f{\"u}hrt, wurde in TEVC-Messungen gezeigt. Mit diesen Erkenntnissen um die ABA-Signaltransduktionskette in Schließzellen konnten in in vitro Kinase Experimenten ihre einzelnen Glieder zusammengesetzt und der ABA-vermittelte Stomaschluss nachvollzogen werden. In dieser Arbeit zeigte sich, dass, das unter Wasserstress-Bedingungen synthetisierte Phytohormon, ABA von Rezeptoren der RCAR/PYR/PYL-Familie percepiert wird. Anschließend bindet die Phosphatase ABI1 an den ABA-RCAR1 Komplex. In ihrer freien Form inhibiert die Phosphatase ABI1 die Kinasen OST1, CPK3, 6, 21 und CPK23 durch Dephosphorylierung. Nach Bindung von ABI1 an RCAR1 sind diese Kinasen von dem inhibierenden ABI1 entlassen. Die Kinasen OST1, CPK6 und CPK23 stellen ihre Aktivit{\"a}t durch Autophosphorylierung wieder her. Die stark Ca2+-abh{\"a}ngigen Kinasen CPK3 und 21 ben{\"o}tigt hierzu noch einen ABA induzierten Ca2+-Anstieg im Zytoplasma. Diese Kinasen phosphorylieren anschließend SLAC1 am N-Terminus. Diese Phosphorylierung bewirkt die Aktivierung von SLAC1 woraufhin Anionen aus der Schließzelle entlassen werden. Das Fehlen dieser negativen Ladungen f{\"u}hrt zur Depolarisation der Membran woraufhin der ausw{\"a}rtsgleichrichtende Kaliumkanal GORK aktiviert und K+ aus der Schließzelle entl{\"a}sst. Der Verlust an Osmolyten bewirkt einen osmotisch getriebenen Wasserausstrom und das Stoma schließt sich.},
  subject      = {Schließzelle},
  language  = {de}
}
@article{ScherzerHuangIosipetal.2022,
  author    = {Scherzer, S{\"o}nke and Huang, Shouguang and Iosip, Anda and Kreuzer, Ines and Yokawa, Ken and Al-Rasheid, Khaled A. S. and Heckmann, Manfred and Hedrich, Rainer},
  title     = {Ether anesthetics prevents touch-induced trigger hair calcium-electrical signals excite the Venus flytrap},
  series = {Scientific reports},
  volume    = {12},
  journal   = {Scientific reports},
  doi       = {10.1038/s41598-022-06915-z},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-300411},
  year      = {2022},
  abstract  = {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.},
  language  = {en}
}