TY - JOUR A1 - Graus, Dorothea A1 - Li, Kunkun A1 - Rathje, Jan M. A1 - Ding, Meiqi A1 - Krischke, Markus A1 - Müller, Martin J. A1 - Cuin, Tracey Ann A1 - Al‐Rasheid, Khaled A. S. A1 - Scherzer, Sönke A1 - Marten, Irene A1 - Konrad, Kai R. A1 - Hedrich, Rainer T1 - Tobacco leaf tissue rapidly detoxifies direct salt loads without activation of calcium and SOS signaling JF - New Phytologist N2 - 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. KW - calcium signaling KW - cytosolic pH KW - leaf response KW - NaCl transport KW - NHX1 KW - osmotic effects KW - Salt Overly Sensitive pathway KW - salt stress Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-312152 VL - 237 IS - 1 SP - 217 EP - 231 ER - TY - JOUR A1 - Zhou, Yang A1 - Ding, Meiqi A1 - Duan, Xiaodong A1 - Konrad, Kai R. A1 - Nagel, Georg A1 - Gao, Shiqiang T1 - Extending the Anion Channelrhodopsin-Based Toolbox for Plant Optogenetics JF - Membranes N2 - Optogenetics was developed in the field of neuroscience and is most commonly using light-sensitive rhodopsins to control the neural activities. Lately, we have expanded this technique into plant science by co-expression of a chloroplast-targeted β-carotene dioxygenase and an improved anion channelrhodopsin GtACR1 from the green alga Guillardia theta. The growth of Nicotiana tabacum pollen tube can then be manipulated by localized green light illumination. To extend the application of analogous optogenetic tools in the pollen tube system, we engineered another two ACRs, GtACR2, and ZipACR, which have different action spectra, light sensitivity and kinetic features, and characterized them in Xenopus laevis oocytes, Nicotiana benthamiana leaves and N. tabacum pollen tubes. We found that the similar molecular engineering method used to improve GtACR1 also enhanced GtACR2 and ZipACR performance in Xenopus laevis oocytes. The ZipACR1 performed in N. benthamiana mesophyll cells and N. tabacum pollen tubes with faster kinetics and reduced light sensitivity, allowing for optogenetic control of anion fluxes with better temporal resolution. The reduced light sensitivity would potentially facilitate future application in plants, grown under low ambient white light, combined with an optogenetic manipulation triggered by stronger green light. KW - optogenetics KW - rhodopsin KW - light-sensitive anion channel KW - surface potential recording KW - pollen tube Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-236617 SN - 2077-0375 VL - 11 IS - 4 ER - TY - JOUR A1 - Huang, Shouguang A1 - Ding, Meiqi A1 - Roelfsema, M. Rob G. A1 - Dreyer, Ingo A1 - Scherzer, Sönke A1 - Al-Rasheid, Khaled A. S A1 - Gao, Shiqiang A1 - Nagel, Georg A1 - Hedrich, Rainer A1 - Konrad, Kai R. T1 - Optogenetic control of the guard cell membrane potential and stomatal movement by the light-gated anion channel GtACR1 JF - Science Advances N2 - 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. KW - abscisic-acid activation KW - Arabidopsis thaliana KW - H+-atpase KW - signal transduction KW - potassium channel KW - intact plants KW - K+ channels KW - R-type KW - CO2 KW - SLAC1 Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-260925 VL - 7 IS - 28 ER -