@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{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} }