TY  - JOUR
A1  - Lehmann, Julian
A1  - Jørgensen, Morten E.
A1  - Fratz, Stefanie
A1  - Müller, Heike M.
A1  - Kusch, Jana
A1  - Scherzer, Sönke
A1  - Navarro-Retamal, Carlos
A1  - Mayer, Dominik
A1  - Böhm, Jennifer
A1  - Konrad, Kai R.
A1  - Terpitz, Ulrich
A1  - Dreyer, Ingo
A1  - Mueller, Thomas D.
A1  - Sauer, Markus
A1  - Hedrich, Rainer
A1  - Geiger, Dietmar
A1  - Maierhofer, Tobias
T1  - Acidosis-induced activation of anion channel SLAH3 in the flooding-related stress response of Arabidopsis
JF  - Current Biology
N2  - Plants, as sessile organisms, gained the ability to sense and respond to biotic and abiotic stressors to survive severe changes in their environments. The change in our climate comes with extreme dry periods but also episodes of flooding. The latter stress condition causes anaerobiosis-triggered cytosolic acidosis and impairs plant function. The molecular mechanism that enables plant cells to sense acidity and convey this signal via membrane depolarization was previously unknown. Here, we show that acidosis-induced anion efflux from Arabidopsis (Arabidopsis thaliana) roots is dependent on the S-type anion channel AtSLAH3. Heterologous expression of SLAH3 in Xenopus oocytes revealed that the anion channel is directly activated by a small, physiological drop in cytosolic pH. Acidosis-triggered activation of SLAH3 is mediated by protonation of histidine 330 and 454. Super-resolution microscopy analysis showed that the increase in cellular proton concentration switches SLAH3 from an electrically silent channel dimer into its active monomeric form. Our results show that, upon acidification, protons directly switch SLAH3 to its open configuration, bypassing kinase-dependent activation. Moreover, under flooding conditions, the stress response of Arabidopsis wild-type (WT) plants was significantly higher compared to SLAH3 loss-of-function mutants. Our genetic evidence of SLAH3 pH sensor function may guide the development of crop varieties with improved stress tolerance.
KW  - SLAH3
KW  - S-type anion channel
KW  - hypoxia
KW  - pH
KW  - cytosolic acidification
KW  - flooding
KW  - PALM
KW  - stoichiometry
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-363320
VL  - 31
ER  - 
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  -