Article révisé par les pairs
Résumé : Ca2+ signals in plant cells are important for adaptive responsesto environmental stresses. Here, we report that the ArabidopsisCATION/Ca2+ EXCHANGER2 (CCX2), encoding a putative novelcation/Ca2+ exchanger that localizes to the endoplasmic reticulum,is strongly induced by salt and osmotic stresses. Compared withthe wild type, CCX2 loss- and gain-of-function mutants were lessand more tolerant to different osmotic stress, respectively, anddisplayed the most noteworthy phenotypes during salt stress.Remarkably, Cameleon Ca2+ sensors revealed that CCX2 activityimpacts cytosolic and Endoplasmic Reticulum (ER) Ca2+ concentrations.To our knowledge, ccx2 is the first plant mutant with ameasured alteration in ER Ca2+ concentrations. In this study, weidentified CCX2 as a pivotal player in the regulation of ER Ca2+dynamics that heavily impinge on plant growth upon salt stress.