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- Title
OPEN STOMATA 1 phosphorylates CYCLIC NUCLEOTIDE-GATED CHANNELs to trigger Ca<sup>2+</sup> signaling for abscisic acid-induced stomatal closure in Arabidopsis.
- Authors
Yang, Yang; Tan, Yan-Qiu; Wang, Xinyong; Li, Jia-Jun; Du, Bo-Ya; Zhu, Meijun; Wang, Pengcheng; Wang, Yong-Fei
- Abstract
Multiple cyclic nucleotide-gated channels (CNGCs) are abscisic acid (ABA)-activated Ca2+ channels in Arabidopsis (Arabidopsis thaliana) guard cells. In particular, CNGC5, CNGC6, CNGC9, and CNGC12 are essential for ABA-specific cytosolic Ca2+ signaling and stomatal movements. However, the mechanisms underlying ABA-mediated regulation of CNGCs and Ca2+ signaling are still unknown. In this study, we identified the Ca2+-independent protein kinase OPEN STOMATA 1 (OST1) as a CNGC activator in Arabidopsis. OST1-targeted phosphorylation sites were identified in CNGC5, CNGC6, CNGC9, and CNGC12. These CNGCs were strongly inhibited by Ser-to-Ala mutations and fully activated by Ser-to-Asp mutations at the OST1-targeted sites. The overexpression of individual inactive CNGCs (iCNGCs) under the UBIQUITIN10 promoter in wild-type Arabidopsis conferred a strong dominant-negative-like ABA-insensitive stomatal closure phenotype. In contrast, expressing active CNGCs (aCNGCs) under their respective native promoters in the cngc5-1 cngc6-2 cngc9-1 cngc12-1 quadruple mutant fully restored ABA-activated cytosolic Ca2+ oscillations and Ca2+ currents in guard cells, and rescued the ABA-insensitive stomatal movement mutant phenotypes. Thus, we uncovered that ABA elicits cytosolic Ca2+ signaling via an OST1-CNGC module, in which OST1 functions as a convergence point of the Ca2+-dependent and -independent pathways in Arabidopsis guard cells. Abscisic acid activates CYCLIC NUCLEOTIDE-GATED CHANNELs via OST1 kinase-mediated phosphorylation to elicit and regulate cytosolic Ca2+ signaling for stomatal closure in Arabidopsis.
- Subjects
STOMATA; CALCIUM channels; ARABIDOPSIS; ARABIDOPSIS thaliana; ABSCISIC acid; PROTEIN kinases; CURRENT fluctuations
- Publication
Plant Cell, 2024, Vol 36, Issue 6, p2328
- ISSN
1040-4651
- Publication type
Article
- DOI
10.1093/plcell/koae073