MAP4K1 and MAP4K2 regulate ABA-induced and Ca²⁺-mediated stomatal closure in <i>Arabidopsis</i>.

ABSTRACT: Abscisic acid (ABA)-induced stomatal closure limits water loss from plants under drought stress. To investigate the signaling pathways involved in ABA-induced stomatal closure, we performed a phosphoproteomic analysis of ABA-treated Arabidopsis guard cell protoplasts (GCPs). We found that ABA-responsive phosphorylation of MITOGEN-ACTIVATED PROTEIN 4 KINASE 1 (MAP4K1) was significantly down-regulated in SnRK2-disrupted mutants. Subsequent biochemical assays showed that Ser⁴⁷⁹ of MAP4K1 is directly phosphorylated by SRK2E/OST1, a central ABA kinase. Mutational analyses of MAP4K1 and MAP4K2 revealed that both kinases positively regulate ABA-induced stomatal closure and that Ser⁴⁷⁹ of MAP4K1 is required for this phenotype. In map4k1map4k2 double mutants, sto

SUBMITTER: Yamashita K 

PROVIDER: S-EPMC12716388 | biostudies-literature | 2025 Dec

REPOSITORIES: biostudies-literature