MsCDPK29 ‐ MsbZIP14 modulates ABA accumulation in response to saline‐alkali stress in alfalfa

), and malondialdehyde (MDA) contents were lower than wild-type (WT). Conversely, MsCDPK29 RNA interference (RNAi) alfalfa displayed opposite phenotypes. Additionally, MsbZIP14, a basic region-leucine zipper transcription factor, was identified as a MsCDPK29-interacting protein. OE of MsbZIP14 promotes abscisic acid (ABA) accumulation and enhances saline-alkali tolerance. Meanwhile, we showed that MsbZIP14 was phosphorylated by MsCDPK29 at threonine236 (T236) and serine237 (S237) sites, and the phosphorylation is required for the biological function of MsbZIP14 in regulating ABA biosynthesis and saline-alkali stress response. MsbZIP14 directly binds to the promoter of MsNCED3 and activates its expression. Moreover, MsCDPK29 activated MsbZIP14 to enhance the expression of MsNCED3. Collectively, this study uncovered the mechanism whereby MsCDPK29 positively regulates saline-alkali tolerance in alfalfa by phosphorylation of MsbZIP14 to activate MsNCED3 expression.