A novel OsCRK14-OsRLCK57-MAPK signaling module activates OsbZIP66 to confer drought resistance in rice.

Drought stress severely limits rice productivity, making the understanding of drought response mechanisms essential for developing climate-resilient varieties. While cysteine-rich receptor-like kinases (CRKs) are primarily implicated in plant development and immunity, their role in drought response remains poorly understood. Here, we identify a cysteine-rich receptor-like kinase, OsCRK14, as a key positive regulator of drought resistance in rice. We demonstrate that plasma membrane-localized OsCRK14 phosphorylates the receptor-like cytoplasmic kinase OsRLCK57 under drought stress, initiating a MAPK cascade (OsMKKK10-OsMKK4-OsMPK6). Activated OsMPK6 directly phosphorylates the ABA-responsive transcription factor OsbZIP66 at conserved SP/TP motifs, enhancing its stability and promoting drought-responsive gene expression. Furthermore, natural variations in the OsCRK14 promoter influence its transcriptional activity by altering OsMYB72 binding affinity, correlating with drought resistance differences among rice varieties. Our study reveals a complete CRK-RLCK-MAPK-bZIP signaling pathway connecting membrane sensing to transcriptional regulation in drought response, providing both mechanistic insights and genetic resources for breeding drought-resistant rice.