Monoculm1 confers cold tolerance at the seedling stage in rice

Transcriptional regulation of cold-responsive genes plays crucial roles in plant cold tolerance, but the transcription factors (TFs)-centered regulatory networks remain largely unclear. In this study, we show that Monoculm1 (MOC1), a critical TF controlling tiller number and plant height in rice, positively regulates rice cold tolerance at the seedling stage. We found that OsMPK4, a mitogen-activated protein kinase, phosphorylates and stabilizes MOC1 under cold stress. Further investigations revealed that MOC1 recruits the TFs OsbZIP79 and OsNAC5 to form a triple complex and subsequently enhances their stability by inhibiting proteasome-mediated degradation under cold stress. Notably, we found that the OsbZIP79-MOC1-OsNAC5 complex activates several cold-responsive genes, including Dehydration-responsive element-binding factor 1G (OsDREB1G), to confer rice cold tolerance. Haplotype analysis of the OsDREB1G promoter in > 10,000 rice accessions identified the favorable haplotype and key variants that endow rice cold tolerance. Collectively, our work demonstrates a pivotal role of the OsMPK4-OsbZIP79-MOC1-OsNAC5-OsDREB1G module in regulating rice cold tolerance and provides genetic targets for improving cold tolerance through molecular breeding.