The <scp>RNA</scp>‐binding protein <scp>OsDMCK1</scp> is required for meiotic cytokinesis by regulating cell plate formation in rice

Plant cytokinesis is distinguished from animal cytokinesis by the formation of a cell plate between dividing cells. While meiotic cytokinesis involves two successive nuclear divisions with distinct regulatory mechanisms from mitosis, the underlying mechanisms remain poorly understood. In this study, we identified OsDMCK1, a novel rice RNA-binding protein essential for male fertility. The osdmck1-1 mutants exhibit defective meiotic cytokinesis, manifested by misoriented spindle orientation during meiosis II and disrupted callose deposition at both the cell plate and the outer wall of pollen mother cells (PMCs). Transcriptome analysis revealed significant downregulation of cytokinesis-related genes in osdmck1-1 PMCs, including regulators of microtubule organization (MAP65-3.2, BUB3.2, CDC20.3, TPX2) and callose synthase genes (GSL2, GSL5). Importantly, RNA immunoprecipitation assays confirmed these genes as direct mRNA targets of OsDMCK1. Taken together, our study establishes OsDMCK1 as a crucial regulator of meiosis progression and reveals a novel post-transcriptional regulatory mechanism controlling rice meiotic cytokinesis.