OsMYB94 functions as a master regulator of metabolic pathways associated with rice caryopsis maturation and quality formation

Rice (Oryza sativa) caryopses supply essential carbohydrates, energy, and protein to over half the world's population. Caryopsis quality depends on the biosynthesis, modification, and accumulation of primary and secondary metabolites during maturation. Yet, the regulatory and biochemical pathways remain poorly understood. Emerging evidence implicates transcription factors, particularly MYB family members, in this regulation. In this study, the function of R2R3 MYB transcription factor OsMYB94 in regulating metabolic pathways underlying rice caryopsis maturation and quality formation was characterized using integrative approaches. OsMYB94 orchestrates secondary metabolism (for protection), reserve accumulation (for energy storage), reactive oxygen species homeostasis (for antioxidant defense), and hormonal signaling (for desiccation and dormancy) to ensure proper maturation and high-quality formation of rice caryopses. osmyb94 caryopses exhibit poor appearance quality, milling quality, and eating and cooking quality, correlating with incomplete caryopsis filling, thinner aleurone and coat layers, reduced starch and triglyceride accumulation, disrupted lipid metabolism, and downregulation of genes associated with ripening-related metabolic pathways. Furthermore, the OsMYB94-OsLTPL12 module is a key regulator of rice caryopsis glossiness. This study highlights that OsMYB94 is a master regulator of metabolic pathways associated with rice caryopsis maturation and quality formation, offering a genetic target for improvement.