Sucrose signaling regulates storage protein synthesis in maize endosperm

Sucrose plays a crucial role as a primary carbon source during seed development. In addition to this metabolic function, sucrose and its breakdown products (hexoses) serve as important signaling molecules that regulate cell fate and seed development in maize. However, the precise molecular mechanisms through which sucrose influences storage protein synthesis during seed development remain poorly understood. In this study, we identified a novel allelic mutant of <italic>Incw2</italic>, named <italic>vitreous endosperm 2</italic> (<italic>ven2</italic>). The loss-of-function mutation in <italic>Incw2</italic> led to a significant reduction in grain weight, accompanied by a marked increase in sucrose levels in the basal endosperm. This was also associated with substantial increases in the accumulation of the 19 kDa and 22 kDa α-zein proteins. In contrast, overexpression of <italic>Incw2</italic> resulted in lower sucrose and zein contents. Furthermore, we discovered that the transcription factor Sugar Response Factor 1 (SRF1), which is responsive to sucrose, regulates the expression of the <italic>19 kDa</italic> and <italic>22 kDa α-zein</italic> genes by directly binding to their promoters. These findings suggest that disruption of sucrose metabolism due to the <italic>Incw2</italic> mutation modulates <italic>α-zein</italic> gene expression and affects protein synthesis during seed development.