ZmEREB25 transcription factor mediates transactivation of core starch synthetic genes in maize endosperm via interaction with ZmARF27.

Starch, as the primary storage material in maize endosperm, is essential in determining yield and quality. Although the starch biosynthetic pathway in maize has been well-documented, the transcriptional network underlying endosperm starch synthesis remains elusive. Through a comprehensive co-expression analysis, we screened an endosperm-preferential AP2/ERF transcription factor ZmEREB25, which exhibited a strong correlation with the expression pattern of starch biosynthetic genes in maize endosperm. ZmEREB25 enhanced the promoter activities of the core starch biosynthetic genes, namely Sh2, SSIIIa and SSI, through specific binding to the GCCGAC-containing elements present in their promoters. Given that ZmEREB25 lacked the transactivation capacity, we further identified an ARF transcription factor, ZmARF27, that interacted with ZmEREB25 to coordinately transactivate the promoters of Sh2, SSIIIa and SSI genes via direct binding to these promoters. Our present study demonstrated that the ZmEREB25-ZmARF27 complex is crucial for transactivating core starch synthetic genes in maize endosperm and uncovered a novel regulatory pathway for starch synthesis in maize endosperm.