WRKY10 Regulates Seed Size through the miR397a-LAC2 Module in .

In angiosperms, seed size is a critical trait that is influenced by the complex interplay between the endosperm and seed coat. The () pathway, involving the transcription factor WRKY10, plays a crucial role in regulating seed size in . However, the downstream targets of WRKY10 and their roles in seed size determination remain largely unexplored. Here, we identified (), a laccase gene involved in lignin biosynthesis, as a new downstream target of WRKY10. We observed that the expression of was upregulated in the mutant, which is defective in WRKY10. We demonstrated that WRKY10 directly binds to the promoter of miR397a, activating its expression. miR397a, in turn, represses the expression of . Genetic analyses revealed that a mutation in or overexpression of miR397a partially rescued the small seed phenotype of the () mutant . Conversely, the overexpression of in the wild type led to a decrease in seed size. These findings suggest that functions as a negative regulator of seed size, and its expression is modulated by WRKY10 through miR397a. Our study uncovers a novel WRKY10-miR397a-LAC2 pathway that regulates seed size in , providing new insights into the complex regulatory network governing seed development in plants.