Transactivation of Dek601 by the Opaque2-OHP2-EREB58-EREB177 module regulates kernel development in maize.

Abstract

BAHD acyltransferases are a specialized class of plant enzymes involved in the acylation of secondary metabolites, yet their roles in seed development remain poorly understood. In this study, we identified the defective kernel 601 (dek601) mutant in the maize (Zea mays) W22 genetic background, which exhibits defective embryo and endosperm development, leading to smaller and shrunken kernels compared to wild type (WT). Using positional cloning, we localized the causal gene, Zm00001d039535 (also known as Disorganized wall 1, Dow1), to chromosome 3. A mutation in this gene causes a frameshift and disrupts protein function, which was confirmed through complementation tests. Dek601 encodes a BAHD family acyltransferase, and its expression is regulated by the transcription factors Opaque2 (O2), Ethylene-Responsive Element Binding Protein 58 (EREB58), and Ethylene-Responsive Element Binding Protein 177 (EREB177). These factors bind to the Dek601 promoter and modulate its expression. Furthermore, DEK601 interacts with the Acyl-activating enzyme 19 (ZmAAE19), suggesting their potential functional synergy in downstream enzymatic processes. Metabolomic analysis of dek601 kernels revealed significant shifts in metabolic profiles, including a downregulation of carbohydrate compounds and an upregulation of amino acids and metabolites from the phenylpropanoid and flavonoid pathways. This study demonstrates that the Opaque2-OHP2-EREB58-EREB177 regulatory module controls Dek601 expression, and DEK601 and ZmAAE19 likely collaborate to influence metabolite biosynthesis, thereby regulating kernel development in maize.