Multifaceted roles of a light-responsive factor LhWRKY44 in promoting anthocyanin accumulation in Asiatic hybrid lilies (Liliumspp.)

Abstract

AbstractThe coloration of Asiatic hybrid lily results mostly from anthocyanin accumulation in flowers. Although anthocyanin accumulation-related genes and MBW complexes are well studied, the transcriptional regulation of WRKY transcription factors involved in anthocyanin accumulation remains poorly understood.Here, we identified a lily WRKY protein, LhWRKY44, whose expression is highly expressed downstream of LhHY5 by light and positively correlated with anthocyanin accumulation.LhWRKY44overexpression enhanced anthocyanin accumulation and silencing decreased anthocyanin accumulation in flowers. As a trans-acting regulator, LhWRKY44 activited the anthocyanin biosynthesis pathway-related genesPALandF3Hby binding to the their promoters. And the encoded TF also participates in anthocyanin transport and targets the intracellular anthocyanin transport proteinGSTpromoters. Additionally, a novel dual activity of LhWRKY44 and LhMYBSPLATTER regulatory module, with LhWRKY44 binds to the promoter ofLhMYBSPLATTERand interacts with LhMYBSPLATTER, strongly enhanced the interaction of LhMYBSPLATTER and LhbHLH2, indirectly enhancingDFR, UFGTandGSTexpression targeted by LhMYBSPLATTER. These results show a regulatory mode for light-induced anthocyanin accumulation enhancement by LhWRKY44 in lily, expanding our understanding of the complex transcriptional regulatory hierarchy modulating anthocyanin accumulation.