The VcNAC072–VcF3′5′H4 module regulates anthocyanin biosynthesis in blueberry: molecular mechanism

Light intensity is a pivotal environmental factor governing anthocyanin accumulation in plants; however, the molecular mechanism by which it regulates anthocyanin biosynthesis in blueberry ( Vaccinium corymbosum L.) remains elusive. Combined transcriptomic and metabolomic analyses revealed that VcF3'5'H4 , a gene encoding flavonoid 3',5'-hydroxylase (F3'5'H), is closely associated with anthocyanin accumulation in blueberry. Light treatment significantly induces VcF3'5'H4 transcription, and its expression level is strongly positively correlated with anthocyanin content. Overexpression of VcF3'5'H4 in blueberry callus markedly promotes anthocyanin biosynthesis. Dual-luciferase reporter, yeast one-hybrid, chromatin immunoprecipitation coupled with quantitative polymerase chain reaction (ChIP-qPCR), and electrophoretic mobility shift assay (EMSA) assays confirmed that the transcription factor VcNAC072 specifically binds to the VcF3'5'H4 promoter and functions as a transcriptional activator to positively regulate its expression. Overexpression or silencing of VcNAC072 in blueberry callus, tobacco and Arabidopsis thaliana plants significantly alters VcF3'5'H4 transcription and anthocyanin accumulation. Further investigations demonstrated that the key light-responsive transcription factor VcHY5 directly targets the VcNAC072 promoter and enhances its transcriptional activity under light conditions. Collectively, this study elucidates the regulatory mechanism by which the VcHY5-VcNAC072-VcF3'5'H4 molecular module mediates light-induced anthocyanin biosynthesis in blueberry, providing novel theoretical insights into the coordinated regulation of light signal transduction, secondary metabolism, and stress adaptation in plants.