A transcription factor CabHLH96 positively regulates the biosynthesis of anthocyanins in chili peppers

The bHLH transcription factors are considered to play an important role in regulating anthocyanin biosynthesis. In previous research, we identified a transcription factor CabHLH96 from the bHLH family which can acts alone in regulating anthocyanin biosynthesis. It exhibits high expression levels during the early purple stage of pepper CS03, while showing low expression in white or green peppers. Subcellular localization experiments confirmed that it is located in the nucleus.Tissue-specific expression analysis further revealed that it is predominantly expressed in the leaves and fruits of pepper CS03. Subsequent functional verification of gene demonstrated that the relative expression levels of structural genes involved in anthocyanin biosynthesis were either reduced or elevated following virus-induced gene silencing (VIGS) and transient overexpression of CabHLH96 . Yeast one-hybrid and dual-luciferase reporter gene assays indicated that CabHLH96 can regulate anthocyanin biosynthesis directly in chili peppers by interacting with upstream promoters of structural genes CaF3′H and CaDFR. These findings offer a novel perspective for a more profound understanding of the mechanisms underlying anthocyanin biosynthesis in chili peppers, and provide potential candidate genes for future genetic enhancement of chili germplasm resources.