Integrated metabolomic and transcriptomic analyses reveal genetic regulation of anthocyanin accumulation in the peel of three jaboticaba cultivars

This is the authors' abstract. We don't add key points for this paper.

Differences in the fruit peel color of jaboticaba (Myrciaria cauliflora) are primarily determined by the content and composition of anthocyanins. In this study, a combined strategy of targeted metabolomics and transcriptomics was employed to systematically elucidate the molecular regulatory mechanisms underlying fruit peel coloration in the 'White', 'Evergreen', and 'Sabara' cultivars. The results indicated that cyanidin and delphinidin were the major anthocyanin components dominating peel coloration, with cyanidin making the most significant contribution. Notably, the 'Sabara' cultivar exhibited an extremely high anthocyanin content, resulting in a deep black peel color. Weighted Gene Co-expression Network Analysis (WGCNA) and Mfuzz clustering identified nine key structural genes (PAL_2, 4CL_4, C4H, CHS, CHI_1, CHI_2, F3H, F3'H, and ANS) involved in the entire biosynthetic pathway, whose expression profiles were highly consistent with anthocyanin accumulation. Simultaneously, 7 McMYB and 12 McbHLH transcription factors were found to be co-expressed with these structural genes, displaying contrasting expression patterns between 'White' and 'Sabara'. Furthermore, potential binding sites for McMYB4, McMYB24, McMYB73, and McbHLH130 were discovered in the promoter regions of these structural genes. Dual-luciferase reporter assays further demonstrated that McMYB4 significantly suppressed the promoter activities of McPAL_2 and McC4H, which was consistent with the co-expression network analysis. This study reveals the molecular regulatory mechanisms governing the differences in fruit peel color among 'White', 'Evergreen', and 'Sabara' at the mature stage, providing a theoretical basis for the genetic improvement of color traits in jaboticaba.