Eggplant SmMYB6.2 positively regulates anthocyanin biosynthesis by activating SmANS gene expression

Anthocyanins significantly influence both the visual quality and nutritional value of eggplants. Exogenous application of jasmonic acid enhanced anthocyanin biosynthesis in eggplant peel under low-light conditions and induced the expression of several MYB genes. In this paper, these MYB proteins were investigated by yeast one-hybrid experiments, and it was found that SmMYB6.2 could directly bind to the promoter sequence of the anthocyanin synthesis structural gene SmANS. SmMYB6.2 was a nuclear-localized protein whose expression could be induced by various stimuli, including UV-B radiation, blue light, ABA treatment, PEG stress, and low-temperature exposure at 4 °C. Next, overexpression of SmMYB6.2 in Arabidopsis promoted anthocyanin accumulation and enhanced the gene expression of AtANS. Further, Dual-LUC assays demonstrated that SmMYB6.2 enhanced its transcriptional activation of the SmANS promoter through protein-protein interactions with the bHLH proteins SmTT8, SmbHLH79, and SmGLABRA3. These findings deepen our understanding of the regulatory mechanisms underlying anthocyanin biosynthesis in eggplant peel and provide candidate genes for breeding anthocyanin-enriched eggplant varieties.