R2R3-MYB transcription factor SmMYB75 promotes anthocyanin biosynthesis in eggplant (Solanum melongena L.)

Eggplant is rich in anthocyanin, a natural pigment that is beneficial to human health. R2R3-MYB transcription factors (TFs) play a vital role in the anthocyanin pathway. In the present study, SmMYB75, an R2R3-MYB TF, was isolated from the petals of eggplant ‘116’ and its functionality characterized. SmMYB75 was localized in the nucleus, induced by light, and expressed specifically in petals. Overexpression of SmMYB75 caused much increased accumulation of anthocyanins, and resulted in a change in the calli’s color from green to purple. Yeast one-hybrid (Y1H) and dual-luciferase (Dual-LUC) assays showed that SmMYB75 could bind to the promoter of SmCHS and activate its expression. Yeast two-hybrid (Y2H) and Bimolecular fluorescence complementation (BiFC) assays showed the interaction between SmMYB75 and SmTT8. In addition, the transient expression assays demonstrated that co-infiltrating SmMYB75 and SmTT8 prominently improved both the contents of anthocyanins and the expression levels of anthocyanin structural genes in tobacco. In summary, these results revealed the positive regulatory role of SmMYB75 of anthocyanin biosynthesis in eggplant.