Anthocyanins give fruits and vegetables their red, purple, and blue colors, offering health benefits. Their biosynthesis involves specific enzymes and is regulated by the MBW complex of transcription factors. Research has linked color variations in plants to anthocyanin content and structure, with transcriptomic analyses revealing genes involved in these differences. In eggplants, SmMYB113 has been identified as a key regulator of anthocyanin biosynthesis, affecting peel color. Despite progress, the precise molecular mechanisms behind color diversity in eggplants remain unclear, indicating a need for further investigation into anthocyanin biosynthesis and regulation.

Researchers at NanJing Agricultural University explored the expression patterns of anthocyanin biosynthesis genes in eggplants of different colors and developmental stages, and found that anthocyanin biosynthesis genes were more expressed in purple eggplant varieties, especially in the rapid growth stage.

RNA seq analysis was performed on the G stage eggplant skin to identify differentially expressed genes (DEGs) related to anthocyanin and flavonoid biosynthesis. Particularly, specific genes, including SmMYB113 and WRKY44, were up-regulated in cultivars with higher delphinidin/flavonoids ratios, suggesting their involvement in color variation. Furthermore, the study uncovered 27 novel genes potentially linked to color differences and 32 novel genes within the SmMYB113-regulated anthocyanin biosynthesis network.

Notably, five genes (SmCytb5, SmGST, SmMATE, SmASAT3, and SmF3’5’M) were identified as crucial for both color variation and anthocyanin accumulation.  The expression of these five genes was directly activated by SmMYB113 through yeast one-hybrid, electrophoretic mobility shift assay, and dual luciferase experiments.

A regulatory model for differences in color formation in eggplant peels

SmMYB113 regulates the activity of SmF3’5’H, which is critical for shaping variation in purple peels, by enhancing SmCytb5 expression. The acylation (ASAT and AT)/glycosylation (GT) ratio of delphinidins determines the reddish-purple and black-purple peel color. The activity of GST and MATE, which are responsible for anthocyanin transport, is also regulated by SmMYB113.

Overall, the research not only elucidates the transcriptional basis of color variation in eggplant peels but also highlights SmMYB113’s central role in regulating anthocyanin biosynthesis, offering insights for future genetic and breeding strategies to enhance fruit coloration.

Source – Eurekalert