A novel bZIP transcription factor VvbZIP026 induces anthocyanin biosynthesis and acylation modification in response...

High groundwater levels, short light hours, and high temperatures and rainy conditions during the ripening period in southern China lead to insufficient sugar accumulation and difficulty in coloring, which severely affects the quality of the grapes. In our study, 7-year-old 'Summer Black' grapes were selected as experimental materials to study the effect of abscisic acid on grape quality. The results showed that the color of grapes turned earlier after ABA soaking, the glucose and fructose, and all 6 detected amino acid contents were significantly higher than those in the untreated group in the veraison period. However, ABA can significantly increase the anthocyanin and flavonol contents, but has no significant effect on soluble sugars, flavanols, phenolic acids, phloridzin, and naringenin-7-O-glucoside at maturity. Curiously, ABA treatment had no significant effect on the metabolism of organic acids, while it also has a positive effect on the aroma of the grape. Furthermore, by integrating phylogenetic analysis with transgenic techniques in Arabidopsis thaliana, grapefruit, and callus, we demonstrate that a novel bZIP transcription factor, VvbZIP026, induces anthocyanin accumulation and enhances levels of anthocyanin acylation modification, thereby improving anthocyanin stability and bioavailability. Our results provide theoretical and practical value for grape quality improvement and theoretical support for anthocyanin metabolism.