Hydrogen Sulfide, Regulated by Vvwrky30, Promotes Berry Color Changes in Grapevine Cabernet Sauvignon

Since hydrogen sulfide (H2S) is a newly discovered gas signal molecule in plants, minimal studies are available regarding its role in grape berries color changes. This study found that 0.1 mM NaHS (H2S donor) could significantly promote color changes in grape berries, mainly by affecting the upregulated expression of anthocyanin synthesis-related genes. Further studies showed that the endogenous H2S content gradually accumulated as the grape berries ripened and mainly depended on the upregulation of the H2S synthetase gene VvSiR and its enhanced enzyme activity. More results showed that VvWRKY30 gene expression was also significantly upregulated during veraison. The overexpression of VvWRKY30 could induce VvSiR expression and H2S accumulation. Experiments involving the yeast one-hybrid and dual-luciferase reporter assay system showed that VvWRKY30 could directly interact with the VvSiR promoter. The overexpression of VvWRKY30 and VvSiR during the grape berry development stage, both promoted the anthocyanin accumulation and berry color changes. These findings indicated that H2S encouraged anthocyanin accumulation and color changes in grape berries, while the H2S accumulation in vivo depended on VvWRKY30 promoting the expression of its synthetase gene, VvSiR.