Functional analysis of the fruit-specific promoter of VqSTS6 from the Chinese wild grape, Vitis quinquangularis

Stilbene synthase plays important roles in the secondary metabolic pathways of many plants as polyketide synthase. Increased consumption of its metabolite, resveratrol, is highly beneficial to our health. The stilbene synthase 6 gene (VqSTS6) has been obtained from the Chinese wild Vitis quinquangularis accession 'Danfeng-2'. Our previous studies have shown that this stilbene synthase gene exhibits higher levels of expression than other VqSTSs in the all six grape organs. To characterize gene expression, we cloned the promoter of VqSTS6 by homologous cloning. Alignment between the VqSTS6 gene sequence and Vitis vinifera VvSTS48 showed 99.24% identity. The promoter of VqSTS6 fused with the β-glucuronidase (GUS) gene was transformed into tomato (Solanum lycopersicum L. 'Micro-Tom') and the activity expression in four organs (roots, stems, leaves and fruits) was analyzed. This revealed that expression was much higher in the fruit than in the other three organs. We also used promoter deletion to show that the -518 bp to -411 bp region contained skn-1_motifs are the core functional promoter region in fruit development. These results evidence the special role of VqSTS6 promoter in regulating its expression in a high-resveratrol grapevine.