PhAN2 regulated Ph3GT silencing changes the flower color and anthocyanin content in petunias

Anthocyanins are important secondary metabolites in plants. After the formation of anthocyanidins, Flavonoid 3-O-glucosyltransferase (3GT) mediated glycosylation first occurs at the C-3 site, forming a stable anthocyanin 3-O-glucoside. Several studies have investigated the function of 3GT using biochemical methods. However, it is necessary to provide further genetic evidence for the role of Ph3GT in petunia (Petunia hybrida). In addition, there is no information regarding the subcellular localization of Ph3GT and the regulation of transcription factors on Ph3GT. In this study, the full-length Ph3GT gene from petunia (Petunia hybrida) was isolated. We found that Ph3GT is localized in the cytoplasm. Ph3GT exhibited high expression levels in the corollas during the coloring period of petunia flowers. VIGS-mediated Ph3GT silencing resulted in a lighter corolla color and a significant decrease in the anthocyanin content in six petunia cultivars. The silencing of Ph3GT affected the expression levels of eight key genes in the anthocyanin synthesis pathway. Additionally, dual luciferase and yeast one-hybrid assays showed that R2R3-MYB transcription factor PhAN2 directly regulates the transcript of Ph3GT.