A glycosyltransferase, UGT84J2, regulates the level of anthocyanin in tea plants

Glycosyltransferase CsUGT84J2 can glycosylate p-coumaric acid and inhibit the expression of flavonol synthase under drought condition, which can both regulate anthocyanin synthesis in tea plants. Anthocyanins are the main substances in plants that produce rich colors, and they have received attention owing to their antioxidative functions. In this study, we identified a tea plant (Camellia sinensis) glycosyltransferase gene, CsUGT84J2, that regulates anthocyanin accumulation through a dual mechanism. p-Coumaric acid, a precursor of anthocyanin, can be glycosylated by CsUGT84J2. Furthermore, CsUGT84J2 overexpression significantly inhibited the flavonol synthase expression level, whereas dihydroflavonol 4-reductase dominated the substrate competition, which is the major step in the anthocyanin synthesis pathway. Drought tolerance was not enhanced in the CsUGT84J2-overexpressing plants. Even though anthocyanins accumulated in large amounts, the photosynthetic and oxidation systems were more seriously damaged in the CsUGT84J2-overexpressing plants than in the wild-type. Anthocyanins have a role in active oxygen scavenging, and the superoxide dismutase activity was lower than that in wild-type, even at a higher oxidative damage level. This study identified a close relationship between CsUGT84J2 and anthocyanin synthesis, which helps increase our understanding of the anthocyanin anabolic regulatory network.