Abstract
Anthocyanidin glycosyltransferase plays a key role in the stability of anthocyanidins. Red or magenta petals of roses (Rosa hybrida) contain cyanidin 3,5-O-diglucoside as a major anthocyanin. In roses, the enzymes that transfer glucose to the 3- and 5-OH positions of anthocyanidin have not been identified. In previous studies, enzymes from various flower petals show to transfer glucose residue, first, to 3-OH position of anthocyanidin. Therefore, the first glucosylation reaction is assumed to occur at 3-OH position of anthocyanidin also in roses. However, enzyme extracts roses catalyze the transfer of glucose residue to 5-OH position of cyanidin. The enzyme extracts also showed to glucosylate at 3-OH position of cyanidin 5-O-glucoside. In addition, this enzyme extracts did not transfer glucose residue to 5-OH position of cyanidin 3-O-glucoside. These results indicate that first glucosylation occurs at 5-OH position of anthocyanidin, thereafter, followed by 3-OH glucosylation of anthocyanidin 5-O-glucoside during anthocyanin biosynthesis in roses.
