Abstract
From experiments using crude enzyme extracts from rose petals, first glucosylation is supposed to occur at 5-OH position of anthocyanidin following at 3-OH glucosylation of anthocyanidin 5-O-glucoside during anthocyanin biosynthesis. To identify responsible enzymes, we tried to isolate cDNAs of corresponding enzymes. RhGT1 was cloned by RT-PCR using degenerate primer based on PSPG box and RACE from rose petals. The recombinant RhGT1 in E.coli was demonstrated to catalyze the transfer of UDP-glucose to cyanidin at 5-OH position and successively at 3-OH position, resulting in the formation of cyanidin 3,5-O-diglucoside. RNA gel blot analysis revealed that RhGT1 transcripts were most abundant at stages 3-4 likewise the glucosylation activity to 5-OH position as well as the anthocyanin accumulation during flower development. These results indicate that novel glucosyltransferase found in this study carried out both gluscoylation of cyanidin to cyanidine 3,5-O-glucoside from 5-OH to 3-OH positions in rose.
