2020 Volume 89 Issue 5 Pages 516-524
Red mangos (Mangifera indica L.) accumulate appreciable amounts of cyanidin-based anthocyanins in the skin, and previous studies showed that these anthocyanins contain galactose as a sugar moiety. To date, two UDP:flavonoid 3-O-glycosyltransferase (UFGT)-like genes named MiUFGT1 and MiUFGT3 (MiUFGalT3) have been isolated from mango ‘Irwin’ peel as anthocyanin-related UFGT genes, but the function of the proteins of the genes have not yet been elucidated. In this study, we characterized recombinant MiUFGT1 and MiUFGalT3 expressed in Escherichia coli. In the presence of quercetin as an acceptor, rMiUFGT1 showed marginal glucosylation activity, while rMiUFGalT3 exhibited significant galactosylation activity 20-fold higher than its glucosylation activity. Specificity analysis using purified MiUFGalT3 found that rMiUFGalT3 almost equally accepts anthocyanidins and flavonols. The anthocyanins extracted from the ‘Irwin’ skins were cyanidin 3-O-galactoside and 7-O-methylcyanidin 3-O-galactoside by instrumental analyses, which is consistent with previous results obtained for other red mango cultivars. The results suggest that MiUFGalT3 is responsible for the red coloration of ‘Irwin’ mango fruit skins.
