Cloning, Expression, and Functional Characterization of Two Highly Efficient Flavonoid-di--glycosyltransferases ZmUGT84A1 and ZmUGT84A2 from Maize ( L.).

The maize ( L.) glycosyltransferase family 1 comprises many uridine diphosphate glycosyltransferase (UGT) members. However, UGT activities and biochemical functions have seldom been revealed. In this study, the genes of two flavonoid di--glycosyltransferases ZmUGT84A1 and ZmUGT84A2 were cloned from maize plant and expressed in . Phylogenetic analysis showed that the two enzymes were homologous to AtUGT84A1 and AtUGT84A3. The two recombinant enzymes showed a high conversion rate of luteolin to its glucosides, mainly 4',7-di--glucoside and minorly 3',7-di--glucoside in two-step glycosylation reactions . Moreover, the recombinant ZmUGT84A1 and ZmUGT84A2 had a broad substrate spectrum, converting eriodictyol, naringenin, apigenin, quercetin, and kaempferol to monoglucosides and diglucosides. The highly efficient ZmUGT84A1 and ZmUGT84A2 may be used as a tool for the effective synthesis of various flavonoid -glycosides and as markers for crop breeding to increase -glycosyl flavonoid content in food.