Characterization of As a Multi-substrate UDP:Flavonoid Glucosyltransferase Gene in

L., a "living fossil" and medicinal plant, is a well-known rich source of bioactive flavonoids. The molecular mechanism underlying the biosynthesis of flavonoid glucosides, the predominant flavonoids in , remains unclear. To better understand flavonoid glucosylation in , we generated a transcriptomic dataset of leaf tissue by high-throughput RNA sequencing. We identified 25 putative UDP-glycosyltransferase () unigenes that are potentially involved in the flavonoid glycosylation. Among them, we successfully isolated and expressed eight genes in , and found that recombinant UGT716A1 protein was active toward broad range of flavonoid/phenylpropanoid substrates. In particular, we discovered the first recombinant UGT protein, UGT716A1 from , possessing unique activity toward flavanol gallates that have been extensively documented to have significant bioactivity relating to human health. expression level paralleled the flavonoid distribution pattern in . Ectopic over-expression of in led to increased accumulation of several flavonol glucosides. Identification and comparison of the enzymatic activity of UGT716A1 homologs revealed a UGT from the primitive land species also showed broader substrate spectrum than those from higher plants , and . The characterization of from bridges a gap in the evolutionary history of in gymnosperms. We also discuss the implication of for biosynthesis, evolution, and bioengineering of diverse glucosylated flavonoids.