Identification and Characterization of Glucosyltransferase That Forms 1-Galloyl--d-Glucogallin in L., a Functional Fruit Rich in Hydrolysable Tannins.

Hydrolysable tannins (HTs) are useful secondary metabolites that are responsible for pharmacological activities and astringent taste, flavor, and quality in fruits. They are also the main polyphenols in L. (Chinese olive) fruit, an interesting and functional fruit that has been cultivated for over 2000 years. The HT content of fruit was 2.3-13 times higher than that of berries with a higher content of HT. 1-galloyl--d-glucose (G) is the first intermediate and the key metabolite in the HT biosynthesis pathway. It is catalyzed by UDP-glucosyltransferases (UGTs), which are responsible for the glycosylation of gallic acid (GA) to form G. Here, we first reported 140 UGTs in . Phylogenetic analysis clustered them into 14 phylogenetic groups (A, B, D-M, P, and Q), which are different from the 14 typical major groups (A~N) of . Expression pattern and correlation analysis showed that () was highly expressed and had a positive correlation with GA and G content. Prokaryotic expression showed that could catalyze GA to form G. These results provide a theoretical basis on in , which will be helpful for further functional research and availability on HTs and polyphenols.