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Article|20 Jun 2022|OPEN
Identification of UDP-rhamnosyltransferases and UDP-galactosyltransferase involved in flavonol glycosylation in Morella rubra
Chuanhong Ren1,2 , Yan Guo1,2 , Linfeng Xie1,2 , Zhikang Zhao1,2 , Mengyun Xing1,2 , Yunlin Cao1,2 and Yilong Liu1,2 , Jing Lin1,2 , Donald Grierson1,2,3 , Bo Zhang1,2 , Changjie Xu1,2 , Kunsong Chen1,2 , Xian Li,1,2 ,
1Zhejiang Provincial Key Laboratory of Horticultural Plant Integrative Biology, Zhejiang University, Zijingang Campus, Hangzhou 310058, China
2The State Agriculture Ministry Laboratory of Horticultural Plant Growth, Development and Quality Improvement, Zhejiang University, Zijingang Campus, Hangzhou 310058, China
3Plant and Crop Sciences Division, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough, LE12 5RD, UK
*Corresponding author. E-mail: xianli@zju.edu.cn

Horticulture Research 9,
Article number: uhac138 (2022)
doi: https://doi.org/10.1093/hr/uhac138
Views: 96

Received: 07 Mar 2022
Accepted: 12 Jun 2022
Published online: 20 Jun 2022

Abstract

Flavonol glycosides are health-promoting phytochemicals important for human nutrition and plant defense against environmental stresses. Glycosylation modification greatly enriches the diversity of flavonols. Morella rubra, a member of the Myricaceae, contains high amounts of myricetin 3-O-rhamnoside (M3Rha), quercetin 3-O-rhamnoside (Q3Rha), and quercetin 3-O-galactoside (Q3Gal). In the present study, MrUGT78R1 and MrUGT78R2 were identified as two functional UDP-rhamnosyltransferases, while MrUGT78W1 was identified as a UDP-galactosyltransferase. Site-directed mutagenesis identified Pro143 and Asn386 as important residues for rhamnosyl transfer activity of MrUGT78R1, while the two corresponding positions in MrUGT78W1 (i.e. Ser147 and Asn370) also play important roles in galactosyl transfer activity. Transient expression data for these three MrUGTs in Nicotiana benthamiana tested the function of MrUGT78R1 and MrUGT78R2 as rhamnosyltransferases and MrUGT78W1 as a galactosyltransferase in glycosylation of flavonols. This work enriches knowledge of the diversity of UDP-rhamnosyltransferase in planta and identifies two amino acid positions important for both rhamnosyltransferase and galactosyltransferase.