Abstract
Lignins and flavonoids, which are derived from the phenylpropanoid pathway and share common precursors, play an important role in Boehmeria nivea (ramie). Uridine diphosphate-glycosyltransferases (UGTs) are essential for the glycosylation of secondary metabolites and are involved in plant growth and stress responses. Hence, this study aimed to screen candidate UGTs related to lignin/flavonoid glycosylation and stress responses. A total of 84 BnUGTs were identified, and all BnUGTs contain a conserved PGPS domain. Phylogenetic analysis suggested that 10, 5, 1, and 1 putative BnUGTs might be associated with lignin glycosylation, flavonoid glycosylation, and adverse stress, respectively. Further analysis showed that Bnt05T007753.1 expression was upregulated and showed a significant positive correlation with lignin content in the phloem and leaf, reaching up to 710 in the xylem after 75 days of germination. Bnt14T019888.1 expression (in the leaf and xylem) and Bnt06T010117.1 expression (in the xylem) were upregulated and showed a significant positive correlation with lignin and flavonoid content. In the phloem, Bnt14T019888.1 expression was downregulated and showed a significant negative correlation with lignin content. Bnt04T006105.1 expression was upregulated in the stem and leaf under Cd treatment. Overall, we successfully identified four candidate BnUGTs (Bnt05T007753.1, Bnt14T019888.1, Bnt06T010117.1, and Bnt04T006105.1); these findings provide insight into the glycosylation mechanisms of lignins and flavonoids and stress responses in ramie.