A Higher Lignin Content in ugt72b37 Poplar Mutants Indicates a Role of Monolignol Glycosylation in Xylem Lignification

Plant UDP-glycosyltransferases (UGT) transfer sugars to small acceptor molecules and thereby play key roles in the biosynthesis of secondary metabolites, including phenylpropanoids. Some those metabolites are involved xylem lignification a broad range terrestrial plants, particularly trees. Here, we focused on poplar UGT72B37, coding for an enzyme glycosylating monolignols by investigating CRISPR/Cas9 mutant lines. The cell wall characterization revealed 10% lignin content increase three-month-old lines compared wild type. No ectopic was evidenced pith stems mutants, suggesting that increased deposition is restricted lignified walls. analysis expression level polymerization genes did not show significant changes between WT ugt72b37 except CINNAMOYL-COA REDUCTASE 2 which significantly upregulated 1.2–1.5-fold. Noticeably, UGT72B38, closest related gene lines, functional compensation UGT72B37 UGT72B38 possibly linked with accumulation poplar. Overall, these results reinforce plausible role monolignol glycosylation process.