-Mediated Glycosylation Plays an Important Role in Lignin Formation and Stone Cell Development in Pears ().

Glycosylation is necessary for many processes of plant secondary metabolism. It can maintain plant homeostasis and is of great significance to normal plant growth and development. At present, the significance of glycosylation for lignin biosynthesis has been proven in some plants, but it has not yet been reported in pears. We used in situ hybridization, in vitro expression, substrate catalysis, transgenic , and transient transformation of pear fruit in our investigation, which was predicated on the identification of a gene that may be involved in lignin monolignol glycosylation according to our previous work. These results revealed that transcripts were localized to some pulp cell walls, lignin deposition, and stone cell areas of pear fruit. The recombinant PbUGT72AJ2-pGEX4T-1 protein had activity against coniferyl alcohol and sinapyl alcohol, and its catalytic efficiency against coniferyl alcohol was higher than that against sinapyl alcohol. When was transferred into mutants, it was found that some characteristics of mutants were restored. In , overexpression of enhanced the contents of coniferin and syringin, whereas lignification did not change significantly. Transient transformation of pear fruit showed that when in pear fruit was silenced by RNA interference, the content of lignin and stone cells in pear fruit increased, whereas the gene was overexpressed in pear fruit, and there was almost no change in the pear fruit compared with the control. Lignin deposition in pear fruit was closely related to stone cell development. In this study, we proved that plays an important role in lignin deposition and stone cell development in pear fruit, which provides a molecular biological basis for improving pear fruit quality at the molecular level.