UGT85A53 promotes flowering via mediating abscisic acid glucosylation andFLCtranscription inCamellia sinensis

Abstract

Uridine-diphosphate dependent glycosyltransferases catalyse the glycosylation of small molecules and play an important role in maintaining cell homeostasis and regulating plant development. Glycosyltransferases are widely distributed, but their biological roles in regulating plant growth and development are largely unknown. In this study, we identified a UDP-glycosyltransferase CsUGT85A53 from Camellia sinensis, whose expression is strongly induced by various abiotic stress factors and its protein product distributed in both cytoplasm and nucleus. Ectopically over-expression of CsUGT85A53 in Arabidopsis resulted in an early flowering phenotype under both long-day and short-day conditions. The transcript accumulation of the flowering repressor genes FLC and ABI5, an activator of FLC in ABA-regulated flowering signaling, are all significantly repressed in transgenic Arabidopsis compared with wild-type plants. The decreased expression level of FLC gene might be associated with its increased DNA methylation level in CsUGT85A53-OE plants. Biochemical analyses show that CsUGT85A53 could glucosylate ABA to form inactive ABA-glycoside in vitro and in planta. Over-expression of CsUGT85A53 in Arabidopsis resulted in a decreased level of free ABA and increased level of ABA-glucoside. The early flowering phenotype in the CsUGT85A53-OE transgenic lines were restored due to ABA application. Further, CsUGT85A53 overexpressed plants displayed ABA-insensitive phenotype with higher germination rates compared with control in the presence of lower concentrations of exogenous ABA. Our findings revealed the first UGT in tea plants catalyzing ABA glucosylation and enhancing flowering transition as a positive regulator.

UGT86C11 is a novel plant UDP-glycosyltransferase involved in labdane diterpene biosynthesis

“…S5 B and S7 ) ( 45 ). Although UGTs of the diterpene pathway were not well studied, some UGTs that participate in phenylpropanoid, sterol, and phytohormone pathways were previously characterized ( 10 , 18 , 20 , 21 , 25 , 26 , 46 , 47 , 48 ). To shortlist candidate UGTs of kalmegh diterpene pathway, a phylogenetic analysis was carried out using biochemically characterized UGTs.…”

“…GTs represent one of the largest enzyme families and typically account for 1 to 2% of the protein-coding genes in plants ( 6 , 7 , 8 ). The glycosylation of small molecules catalyzed by UGTs, the largest GT family in plants, plays crucial roles in plant development, metabolism, and stress tolerance ( 9 , 10 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 57 ). In this work, we have identified a previously uncharacterized UGT86 member (ApUGT12/UGT86C11) that catalyzed C19-O-glucosylation with strict scaffold selectivity and is involved in developmental and tissue-specific biosynthesis of bioactive labdane diterpenes in the medicinal plant kalmegh.…”

“…The glycosylation most often represents a final step in the biosynthesis of phytochemicals, thereby, influencing their solubility, storage, and bioactivity ( 17 , 18 , 19 ). Consequently, understanding the biochemical features of UGTs will be essential to engineer bioactive chemicals in plants to improve plant function and provide benefits to human health ( 14 , 20 , 21 , 22 , 23 , 24 ). However, considering a huge diversity of UGTs even in a single plant species and the diversity of specialized metabolites produced in plants, it is quite impossible to assign biochemical function of UGTs in plant specialized metabolism, solely based on sequence similarity.…”

Feasible strategies for studying the involvement of DNA methylation and histone acetylation in the stress-induced formation of quality-related metabolites in tea (Camellia sinensis)

“…From the perspective of proteomics, elucidating the regulation of specific modification sites with regard to the formation of secondary metabolites has provided important insight into the regulatory role of lysine acetylation in secondary metabolism in tea plants 40 , 41 . Based on changes in the DNA methylation level and histone modification of the target genes, the regulatory factors involved in the regulation of tea processing, low temperature and long illumination have been identified, clarifying the specific regulatory mechanism of the formation of secondary metabolites 19 , 20 , 42 – 44 . These results suggest that epigenetic modifications help to regulate stress responses and secondary metabolite biosynthesis in tea.…”

Genome-Wide Identification of the PMEI Gene Family in Tea Plant and Functional Analysis of CsPMEI2 and CsPMEI4 Through Ectopic Overexpression

“…Therefore, more and more studies have been focused on the molecular mechanisms of tea plant stress responses. At present, many functional genes involved in vegetative (Xia et al, 2021), reproductive (Jing et al, 2020), nutrient uptake (Arkorful et al, 2020), secondary metabolism (Yu et al, 2021;Zhao et al, 2021), and stress response (Qian et al, 2018;Wang et al, 2018;Yao et al, 2020) have been extensively explored. However, the functions of PMEIs in tea plant still remain unknown.…”