近年来, UGTs基因在植物响应非生物胁迫中的作用被逐渐揭示。基于转录组数据, 筛选出2个在低温胁迫下显著上调, 且与茶树( Camellia sinensis)花青苷合成相关的糖基转移酶基因 CsUGT73B4(CSS0039619)和 CsUGT85K5(CSS0047548)。为探究这2个基因在响应低温胁迫下调控茶树花青苷代谢的分子机制, 克隆了 CsUGT73B4和 CsUGT85K5并进行生物信息学分析, 通过拟南芥( Arabidopsis thaliana)过表达和茶树瞬时沉默实验验证其功能。结果显示, 低温胁迫下 CsUGT73B4/ CsUGT85K5基因的表达与花青苷积累呈正相关; 过表达拟南芥植株的花青苷含量和抗氧化酶活性显著提高, 丙二醛含量和相对电导率则显著下降; 在茶树中瞬时沉默 CsUGT73B4或 CsUGT85K5后, 花青苷含量及其合成相关基因的表达水平均显著下调。该研究初步探讨了茶树 CsUGT73B4和 CsUGT85K5基因的功能, 揭示了其通过调控花青苷代谢提高茶树抗寒性的分子机制, 为茶树抗寒分子育种提供了相关候选基因。

INTRODUCTION: Glycosyltransferases are key enzymes involved in various biological processes in plants. To date, glycosyltransferases have been classified into 138 families, among which the glycosyltransferase family I is the largest. This family primarily uses UDP-glucose as the glycosyl donor and is referred to as the UGT family. In recent years, the role of UGT genes in plant responses to abiotic stresses has gradually been revealed. However, currently, only a few UGT genes have been clearly identified as being involved in anthocyanin biosynthesis. RATIONALE: To explore the mechanisms of anthocyanin and its glycosylation-related genes in tea plants under low-temperature stress, this study used FudingDabai Tea as the experimental material. Based on the transcriptome sequencing data, two genes, CsUGT73B4 (CSS0039619) and CsUGT85K5 (CSS0047548), which significantly upregulate anthocyanin expression, were identified. We further investigated the changes of gene expression and explored their relationship with anthocyanin metabolism under low-temperature stress. Additionally, the functions of these two genes were verified through heterologous overexpression in Arabidopsis thaliana and gene silencing experiments. RESULTS: Under low-temperature stress, the expression of CsUGT73B4 and CsUGT85K5 genes was positively correlated with anthocyanin accumulation. In Arabidopsis thaliana plants overexpressing these genes, anthocyanin content and antioxidant enzyme activities (SOD, POD, and CAT) were significantly increased, while malondialdehyde (MDA) content and relative electrical conductivity were reduced. After transient silencing of CsUGT73B4 or CsUGT85K5 in tea plants, the anthocyanin content and the expression levels of its biosynthesis-related genes were significantly down-regulated. CONCLUSION: In summary, the CsUGT73B4 and CsUGT85K5 genes are involved in the response to low-temperature stress, regulate anthocyanin metabolism, and may enhance the cold tolerance of tea plants.