目的 对参与多糖合成途径的茶树尿苷二磷酸-葡萄糖-脱氢酶基因（Camellia sinensis UDP-glucose-dehydrogenase gene，CsUGD）进行克隆、生物信息学分析、组织表达特异性分析及测定茶树不同器官组织多糖含量。方法 通过转录组数据获得茶树同源基因序列。利用ProtParam、TMpred、signalP、NetPhos、SMART、SSPro 4.0等在线软件进行生物信息学分析。VMD编辑CsUGD基因蛋白质三维结构；Jalview软件进行多序列比对；MEGA5.0构建系统进化树。采用qRT-PCR对不同器官组织进行基因表达差异分析，通过蒽酮硫酸比色法测定不同器官的多糖含量。结果 获得茶树CsUGD基因（MG366591）全长cDNA序列，该序列全长1 866 bp，编码480个氨基酸。CsUDP蛋白属于稳定亲水蛋白，不含信号肽，具有跨膜结构，并与柿树亲缘关系最近。荧光定量PCR显示，CsUGD在茶树的侧根中表达量最高；蒽酮硫酸比色法测定显示，在侧根中多糖含量最高。结论 首次从茶树中克隆出CsUGD基因，阐明该基因在茶树生长发育中的重要作用，在茶树多糖合成途径中起到关键作用，为茶树育种并提高茶叶药用价值提供科学依据。

Objective To clone the UGD-glucose-dehydrogenase (CsUGD) gene involved in the polysaccharide metabolic pathway, and to analyze by bioinformatics analysis, tissue expression specificity analysis, and determination of polysaccharide content in different organs of Camellia sinensis. Methods The sequence of homologous gene was obtained by transcriptome. The bioinformatics analysis was carried out by using ProtParam, TMpred, signalP, NetPhos, SMART, SSPro 4.0 and so on. Three-dimensional structure of CsUGD protein was edited by VMD; Jalview software was used for multiple sequence alignment; MEGA5.0 was used for phylogenetic tree construction. Gene expression analysis in difference organs was performed by Real-time PCR and the determination of polysaccharide content in different organs was done by anthrone sulfuric acid colorimetric method. Results The cloned CsUGD gene (GenBank accession number MG366591) had a full length of 1 866 bp encoding a predicted protein of 480 amino acids. The results of bioinformatics showed that the protein encoded by CsUGD gene belongs to the stable hydrophilic protein with transmembrane structure but no signal peptide; Phylogenetic tree analysis showed that CsUGD keeps closest genetic relationship with Diospyros kaki. The highest expression was observed in lateral roots by RT-PCR. Determination of polysaccharides in different organs of C. sinensis by colorimetric method of anthrone and sulphuric acid showed that the content of tea polysaccharide (TPS) in lateral root was higher than other parts of C. sinensis. Conclusion The CsUGD gene was cloned from the tea plant for the first time and its important role in the growth and development of the tea tree was clarified. It also played a key role in the pathways of synthesis of C. sinensis polysaccharides, which provided a scientific basis for quality breeding of C. sinensis and improving the medicinal value of tea.

国家现代农业（茶叶）产业技术体系建设专项资金项目（CARS-19）；福建省"2011协同创新中心"中国乌龙茶产业协同创新中心专项（闽教科[2015]75号）；福建农林大学科技创新专项基金项目（CXZX2017181）