茶树乙醇脱氢酶基因家族的鉴定及其在白茶萎凋过程的表达分析

乙醇脱氢酶（Alcohol dehydrogenase,ADH）作为植物香气物质合成的脂肪酸代谢等途径中关键酶之一,对茶叶芳香物质的形成有着重要作用。从茶树染色体级别的基因组数据库中鉴定到19个CsADH基因家族成员。系统进化树显示,茶树的ADH基因家族成员分成6个亚家族;共线性分析发现,茶树和拟南芥、葡萄与猕猴桃的ADH基因家族之间分别存在2、4、12对共线性关系;茶树ADH基因家族含有1~13个外显子,编码其氨基酸的数目为236~669,分子量为26.15~73.83 kDa,且主要定位于细胞质和叶绿体,仅CsADH1定位于细胞核。此外,对上游启动子区域分析发现了大量与光响应、植物生长发育、胁迫和激素响应密切相关的顺式作用元件。荧光定量检测发现,CsFDH2在萎凋4 h时表达量最高;CsADH4和CsADH10在萎凋32 h时表达量最高,分别是对照的4.11倍和3.54倍;CsADH3在萎凋48 h时达到峰值,略高于萎凋32 h的表达量;CsADH-like1在萎凋40 h时表达量达到最高值;CsADH-like3在萎凋24 h时表达量最高。以上结果为探究萎凋过程中乙醇脱氢酶基因对白茶脂肪族类芳香物质形成的分子机理提供参考。

Identification of Alcohol Dehydrogenase Gene Family and Their Expression Analysis in the Withering Process of White Tea

Alcohol dehydrogenase (ADH) plays an important role in the formation of tea aroma as one of the key enzymes in the synthesis of fatty acid metabolism pathway. In this study, 19 CsADH gene family members were identified from the chromosome level genome database of tea plants for the first time. Bioinformatics analysis shows that the members of ADH gene family were divided into six subfamilies. Collinearity analysis shows that there were 2, 4 and 12 pairs of collinearity between ADH gene family of Camellia sinensis and Arabidopsis thaliana, Vitis vinifera and Actinidia chinensis, respectively. The tea ADH gene family contains 1-13 exons, which encode 236-669 amino acids with molecular weight of 26.15-73.83 kDa. It is mainly located in cytoplasm and chloroplast, and only CsADH1is located in nucleus. In addition, a large number of cis-acting elements closely related to light responsive, plant growth, stress and phytohormone responsive were found in the upstream promoter region. Fluorescence quantitative detection shows that the expression of CsFDH2 was the highest at 4 h of withering. The expressions of CsADH4 and CsADH10 were the highest at 32 h of withering, which were 4.11 and 3.54 times that of the control respectively. The expression of CsADH3 reached the peak at 48 h of withering, which was slightly higher than that at 32 h of withering. The expression of CsADH-like1 reached the highest value at 40 h of withering. The highest expression of CsADH-like3 was at 24 h of withering. This study provided a reference for exploring the molecular mechanism of alcohol dehydrogenase genes acting on the formation of aliphatic aromatic substances in the withering process of white tea.