Tea Science Research Institute, College of Horticulture, Nanjing Agricultural University, 1 Weigang, 210095, Nanjing, People's Republic of China.
Protoplasma. 2021 Jan;258(1):115-127. doi: 10.1007/s00709-020-01555-4. Epub 2020 Sep 15.
Tea plant, an economically important crop, is used in producing tea, which is a non-alcoholic beverage. Lignin, the second most abundant component of the cell wall, reduces the tenderness of tea leaves and affects tea quality. Caffeoyl-coenzyme A O-methyltransferase (CCoAOMT) involved in lignin biosynthesis affects the efficiency of lignin synthesis and lignin composition. A total of 10 CsCCoAOMTs were identified based on tea plant genome. Systematic analysis of CCoAOMTs was conducted for its physicochemical properties, phylogenetic relationships, conserved motifs, gene structure, and promoter cis-element prediction. Phylogenetic analysis suggested that all the CsCCoAOMT proteins can be categorized into three clades. The promoters of six CsCCoAOMT genes possessed lignin-specific cis-elements, indicating they are possibly essential for lignin biosynthesis. According to the distinct tempo-spatial expression profiles, five genes were substantially expressed in eight tested tissues. Most CsCCoAOMT genes were expressed in stems and leaves in three tea plant cultivars 'Longjing 43,' 'Anjibaicha,' and 'Fudingdabai' by RT-qPCR detection and analysis. The expression levels of two genes (CsCCoAOMT5 and CsCCoAOMT6) were higher than those of the other genes. The expression levels of most CsCCoAOMT genes in 'Longjing 43' were significantly higher than that those in 'Anjibaicha' and 'Fudingdabai.' Correlation analysis revealed that only the expression levels of CsCCoAOMT6 were positively correlated with lignin content in the leaves and stems. These results lay a foundation for the future exploration of the roles of CsCCoAOMTs in lignin biosynthesis in tea plant.
茶树是一种重要的经济作物，用于生产茶，茶是一种非酒精饮料。木质素是细胞壁中第二丰富的成分，它降低了茶叶的嫩度，影响了茶叶的品质。咖啡酰辅酶 A-O-甲基转移酶（CCoAOMT）参与木质素的生物合成，影响木质素合成的效率和木质素的组成。基于茶树基因组，共鉴定了 10 个 CsCCoAOMTs。对 CCoAOMTs 进行了系统的分析，包括其理化性质、系统发育关系、保守基序、基因结构和启动子顺式元件预测。系统发育分析表明，所有 CsCCoAOMT 蛋白可分为三个分支。六个 CsCCoAOMT 基因的启动子具有木质素特异性顺式元件，表明它们可能对木质素生物合成至关重要。根据不同的时空表达谱，五个基因在八个测试组织中大量表达。通过 RT-qPCR 检测和分析，在三个茶树品种“龙井 43”、“安吉白茶”和“福鼎大白”中，大多数 CsCCoAOMT 基因在茎和叶中表达。两个基因（CsCCoAOMT5 和 CsCCoAOMT6）的表达水平高于其他基因。在“龙井 43”中，大多数 CsCCoAOMT 基因的表达水平明显高于“安吉白茶”和“福鼎大白”。相关性分析表明，只有 CsCCoAOMT6 的表达水平与叶片和茎中的木质素含量呈正相关。这些结果为进一步探索 CsCCoAOMTs 在茶树木质素生物合成中的作用奠定了基础。
