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.

中文翻译：

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茶树（Camellia sinensis）木质素生物合成相关咖啡酰辅酶A O-甲基转移酶家族基因的鉴定及表达分析

茶树是一种重要的经济作物，用于生产茶，这是一种非酒精饮料。木质素是细胞壁中含量第二丰富的成分，会降低茶叶的嫩度并影响茶叶品质。参与木质素生物合成的咖啡酰辅酶 AO 甲基转移酶 (CCoAOMT) 会影响木质素合成和木质素组成的效率。基于茶树基因组共鉴定出 10 个 CsCCoAOMT。对其理化性质、系统发育关系、保守基序、基因结构和启动子顺式元件预测进行了系统分析。系统发育分析表明，所有的 CsCCoAOMT 蛋白都可以分为三个进化枝。六个 CsCCoAOMT 基因的启动子具有木质素特异性顺式元件，表明它们可能是木质素生物合成所必需的。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，大多数CsCCoAOMT基因在'龙井43'、'安吉白茶'和'福鼎大白'三个茶树品种的茎和叶中表达。两个基因（CsCCoAOMT5 和 CsCCoAOMT6）的表达水平高于其他基因。'龙井43'中大多数CsCCoAOMT基因的表达水平显着高于'安吉白茶'和'福鼎大白'。相关分析表明，只有CsCCoAOMT6的表达水平与叶和茎中木质素含量呈正相关。