茶树树型相关CYC/TB1家族全基因组鉴定及表达分析

Genome-wide identification and expression analysis of tree architectures related CYC/TB1 family in tea plant(Camellia sinensis)

TCP(TEOSINTE BRANCHED 1/CYCLOIDEA/PROLIFERATING CELL FACTOR)是植物所特有的一类转录因子,广泛参与调控植物的生长发育。本研究从茶树基因组中获得茶树TCP家族CYC/TB1亚类分支的4个成员,分别命名为CsTCP1、CsTCP8、CsTCP12和CsTCP18。保守结构域分析发现,它们均包含典型的TCP结构域。亚细胞定位预测表明,其编码蛋白均定位于细胞核。系统进化分析可将CYC/TB1亚类分为四个分支(CYC1、CYC2、CYC3和TB1),其中CsTCP1和CsTCP18同属于CYC1支,CsTCP8属于CYC2支,CsTCP12属于CYC3支。q RT-PCR分析发现,这四个基因在不同茶树树型不同部位中存在组织特异性表达:CsTCP1在成熟叶中表达量最高;CsTCP8主要在腋芽和嫩茎中表达;CsTCP12的表达量较低,在多个品种中未检出;而CsTCP18在6个茶树品种的各部位均有表达,但有一定差异,推测该亚族基因可能参与茶树的腋芽生长并调控茶树分枝。进一步对缺氮条件下这四个基因的表达量分析发现,CsTCP1在新梢中的表达量逐渐降低;CsTCP8的表达先升高后降低;CsTCP18的表达趋势与CsTCP8相反,表达量在缺氮12h时达到最高;而CsTCP12的表达量较低,在缺氮条件下未被检出,推测该亚族基因可能参与缺氮响应。

TCP(TEOSINTE BRANCHED 1/CYCLOIDEA/PROLIFERATING CELL FACTOR) belongs to a set of plant-specific transcription factors,which are widely involved in the regulation of plant growth and development.In this study,four CYC/TB1 genes were identified from C.sinensis genome,designated as CsTCP1,CsTCP8,CsTCP12,and CsTCP18,respectively.Their deduced amino acids sequences contain the conserved TCP domain.Subcellular localization prediction indicated that the four proteins were located in the nucleus.Evolutionary relationship analysis found the CYC/TB1 subclass could be divided into four subfamilies(i.e.,CYC1,CYC2,CYC3,and TB1).CsTCP1 and CsTCP18 belong to the CYC1 subfamily,CsTCP8 belongs to CYC2,and CsTCP12 belongs to CYC3.Quantitative real-time PCR suggested that their expression levels were different in four tissues of three different tea tree architectures.The expression of CsTCP1 was the highest in mature leaves,CsTCP8 was highly expressed in axillary buds and tender stems,and the expression of CsTCP12 was too low to be detected in six tea plant cultivars.Moreover,the expression of CsTCP18 could be detected in all samples,and its expression levels were different in the six tea plant cultivars.Hence,we speculated that this subclass may be involved in the development of axillary buds and regulate the branching of tea plants.Additionally,when exposed to nitrogen deficiency conditions,the expression of CsTCP1 decreased gradually;the expression of CsTCP8 increased first and then decreased;in contrast,the expression of CsTCP18 decreased first and then increased and reached the highest level at 12 h,which suggested that these genes may be involved in the response to nitrogen deficiency.