茶树小G蛋白CsRAC5基因的克隆与低温胁迫下的表达分析

小G蛋白是一类重要的信号转导蛋白,参与植物的各项生命活动,但目前在茶树中的研究尚少。本研究以茶树品种龙井长叶为实验材料,克隆获得1个小G蛋白基因,命名为CsRAC5。序列分析显示,CsRAC5含有597βbp,编码198个氨基酸,具有Rho蛋白的保守结构域;序列多重比对发现,该序列与其他物种序列的一致性高达95.96%。CsRAC5蛋白质的相对分子质量为21.79βkDa,为亲水性蛋白;烟草瞬时表达实验显示,CsRAC5定位于细胞膜和细胞核中。荧光定量PCR结果显示,CsRAC5在茶树中的表达具有明显的组织特异性,其中在叶片中的表达最高,在花粉中的表达最低;低温（4℃）胁迫抑制茶树叶片中CsRAC5的表达。

Cloning and Expression Analysis of Small GTPase (CsRAC5) under Cold Stress in Tea Plant (Camellia sinensis)

Small GTPase binding proteins are a kind of important signal transduction proteins, which are involved in various life activities of plants.However,few relative studies were reported in tea plants(Camellia sinensis).Here,a small GTPase binding protein named CsRAC5 was cloned by using a cDNA template from tea cultivar'Longjingchangye'. The results showed that the length of its open reading frame (ORF) is 597 bp, encoding 198 amino acids. It has a conserved Rho domain which belongs to ROP family. Multiple alignment of CsRAC5 with homologue genes in other plant species showed that their identity could reach 95.96%. CsRAC5 is a hydrophilic protein with the theoretical relative weight of 21.79 kDa. The subcellular assay showed that CsRAC5 was localized in the nuclear and membrane. In addition, the results of RT-PCR analysis showed that the highest expression level of CsRAC5 was in leaves but the lowest in pollen.The expression level of CsRAC5 was decreased under cold stress.