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TS2是最早在玉米中发现的性别决定基因,但是在其他的单性花或者两性花的被子植物中其同源基因是否也与花的性别形成有关以及其进化特征仍不清楚.以玉米性别决定基因TASSELSEED2(TS2)为检索序列,通过BLAST搜索得到21个测序植物物种的27个TS2同源基因,并利用生物信息学和比较基因组学方法详细分析了这些TS2基因的序列特征、进化关系及选择压力.结果表明,植物TS2基因具有3种基因结构类型、2种典型的功能结构域和7种保守基序组织模式,且单性花和两性花植物间并没有表现出特异性.系统进化树显示,以江南卷柏TS2蛋白为系统树基部,除了PtrTS2b、SlaTS2、CsaTS2和CpaTS2这4种单性花的TS2蛋白外,剩余22个植物TS2蛋白被划分为4个亚群.值得注意的是,除杨树外,其余4种单性花植物的TS2基因距离较远,均单独为一分支.进一步对4个亚群的选择位点分析发现,这些亚群共包含出24个正选择位点(P>0.05),说明各亚群TS2基因均受控于纯净选择或松弛的纯净选择.由上述结果可知,TS2基因在进化过程中发生了多次重复和基因扩增事件,而多次独立的重复或者基因扩增事件导致TS2基因失去了对性别的决定或者调控作用.
TS2 is the earliest sex-determining gene found in maize, but its homologous genes are also related to sex and its evolutionary characteristics in other hermaphrinae or angiosperm. A total of 27 TS2 homologous genes of 21 sequenced plant species were obtained by BLAST search using the gene TASSELSEED2 (TS2). The sequence features, evolutionary relationships and selection of these TS2 genes were analyzed in detail using bioinformatics and comparative genomics Pressure.The results showed that the plant TS2 gene has three kinds of gene structure types, two kinds of typical functional domains and seven kinds of conservative motif organization patterns, and the monomorphic flowers and bisexual plants did not show the specificity between phylogenetic tree The results showed that TS2 protein was divided into four subgroups except TS2 protein of four uniploid flowers, PtrTS2b, SlaTS2, CsaTS2 and CpaTS2, , Except for the poplar, the other four species of monotypic plants TS2 genes are far apart, are a separate branch.Further analysis of the four sub-groups of selected sites found that these sub-groups contain a total of 24 Positive selection sites (P> 0.05), indicating that each sub-group of TS2 genes are controlled by the pure choice or relaxation of the pure choice from the above results we can see, TS2 gene in the evolutionary process occurred multiple duplications and gene amplification events, However, multiple independent duplications or gene amplification events lead to the loss of sex-determining or regulation of the TS2 gene.