普通小麦祖先种类TaNAC2a基因的鉴定分析和表达模式研究

Bioinformatic Analysis and Expression Pattern of NAC Transcription Factor Genes Homologous to TaNAC2a in Bread Wheat Progenitors

采用生物信息学方法,利用核酸、蛋白数据库对普通小麦祖先种乌拉尔图小麦(Triticum urartu L.)和粗山羊草(Aegilops tauschii L.)NAC转录因子基因家族进行分析,分别鉴定出107、126个NAC蛋白家族成员。根据拟南芥、水稻NAC基因家族分类系统,将其分为15个亚族。通过与抗逆相关基因TaNAC2a进行同源进化树分析,发现5个TuNAC、6个AetNAC基因与其高度同源,对这些基因的蛋白结构域、基因结构、启动子顺式作用元件及组织表达特性进行分析。结果表明,11个NAC蛋白具有典型的NAC结构域。进化关系较近的基因具有相似基因结构;启动子区域预测发现其均含有逆境胁迫响应作用元件。实时荧光定量PCR结果显示,TuNAC、AetNAC基因分别在乌拉尔图小麦和粗山羊草根、胚芽鞘、叶组织中均有表达,并呈现出明显的组织表达特异性。通过芯片表达数据和逆境胁迫基因表达试验,推测AetNAC2c基因可能参与植物干旱胁迫响应,AetNAC2b可能参与调控植物的耐旱、耐低温胁迫反应。上述分析结果为普通小麦祖先种基因家族的系统研究,优异候选功能基因的预测、筛选提供了试验依据。

In this study,107 and 126 NAC transcription factor family members in Triticum urartu L. and Aegilops tauschii L. genome were identified respectively by HMM profile search. They were further classified into two groups,consisting of 15 subgroups based on the classification method of Arabidopsis and rice. Phylogenetic analysis revealed that 5 TuNAC genes and 6 AetNAC genes were found to be similar in protein sequence with TaNAC2 a,which had been reported involving in the response to diverse stresses in plant. Phyletic evolution,protein domains,gene structure,cis-acting elements in the promoter region,and tissue-specific expression pattern of these 11 NAC genes were further analyzed. Results showed that these 11 NAC proteins possessed typical NAC domains and several pairs of genes with close evolutionary relationship had similar gene structure. Prediction of cis-acting elements revealed that they all had stress-responsive cis-acting elements in their promoter region. Gene expression pattern analysis revealed that the transcripts of TuNAC and AetNAC genes were detected in root,coleoptile and leaf of Triticum urartu and Aegilops tauschii,respectively,and exhibited obvious tissue-specific expression pattern. It was speculatedfrom microarray data and expression patten under stress conditions that AetNAC2 c had a role in the response to drought stress and AetNAC2 b was more likely to be involved in the regulation of plant reaction to low temperature and drought stress. Our analysis would lay a foundation for systematical research of gene family in bread wheat progenitors and provide an experimental basis for the identification of excellent functional genes.