长穗偃麦草LBD基因家族的鉴定与进化分析

Identification and Evolution Analysis of LBD Gene Family in Thinopyrum elongatum

为深入研究长穗偃麦草LBD基因家族中基因的结构与功能以及小麦与其近缘属的进化关系,以长穗偃麦草LBD(Lateral organ boundaries domain)基因家族为研究对象,生物信息学分析发现该基因家族含有32个成员,根据其结构域特征,可分为ClassⅠ和ClassⅡ两个亚家族,ClassⅠ又可分为ⅠA、ⅠB、ⅠC、ⅠD和ⅠE,ClassⅡ可分为ⅡA和ⅡB;该基因家族的结构域、基因结构相对保守,不同成员之间具有相似的蛋白二级和三级结构。对32个基因的上游序列预测,发现基因上游序列中含有光响应、多种激素、逆境响应等顺式作用元件,说明LBD基因的表达受到光、激素、逆境等多种因素的诱导。与普通小麦、圆锥小麦、乌拉尔图小麦、粗山羊草、大麦进行共线性分析发现,Tel-2E-LBD2、Tel-3E-LBD4、Tel-4E-LBD1和Tel-4E-LBD6为长穗偃麦草特有的LBD基因,而其他28个LBD基因在进化中具有高度的保守性;在普通小麦、圆锥小麦、乌拉尔图小麦和大麦基因组中均发现第1、3部分同源群染色体上存在染色体间的片段重复;普通小麦、圆锥小麦和乌拉尔图小麦的A基因组中第4、5部分同源群染色体均有易位现象,同时,乌拉尔图小麦4A染色体上存在染色体内片段重复而在普通小麦和圆锥小麦的A基因组上发现第4部分同源群染色体内易位与倒位。

As an important wild relative of wheat,Thinopyrum elongatumplays an important role in wheat improvement.Gene family of Thinopyrum elongatumwas studied in this paper to analyze the LBD(Lateral organ boundaries domain).Bioinformatics analysis showed that the LBD gene family contained 32 members in Thinopyrum elongatum.According to its characteristic domain,the LBD gene familycould be divided into two subfamilies of ClassⅠand ClassⅡ.ClassⅠwas divided into IA,IB,IC,ID and IE,and ClassⅡwas divided into IIA and IIB.The domain and structure of the gene family were relatively conservative,all members had similar secondary and tertiary structure of protein.Through prediction and analysis of the upstream sequences of 32 LBD genes,it was found that the upstream sequences contained cis-acting elements,such as light response,multiple hormones and stress response.Therefore,it was speculated that the expression of LBD genes were induced by multiple factors such as light,hormones and stress.Furthermore,collinearity analysis between Thinopyrum elongatum LBD gene family among Triticum aestivum L.,Triticum turgidum L.,Triticum urartu,Aegilops tauschii and Hordeum vulgare were carried out,four LBD genes,including Thinopyrum elongatum,Tel-2E-LBD2,Tel-3E-LBD4,Tel-4E-LBD1 and Tel-4E-LBD6,were identified,and the rest 28 LBD genes had good collinearity.Triticum aestivum L.,Triticum turgidum L.,Triticum urartu,and Hordeum vulgare,chromosomes between the homoeologous group 1 and the homoeologous group 3 had inter-chromosome fragment duplication in genomes.What’s more,there were translocations that the chromosome segment from chromosome 4A to chromosome 5A in Triticum aestivum L.,Triticum turgidum L.and Triticum urartu,and chromosome 4A of Triticum urartu had intra-chromosome fragment duplication.The chromosomes 4A of Triticum aestivum L.and Triticum turgidum L.,intra-chromosome translocations and inversions were identified.This study lays foundation for further study on functions of Thinopyrum elongatum LBD genes and also provides a reference for studying the evolution of wheat and its relatives.