小麦MBD基因家族的鉴定和特征分析

Identification and Characterization of MBD Gene Family in Wheat

MBD蛋白是一类与甲基化DNA结合的反式作用因子,在植物生长发育调控过程中发挥重要功能。该研究以‘中国春’小麦为材料,利用生物信息学方法分析了小麦基因组中MBD基因家族成员的组成、序列特征、染色体定位和表达模式,利用qRT-PCR技术分析TaMBD 6和TaMBD 9基因的时空表达模式。结果显示:(1)小麦MBD基因家族包含16个成员(44个基因位点)分布于第1、2、5、6和7号染色体群;聚类分析表明,小麦MBD蛋白分别属于第Ⅰ、Ⅱ、Ⅲ、Ⅴ、Ⅶ和Ⅷ亚类,其中第Ⅱ、Ⅲ和Ⅷ亚类的MBD蛋白含有5个识别甲基化DNA的保守位点;基因结构分析显示,小麦MBD基因家族成员的内含子数目在1~10之间,启动子区域普遍存在光响应和激素应答元件,且基因组结构特征在同一亚类内高度相似。(2)RNA-Seq数据的基因表达谱分析显示,小麦MBD基因家族多数成员在穗和籽粒发育早期均有较高的表达水平,而且部分成员对干旱和热胁迫有明显响应。(3)qRT-PCR分析显示,TaMBD 6和TaMBD 9的3个部分同源基因在不同组织间差异表达,但均在幼穗中表达量最高。结果表明,小麦MBD基因可能在小麦发育及非生物胁迫响应过程中发挥调控功能,为进一步探讨小麦MBD基因的功能奠定了基础。

Methyl-binding domain proteins(MBDs)are a group of trans-acting factors that bind to methylated DNA sites,and play important roles during the developmental regulation in plants.In this study,we used‘Chinese Spring’as materials,and bioinformatic analyses were performed to identify the TaMBD genes in the wheat genome,including composition,sequence characteristics,chromosomal location and expression patterns,Additionally,the spatiotemporal expression patterns of TaMBD 6 and TaMBD 9 genes were studied by using qRT-PCR technology.The results showed that:(1)16 TaMBD members(44 gene loci)were included in the wheat genome,and they were distributed on the 1st,2nd,5th,6th and 7th chromosome groups,respectively.Cluster analysis indicated that TaMBDs were sorted into six subclassesⅠ,Ⅱ,Ⅲ,Ⅴ,ⅦandⅧof eight MBD subclasses in plants.Additionally,5 conserved binding sites,specific to methylated DNA regions,were found in the TaMBD members of the subclassⅡ,ⅢandⅧ.Gene structure analysis showed that the number of introns is varied at the range of 1 to 10 in TaMBD genes,and the light-and hormone-responsive elements were commonly found in the region of TaMBD promoters.The distribution characteristics of genomic structure and regulatory elements were highly similar among TaMBD members in the same subclass.(2)Gene expression profile analysis of RNA-Seq data showed that most members of TaMBD gene family were highly expressed in grain and spike tissues at the time point of earlier development stages,and some members were obviously responding to both of drought and heat stresses.(3)The qRT-PCR results showed that the 3 homologous genes of TaMBD 6 and TaMBD 9 were differentially expressed in different tissues,but they were all expressed at the highest level in young spike tissues.The results indicated that the MBD genes might play important regulatory roles during the process of developmental regulation and abiotic stress responding in wheat.