水稻抗逆相关基因的分子进化分析

The molecular evolution of rice stress-related genes

植物在进化过程中为了适应外界环境,已经具有一套完整的抵抗外界特殊环境的调控系统。但是,关于水稻抗逆相关基因的分子进化方面的研究还未见报道。文章通过Plant Tolerance Gene Database数据库,获得22个水稻抗逆相关基因。利用比较基因组学和生物信息学方法对水稻抗逆相关基因的进化动态进行研究,结果表明水稻抗逆相关基因在低等植物中比较保守;随着植物的不断进化和生存环境的改变,其基因数量也随之增加。具有相似抗性功能的基因往往具有相似的基因结构和基序(motif)结构。文章还发现4个保守motif的存在:HRDXK、DXXSXG、LLPR和GXGXXG(X代表任意氨基酸)。在GSK1、RAN2抗逆基因中发现了3个特有的motif结构:GSK1特有的P-rich motif,RAN2特有的G-rich motif和E-rich motif。推测这些保守的motif结构与基因的抗逆功能密切相关。进化速率分析结果表明,尽管植物抗逆性相关基因在进化过程中受到较强的纯化选择作用,但是仍然有50%的抗逆性相关基因存在正选择位点。这些正选择位点的存在有可能为基因适应外界环境变化提供了重要的物质基础。

In the processes of evolution, plants have formed a perfect regulation system to tolerate adverse envi-ronmental conditions. However, there has not been any report about the molecular evolution of rice stress-related genes. We derived a family of 22 stress-related genes in rice from Plant Stress Gene Database, and analyzed it by bioinformatics and comparative genome method. The results showed that these genes are relatively conservative＆amp;nbsp;in low organisms, and their copy numbers increase along with the environmental changes and the evolution. We also found four conserved sequence motifs and three other specific motifs. We propose that these motifs are closely asso-ciated with the function of rice stress-related genes. The analysis of selection pressure showed that about 50% rice stress-related genes have positive selection sites, although they were subject to a strong purifying selection. Positive selection sites might be very significant for plants to adapt to environmental changes.