植物DXS基因的系统发育和分子进化分析

Phylogenetic and molecular evolution analyses of DXS gene in plants

为了解DXS基因的系统发育、密码子偏好性和分子进化等特性,选取44个代表性物种的DXS基因序列进行分析。结果表明:DXS基因家族具有较高的保守性,序列间的平均遗传距离为0.243;DXS基因的分化时间先于对应的物种分化,DXS基因树和对应物种树的拓扑结构基本一致;所选的裸子植物和单子叶植物及同科的双子叶植物均分别聚类在一块;DXS基因的密码子偏好性较低,平均有效密码子数、GC3和G+C含量分别为47.25、0.49和0.51;DXS基因在进化过程中主要受纯化选择作用,野大豆DXS基因受到的选择压最大为0.981,黍属DXS基因受到的选择压最小为0.001,平均选择压大小为0.094;在各模型中均未检测到后验概率大于0.95的受正向选择作用位点;DXS基因的有效密码子数、GC3和G+C含量与选择压的大小均无显著的相关性。研究为进一步了解DXS基因的功能及其在MEP途径中的调控机制提供一定的理论基础。

In order to understand the phylogenetic,codon bias and molecular evolution characteristics of DXS gene,the DXS gene sequences from 44 representative species were selected for analysis.The results showed that the DXS gene family was highly conserved and the mean genetic distance between sequences was 0.243.The differentiation time of DXS gene preceded the species differentiation,and the phylogenetic tree of DXS gene and species was the same topological structure.The gymnosperm,monocotyledonts and the same family plants of dicotyledonts were clustered together,respectively.The codon bias of DXS gene was low,and the average effective number of codon,GC3 and G+C contents were 47.25,0.49 and 0.51,respectively.DXS gene was mainly subjected to purification selection in the evolutionary process,the DXS gene of Glycine soja with the maximum dN/dS of 0.981,and the DXS gene of Panicum hallii with the minimum dN/dS of 0.001,the average dN/dS was 0.094.There were no positive selection sites with BEB greater than 0.95 detected in all models.There was no significant correlation between the effective number of codon,GC3,G+C contents and the dN/dS of DXS gene.This study provided a theoretical basis for further research on the function of DXS gene and its regulatory mechanism in the MEP pathway.