高粱·玉米核及细胞器基因核苷酸替代率与选择压力关系分析

Analysis the Relationship between Selective Pressure and Nucleotide Substitution Rate in Nuclear and Organelle genes of Sorghum and Maize

[目的]探讨选择压力与核苷酸替代率的关系。[方法]采用统计学方法分析高粱、玉米中部分核基因、细胞器基因的同义替代率、非同义替代率以及二者之间的比值,并对一些相关功能基因进行对比分析。[结果]相关功能基因在核与叶绿体中所受的纯化选择压力相近,在线粒体中则较低。高粱、玉米核同源基因间及核中不同功能基因间核苷酸替代的差异主要由非同义替代的差异造成。[结论]选择压力影响不同功能基因、不同物种的分子进化速率,而核与细胞器基因间进化速率的差异与选择压力间并无直接联系。

[Objective] The aim was to research the relationship between nucleotide substitutions rate and selective pressure.[Method]Synonymous and nonsynonymous substitutions and their ratios for some sorghum and maize genes in nuclear and organelle genomes were analyzed by statistical method,and comparative analysis of related functional genes were carried out.[Result]The pure selective pressures of the related functional genes were similar between nuclear and chloroplast genomes,but was lower in mitochondrial genome.The significant differences of nucleotide substitution rate between sorghum and maize orthologous genes,and among different functional genes in nuclear genome were mainly due to the nonsynonymous substitution difference.[Conclusion] The molecular evolutional rate of different functional genes and different lineages were influencedly selective pressure.The differences of molecular evolutional rate among nuclear,chloroplast and mitochondria genomes had no direct relationship with selective pressure.