小麦和水稻叶绿体基因组进化中核苷酸替代的种属特异性

Lineage-specific Nucleotide Substitution Patterns in Wheat and Rice Chloroplast Genomes

以玉米叶绿体基因组为参照序列,采用三序列比较法系统分析了小麦和水稻分化过程中叶绿体基因组核苷酸替代的发生方式.结果表明,小麦中存在(A+T)/(G+C)替代偏差,水稻则无,该差异对小麦和水稻分化后叶绿体基因组G+C含量产生不同的影响,替代使小麦叶绿体基因组G+C含量降低、水稻叶绿体基因组G+C含量表现增加.无论在编码区、非编码区,还是不同功能基因区,小麦叶绿体基因组转换与颠换的比值都显著低于水稻.小麦和水稻叶绿体基因组进化中核苷酸替代呈现种属特异性.

Using maize chloroplast genome as reference,we systemically analyzed nucleotide substitution patterns in wheat and rice chloroplast genomic evolution with three-lineage comparisons.The results showed that （A＋T）/（G＋C） bias found in wheat was not so significant in rice chloroplast genomes,which had different influences on two genomic G＋C content.Substitutions decreased the G＋C content of wheat chloroplast genome,and increased that of rice chloroplast genome.The transition/transversion ratio was significantly less in wheat genomes than that in rice genomes in coding,non-coding and different functional genes regions.Nucleotide substitution patterns in wheat and rice chloroplast genomes were lineage-specific.