Molecular evolution of angiosperm mitochondrial introns and exons
Molecular evolution of angiosperm mitochondrial introns and exons
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DOI：
10.1073/pnas.94.11.5722
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发表时间：
1997-05-27
影响因子：
11.1
通讯作者：
Bousquet, J
中科院分区：
文献类型：
--
作者：
Laroche, J;Li, P;Bousquet, J
对植物线粒体的15个蛋白质编码基因和6个内含子的每个位点的替换数进行了估计，以比较外显子和内含子之间的进化模式和节奏，并对内含子中每个位点的插入-缺失数进行了研究，进一步评估了不同分类群之间以及线粒体基因组易位后的核旁系同源物与线粒体基因组易位后的核旁系同源物之间每个位点的替换数的基因内同质性，每个位点的取代数量的基因间差异被发现是高于非同义的同义位点，这可能是由于差异选择，如果突变率是假设恒定的基因组。一些线粒体基因的进化速度与叶绿体基因一样快，因此比以前认为的要快。对于cox I，相对速率测试表明，木本类群在同义位点的进化速度比一年生植物慢。世代时间，种群大小和物种形成率可能是参与这种速率异质性的因素，内含子比其相邻外显子在每个位点的总取代数和插入缺失上受到的限制更少，但是，平均而言，内含子的每个位点的总取代数与外显子的每个位点的同义取代数相似，同一内含子的每个位点的取代数与插入缺失数之间的相关性通常很高，转移到细胞核的线粒体基因每个位点的取代速率加快，这在同义位点处最为显著。两个不同基因组中旁系同源物之间的这些差异可能是不同突变率的结果。
Numbers of substitutions per site for 15 protein-coding genes and six introns of the plant mitochondria were estimated to compare modes and tempos of evolution between exons and introns, and numbers of insertions-deletions per site also were investigated in introns, Intra-gene homogeneity of numbers of substitutions per site was assessed further among different taxa and between mitochondrial and nuclear paralogs translocated from the mitochondrial genome, Gene-to-gene differences in numbers of substitutions per site were found to be higher for nonsynonymous than synonymous sites, and this could be due to differential selection if mutation rate is assumed constant for the genome. Some mitochondrial genes have evolved as fast as chloroplast genes, thus faster than previously thought, For coxI, relative rate tests showed that woody taxa evolved slower than annuals at synonymous sites, Generation time, population size, and speciation rate are likely factors involved in this rate heterogeneity, Introns were less constrained than their adjacent exons for both overall numbers of substitutions per site and indels, but, on average, overall numbers of substitutions per site for introns were similar to numbers of synonymous substitutions per site for exons, Correlations were generally high between numbers of substitutions and numbers of indels per site for the same intron, Mitochondrial genes transferred to the nucleus had an accelerated rate of substitution per site, which was most significant at synonymous sites. These differences between paralogs in two different genomes are likely the result of different mutation rates.