Smith David Roy, Keeling Patrick J
Department of Biology, University of Western Ontario, London, ON, Canada N6A 5B7; and
Canadian Institute for Advanced Research, Department of Botany, University of British Columbia, Vancouver, BC, Canada V6T 1Z4.
Proc Natl Acad Sci U S A. 2015 Aug 18;112(33):10177-84. doi: 10.1073/pnas.1422049112. Epub 2015 Mar 26.
Mitochondrial and plastid genomes show a wide array of architectures, varying immensely in size, structure, and content. Some organelle DNAs have even developed elaborate eccentricities, such as scrambled coding regions, nonstandard genetic codes, and convoluted modes of posttranscriptional modification and editing. Here, we compare and contrast the breadth of genomic complexity between mitochondrial and plastid chromosomes. Both organelle genomes have independently evolved many of the same features and taken on similar genomic embellishments, often within the same species or lineage. This trend is most likely because the nuclear-encoded proteins mediating these processes eventually leak from one organelle into the other, leading to a high likelihood of processes appearing in both compartments in parallel. However, the complexity and intensity of genomic embellishments are consistently more pronounced for mitochondria than for plastids, even when they are found in both compartments. We explore the evolutionary forces responsible for these patterns and argue that organelle DNA repair processes, mutation rates, and population genetic landscapes are all important factors leading to the observed convergence and divergence in organelle genome architecture.
线粒体和质体基因组呈现出各种各样的结构，在大小、结构和内容上差异极大。一些细胞器DNA甚至出现了复杂的异常情况，比如编码区域混乱、非标准遗传密码以及复杂的转录后修饰和编辑模式。在这里，我们比较并对比线粒体和质体染色体之间基因组复杂性的广度。两种细胞器基因组都独立进化出了许多相同的特征，并呈现出相似的基因组修饰，而且往往出现在同一物种或谱系中。这种趋势很可能是因为介导这些过程的核编码蛋白最终会从一个细胞器泄漏到另一个细胞器中，导致这些过程很可能在两个区室中同时出现。然而，即使在两个区室中都存在，线粒体基因组修饰的复杂性和强度始终比质体更为显著。我们探究了导致这些模式的进化力量，并认为细胞器DNA修复过程、突变率和群体遗传格局都是导致观察到的细胞器基因组结构趋同和分化的重要因素。
