University of Lille Nord de France, F-59000 Lille, France.
Genome Biol Evol. 2011;3:723-36. doi: 10.1093/gbe/evr042. Epub 2011 May 21.
Despite their monophyletic origin, mitochondrial (mt) genomes of plants and animals have developed contrasted evolutionary paths over time. Animal mt genomes are generally small, compact, and exhibit high mutation rates, whereas plant mt genomes exhibit low mutation rates, little compactness, larger sizes, and highly rearranged structures. We present the (nearly) whole sequences of five new mt genomes in the Beta genus: four from Beta vulgaris and one from B. macrocarpa, a sister species belonging to the same Beta section. We pooled our results with two previously sequenced genomes of B. vulgaris and studied genome diversity at the species level with an emphasis on cytoplasmic male-sterilizing (CMS) genomes. We showed that, contrary to what was previously assumed, all three CMS genomes belong to a single sterile lineage. In addition, the CMSs seem to have undergone an acceleration of the rates of substitution and rearrangement. This study suggests that male sterility emergence might have been favored by faster rates of evolution, unless CMS itself caused faster evolution.
尽管它们具有单系起源，但植物和动物的线粒体（mt）基因组随着时间的推移已经发展出了截然不同的进化路径。动物的 mt 基因组通常较小、紧凑，并且具有较高的突变率，而植物的 mt 基因组则具有较低的突变率、较小的紧凑性、更大的大小和高度重排的结构。我们展示了五个新的 Beta 属 mt 基因组的（几乎）完整序列：四个来自 Beta vulgaris，一个来自 B. macrocarpa，后者是属于同一 Beta 节的姐妹种。我们将我们的结果与之前已测序的两个 Beta vulgaris 基因组进行了汇总，并在物种水平上研究了基因组多样性，重点关注细胞质雄性不育（CMS）基因组。我们表明，与之前的假设相反，所有三个 CMS 基因组都属于单一的不育谱系。此外，CMS 似乎经历了替代和重排速率的加速。这项研究表明，雄性不育的出现可能得益于更快的进化速度，除非 CMS 本身导致了更快的进化。
