Structural and content diversity of mitochondrial genome in beet: a comparative genomic analysis
Résumé
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, while plant mt genomes exhibit low mutation rates, little compactness, larger sizes and highly rearranged structures. We present the (nearly) whole sequences of 5 new mt genomes in the Beta genus: 4 from Beta vulgaris and 1 from Beta macrocarpa, a sister-species belonging to the same Beta section. We pooled our results with two previously sequenced genomes of Beta vulgaris and studied genome diversity at the species level with an emphasis on cytoplasmic male sterilizing genomes (CMS). We showed that, contrarily 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.