Hypothesis regarding the evolution of six cultivated Brassica mitotypes. Diverse Brassica mitotypes are hypothesized to have evolved from an expanded ancestral parent mitotype and formed through mitochondrial genome speciation and compaction. Jun (B. juncea) is derived from the cam mitotype and pol and nap from a primary mitotype very similar to the cam mitotype, without deletion of the CMS-related orf224 gene region (4.4 kb) or its homolog orf222. The maternal mitotype from which car is derived is unclear (dotted lines). Three mitotypes for the elementary species are also hypothesized to be compaction forms from the large ancestral mitotype.
Chang et al. BMC Genomics 2011 12:497 doi:10.1186/1471-2164-12-497