The rpl5-rps14 mitochondrial region: a hot spot for DNA rearrangements in Solanum spp. somatic hybrids

Southern analysis with rpl5 and rps14 mtDNA gene probes of Solanum tuberosum, S. commersonii and a sample of somatic hybrids, detected polymorphisms between parents and the appearance of a novel restriction fragment in various hybrids. In one of them, detailed mtDNA analyses revealed various configurations of the rpl5-rps14 region present at different stoichiometries. Multiple inter-parental recombination events across homologous sequences were assumed to have caused these rearrangements. Sequence similarity searches detected one sequence putatively involved in the recombination upstream of the rpl5 gene. The presence of a second recombinogenic sequence was inferred. We propose two models to explain the mechanism responsible for obtaining the different rpl5-rps14 arrangements shown after somatic hybridisation. Variability in the rpl5-rps14 region observed in parental species as well as in their somatic hybrids suggests that this region is a hot spot for mtDNA rearrangements in Solanum spp.