Several different mitochondrial DNA regions are involved in intergenomic recombination in Brassica napus cybrid plants

An important mitochondrial (mt) DNA polymorphism was detected by SalI restriction enzyme analysis in five Brassica napus cybrids plants which combine B. napus chloroplasts and a cytoplasmic male sterility (cms) trait from Raphanus sativus. Novel restriction fragments observed in these cybrids were analysed. One of them was found to be constituted by fragments of both parent mt genomes. Sites involved in rut recombination in cybrids were compared by molecular hybridization to sites supposedly implicated in intragenomic mt recombination in B. oleracea The results indicate that mt recombination events arising through protoplast fusion involve several different rut DNA regions. Some of these regions appeared homologous to regions presumably involved in intragenomic mt recombination in B. oleracea.