Organelle DNA variation in parental Solanum spp. genotypes and nuclear-cytoplasmic interactions in Solanum tuberosum (+) S. commersonii somatic hybrid-backcross progeny

Nuclear-cytoplasmic interactions can influence fertility and agronomic performance of interspecific hybrids in potato as well as other species. With the aim of assessing the potential value of a novel recombinant cytoplasm derived by interspecific somatic hybridization, backcross progeny were produced by crossing a somatic hybrid between Solanum tuberosum (tbr) and the wild incongruous species S. commersonii (cmm) with various potato clones. BC₁ clones were evaluated for male fertility and other agronomic traits. Male fertility clearly depended on the cross direction and the cytoplasm source. Genotypes with cytoplasms sensitive to nuclear genes derived from Solanum commersonii and inducing male sterility showed identical mtDNA composition, as based on mtDNA analyses with various PCR-based and RFLP markers. On the other hand, genotypes with cytoplasms not inducing male sterility in the presence of the cmm nuclear genes showed a different mtDNA organisation. Analysis of cpDNA confirmed similarity of cytoplasmic composition in CMS-inducing genotypes and clear differences with the others. Genotypes with recombinant cytoplasm induced by somatic hybridization generally showed similar agronomic performances in reciprocal hybrids with tbr cytoplasm, suggesting that the novel cytoplasm can be used in potato breeding.Contribution no. 24 from the Institute of Plant Genetics, Research Division of Portici