Genetic and molecular analysis of male fertility and cytoplasmic DNA variation in interspecific Solanum spp. somatic hybrids

Somatic hybridization is a useful technique for gene transfer between Solanum species. By contrast with other methodologies, it is also a powerful method to create new nuclear-cytoplasmic organelle assortments and induce variability in organellar DNA (Earle 1995). In potato, male sterility and several important traits are controlled by cytoplasmic genes or their interaction with nuclear ones. However, the genetic control of these traits is not well known. In some interspecific sexual hybrids of Solanum spp., nuclear factors from the wild species interact with cytoplasmic factors of the cultivated one to cause male sterility (CMS) (Kaul 1988). Genetic analysis has revealed that one or few nuclear genes are involved in this interaction; in contrast the cytoplasmic factors involved have not yet been characterized. As a matter of fact, while the chloroplast genome of some Solanum species has been extensively studied, only recently has the organization of the mitochondrial genome of Solanum tuberosum been examined, and very little is known about other Solanum species.