Integration of somatic fusion into Potato breeding: Problems and perspectives

The tetraploid potatoes (Solanum tuberosum L.), with tetrasomic inheritance, asexual mode of propagation, a heavy load of deleterious recessive alleles and varying levels of sexual and EBN (endosperm balance number) incompatibilities are difficult to negotiate at the genome level. Somatic hybridization through targeted protoplast fusion between two dihaploids of tetraploid potatoes, or between a dihaploid and a wild diploid Solanum species across sexual/ EBN barriers, or between two monoploids of diploid/ dihaploid potatoes offers great opportunities for targeted whole genome manipulation vis-a-vis complementation. Although dihaploid breeding and protoplast fusion technologies are successfully integrated into European potato breeding programs through an effective interface between public research institutes and commercial potato breeding companies, these innovative strategies are yet to be functionally integrated into the breeding programs of most of the developing countries. This article analyzes the potential of somatic fusion for augmenting potato improvement, reviews the progress made and identifies the problems to integrate these techniques into a potato breeding program.