ARS | Publication request: OVERCOMING HYBRIDIZATION BARRIERS IN POTATO

Submitted to: Plant Breeding Conference Proceedings
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 12, 2005
Publication Date: January 30, 2006
Citation: Jansky, S.H. 2006. Overcoming hybridization barriers in potato. Plant Breeding Conference Proceedings. 125:1-12.

Interpretive Summary: The cultivated potato is a major crop worldwide. It is a high input crop with complex quality requirements at harvest and during storage. In order to breed potatoes with higher yield and quality, and lower input requirements, scientists must have sources of genes for those traits. In potato, there are many wild relatives containing valuable genes for improvement. In order to utilize these genes, breeders must be able to move them from the wild species into the cultivated potato. This is usually done by crossing wild potatoes with cultivated ones to create hybrids. The chromosome number of wild species is usually different than that of the cultivated potato. By manipulating chromosome number, most wild species can be crossed with the cultivated potato. In some cases, additional techniques must be used to create hybrids. For example, young embryos can be removed from developing fruit and cultured in the lab. In a few instances, hybrids are difficult or impossible to create by making crosses. An alternative is to fuse cells of the two parents in the lab, creating somatic hybrids. Because a large amount of useful genetic diversity exists in wild potato species, and this diversity is accessible to potato breeders, the future looks bright for continued progress in potato improvement.

Technical Abstract: The cultivated potato is a major crop worldwide. It is a high input crop with complex quality requirements at harvest and during storage. Potato breeders are fortunate to have access to a very diverse and accessible germplasm resource. Wild Solanum relatives provide genetic diversity as well as genes for valuable production and quality traits. In most cases, crossing success can be predicted based on endosperm balance number (EBN), or effective ploidy, of the parents. Crossing barriers between most wild species and the cultivated potato are due to differences in EBN and can be easily overcome using ploidy manipulations and bridge crosses. The most common ploidy manipulations include haploid extraction to reduce EBN and 2n gamete production to increase EBN. Additional methods to produce fertile interspecific hybrids include mentor pollination, embryo rescue, hormone treatments, reciprocal crosses, selection of cross-compatible genotypes, and somatic fusion. Knowledge of crossing barriers and mechanisms to overcome them allows potato breeders access to the rich gene pool in the genus Solanum.