ARS | Publication request: Potato Germplasm Enhancement

Submitted to: Plant Breeding Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: July 31, 2009
Publication Date: August 13, 2009
Citation: Jansky, S.H. 2009. Potato Germplasm Enhancement [abstract]. Plant Breeding Conference Proceedings. p. 10.

Technical Abstract: The potato (Solanum tuberosum L.) is the leading vegetable crop produced in the United States. It is a high value crop that requires substantial inputs to maintain yield and quality. Potato breeding efforts focus on disease resistance, fresh market and processing quality, and storability. While genetic variability for these traits is low among commercial cultivars, wild relatives of potato provide an extremely diverse and readily accessible resource for crop improvement. Wild Solanum species are found in 16 countries, from the southwestern United States to central Chile. They grow from sea level to 4,300 m and are found in a diverse array of environments, including the cold high grasslands of the Andes, hot semi-desert and seasonally dry habitats, humid subtropical to temperate mountain rain forests, cultivated fields, and even as epiphytes in trees. These wild species contain genes encoding numerous traits not found in cultivars and represent an especially rich source of disease resistance and tuber quality genes. The goals of this germplasm enhancement project are to: 1) screen wild relatives of potato for traits of interest to potato breeders, 2) determine the genetic basis of those traits, and 3) introgress the traits into the cultivated potato so they can be incorporated into potato breeding programs. Our program has screened wild Solanum species for resistance to white mold (Sclerotinia sclerotiorum), Verticillium wilt (Verticillium dahliae), early blight (Alternaria solani), common scab (Streptomyces scabies), soft rot (Pectobacterium carotovorum), potato virus Y, and Colorado potato beetle (Leptinotarsa decemlineata). In addition, we have evaluated them for processing quality (resistance to cold sweetening) and nutritional quality (amylose content in starch) traits. In all cases, we have found valuable diversity in wild relatives. Most wild relatives are diploid, so we cross them to diploid derivatives (haploids) of tetraploid potato cultivars. We then evaluate the haploid-wild species hybrids for the traits contributed by the wild species, as well as adaptation, fertility, and meiotic mutants that produce 2n gametes (gametes with an unreduced chromosome number). Selected hybrids are crossed to tetraploids and, due to a triploid block in potato, only tetraploid offspring are produced. Using this strategy, we have created haploid-wild species hybrids with attractive tubers, adaptation to field conditions, male and female fertility, 2n pollen and 2n egg production, and resistance to disease (Verticillium wilt, early blight, soft rot, and common scab) and cold sweetening. Efforts are underway to introgress additional traits through the production of haploid-wild species hybrids. Crosses between selected hybrids and tetraploid cultivars have produced tetraploid clones that are being used as parents in U.S. potato breeding programs. The recently released cultivars Kalkaska (from Michigan State University) and White Pearl (from the University of Wisconsin) have a haploid-wild species hybrid from this program in their pedigrees.