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Oral: Host Plant Resistance


Development of molecular markers tightly linked to Potato virus Y resistance gene Rychc in a diploid potato population
A. FULLADOLSA (1), S. Jansky (2), D. Halterman (3), A. Charkowski (1) (1) University of Wisconsin-Madison, U.S.A.; (2) USDA-ARS, University of Wisconsin-Madison, U.S.A.; (3) USDA-ARS, U.S.A.

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In the last 15 years, Potato virus Y (PVY) has been the main plant pathogen limiting seed potato certification in North America. The emergence of necrotic and recombinant PVY strains that cause mild foliar symptoms has resulted in increased PVY incidence. The use of cultivars that do not express foliar symptoms has also contributed to the problem. Several PVY resistance genes have been identified in wild relatives of potato, but few have been introduced into North American cultivars. We identified a diploid Solanum chacoense clone (CHC 39-7) in accession 275138, carrying PVY resistance gene Rychc, and used it in a cross with the susceptible, diploid Solanum tuberosum US-W4. A heterozygous resistant F1 progeny, XD3, was self-pollinated and the resulting population was phenotyped and used to develop molecular markers for genotyping. The phenotypic and genotypic results showed skewed segregation ratios, suggesting that a lethal factor is associated with susceptibility in the population. In addition, the development of markers that are more tightly linked to resistance in CHC 39-7 has aided in fine mapping Rychc and elucidating gene organization on chromosome IX. Furthermore, XD3 was crossed with a high yielding, adapted diploid S. tuberosum-S. chacoense hybrid and several progeny were selected for their high yields and good tuber type. These breeding clones and molecular markers provide new tools for breeders to introduce PVY resistance into North American cultivars.