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Development of a molecular marker to detect the Potato virus Y resistance gene Rychc in diploid populations of potato
A. C. FULLADOLSA (1), S. H. Jansky (2), D. A. Halterman (3), A. O. Charkowski (1). (1) University of Wisconsin-Madison, Madison, WI, U.S.A.; (2) University of Wisconsin-Madison/USDA-ARS, Madison, WI, U.S.A.; (3) USDA-ARS, Madison, WI, U.S.A.

The wild relatives of cultivated potato (<i>Solanum tuberosum</i> L.) are a valuable reservoir of useful traits, including plant resistance to biotic and abiotic stresses. The major disease problem in seed potato production and certification is <i>Potato virus Y</i> (PVY), a rapidly evolving and widespread aphid-transmitted potyvirus, for which resistance has been identified but narrowly used in breeding programs in North America. The gene <i>Rychc</i> confers extreme resistance to PVY and was found in accessions of the diploid species <i>S. chacoense</i>. To use this source of resistance in marker-assisted breeding, we developed diploid populations of potato segregating for the resistance phenotype by crossing a <i>S. chacoense</i> plant, heterozygous for <i>Rychc</i>, with a diploid, susceptible <i>S. berthaultii</i> plant. 175 F1 progeny were genotyped using the SolCAP 8303 SNP Infinium array and five single nucleotide polymorphisms (SNPs) on chromosome IX correlated with the resistance phenotype. Additionally, we sequenced the genome of a <i>S. chacoense</i> plant, homozygous for <i>Rychc</i>, from which a useful breeding clone and several populations have been developed, and are searching for polymorphisms to develop a tightly linked molecular marker by using published mapping data and the identified SNPs. The improved tools to use <i>Rychc</i> as a source of resistance will equip potato breeders for effective selection of resistant potato varieties that will reduce the incidence of PVY.

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