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Poster: Biology & Disease Mgmt: Genetics of Resistance


Marker development and fine-mapping for the Phytophthora crown rot resistance locus, Pc1, in strawberry
Y. NOH (1), J. Mangandi (1), S. Verma (1), V. Whitaker (1), S. Isobe (2), J. Cha (3), S. Lee (1) (1) University of Florida, U.S.A.; (2) Kazusa DNA Research Institute, Japan; (3) Chungbuk National University, South Korea

Phytophthora crown rot (PhCR) caused mainly by Phytophthora cactorum is a destructive disease and can cause economic losses to strawberry growers in US. In our previous study, a major QTL for PhCR resistance, Pc1, located on the linkage group 7D, was discovered in complex and multi-family populations using the whole-genome SNP genotyping (IStraw90 Axiom® SNP Array) and pedigree-based marker-trait association analysis (FlexQTL™). For the fine-mapping of Pc1, a total of 25 SNP-based high resolution melting (HRM) markers and 63 simple sequence repeat (SSR) markers were selected in the Pc1 region. All markers were tested with five strawberry varieties and 20 advanced breeding selections that inherited putative functional allele combinations of Pc1pc1 (heterozygous resistant) or pc1pc1 (susceptible). Total five markers were found to co-segregate with the resistance locus, Pc1. In addition, we developed three populations (n=339) by crossing the resistance parent (Pc1pc1), ‘12.55-220’, with three susceptible accessions (pc1pc1), ‘12.82-44’, ‘11.116-56’, and ’11.98-41’. All populations were planted to the field (Wimauma, FL) and evaluated for the PhCR disease resistance. The HRM and SSR markers linked to the Pc1 resistance locus were tested for the PhCR fine-mapping population, and the linkage analysis was conducted. The precise location of Pc1 and DNA markers developed in this study will be utilized for the PhCR resistance breeding program.