Crown rot caused by Phytophthora cactorum is one of several serious, widespread diseases that cause problems in strawberry (Fragaria × ananassa Duch.) cultivation. In this study, we aimed to identify a strawberry resistant to P. cactorum through bioassay. A total of 104 wild and cultivated strawberry accessions, including ‘Sulhyang’ and ‘Akihime’, were inoculated with an isolate of P. cactorum, ‘PC151111’. A zoospore suspension was used with a density of approximately 10⁶ zoospores·mL^-1. Three strawberry seedlings were tested three times independently. The disease index was scored on a scale from 0–4 through symptom observation while the inoculated plants were incubated at 25±3°C under 16 h/8 h (light/dark) conditions for three weeks. The results showed that the mean disease index varied from 0.78–3.78, and the ‘Pechika’ and ‘Kaorino’ cultivars were highly resistant to P. cactorum, with mean disease indexes of 0.78 and 0.89, respectively. These cultivars will be useful resources in breeding strawberries resistant to crown rot.

An allo-octoploid strawberry (Fragaria × ananassa Duch.) is one of the most important vegetable crops in Korea. However, there were few genomic researches of strawberry due to polyploidy and complexity of its genome. In this study, we aimed to construct a genetic linkage map of strawberry using single nucleotide polymorphism (SNP) markers that were developed through a next-generation sequencing (NGS) analysis. Two strawberry varieties, ‘Sulhyang’ and ‘Senga-sengana’, were used as a maternal and a paternal parent, respectively, and their F1 generation consisting of 94 individuals was used for construction of a genetic linkage map. A total of 19.0 Gbp (‘Sulhyang’) and 21.8 Gbp (‘Senga-sengana’) of genomic sequences were obtained through NGS analysis. Subsequently, approximately 87,000 SNPs were identified and 1,154 primer sets for high-resolution melting (HRM) analysis were designed through bioinformatic analysis. In result, a total of 224 polymorphic HRM markers were developed and 205 markers were mapped on the genetic linkage map of strawberry, which total length was 800.8 cM and the number of linkage groups were 30. This SNP-based genetic linkage map and the 224 SNP markers will be very helpful for the genomic and genetic researches of allo-octoploid strawberry.