Mapping of the RPc-1 locus for Phytophthora cactorum resistance in Fragaria vesca

The woodland strawberry (Fragaria vesca) has become the model plant for the economically important, but genetically complex, octoploid F. x ananassa. Crown rot caused by the oomycete Phytophthora cactorum is a major problem for the strawberry industry and the identification and incorporation of efficient resistance genes into superior cultivars are important for breeding. In the present study, two experimental populations were used in inoculation experiments under controlled greenhouse condition. Studies of a sparse diallel cross between resistant and susceptible F. vesca genotypes concluded that resistance to crown rot is inherited as a dominant trait under nuclear control. Subsequently, an F-2 population derived from the grandparents Bukammen (resistant) and Haugastol 3 (susceptible) collected in Norway, were phenotyped in infection experiments and genotyped using genotyping-by-sequencing. A 416.2-cM linkage map was constructed, and a single major gene locus was identified on linkage group 6 that we attributed to resistance to Phytopthora infection. We propose to name the resistance locus RPc-1 (Resistance to Phytophthora cactorum 1). Gene prediction of the 3.3 Mb QTL recovered 801 genes of which 69 had a potential role in plant disease resistance.