Identification and Molecular Mapping of Rps11, a Novel Resistance Gene Conferring Resistance to Phytophthora Sojae in Soybean.

Phytophthora Root and Stem Rot (PRSR), caused by the soil-borne pathogen Phytophthora sojae is a devastating disease of soybean [Glycine max (L.) Merr.] throughout the world. Deploying resistant soybean cultivars is the most effective and environmentally friendly approach to managing the disease. The soybean landrace, designated USDA 046, was found to carry excellent resistance to all P. sojae isolates examined, some of which were capable of overcoming the major Rps genes, such as Rps-1k, Rps-1c, and Rps-3a, predominantly used for soybean protection in the last few decades. A mapping population consisting of 58 F₂ individuals and 209 F_2:3 families derived from a cross between USDA 046 and the susceptible cultivar ‘Williams’ was used to characterize the inheritance pattern of the resistance to P. sojae (Rps) in USDA 046. It was found that the resistance was conferred by a single Rps gene, designated Rps11, which was initially defined to an ~5Mb genomic region at the beginning of chromosome 7 by bulk segregant analysis (BSA) with a nucleotide polymorphism (SNP) chip comprised of 7,039 SNP markers. Subsequently, simple sequence repeat (SSR) markers in the defined region were used to genotype the F_2:3 mapping population to map Rps11 to a 225.3kb genomic region flanked by SSR markers BARCSOYSSR_07_0286 and BARCSOYSSR_07_300, according to the soybean reference genome sequence. Particularly, a SSR marker (ie., BARCSOYSSR_07_0295) was found to co-segregate with Rps11 in the mapping population and can be effectively used for marker-assisted selection of this gene for development of resistant soybean cultivars.