Identification of Quantitative Disease Resistance Loci Toward Four Species in Soybean.

In this study, four recombinant inbred line (RIL) soybean populations were screened for their response to infection by , , , and The parents, PI 424237A, PI 424237B, PI 408097, and PI 408029, had higher levels of resistance to these species in a preliminary screening and were crossed with "Williams," a susceptible cultivar. A modified seed rot assay was used to evaluate RIL populations for their response to specific species selected for a particular population based on preliminary screenings. Over 2500 single-nucleotide polymorphism (SNP) markers were used to construct chromosomal maps to identify regions associated with resistance to species. Several minor and large effect quantitative disease resistance loci (QDRL) were identified including one large effect QDRL on chromosome 8 in the population of PI 408097 × Williams. It was identified by two different disease reaction traits in , , and . Another large effect QDRL was identified on chromosome 6 in the population of PI 408029 × Williams, and conferred resistance to and . These large effect QDRL will contribute toward the development of improved soybean cultivars with higher levels of resistance to these common soil-borne pathogens.