Identification of Aphid Resistance Genes by Modified Nested Association Mapping in Soybean PI 567598B.

Abstract The soybean aphid (Aphis glycines) has become an important pest of soybean [Glycine max (L.) Merr.] in the U.S. since 2000. PI 567598B was found to possess antibiosis resistance to the soybean aphid. In this study, modified nested association mapping (MNAM) was used to locate resistance genes on the integrated soybean linkage map. PI 567598B was crossed with 10 different susceptible cultivars to construct 10 recombinant inbred lines (RILs) populations, where only resistant progenies were selected in individual populations for MNAM. We expect that the genomic regions containing the aphid resistant genes from PI567598B present in the resistant progenies. Chi-square test was used to discover the significant association between aphid resistance and single sequence repeat (SSR) markers. False discovery rate and Bonferroni correction were applied to control the type I error rate. Genomic regions on linkage groups F, J were found associated with soybean aphid resistance in MNAM.  Linkage analysis in a F2 population derived from E06902 (elite advance breeding line developed from PI567598B) was used to confirm the MNAM results. These two QTL mapping approaches both showed the association of genomic regions on linkage group F and J with aphid resistance. No association of the genomic regions on linkage groups G and M with aphid resistance was detected in linkage analysis and MNAM, respectively. Recombination among multiple alleles and population structure were discussed as possible reasons for these findings. Ultimately, we showed that MNAM was more efficient for discovery of aphid resistance genes in soybean breeding and germplasm improvement.