Molecular marker Satt481 is associated with iron-deficiency chlorosis resistance in a soybean breeding population

Soybean [Glycine max. (L.) Merr.] breeders have improved resistance to iron-deficiency chlorosis (IDC) using conventional breeding approaches; however, many IDC-resistant cultivars have lower yields compared to IDC-susceptible cultivars. The importance of environment on IDC-resistance expression hinders progress in breeding for resistance. An environment-independent selection strategy, such as marker-assisted selection (MAS), may increase breeding efficiency. Our objective was to determine whether simple sequence repeat (SSR) markers located in previously reported quantitative trait loci (QTL) for IDC resistance would be associated with IDC resistance in a breeding population. One-hundred and eight SSR markers genetically linked to eight QTLs on eight molecular linkage groups (MLGs) previously identified for IDC were tested in a breeding population evaluated for IDC resistance on calcareous soils in Iowa. The breeding population was developed from a cross between Pioneer 9254 and A97-770012. The F-2 lines were genotyped with markers and the F-2-derived lines (F-2.4 and F-2:5) were evaluated for IDC resistance. Three markers were associated with IDC resistance: Satt211, Satt481, and Sat_104. However, of the three markers, only Satt481 was associated to IDC resistance across environments. Although Satt481 accounted for only 12% of the total phenotypic variation, molecular analysis of the eleven-most resistant lines in the population indicated that 73% of the lines were homozygous for the resistant allele at the Satt481 locus. Our results indicated that Satt481 may be useful to improve IDC resistance in this soybean population and that additional QTLs conferring resistance to IDC might exist in soybean.