Association Mapping of Iron Deficiency Chlorosis (IDC) In Glycine max

Iron deficiency chlorosis (IDC), an important yield-limiting factor for soybeans grown on calcareous soil, commonly present in the north-central regions of the United States. About 30% of yield losses in world and 24% in north-central regions due to IDC have been reported. A total of 42 and 88 loci were significant for IDC for 143 and 141 genotypes in the years 2005 and 2006 respectively. Nine IDC loci from seven genomic locations were significant in both populations. A total of 15 genes known to be involved in iron metabolism mapped in the vicinity (<500 kb) of significant markers in one or both populations. The significance of these nine common loci were further tested  with advanced soybean breeding lines in the years 2008, 2009 and 2010 with 265, 201, and 245 genotypes respectively. Additionally, Genotype by Sequencing (GBS) data was used to fine map the QTL for 143 and 141 genotypes of 2005 and 2006. Around 44,000 loci (MAF > 0.01) were used in each of the years separately in multiple regression models. Results from both the analysis will be presented.