Mapping Iron Deficiency Chlorosis Resistance in Soybean
Iron Deficiency Chlorosis (IDC) is a nutritional stress exhibited by soybean plants that do not uptake enough soluble ferrous iron (Fe2+). Symptoms of this stress appear as interveinal chlorosis of leaves and stunting. IDC causes yield loss and is a prevalent issue in calcareous and alkaline soil conditions which makes iron unavailable for plant uptake. There is some genetic variation in plants' response to IDC. Some genotypes are resistant to IDC, and efforts are being made to characterize and map this resistance. A bi-parental near-isogenic line (NIL) mapping population was developed from crossing a susceptible and resistant soybean variety. Resistance has been mapped to an 137kb region on chromosome 5, spanning 17 candidate genes. To narrow down the candidate gene(s), four Kompetitive allele specific PCR (KASP) markers were designed to genotype new recombinants. New recombinants were screened for their IDC phenotype in the greenhouse, IDC scores were collected and were associated with the genotypic data to further fine map resistance. Markers designed in the fine-mapped region can also be utilized for selection to introgress the IDC resistance trait into new soybean cultivars.