Identification and Fine-Mapping of a Soybean Quantitative Trait Locus on Chromosome 5 Conferring Tolerance to Iron Deficiency Chlorosis

CORE IDEAS: 'Fiskeby III' harbors a combination of abiotic stress traits, including iron deficiency chlorosis (IDC) tolerance. An IDC quantitative trait locus on chromosome Gm05 was identified in genome-wide association studies and biparental populations. Fine-mapping resolved a 137-kb interval containing strong candidate genes. Iron deficiency chlorosis (IDC) is an important nutrient stress for soybean [Glycine max (L.) Merr.] grown in high-pH soils. Despite numerous agronomic attempts to alleviate IDC, genetic tolerance remains the most effective preventative measure against symptoms. In this study, two association mapping populations and a biparental mapping population were used for genetic mapping of IDC tolerance. Quantitative trait loci (QTLs) were identified on chromosomes Gm03, Gm05, and Gm06. Heterogenous inbred families were developed to fine-map the Gm05 QTL, which was uniquely supported in all three mapping populations. Fine-mapping resulted in a QTL with an interval size of 137 kb on the end of the short arm of Gm05, which produced up to a 1.5-point reduction in IDC severity on a 1 to 9 scale in near isogenic lines.