Nested Association Mapping Population Resource for Studying the Genetic Basis of Trait Variation in Wheat

Nested association mapping (NAM) combines the advantages of both linkage and association mapping in order to dissect complex traits in a single unified mapping population. Here, we report on the characterization of the spring wheat NAM population developed as a community resource to aid in identification of important agricultural trait loci to be integrated into international breeding efforts to improve wheat. This NAM population was derived from 32 genetically and geographically diverse founders crossed in a common parent design, utilizing the well-adapted cultivar Berkut. The population consists of 2,400 individuals, which are comprised of 32 separate mapping populations of 75 progenies each. Genetic maps for each population were constructed with nearly 50,000 markers per map. More than 235,000 SNP sites were genotyped across the entire population providing high-density marker data for GWAS. Utilizing the existing reference genome of wheat, the locations of more than 105,000 markers were inferred. Joint linkage mapping of QTL for recombination rate and heading date revealed 42 and 25 QTL, respectively, encompassing several candidate genes known to affect both traits as well as many novel loci. Details of population construction, LD patterns, and trait mapping will be presented, and examples of how this resource can assist in studying the genetics of complex traits in wheat.