Development of the nested association mapping population HEB-25. HEB-25 is made of 25 families with 1,420 NAM lines in BC1S3. Per NAM line, one chromosome pair is illustrated as a double bar. Black and colored bars represent chromosome segments originating from Barke and the exotic donor accessions, respectively. At each SNP locus, HEB-25 is expected to segregate into 71.875% homozygous Barke, 6.25% heterozygous and 21.875% homozygous donor genotypes.