Bread wheat (Triticum aestivum) is one of the dominant grain crops across the world. As a mainstay of diets across the world, there is a constant pressure by the breeders and geneticists to identify yield promoting loci. In previous work, significant SNP associations were found on the 2D chromosome (approximately at 23.5 Mb and 25.2 Mb) for yield variation in a genome-wide association study (GWAS) of the D-genome Nested Association Mapping population (DNAM), an advanced-backcross nested association mapping population of five Ae. tauschii lines into an elite bread wheat background. To identify the signal source more precisely, fine-mapping tools were created in this work. Seven Kompetitive Allele Specific PCR (KASP) primer sets were designed for SNP markers between 22 Mb and 30 Mb, six of which displayed codominant behavior and one dominant. The KASP primer sets were identified the U6718 BC1F1 subpopulation within the DNAM as segregating for bread wheat and Ae. tauschii alleles between 22 Mb and 30 Mb on 2D chromosome. Linkage maps were created for the seven D-genome chromosomes for the U6718 subpopulation. QTL analysis defined the QTL as being between 21.3 cM to 28.3 cM on the 2D linkage map and 23.3 Mb to 30.3 Mb on the physical map. Using the defined 2DS QTL and the KASP primer sets, a fine-mapping population was created consisting of five heterozygous inbred families fixed 16 unique recombination events across the 2DS QTL. These developed tools will prove instrumental tools towards refining the understanding of causal loci of this yield QTL.
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