D-Genome Introgressions Yield Phenotypic Variation in Wheat.

New sources of genetic diversity are required to combat slowing yield gains in wheat breeding programs worldwide. However, many breeding programs continue to practice best by best crosses as introgressing exotic alleles from unadapted germplasm is time consuming and labor intensive. Advanced backcross-QTL mapping is a useful strategy to simultaneously perform QTL analysis with variety development, designed specifically for the discovery and transfer of wild alleles to elite germplasm. Aegilops tauschii, the D genome progenitor of Triticum aestivum, has been used extensively as a source of genetic variation through the creation of synthetic hexaploids. This method produces segregating alleles in all three wheat genomes, making D genome specific contributions difficult to isolate. In order to identify D genome specific contributions to wheat yield in an elite background, we analyze an advanced backcrossed nested association mapping population derived from direct hybridization of 7 A. tauschii parents and the recurrent T. aestivum parent ‘KS05HW14’. A total of 421 BC2F7 lines were characterized using genotyping-by-sequencing and phenotyped in multiple environments (Ashland Bottoms, KS 2015 and 2016; Hays, KS 2015 and 2016; Richville, MI 2015 and 2016; Champaign, IL 2016; Marianna, AK 2016). Quantitative variation for yield was seen with 10% of all lines yielding higher than the recurrent parent, suggesting that D genome specific alleles are contributing significantly to yield. Stable and highly significant yield QTL have been identified across environments on chromosomes 2D and 6D in addition to numerous environment specific QTL. These results provide unique insight on D genome contributions to yield, and provide a model approach to further unlock genomic potential contained within it.