Introgression of Alleles from Wild Barley to Enhance Grain Yield: Breeding Design and Selection Methodology

Wild ancestors to crop species have been used as sources of novel alleles for qualitative traits such as disease resistance; however, there has been limited success for quantitative traits like yield. Introgressing alleles from genetically diverse sources often comes at the cost of perturbing favorable allele complexes. Backcross breeding and marker assisted selection have been used historically to introgress small exogenous genetic regions into otherwise elite backgrounds. More recently genomic selection (GS) is being used to improve quantitative traits using genome-wide markers to predict phenotypic performance. We have initiated a project to use GS to introgress alleles from wild barley into an elite malting background to improve yield. We are using the wild-barley introgression population (WBIP), which was developed by backcrossing 25 diverse wild barley parents into the elite, high-yielding 6-row malting barley Rasmusson, to generate 25 BC₂F₅ bi-parental families. The 796 lines from the WBIP have been genotyped with 384 SNP markers and evaluated for yield in four environments. Using the top 50 yielding lines, descending from 20 wild parents, three methods of parental selection will be employed: 1) randomly intermate lines among families, 2) intermate lines based on marker-calculated genetic distances, 3) intermate lines based on idealized progeny yield values estimated from marker effects. A round of GS will be applied to the resulting segregating populations before further yield testing. Ultimately, we will determine the value of wild barley as a source of useful yield genes and the utility of GS as an introgression method.