Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/12/2015
Publication Date: 8/17/2015
Citation: Dahleen, L.S., Bregitzer, P.P., Mornhinweg, D.W., Esvelt Klos, K.L. 2015. Genetic diversity for Russian wheat aphid resistance as determined by genome-wide association mapping and inheritance in progeny. Crop Science. 55(5):1925-1933. Interpretive Summary: Russian wheat aphids (RWA) attack both barley and wheat, reducing yield and quality. A set of resistant barley lines has been identified and was used along with susceptible lines and a barley genetic marker map to locate genes associated with RWA resistance. Important loci on two chromosomes were confirmed along with additional loci. We were able to identify specific loci in resistant lines which will help in developing resistant lines with multiple diverse genes for resistance to RWA. In addition, genetic variability for resistance was identified among resistant lines. This information will help breeders to select parents of breeding populations that have different genes for resistance as a way to combat the potential for RWA to overcome any single source of resistance.
Technical Abstract: Russian wheat aphid (RWA) is an increasing problem on barley throughout the world. Genetic resistance has been identified and used to create barley germplasm and cultivars adapted to the US. Several mapping studies have been conducted to identify loci associated with resistance, but questions remain, particularly regarding the extent of genetic diversity for RWA among resistance sources and improved lines and cultivars. Association analysis of resistant and moderately resistant unadapted accessions held in the USDA-ARS National Small Grains Germplasm Collection, adapted germplasm lines derived from these accessions and susceptible elite cultivars was conducted using 4509 SNPs to identify markers linked to resistance. Resistance was associated with loci on chromosomes 1H, 2H, 3H, 5H and 7H at p-values <0.0001, and the major 1H and 3H loci identified in previous tests were confirmed. However, the genetics of RWA resistance was shown to be complex, and it is likely that loci involved in resistance in some lines were not identified. Nevertheless, this analysis described diversity among resistant lines, showed that most of the released RWA-resistant cultivars appear to have similar genotypes for loci associated with resistance, and identified resistant lines that appear genetically dissimilar to the released cultivars. This information can guide parental selection for future breeding efforts designed to capture and deploy greater diversity for RWA resistance among new barley cultivars.