Association Mapping of Fusarium Head Blight Resistance in U.S.Hard Winter Wheat.

Fusarium head blight (FHB) is one of the most destructive diseases of wheat worldwide. FHB epidemics can cause severe losses in both grain yield and quality of wheat. One of the most effective approaches to reduce the disease losses is to grow FHB resistant cultivars. To characterize resistance quantitative trait loci (QTLs) in US hard winter wheat, association mapping was conducted using 177 cultivars and breeding lines from the Great Plains. All accessions were evaluated for FHB severity (type II), DON content (type III) and Fusarium damaged kernel (FDK, type IV) using single-point inoculation in greenhouse. Total 146 SSR and 9000 genome-wide SNP markers were genotyped. Population structure analysis divided the population into two subgroups, and Q model was the best for association mapping. In the greenhouse experiments, 6 SSR and 17 SNP markers were associated with type II resistance mainly located in the chromosome of 3B, 4B, 6A, 6B, 7A, etc.; 5 SSR and 23 SNP markers were significantly associated with type IV resistance (resistance to kernel damage), mainly located in the chromosome of 1D, 2B, 3B, 4B, 6A, 7A, etc.; and 12 significant markers (4 SSR and 8 SNP) were associated with type II and FDK resistance. Marker Xumn10 was a significant STS marker associated with all three types of resistance. Several QTL and significant markers associated with different types of resistance identified in this study should be useful for improvement of FHB resistance in hard winter wheat.