Association mapping for Fusarium head blight resistance in European soft winter wheat

Resistance to Fusarium head blight (FHB) is of great importance in wheat breeding programs in the northern hemisphere. In Europe, breeders prefer adapted germplasm as resistance donor because of high grain yield and quality demands. Our objective was to identify chromosomal regions affecting FHB resistance among 455 European soft winter wheat (Triticum aestivum L.) lines using a genome-wide association mapping approach and to analyze the importance of epistatic interactions. All entries were evaluated for FHB resistance by inoculation in two environments and several ratings. Wheat was genotyped by 115 simple sequence repeat markers randomly distributed across the genome and two allele-specific markers for Rht-B1 and Rht-D1 genes. The genome-wide scan revealed nine significant (P < 0.05) marker-phenotype associations on seven chromosomes including dwarfing gene Rht-D1. Using a Bonferroni-Holm correction, three significant associations remained on chromosomes 1B, 1D, and 2D. The proportion of the genotypic variance explained simultaneously by individual markers was 36% and increased to 50% when two digenic epistatic interactions were considered, one of them associated with Rht-B1. In conclusion, new genomic regions on chromosomes 1D and 3A could be found for FHB resistance in European wheat and the effect of epistatic interactions was substantial.