Genetic improvement of FHB and DON resistance by combining the <i>Fhb1</i> gene with additional resistance QTL in winter wheat population

Fusarium head blight (FHB) of wheat (Triticum aestivum L.), caused by Fusarium graminearum, is a major wheat disease that causes significant yield and quality loss. The use of resistant cultivars is an effective tool for managing FHB; however, FHB resistance is a complex trait. The objectives of this study were to identify quantitative trait locus (QTL) associated with FHB resistance in the Triumph/25R51 doubled haploid (DH) population. The DH population was evaluated for FHB resistance across six field environments and an additional greenhouse study. The population was genotyped using single nucleotide polymorphism (SNP) markers, and a linkage map was constructed with a total length of 3018 cM across 26 linkage groups. QTL analysis identified multiple FHB resistance loci, including on chromosomes 2B, 2D, 3B, 5A, and 7D. The QTL on chromosome 3BS was the most important QTL for all FHB-related traits and explained 27%, 25%, 14%, and 13% of phenotypic variation for FHB severity, FHB index, Fusarium-damaged kernels (FDK) level, and deoxynivalenol (DON) content, respectively. Marker validation and haplotype analysis confirmed this QTL was due to Fhb1, with the resistance allele from 25R51 parent. FHB resistance QTL on 2D was collocated with both plant height and days to anthesis QTL at the Ppd-D1 locus. The population segregated for Rht-B1 locus, coincided with plant height QTL on 4B, but was not linked with FHB traits. This study showed that combining Fhb1 with additional resistance alleles enhances resistance to FHB, and the significant QTLs identified will be further useful for introgression in winter wheat breeding.