Novel allele derived from a Japanese wheat cultivar 'Asakazekomugi' for Fusarium head blight resistance without yield penalty and thousand grain weight reduction.

Fusarium head blight (FHB) is a severe disease that affects wheat production. 'Sumai 3' has been used as the FHB resistance genetic resource, and DNA markers linked to known quantitative trait loci (QTL) located on 3BS, 6BS, 5AS, or 2DL have been used to detect the 'Sumai 3'-derived allele. We first developed a near-isogenic line (NIL) of a Japanese cultivar, 'Kitahonami', with 'Sumai 3' FHB resistant allele at the 2DL-located QTL by recurrent backcrossing. Although the 'Sumai 3' allele improved resistance to FHB, it reduced yield and thousand-grain weight (TGW) to unacceptable levels. During the genotype of FHB-resistant QTL in FHB-resistant breeding lines K-1932 and K-1976, we found both lines have a novel allele at the 2DL-located QTL introduced from 'Asakaze'. We confirmed the co-segregation between the FHB resistance phenotype and the novel 'Asakaze'-derived allele in the three breeding populations. Furthermore, we developed two sets of NILs, with and without the 'Asakaze'-derived allele, and examined the FHB resistance, yield, and TGW. The results show that the 'Asakaze'-derived allele improved FHB resistance similar to the 'Sumai 3'-derived allele. Surprisingly, the 'Asakaze'-derived allele did not negatively affect yield and TGW, contrary to the 'Sumai 3'-derived allele. Wheat breeders can improve FHB resistance without reducing yield and TGW using the 'Asakaze'-derived QTL allele.