Quantitative trait loci for Fusarium head blight resistance in wheat cultivars Yangmai 158 and Zhengmai 9023

Fusarium head blight(FHB)is one of the prevalent fungal diseases of wheat worldwide.Exploring new FHB resistance quantitative trait loci(QTL)in adapted wheat cultivars is a critical step for breeding new FHB-resistant cultivars.In this study,we developed a population of 236 F5:7 recombinant inbred lines(RILs)using two popular Chinese wheat cultivars,Yangmai 158 and Zhengmai 9023,with moderate FHB resistance to identify the QTL for FHB type II resistance.This population was evaluated for percentage of symptomatic spikelets per spike(PSS)using single floret injection in repeated greenhouse experiments.Mean PSSs were 33.2%for Yangmai 158 and 30.3%for Zhengmai 9023.A genetic linkage map of 1002 single nucleotide polymorphisms(SNPs)generated by genotyping-by-sequencing(GBS)was constructed for the RIL population.Six QTL were identified for FHB resistance,and three of them were repeatable in the both experiments.Zhengmai 9023 contributed the resistance allele at one repeatable QTL,designated as Qfhb.7D,whereas Yangmai 158 contributed the resistance alleles at the other two repeatable QTL,Qfhb.3AL and Qfhb.2DS.The additional QTL,Qfhb.4AS was significant in the mean PSS,and Qfhb.2DL and Qfhb.7AS were significant in only one experiment.Replacement of each allele individually at the three repeatable QTL significantly changed PSSs.Qfhb.3AL,Qfhb.2DS,and Qfhb.7D explained 8.35%to 9.89%,5.13%to 7.43%,and 6.15%to 9.32%of the phenotypic variations,respectively.The three repeatable QTL contributed by the two parents were additive and stacking the resistance alleles from all the three repeatable QTL showed the highest level of resistance in the current RIL population.Ten SNPs in the QTL regions of Qfhb.3AL,Qfhb.2DS,and Qfhb.7D were converted into KBioscience competitive allele-specific PCR(KASP)assays.One KASP marker for Qfhb.3AL was validated in a panel of wheat cultivars from China.Some of these KASP markers could be useful for marker-assisted selection to stack these QTL.