Identification of a pleiotropic QTL cluster for Fusarium head blight resistance,spikelet compactness,grain number per spike and thousand-grain weight in common wheat

Simultaneously improving Fusarium head blight(FHB)resistance and grain yield is challenging in wheat breeding.The correlations between spikelet compactness(SC),grain number per spike(GNS),thousandgrain weight(TGW)and FHB resistance remains unclear in common wheat.Identification of major quantitative trait loci(QTL)conferring FHB resistance and yield components,and development of breeder-friendly markers for the QTL are prerequisites for marker-assisted selection(MAS).Here,a recombinant inbred line(RIL)population derived from a cross between a resistant cultivar Yangmai 12(YM12)and a susceptible cultivar Yanzhan 1(YZ1)was used to map QTL for FHB resistance and yield components.A total of 22 QTL were identified;among these,six are likely to be new for corresponding traits.A QTL cluster(Qclu.yas-2D)for FHB type II resistance,SC,GNS,and TGW was detected on chromosome 2D.Breeder-friendly kompetitive allele-specific PCR(KASP)markers flanking the interval of Qclu.yas-2D were developed and validated in a diverse panel of 166 wheat cultivars and advanced lines.The YM12 alleles of Qclu.yas-2D significantly increased FHB resistance,SC,and GNS but decreased TGW in the validation population.The KASP markers developed for Qclu.yas-2D have great potential for breeding high-yielding wheat cultivars with enhanced FHB resistance.