Genome-Wide Linkage And Association Mapping Of Resistance Genes To Fusarium Head Blight And Development Of Molecular Markers In Wheat

Fusarium head blight(FHB)is one of most important wheat diseases worldwide,greatly reducing grain yield and end-use quality.Infected grains contain Fusarium toxins making grain unsuitable for food and feed.Genetic improvement of host resistance remains the best approach for controlling this disease,which requires genetic studies of FHB resistance in wheat.To decipher the genetic architecture of FHB resistance in Chinese germplasm,a Wheat Association Panel for Scab Research(WAPS)consisting of 240 Chinese wheat cultivars and elite lines was genotyped using the wheat 90 K single nucleotide polymorphism(SNP)array.The FHB response was evaluated in field nurseries at Wuhan in Hubei province over four consecutive years from 2014 to 2017.To map genetic loci underlying FHB resistance in Chinese modern wheat cultivars,a doubled haploid(DH)population comprising 174 lines was developed from a cross between two widely grown cultivars,Yangmai 16 and Zhongmai 895.The DH population and parents were evaluated in field nurseries under five environments.The DH lines were genotyped with the wheat 660 K SNP array.Five quantitative trait loci(QTL)were consistently identified on chromosome arms 1AS,2DL,5AS,5AL,and 7DS in the WAPS population,explaining 5.6%,10.3%,5.7%,5.4%,and 5.6% of the phenotypic variances,respectively.The QTL on 5AS,5AL,and 7DS are probably novel.Seven stable QTL were detected in the Yangmai 16/Zhongmai 895 population.QFhb.caas-4AS,QFhb.caas-5AL,and QFhb.caas-6BS are likely to be new.Dwarfing loci Rht-B1 and Rht-D1 were coincident with QFhb.caas-4BS and QFhb.caas-4DS,respectively,and were also responsible for anther extrusion(AE).Five molecular markers for FHB resistance,FHB-1AS-STS,FHB-5AS-KASP,FHB-5AL-CAPS,In Del_AX-89588684 and KASP_AX-110917097,were developed.Haplotype analysis of PFT(pore-forming toxin-like),HC(HCBT-like defense response protein)and His(histidine-rich calcium-binding protein)genes in Fhb1 region in 229 wheat cultivars or elite lines indicated that His-I was the resistance haplotype based on phenotypic data.Both pedigree and marker(or sequence)information revealed that Fhb1 in Chinese wheat cultivars was mainly derived from Ningmai 9.Twenty-three FHB-resistant wheat cultivars or elite lines with good agronomic traits were selected from the WAPS population and five resistant DH lines with high yield potential were selected from the Yangmai 16/Zhongmai 895 population.The FHB-resistance QTL and germplasms along with molecular markers will facilitate the improvement of FHB resistance by stacking FHB resistance QTL.