Genome-wide Selection Of The Markers Associated With QTL For FHB Resistance In Wheat

Fusarium Head Blight(FHB)is an epidemic disease in wheat.The resistance of FHB is quantitatively inherited and controlled by a few major QTLs(or genes)and several modifying QTL(or genes).The identified QTLs related to the FHB resistance were distributed on all the 21 chromosomes of wheat.The major QTLs were distributed on chromosomes 2A,3B,4A,4D,5A,5B,6A,6B and 7A,and modifying QTLs were also found on other chromosomes.At present,molecular breeding of FHB-resistant wheat is difficult due to the complex wheat genome,incomplete wheat referecne sequencing and complicated FHB phenotyping.QTL under different genetic background may associate different molecular markers.Locus-specific(single copy)molecular markers should be more useful to localize the target genes and analyze the QTL effect.We obtained 386 SSR markers which were previously reported in the whole wheat genome in recent years.These markers were subjected to e-PCR to record single-copy markers.Single-copy or site-specific markers can be developed within target QTL regions.We evaluated FHB severities of 156 wheat accessions including landraces and commercial varieties in three field and three greenhouse growing seasons,and genotyped this panel with 386 genome-wide informative simple sequence repeats(SSR)markers.Among them,15 markers showed reproducible marker-trait associations(p<0.05)in at least two experiments using a mixed model and these markers involved with FHB resistance QTL on chromosomes 2A,2D,3 A,4A,4D,5A,5B,6A,6D and 7A,and 9 of them are single-copy markers and 6 multiple-copy markers.Chinese wheat landraces and Japanese accessions have more favorable alleles at the majority of the reproducible marker loci.In future breeding work,it is recommended to focus on use of single-copy marker.FHB resistance levels of varieties can be greatly improved by introduction of these favorable alleles and removal of unfavorable alleles simultaneously at these QTL-linked marker loci.