Association Mapping Of Fusarium Head Blight Resistance In The Derivatives Of Founder Parent Funo In Wheat (Triticumaestivum L.)

Fusarium head blight (FHB) is a major wheat disease worldwide. It seviously affects the yield and quality. Exploring elite alleles and developing resistant cultivars are the most economical measures in controlling the disease. During the last decades, a number of quantitative trait loci (QTLs) conferring to FHB resistance were mapped by linkage analysis with molecular markers. In this study FHB severity of Funo and its 264 derivatives was evaluated by using single floret inoculation of the conidia at the flowering stage in years of 2008,2009,2010,2013, and 2014. Genetic diversity and population structure were studied by using 57 and 36 pairs of primers, respectively. Marker-trait association analysis was conducted to explore the resistant loci and elite alleles by General Linear Model with software TASSEL3.0. At the same time, the distribution of elite alleles was analyzed in cultivars with different resistant levels. The main results were as the followings:(1) According to phenotyping results of single floret inoculation of 5 years,13 accessions with good and stable FHB resistance have been screened out. Among them eight entries such as Funong 60212, Funong 50001, Suzhou 8332, Wu7815-5-2-1 and Jian 37 showed better FHB resistance than Sumai 3 in three or four years. Based on the characterization data of agronomic traits at five sites in 2008, Suzhou 8332 was evaluated with better and more comprehensive agronomic traits in addition of its FHB resistance.(2) A total of 264 accessions from Funo derivatives were evaluated for genetic diversity based on 57 molecular markers, and 228 allelic variations were obtained. The average PIC was 0.4279.264 wheat accessions were clustered into 7 main groups according to population structure analysis.(3) Marker-trait association was analyzed by using General Linear Model (GLM) in software TASSEL3.0. Nineteen markers on chromosome 2B,2D,3A,3B,4B,5A and 6B were detected association with FHB scores significantly. On chromosome 3B, six markers between Xgwm493 and Xgwm533 were found to be associated with FHB resistance. Markers Xbarc20, Xwmc48, and Xgwm375 were detected on chromosome 4B, with Xwmc48 was 0.5cM from Fhb4. Markers Xbarcll7, Xbarc100, Xbarc56 and Xgwm415 on the chromosome 5A were associated with FHB resistance. Markers Xwmc756, Xwmc104 and Xgwm508 on chromosome 6B were also related to FHB resistance. It was validated that there were FHB resistance QTLs Fhb1, Fhb2, Fhb4 and Fhb5 on chromosomes 3B,4B,5A and 6B, respectively.(4) Analysis of allelic variation of 19 markers associated with FHB resistance showed that elite alleles could reduce the number of diseased spikelets from 0.01 to 1.28. Xbarc102 on the chromosome 3B contributed the largest average negative allele effect (-1.28) among the associated loci. It was also found that the founder parent Funo contributed elite resistant alleles, such as Xgwm155-A135, Xbarcl47-A112 and XSTS3B-142-A163.(5) Analysis of elite allele frequency in different clusters and resistant accessions showed that the more elite alleles gather togather, the better FHB resistance. Analysis of elite allele frequency showed that identification of several elite alleles on FHB QTL regions could improve both accurancy and efficiency in the molecular marker-assisted selection.