| Fusarium head blight (FHB) is a destructive disease of wheat worldwide, and is particularly epidemic in regions with a warm and humid climate. This disease can greatly decrease the yield and quality of wheat. In a previous study, a major quantitative trait locus (QTL) Fhb5 against Fusarium infection in the resistant wheat germplasm Wangshuibai was mapped to a 0.024-0.036 cM interval flanked by Xmag8217 and Xmag415 on chromosome 5AS.To fine map Fhb5, two secondary F2 populations with 5537 and 5724 plants, respectively, were developed by crossing the Fhb5 near isogenic lines with their recurrent parents Mianyang99-323 and PH691. Furthermore, the collinearity between Fhb5 interval and Brashypodium was analyzed based on the wheat deletion-mapped EST and previously mapped markers in this interval. The homologous genes of Brashypodium were used to screen the sequence of wheat. A total of 48 polymorphic markers were developed based on the collinearity, sequence information of Wangshuibai BAC clones and SNP chip data. Finally, a high-resolution map of Fhb5 interval was constructed by genotyping the two secondary F2 populations with all markers mapped in the interval.A total of 104 and 106 heterozygous recombinants were identified from two F2 populations with Mianyang 99-323 and PH691 background, respectively, using flanking markers Xbarc117 and Xbarc180. The selfed progenies of the identified plants were then genotyped for recombinant screening, and 270 and 266 homozygous recombinants were obtained. Three-year (2012-2014) field resistance evaluation showed that these recombinant lines had significantly different FHB resistance performance and could be clearly classified into resistant or susceptible groups. Compared the genotype and phenotype data of the identified recombinants, the Fhb5 was refined to a 0.017-0.036 cM interval flanked by Xmag8886 and Xwgrb0142. |
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