Key message: New molecular markers were developed and mapped to the FHB resistance QTLregion in high resolution. Micro-collinearity of the QTL region with rice andBrachypodiumwas revealed for a better understanding of the genomic region. Abstract: The wild emmer wheat (Triticum dicoccoides)-derived Fusarium head blight (FHB) resistance quantitative trait locus (QTL) Qfhs.ndsu-3AS previously mapped to the short arm of chromosome 3A (3AS) in a population of recombinant inbred chromosome lines (RICLs). This study aimed to attain a better understanding of the genomic region harboring Qfhs.ndsu-3AS and to improve the utility of the QTL in wheat breeding. Micro-collinearity of the QTL region with rice chromosome 1 and Brachypodium chromosome 2 was identified and used for marker development in saturation mapping. A total of 42 new EST-derived sequence tagged site (STS) and simple sequence repeat (SSR) markers were developed and mapped to the QTL and nearby regions on 3AS. Further comparative analysis revealed a complex collinearity of the 3AS genomic region with their collinear counterparts of rice and Brachypodium. Fine mapping of the QTL region resolved five co-segregating markers (Xwgc1186/Xwgc716/Xwgc1143/Xwgc501/Xwgc1204) into three distinct loci proximal to Xgwm2, a marker previously reported to be closely linked to the QTL. Four other markers (Xwgc1226, Xwgc510, Xwgc1296, and Xwgc1301) mapped farther proximal to the above markers in the QTL region with a higher resolution. Five homozygous recombinants with shortened T. dicoccoides chromosomal segments in the QTL region were recovered by molecular marker analysis and evaluated for FHB resistance. Qfhs.ndsu-3AS was positioned to a 5.2 cM interval flanked by the marker Xwgc501 and Xwgc510. The recombinants containing Qfhs.ndsu-3AS and new markers defining the QTL will facilitate utilization of this resistance source in wheat breeding.
Bibliographical noteFunding Information:
XC and XZ conceived and designed the experiments in this study. XZ performed this study and drafted the manuscript. XC made major revision of the initial draft. SZ provided inoculum for FHB disease evaluation. SC helped in marker genotyping. YQG participated in Brachypodium sequence analysis for comparative mapping. SK provided part of the phenotyping data for QTL analysis. EE was co-PI of the grant that financially supported this research project. All authors reviewed, edited, and approved the manuscript for publication. Acknowledgments
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