Multiple Fusarium head blight resistance loci mapped and pyramided onto elite spring wheat Fhb1 backgrounds using an IBD-based linkage approach

Abstract

Pyramiding QTL for FHB resistance from multiple sources presents an opportunity to enhance the Fhb1 derived resistance of elite spring wheat germplasm. Conventionally, pyramiding QTL using a marker assisted-selection approach requires preliminary mapping studies to identify the resistance QTL from each parental line and validation studies to assess the QTL effects in multiple genetic backgrounds. This study evaluates IBD-based linkage analysis for the purpose of mapping, validation and marker-assisted pyramiding of resistance QTL simultaneously in breeding populations. Eight hundred and twenty nine segregating F1 progeny from 43 four-way crosses among multiple sources of resistance were evaluated in the greenhouse and in field-based progeny tests. IBD-based linkage analysis was conducted using a mixed model extension of Haseman-Elston sib-pair regression. QTL for FHB resistance were identified on chromosomes 2A, 2B, 3B and 7B, cumulatively explaining 18–21 % of the variance for FHB severity in different evaluations. The QTL on chromosome 3B corresponded with Fhb1, and the QTL on chromosomes 2B and 7B are corroborated by previous mapping studies. The QTL mapped to chromosome 2A potentially represents a novel source of resistance derived from elite North American spring wheat germplasm. Marker haplotypes for these QTL regions are being used for marker-assisted selection of resistance alleles in subsequent generations of these breeding populations.