AFLP and STS tagging of a major QTL for Fusarium head blight resistance in wheat

Large-scale field screening for Fusarium head blight (FHB) resistance in wheat is difficult because environmental factors strongly influences the expression of resistance genes. Marker-assisted selection (MAS) may provide a powerful alternative. Conversion of amplified fragment length polymorphism (AFLP) markers into sequence-tagged site (STS) markers can generate breeder-friendly markers for MAS. In a previous study, one major quantitative trait locus (QTL) on chromosome 3BS was identified by using EcoRI-AFLP and a recombinant inbred population derived from the cross Ning 7840/Clark. Further mapping with PstI-AFLPs identified five markers that were significantly associated with the QTL. Three of them individually explained 38% to 50% of the phenotypic variation for FHB resistance. Two of them (pAGT/mCTG57, pACT/mCTG136) were linked to the QTL in coupling, and another (pAG/mCAA244) was linked to the QTL in repulsion. Successful conversion of one AFLP marker (pAG/mCAA244) yielded a co-dominant STS marker that explains about 50% of the phenotypic variation for FHB resistance in the population. The STS was validated in 14 other cultivars and is the first STS marker for a FHB resistance QTL converted from an AFLP marker.