Identification and mapping of quantitative trait loci for Fusarium head blight resistance in a synthetic hexaploid ×...

Fusarium head blight (FHB), caused by Fusarium graminearum Schwabe, is one of the most devastating diseases in wheat (Triticum aestivum L.). The synthetic hexaploid wheat line Largo was developed from a cross between the durum wheat [T. turgidum ssp. durum (Desf.) Husn.] variety Langdon and the Aegilops tauschii Cosson accession PI 268210, and it was previously found to have a moderate level of FHB resistance. This study was conducted to identify quantitative trait loci (QTL) associated with FHB resistance using a population of 188 recombinant inbred lines (RILs) from a cross between Largo and the susceptible wheat line ND495. The RILs were evaluated for Type II resistance in two greenhouse and two field environments. The disease severity and 90K single-nucleotide polymorphism marker data were used for QTL analysis, which revealed six QTL on chromosomes 1D, 2D, 5B, and 7D. Four QTL (QFhb.rwg-1D, QFhb.rwg-5B, QFhb.rwg-7D.1, and QFhb.rwg-7D.3) from Largo had minor effects, whereas two QTL (QFhb.rwg-2D and QFhb.rwg-7D.2) from ND495 showed large effects on FHB resistance. The result suggested that ND495 may possess suppressor or susceptibility gene(s) suppressing or masking FHB resistance controlled by the resistance QTL. Among these QTL, four coincided with previously reported QTL, including Fhb9, and two (QFhb.rwg-1D and QFhb.rwg-7D.1) are likely novel QTL. From the six QTL regions, 10 Kompetitive allele-specific PCR markers were developed and validated for marker-assisted selection. The QTL detected from the resistant and susceptible parents enhance our understanding of FHB resistance expression and provide new resources for improving FHB resistance in wheat.