Development and Validation of Molecular Markers Closely Linked to H32 for Resistance to Hessian Fly in Wheat

Hessian fly [Mayetiola destructor (Say)] is an important insect pest of wheat (Triticum aestivum L.) Host resistance conferred by H genes has been the most effective means to manage Hessian fly populations. More than 32 H genes have been identified in wheat and its relatives. In a previous study, Hessian fly-resistance gene H32 was assigned to the chromosomal bin 3DL3-0.81-1.00, which also harbors H26 The objectives of this study were to develop and validate sequence-tagged site (STS) markers closely linked to H32 and to determine the genetic relationship between H26 and H32. In this study, 11 wheat EST-derived STS markers linked to H26 and three new STS markers were added to the linkage map of H32 using the International Triticeae Mapping Initiative (ITMI) population. Two of the STS markers, Xrwgs10 and Xrwgs12, were found to flank H32 with a genetic distance of 0.5 cM. Another STS marker Xrwgs11, co-segregated with H32 Molecular markers tightly linked to H32 were validated in 12 bread wheat cultivars and an elite breeding line, demonstrating the efficacy of these markers for marker-assisted selection. Comparative mapping analysis indicated that H26 and H32 are either different alleles at the same gene locus or two different, but tightly linked H genes. Ongoing efforts to perform fine mapping and positional cloning of H26 will resolve the relationship between H26 and H32.