Hessian fly populations adapt to overcome newly deployed resistance genes within a few years of release. Although more than 34 genes have been identified that confer resistance against Hessian fly [Mayetiola destructor (Say)] attack in wheat (Triticum aestivum L.), only five genes currently provide resistance against fly populations in the southeastern United States. But even these genes are not 100% effective, leaving Georgia and North and South Carolina with between one and three effective genes for cultivar development. With the goal of providing much needed resistance for this region in a wheat line suitable for use with marker‐assisted selection, we identified a durum wheat line that confers resistance to Hessian fly populations from Maryland, Delaware, North and South Carolina, and Georgia in 100% of the plants tested. Resistance from this tetraploid durum line, PI 134942, was introgressed into hexaploid common wheat to generate the line 97211. Segregating populations of F2:3 families were constructed with the durum donor and with the common wheat recipient to identify resistance genes and provide flanking markers. Although the resistance of the durum donor appeared to involve more than one gene, one partially dominant but very effective gene, H33, was successfully transferred and identified in the hexaploid recipient. This gene was mapped to the short arm of wheat chromosome 3A and is flanked by single sequence repeat markers xgwm218 and hbg284.

The durum wheat [Triticum turgidum L. subsp. durum (Desf.) Husn.] Hessian fly [Mayetiola destructor (Say)] resistance gene H33 was previously introgressed into common wheat (T. aestivum L.) and mapped to chromosome 3AS. However, H33 located to a region that is known to be devoid of molecular markers, with the closest flanking simple‐sequence repeat (SSR) markers 7.4 and 25.1 cM from the gene. This lack of markers flanking economically important genes is a common problem in self‐pollinating crops because of low polymorphism and, in the case of wheat, a large genome size. H33 is currently effective against all virulent Hessian fly populations tested from the southeastern United States, a region where deployed resistance genes are beginning to fail; thus, effort was needed to identify tightly linked flanking markers to use this valuable gene in marker‐assisted selection (MAS). To target the 25.1‐cM segment adjacent to H33 for marker discovery, eight resistant and four susceptible plants were selected for genotyping‐by‐sequencing (GBS). Four single‐nucleotide polymorphisms (SNPs) were identified, with the closest marker being only 6.7 cM away and converted into high‐throughput polymerase chain reaction (PCR)‐based markers for the Kompetitive Allele Specific PCR (KASP) assay. In addition, endonucleases were identified that cut at the SNPs for restriction profiling as an alternate to the KASP assay. Development of these cost‐effective markers provided both low‐ and high‐throughput alternatives for introgressing H33 into wheat cultivars while minimizing linkage drag associated with durum regions of chromosome 3AS.