Septoria nodorum blotch (SNB) of wheat is caused by the necrotrophic fungus Parastagonospora nodorum. The identification of P. nodorum-produced necrotrophic effectors (NEs) by dominant host sensitivity genes in wheat leads to disease development according to the inverse gene-for-gene model. There have been nine host gene-NE interactions reported in the wheat-P. nodorum pathosystem so far, and the Snn2-SnTox2 interaction has been shown to be important in both seedling and adult plant susceptibility. The overall goal of this study is to clone and characterize the Snn2 gene in wheat. A saturated genetic linkage map was developed using a segregating population of 164 F7:8 recombinant inbred lines. Currently, a high-resolution map is being developed using F2 plants derived from a cross between the SnTox2insensitive wheat line BR34 and the SnTox2-sensitive line BG301. Markers were identified by SNP genotyping using the 90K iSelect wheat SNP chip and simple sequence repeat markers. New markers were developed based on whole-genome sequence scaffolds, wheat survey sequences, and the IWGSC RefSeqv1.0 wheat reference genome. Around 7000 gametes have been screened so far for high resolution mapping. We have delineated the Snn2 gene to a genetic interval of 0.14 cM that corresponds to a physical segment of 0.53 Mb on the short arm of wheat chromosome 2D. There are a total of 23 genes in this region, nine of which we consider strong candidates including three NB-ARC domain-containing genes, five protein kinase-containing genes, and one gene with leucine rich-repeats. Work to continue high-resolution mapping and marker development to further narrow down the Snn2 candidate region is in progress. In addition, we have developed seven EMS-induced Snn2-disrupted mutants for gene validation and functional analyses. Results of this study will increase our knowledge of wheat-P. nodorum interactions, which will help to develop better host resistance in the future.