The deployment of resistance genes (R genes) in breeding programmes has been shown to be a useful strategy to reduce farmer’s reliance on fungicides and offset the constant disease pressures on Ireland’s primary crops. However, the durability of varieties with R genes can be tenuous due to the ability of fungal pathogens to rapidly evolve and overcome the resistant phenotype. Recently, the use of susceptibility genes (S genes) has emerged as a viable alternative. While the products of S genes can be exploited by pathogens to promote infection, crops with specific, non-functional S genes have reported strong pathogen resistance. Barley is the primary Irish tillage crop and current varieties are susceptible to the pathogen Rhynchosporium commune. The goal of this project was to investigate the barley – R. commune interaction and identify and characterise the activity of candidate barley S genes. To achieve this, an in silico analysis first identified 682 potential barley orthologues to known S genes. In parallel, the temporal transcriptomic response of barley to two diverse R. commune isolates identified 245 of these genes associated with a response to R. commune. Three of these genes were brought forward with the aim of validating functionality via transient knockdown. This project has delivered important insights into early signalling events in barley in response to R. commune and provided a fundamental dataset on the transcriptomic response of barley after R. commune infection that will support future investigations into the barley x R. commune interaction.