Plants remain permanently resistant to the majority of potential pathogens, even those which are pathogenic on related species. The potential of this type of durable resistance, which is referred to as nonhost resistance, has been clearly underexplored in crop plants. The scientific aim of this project is to identify and explore the genetic framework for nonhost resistance in wheat and barley to three pathogens of enormous economic and ecological impact, causing rust (Puccinia spp.), powdery mildew (Blumaria spp.) and blast (Magnaporthe spp.) disease in cereals. A global, differential gene-expression analysis, comparing compatible host and nonhost interactions will allow the identification of common, plant species-specific and pathogen species-specific pathways involved in nonhost resistance in wheat and barley. Functional genomics approaches will be used to test the potential of nonhost resistance-related genes in the corresponding cereal species for mediating resistance to adapted as well as non-adapted pathogens. The phenomics data will be combined with quantitative genetic data from novel populations segregating for nonhost resistance in order to provide convergent evidence for a role of the candidate genes in nonhost resistance of Triticeae. The outputs from this project will provide a new level of understanding of the fundamental inner workings of the biology of nonhost resistance in cereals that will provide the European plant breeding industry with the knowledge and tools required to achieve sustainable resistance to major pathogens.