A pattern recognition receptor-like protein conserved in wheat controls gene-for-gene resistance to an extracellular fungal pathogen

Deployment of fast-evolving disease resistance genes represent one of the most successful strategies used by plants to fend off pathogens. In gene-for-gene relationships, the clear majority of cloned disease resistance (R) genes encode intracellular nucleotide-binding leucine rich repeat proteins (NLRs) recognizing pathogen-secreted isolate-specific avirulence (Avr) effectors delivered to the host cytoplasm. This often triggers a localized hypersensitive response (HR), which halts further disease development. Here we report the map-based cloning of the wheat Stb6 gene and demonstrate that it encodes a conserved wall-associated receptor kinase (WAK)-like protein, which detects the presence of a matching apoplastic effector and confers pathogen resistance without HR. This is the first report demonstrating gene-for-gene disease resistance controlled by this class of proteins in plants. Moreover, Stb6 is the first cloned gene specifying resistance to Zymoseptoria tritici, one of the most important foliar fungal pathogens of wheat that causes economically damaging Septoria tritici blotch (STB) disease.