How fungi attack wheat

During colonisation of a host, fungi produce proteins called effectors that contribute to disease development. As a defence strategy, the host creates resistance (R) proteins to counteract these effector proteins, in a process akin to an animal's antibody-mediated immune response.

The EU-funded 'Effector discovery and validation of Puccinia striiformis sp. f. tritici, a wheat pathogen' (RUST-SAFE) project aimed to identify novel fungal effector proteins. Researchers looked at a specific fungus, Puccinia striiformis sp. f. tritici, which causes wheat stripe, or yellow rust disease.

They infected differentially resistant wheat varieties with fungal isolates known to differ in their virulence or ability to cause disease. The infection process relies on the ability of fungi to secrete effector proteins into the host via a network of filaments.

Five different candidate effector proteins that were produced at high levels in the fungal filamentous network were identified. When researchers delivered these directly into wheat cells, two of the potential effectors initiated the plant's immune response upon recognition by the host R proteins.

Identifying and understanding the role of pathogenic fungal effectors will lead to more effective disease resistance strategies for wheat and other important crops. As such, this work contributes to curbing fungal epidemics in wheat, a staple food for 40 % of the world's population.