UKRI/BBSRC-NSF/BIO Determining the Roles of Fusarium Effector Proteases in Plant Pathogenesis

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Small proteins called effectors secreted by plant infecting pathogens are a focus of research in numerous laboratories in the USA, UK and elsewhere, because their study sheds light on how pathogenic microbes cause plant disease. Often these effector studies also reveal the identity of key host proteins in the attacked plants that regulate immunity. However, our knowledge of effectors produced by microscopic filamentous fungi that cause different plant diseases is still quite limited, even though fungal pathogens represent very serious risks to global food security and in some cases human and animal health. One such pathogen is Fusarium graminearum (Fg), which causes Fusarium Head Blight (FHB) on wheat and barley, but which also infects dozens of other plant species, including the import global crop species maize, rice, soybean and the model experimental species Arabidopsis. FHB disease in cereal crops occurs just after crop flowering (anthesis) and goes on to reduce grain yield and grain quality. Particularly concerning is that this disease contaminates grain with toxic compounds called mycotoxins, with the most common being deoxynivalenol (DON). Current FHB control measures are complex but inadequate, involving deploying partially resistant cultivars, using partially effective fungicides and altering agricultural practices. As a consequence, strict legislation and the removal/reduction of mycotoxin contaminated grains post-harvest and in processor chains is needed to ensure food and feed are safe for grain consumers (i.e., humans, farmed animals and birds). To meet expected food demand in 2050, when the world is projected to have an additional 2 billion people, it is imperative that we reduce crop losses to FHB. The goal of this project is to develop genetic-based resistance in wheat and barley to Fusarium species that cause FHB disease. Plants have the ability to detect disease-causing pathogens and then activate a robust defence response that ultimately leads to localised cell death to stop the invader. To detect pathogens, plants use sensor proteins that are modified by enzymes that pathogens secrete during the infection process. This project focuses on identifying enzymes secreted by the fungus Fg that are required for infection of wheat and barley floral tissues. Once such enzymes are identified, sensor proteins will be designed that can activate defence responses in wheat and barley upon modification by these Fg enzymes. Such a system would thus confer resistance to infection by Fusarium species that cause FHB disease without the use of costly and environmentally damaging pesticides. This approach to Fusarium control should be transferrable to a wide array of important crop plants that are damaged by other Fusarium species. This collaborative US-UK project will involve multidisciplinary teams at Rothamsted Research, UK, Indiana University, Indiana, USA and the USDA-ARS laboratory at Purdue University, Indiana, USA.