Final Report Summary - GENBLAST (Investigating the biology of plant infection by the rice blast fungus Magnaporthe oryzae)
Rice blast disease is the most significant constraint on worldwide rice production and each year destroys enough rice to feed 60 million people. Controlling rice blast disease is therefore of paramount importance to ensure global food security. This project has provided new fundamental information regarding the way in which the fungus that causes rice blast disease, is able to enter rice cells, grow rapidly within living rice tissue, and cause devastating disease symptoms. The rice blast fungus produces a specialised, pressure-generating cell, called an appressorium, which punctures the rice leaf to enable the fungus to infect plants. We have identified the major regulatory processes required for the appressorium to function, demonstrating the role of a class of proteins called septins in plant infection for the first time. We have characterised a hierarchical network of genetic regulatory proteins that enable the appressorium to form correctly and infect rice leaves. We have also discovered a new secretion system by which the fungus is able to deliver proteins directly into rice cells, once it has entered the leaf, where they act to suppress plant immunity. The project has also mapped the route by which the fungus is able to rapidly colonise rice tissue, using advanced live cell imaging techniques, coupled with an analysis of the global patterns of gene expression of both the fungus and its host, during establishment of the disease. We have discovered how cell-to-cell movement by the rice blast fungus is regulated, allowing the fungus to invade living rice tissue. The project has also led to the discovery and characterisation of a large set of effector proteins that the rice blast fungus uses to suppress plant immunity and enhance its own growth in rice tissue. When considered together, the discoveries in GENBLAST have led to a step-change in understanding of this devastating rice disease and provided new information that can be used to devise new, durable control strategies that will, in the long-term, help prevent the significant losses caused by rice blast to the global rice harvest.