University of Dundee

"Effectors to go: unexpected essential functions of core effectors in smut fungi"

Event Date: 
Wednesday, December 12, 2018 - 11:00 to 12:00
Event Location: 
New Seminar Room James Hutton Institute Errol Road, Invergowrie, DD2 5DA
Host: 
Professor Paul Birch FRSE
Event Speaker: 
Prof Regina Kahmann
Institution: 
Max Planck Institute for Terrestrial Microbiology, Marburg
Event Type: 
Seminar
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Abstract
To colonize plants successfully and cause disease, fungi need to down-regulate plant defense responses and reprogram the metabolism of the host to support pathogen growth and development. We are using the biotrophic fungus Ustilago maydis, which causes corn smut disease, to study these processes molecularly. During colonization U. maydis secretes a cocktail of several hundred effector proteins whose expression correlates with distinct phases of colonization. The majority of these proteins lack known domains and their function remains to be determined. In the few cases where the molecular function of such novel effectors has been elucidated, they interact with plant proteins and inhibit or modulate their activity. Based on a comparative analysis of seven smut genomes, we have now identified a set of core effectors and have systematically deleted them in U. maydis. More than 50% of the mutants were affected in virulence and in eight mutants virulence was completely abolished. These latter mutants were able to penetrate, but their growth stopped in epidermal tissue. We now show that these essential effectors, whose expression coincides with the establishment of biotrophy, reside in distinct protein complexes. We demonstrate genetically that complex formation is critical for disease progression and speculate that the complexes are structural parts of the machinery responsible for contact with the host.