Submitted to: ARS Workshop on Fusarium Toxins Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: September 26, 1995
Publication Date: N/A
Technical Abstract: Fusarium graminearum causes head blight (scab) of wheat, a disease that causes severe losses in the wheat crop of the Eastern and Central United States. The fungus reduces yield, but also produces trichothecene mycotoxins (e.g. deoxynivalenol) in infected grain. To determine whether trichothecene production contributes to the ability of F. graminearum to cause head blight, we generated trichothecene nonproducing mutants of the fungus by transformation-mediated gene disruption of the Tri5 gene, which encodes trichodiene synthase, the enzyme that catalyzes the first step in trichothecene biosynthesis. The virulence of two trichothecene nonproducing mutants was examined on wheat plants under field conditions. The mutants caused less disease compared to the wild type trichothecene producing strain from which they were derived. To confirm that the reduced virulence of the mutants was due specifically to disruption of Tri5 rather than some nonspecific effect of transformation, a mutant was induced to revert to wild type. In the revertant strain, the disrupted Tri5 reverted to the wild type Tri5, and as a result, the strain regained the ability to produce trichothecenes. The revertant strain also regained the ability to cause high levels of disease. These results indicate that trichothecene contributes to the ability of F. graminearum to cause head blight and suggest that trichothecene resistant wheat may offer a means to control head blight and the resulting mycotoxin contamination problem.