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Title: TRICHOTHECENES AS VIRULENCE FACTORS IN FUSARIUM WHEAT HEAD SCAB: IMPLICATIONS FOR NEW SOURCES OF FUSARIUM RESISTANCE IN WHEAT

Author
item Hohn, Thomas
item Desjardins, Anne
item Proctor, Robert
item McCormick, Susan
item Alexander, Nancy

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 10/30/1996
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: To investigate the role of trichothecenes in wheat head scab caused by Fusarium graminearum, we have used the technique of gene disruption to generate mutants blocked in the production of trichothecenes. Tri5- mutants were prepared using both additive and replacement methods of gene disruption. To determine whether unintended changes resulting from the transformation procedure used in gene disruption may have affected the virulence of Tri5- mutants, Tri5+ revertants were obtained from both types of disrupted mutants. Growth chamber and field trials using several different wheat varieties have shown that mutants unable to produce trichothecenes (Tri5-) are significantly reduced in virulence when compared to the trichothecene-producing strains (Tri5+). Tri5+ revertants had levels of virulence that were indistinguishable from the wild-type parent strain. Identification of trichothecenes as virulence factors has implications for efforts to improve wheat resistance to head scab. Specifically, improvement of wheat resistance to trichothecenes or the identification of wheat genotypes with increased trichothecene resistance should result in improved resistance to Fusarium; one approach is to introduce foreign genes (plant or microbial) specifying resistance. We are focusing on the trichothecene- producing fungi themselves as a source of these resistance genes. Trichothecene producing Fusarium species are likely to contain genes for trichothecene resistance. Two apparent fungal trichothecene resistance genes are being characterized regarding their effectiveness in heterologous hosts.