Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/9/2004
Publication Date: 8/28/2004
Citation: Desjardins, A.E., Jarosz, A.M., Plattner, R.D., Alexander, N.J., Brown, D.W., Jurgenson, J.E. 2004. Patterns of trichothecene production, genetic variability, and virulence to wheat of fusarium graminearum from smallholder farms in Nepal. Journal of Agricultural and Food Chemistry. 52:6341-6346. Interpretive Summary: The fungus Fusarium graminearum causes wheat head blight worldwide and contaminates grain with mycotoxins. Fusarium graminearum strains from the United States produce the mycotoxin DON only, but strains from Nepal produce both DON and the closely-related mycotoxin NIV. Our study of more than 500 fungal strains from Nepal showed that DON-producing strains cause more wheat head blight than NIV-producing strains. These data indicate that production of DON rather than NIV confers a selective advantage to this important wheat pathogen, and help explain why DON-producing strains predominate on wheat in the United States.
Technical Abstract: Fusarium graminearum causes wheat head blight and contaminates grain with the trichothecenes 4-deoxynivalenol (DON) and nivalenol (NIV). Sequence analysis of trichothecene genes indicates that NIV production is the ancestral trait, however, DON-producers occur worldwide and predominate in North and South America and in Europe. Analysis of a large field population (>500 strains) from Nepal identified three groups that were both genetically distinct and polymorphic for trichothecene production: SCAR1 comprising 95% DON-producers, SCAR2 comprising 94% NIV-producers, and SCAR 3/5 comprising 34% DON-producers/63% NIV-producers. Ability to cause wheat head blight differed between SCAR groups and trichothecene chemotypes: DON-producers were more virulent than NIV-producers across all three SCAR groups and within the SCAR3/5 genetic background. These data support the hypothesis that production of DON rather than NIV confers a selective advantage to this important wheat pathogen.