Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/28/1999
Publication Date: N/A
Citation: Interpretive Summary: Deoxynivalenol is a toxin that is produced by a fungus that is often found on corn. When present in high levels in grains contaminated with fungus, this toxin can cause health problems in animals that eat corn. Although we know a lot about how this toxin accumulates in corn, we know very little about why the fungus produces toxin. In this study we developed special strains of the fungus that are unable to produce toxin. We showed that these toxin nonproducing strains are less able to cause corn ear rot than strains that produce toxin. These results show that the toxin plays an important role in the ability of this fungus to cause disease on corn. This information should help plant breeders in developing corn plants that are more resistant to this fungus.
Technical Abstract: Trichothecene-producing and -nonproducing Fusarium graminearum strains were tested for their ability to cause gibberella ear rot in replicate field trials at two locations, Ottawa, Ontario and Peoria, Illinois, in 1996. This was accomplished by inoculating Zea mays ears with transgenic F. graminearum strains in which the trichothecene biosynthetic pathway had been knocked out by the specific disruption of the trichodiene synthase gene. A derivative revertant strain in which trichothecene production had been restored through recombination was also used. A silk channel inoculation method was employed at both locations. In addition, a kernel puncture inoculation method was used at the Ontario location. Harvested corn was analyzed for visual disease severity, yield, deoxynivalenol (DON) concentration, and fungal biomass by quantitative PCR and/or ergosterol quantitation. There was a good correlation between data obtained from the two different methods of quantifying fungal biomass. The trichothecene-nonproducing strains were still pathogenic but less virulent on corn than the trichothecene-producing progenitor and revertant strains, as assayed by most parameters. This suggests that the trichothecenes act as virulence factors to enhance the aggressiveness of F. graminearum on corn.