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Title: DEOXYNIVALENOL-NONPRODUCING FUSARIUM GRAMINEARUM CAUSES INITIAL INFECTION, BUT DOES NOT CAUSE DISEASE SPREAD IN WHEAT SPIKES

Author
item BAI, G-H - OK STE UNIV, STILLWTR, OK
item Desjardins, Anne
item Plattner, Ronald

Submitted to: Mycopathologia
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/29/2001
Publication Date: N/A
Citation: N/A

Interpretive Summary: Fusarium graminearum causes fusarium head blight in wheat and produces mycotoxins in infected grain. Toxin production plays a significant role in the spread of Fusarium graminearum within a wheat head but toxin production is not necessary for initial infection by the fungus. In this study, we showed mycotoxins can be harmful to humans and animals that consume infected grain.

Technical Abstract: Fusarium graminearum is a major pathogen that causes fusarium head blight (FHB) in wheat and produces deoxynivalenol (DON) in infected grain. In previous studies, the trichodiene synthase gene (Tri5) in the fungal strain GZ3639 was disrupted to produce the DON-nonproducing strain GZT40. In this report, the virulence of strains GZ3639 and GZT40 was tested under both field and greenhouse conditions on wheat cultivars with various resistance levels by using methods of spray inoculation and injection inoculation with fungal conidia. Under field and greenhouse conditions, the wild-type strain GZ3639 produced significantly more disease symptoms and reduced yield more than the Tri5-disrupted strain GZT40 in all wheat cultivars tested. Conidia of strain GZT40 germinated and infected inoculated spikelets, but infection was limited to inoculated spikelets without spread to uninoculated spikelets. When strain GZT40 was inoculated using the spray method, multiple initial infection sites in a spike resulted in higher levels of disease symptoms than in spikes inoculated by a single injection. Greenhouse tests confirmed that strain GZT40 did not produce DON in the infected kernels following either inoculation method. The results confirm that DON production plays a significant role in the spread of FHB within a spike, and are the first report that DON production is not necessary for initial infection by the fungus.