Submitted to: International Wheat Quality Conference
Publication Type: Proceedings
Publication Acceptance Date: 3/29/2005
Publication Date: 5/22/2005
Citation: Blechl, A.E., Somleva, M.N., Okubara, P.A., Dill-Mackey, R. 2005. New approaches to overcome fusarium head blight. International Wheat Quality Conference. p. 85-95.
Interpretive Summary: Fusarium Head Blight or scab is a fungal disease of wheat that has caused billion dollar losses to producers and grain handlers in the Midwestern United States over the last 15 years. No domesticated wheats are immune to this disease and many currently grown cultivars are highly susceptible. Fusarium Head Blight causes yield losses and can also reduce the value of the harvested grain because of the presence of mycotoxins produced by the fungus during infection. Several research groups aim to make wheat less susceptible to scab by using a biotechnology approach to introduce new genes by genetic transformation. This paper is an overview of the strategies being undertaken by the authors and other researchers. The anti-Fusarium genes are designed to be expressed in the young flowers, the site of initial Fusarium invasion. The proteins made by these genes can enhance the defense responses of the wheat plant, attack the fungus directly, and/or decrease the toxic effects of fungal mycotoxins. The plants produced by these approaches are being tested for scab resistance in greenhouses and fields. Any plants that exhibit resistance can be cross-bred to adapted cultivars to make them less susceptible to Fusarium Head Blight.
Technical Abstract: Fusarium Head Blight or scab is a devastating disease of wheat and other small grains that has resulted in billion dollar losses to U.S. producers and grain industries over the last dozen years. In addition to yield losses, Fusarium infection can reduce grain quality and result in grains that contain trichothecene mycotoxins such as deoxynivalenol (DON). Breeders have made progress in incorporating resistance genes that limit the spread of the fungus in infected heads into elite U.S. wheat germplasm. However, the currently utilized resistances are incomplete and may be overcome by high inoculum pressure under environmental conditions favorable for disease development. It would be desirable to incorporate additional types of resistance, such as resistances to initial infection and to trichothecenes, which may act as aggressiveness factors. To meet these needs, we and others have taken a biotechnology approach that allows introduction of novel anti-Fusarium genes into wheat. The products of these genes may attack fungal structures directly, induce wheat defense responses, or decrease the toxicity of trichothecenes to plant cells. To direct anti-Fusarium gene expression to the appropriate tissues, a variety of promoters have been used. The promoter-gene fusions have been transformed into wheat, their expression levels measured, and the resultant plants tested for scab resistance. This overview describes several different strategies for engineering Fusarium Head Blight resistance into wheat.