|Schisler, David - Dave|
|Slininger, Patricia - Pat|
Submitted to: Biological Control
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/11/2006
Publication Date: 8/15/2006
Citation: Schisler, D.A., Khan, N.I., Boehm, M.J., Lipps, P.E., Slininger, P.J., Zhang, S. 2006. Selection and evaluation of the potential of choline-metabolizing microbial strains to reduce Fusarium head blight. Biological Control. 39:497-506. Interpretive Summary: The disease Fusarium head blight (FHB), or scab, of wheat causes devastating losses to producers who raise wheat and barley in the United States and around the globe. This disease is very difficult to control because registered fungicides have residue and cost concerns, and cultivars of wheat that are highly resistant to FHB are not available. In our laboratory, we have discovered a particularly effective yeast biological control agent that has great potential for combating this devastating disease. Because combinations of biocontrol agents can increase the efficacy and consistency of biocontrol, we sought in this study to isolate new biocontrol agents that could be combined with our yeast biocontrol agent in future investigations. Choline is a compound that is found, during wheat flowering, in especially high concentrations in wheat heads where the fungus that causes Fusarium head blight of wheat infects. This compound stimulates the FHB pathogen to grow so we tested more than 700 microorganisms that were isolated from wheat heads to find those that could quickly utilize choline, and therefore likely slow or stop the FHB pathogen. We discovered that about 17% of microbes obtained from wheat heads could use choline as a food source and about 25% of these reduced FHB disease in the greenhouse by at least 25%. The best of these microbes were then tested in field trials in Peoria, IL, and Wooster, OH; and we discovered several strains that consistently reduced FHB in the field. The discovery of these new biocontrol strains that reduce FHB should enable us to create a more reliable and effective biocontrol product composed of two or more microbes and represents a significant step in the development of a new tool for wheat producers to use in the integrated management of FHB.
Technical Abstract: Choline and betaine are found in wheat flower tissues and have been implicated in stimulating hyphal growth of the primary causal agent of Fusarium head blight (FHB), Gibberella zeae. Choline utilizing strains (CUS) from wheat anthers may therefore be a useful source of antagonists of G. zeae. One-hundred twenty-three of 738 microbial strains that were recovered from wheat anthers collected from plants grown in Illinois and Ohio were CUS as determined by growth in a liquid medium containing choline as a sole carbon and nitrogen source and a colorimetric, choline oxidase-based assay of culture filtrate. Thirty-one out of 123 CUS reduced FHB disease severity by at least 25% in greenhouse tests on wheat and 17 reduced FHB severity by at least 50%. All five CUS selected for field testing in 2003 reduced disease severity compared to the untreated check at both field locations on moderately resistant cultivar Freedom. Freedom wheat treated with Pseudomonas sp. AS 64.4 had 63% and 46% less FHB severity than untreated wheat at the two sites. Three of 5 CUS reduced severity at both locations on susceptible cultivar Pioneer Brand 2545. Disease control was comparable to that obtained using the fungicide Folicur 3.6F. Selection of wheat anther colonists for ability to utilize choline as a sole carbon and nitrogen source has utility as a screening tool in the search for efficacious antagonists of G. zeae although choline utilization does not insure that an isolate will be an effective biocontrol agent against Fusarium head blight.