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United States Department of Agriculture

Agricultural Research Service

Research Project: ENHANCED INSECT RESISTANCE AND CROP MANAGEMENT FOR REDUCTION OF MYCOTOXINS IN MIDWEST CORN
2006 Annual Report


1.What major problem or issue is being resolved and how are you resolving it (summarize project aims and objectives)? How serious is the problem? Why does it matter?
The problem of ear mold toxins/carcinogens (mycotoxins) in corn causes hundreds of millions of dollars of losses to the U.S. each year and also limits the exportability of U.S. corn. Insects can carry mycotoxin producing fungi and damage corn so that these fungi may more readily colonize corn. One objective of the project is to make publicly available a predictive computer program for mycotoxin levels in Midwest corn developed during the last project and adapt as necessary for a wider range of human food use corn varieties. Pursuit of this objective will involve farmers and data collection in farmers fields, companies or other entities (i.e., extension) that support farmers, and end users, all as available and appropriate.

The second objective is to use molecular biological approaches to discover, introduce, and evaluate new insect resistance genes (producing bioactive proteins and secondary metabolites), alone and in combination. Bioactive molecules and regulatory genes from resistant plants will be identified, genes coding for resistance proteins or production of secondary metabolites will be expressed in model plants and corn and then evaluated for insect resistance, and in vitro molecular evolution of potential resistance genes will be explored.

The third objective is to use molecular biological approaches to discover, introduce, and evaluate plant-derived selectable markers for transgenic plant production, in order to facilitate consumer acceptance of transgenic material containing insect resistance genes. Leads will also be taken from other groups of organisms, and material expressing these genes will also be evaluated for insect resistance as some current lead genes have the potential to also enhance resistance to insects when expressed in plants.

The work is relevant to corn growers, end users, and people and animals who consume corn and its byproducts, whether in the U.S. or abroad. Mycotoxins are acutely toxic and/or cause cancer (e.g., aflatoxins and fumonisins). The health of the U.S. and world population is at risk due to mycotoxins. Their presence in animal feed can cause death, reduced growth rates, or inability to sell the products (such as milk) which may become contaminated with the mycotoxins consumed by the animal. In some cases, direct losses in the U.S. alone due to mycotoxins have approached a billion dollars. Indirect losses and costs due to the need for monitoring further add to this value. Successful completion of the project will save growers and end users money loss, increase the exportability of U.S. corn, and improve the health of people and animals in the U.S. and other countries that consume U.S. corn.

The proposed objectives address the mycotoxin component of the National Program on Food Safety (108), specifically Priority Objectives 2.1.2 (Crop/Fungal/Insect/Toxin Relationships) and 2.1.3 (Production Practices and Expert Systems).


2.List by year the currently approved milestones (indicators of research progress)
FY 2006: No milestones are to occur until the 24 month period.

FY 2007: Objective 1 - Predictive program--Have predictive computer program available on website. Objective 2 - Insect resistance genes--Complete examination of inbred plant transformant expressing initial insect skin degrading enzyme.

FY 2008: Objective 2 - Insect resistance genes--Complete examination of plant transformants expressing new secondary metabolite in colored pigment insect resistance group. Objective 2 - Insect resistance genes--Complete analysis of molecularly evolved protein. Objective 3 - Plant selectable markers--Complete analysis of utility of corn-derived selectable marker gene.

FY 2009: Objective 1 - Predictive program--Complete data collection to validate computer program for food grade corn. Objective 2 - Insect resistance genes--Complete examination of plant transformants expressing new secondary metabolite in major branch pathway group. Objective 2 - Insect resistance genes--Complete characterization of resistance mechanism in palm and sedge.

FY 2010: Objective 1 - Predictive program--Complete necessary changes in computer program for food grade corn validation. Objective 2 - Insect resistance genes--Complete analysis of microarray data. Objective 2 - Insect resistance genes--Complete analysis of multi-resistance gene transgenic plants. Objective 2 - Insect resistance genes--Complete analysis of fungal secondary metabolite activity. Objective 3 - Plant selectable markers--Complete analysis of additional plant selectable marker gene.


4a.List the single most significant research accomplishment during FY 2006.
Corn-derived regulatory genes have the potential to increase insect resistance and indirectly reduce mycotoxins (NP108 Food Safety, Component 2 - Mycotoxins): Insect damage and associated ear mold toxins cause hundreds of millions of dollars in losses each year. ARS scientists evaluated corn plants engineered to produce a corn protein in the silks that potentially promotes production of several different insect resistance chemicals that naturally occur in silks only at low levels in most lines. Production of some resistance chemicals was significantly enhanced, and insect resistance was significantly enhanced in milk stage ear silks. Expression of the protein is a potentially useful method for developing an effective combination of naturally derived plant resistance traits to insects, thereby reducing the ear mold toxins and improving the health of animals and people, and increasing the exportability of U.S. corn.


4b.List other significant research accomplishment(s), if any.
None.


4c.List significant activities that support special target populations.
A predictive computer program used as part of an ear mold toxin (mycotoxin) management program with representative farmers from a 200-farmer organization again provided useful predictions of fumonisin and aflatoxin levels for corn (including popcorn) in 2005, predicting values close to those actually encountered. Results from the program were included in the decision making process of local grain elevators in deciding if and how to monitor for aflatoxin (which was subsequently detected in some elevator loads at multiple locations). A Cooperative Research and Development Agreement designed to expand the scope of validation is pending. Once made widely available, this computer program should allow farmers to more economically produce larger amounts of healthier, high-quality corn with reduced levels of mycotoxins. This higher quality product should help the farmers increase sales and help livestock productivity of farmers using corn for on-farm animal feed.


4d.Progress report.
Inbred corn plants transformed to produce an insect skin degrading enzyme were evaluated for insect resistance. Initial corn plants transformed to produce a branch pathway enzyme and an anticell death protein were evaluated for insect resistance. Tobacco (model plants) transformed to produce a combination of functionally different proteins were evaluated for insect resistance. Constructs designed to produce an insect resistance plant pigment were designed. Constructs to produce a corn-derived selectable marker protein were produced and sent out for transformation. Additional data was collected for validation of the predictive computer program, including several popcorn fields.


5.Describe the major accomplishments to date and their predicted or actual impact.
The proposed objectives address the mycotoxin component of the National Program on Food Safety (108), specifically Priority Objectives 2.1.2 (Crop/Fungal/Insect/Toxin Relationships) and 2.1.3 (Production Practices and Expert Systems). Mycotoxin contamination of corn causes economic crop losses to farmers and to potential users nearly a billion dollars in the U.S. alone each year and threatens the health of animals and people who eat corn. Insect damage significantly increases mycotoxin levels in corn, and insect-resistant corn containing a bacterial gene has significantly reduced mycotoxins where the target insect occurs at high levels. However, there is no existing corn that has high resistance to all corn ear pests. We are examining plant-derived genes to enhance insect resistance. Nine months into the project, we have introduced new genes potentially active against insects into plants and evaluated their effects. For example, the most thoroughly examined gene from corn increased insect resistance in silks. These genes have the potential to be combined into a durable resistance complex, thereby greatly reducing ear damage and indirectly reducing mycotoxins. Such corn lines will thereby save farmers and users hundreds of millions of dollars, and result in healthier corn for consumers, and more acceptable corn for importers.


6.What science and/or technologies have been transferred and to whom? When is the science and/or technology likely to become available to the end-user (industry, farmer, other scientists)? What are the constraints, if known, to the adoption and durability of the technology products?
The components of a mycotoxin management plan have been distributed to local farmers for relevance testing and refinement. We have similar constraints to adoption as reported last year. One constraint to adoption is the resistance of overseas markets to new Bt corn lines where the gene has been combined with other transgenic traits (such as herbicide resistance), which are being much more commonly planted by farmers. Bt corn is a key component of the management strategy. Although we now have the mycotoxin predicting computer program in a Windows-complied version, we still need to find a company to produce and market it so that it can more readily be put in the hands of farmers. Internet conference demonstrations and continued presentations have led to commercial interest. A CRADA is pending to expand the scope of validation to a wider area and to specific hybrids. This information has been dispersed at research meetings involving farmers and at field days. Budget cuts this year delayed the process of making the program available on a web site.


7.List your most important publications in the popular press and presentations to organizations and articles written about your work. (NOTE: List your peer reviewed publications below).
Research presentation to Central Illinois Irrigated Growers Association, February 2006 and July 2006, Havana IL (50-75 farmers present), "Mycotoxin Management Plan" and "Mycotoxin Predictive Computer Program for Corn."

Research presentation to Peoria area scientific and business community (Peoria NEXT All Scientists Assembly), P.F.Dowd, E.T. Johnson, and T.S. Pinkerton. Plant-Derived Genes for Insect Pest Management. p. 13.


Review Publications
Shim, S.H., Swenson, D.C., Gloer, J.B., Dowd, P.F., Wicklow, D.T. 2006. Penifulvin A: A sesquiterpenoid-derived metabolite containing a novel dioxa[5,5,5,6]fenestrane ring system from a fungicolous isolate of Penicillium griseofulvum. Organic Letters. 8(6):1225-1228. DOI: 10.1021/o1060107c

Dowd, P.F., Holmes, R.A., Pinkerton, T.S., Johnson, E.T., Lagrimini, L.M., Boston, R.S. 2006. Relative activity of a tobacco hybrid expressing high levels of a tobacco anionic peroxidase and maize ribosome-inactivating protein against Helicoverpa zea and Lasioderma serricorne. Journal of Agricultural and Food Chemistry. 54(7):2629-2634.

Dowd, P.F., Lagrimini, M. 2006. Examination of the biological effects of high anionic peroxidase production in tobacco plants grown under field conditions. I. Insect pest damage. Transgenic Research. 15(2):197-204.

Johnson, E.T., Dowd, P.F., Berhow, M.A. 2006. P1-mediated transgenic secondary metabolite production in corn silks moderately enhances insect resistance [abstract]. Phytochemical Society of North America Meeting and Newsletter. p. 16.

Pinkerton, T.S., Dowd, P.F., Behle, R.W. 2006. Examination of the effects of the anti-apoptotic protein p35 on caterpillars when expressed in corn [abstract]. American Society for Plant Biologists. Paper No. P46027.

Last Modified: 12/19/2014
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