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United States Department of Agriculture

Agricultural Research Service

Title: Assessment of Plant Pathogenicity of Endophytic Beauveria Bassiana in Bt Transgenic and Non-Transgenic Corn

Authors
item Lewis, Leslie
item Bruck, Denny
item Gunnarson, Robert
item Bidne, Keith

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 20, 2001
Publication Date: N/A

Interpretive Summary: The European corn borer is a serious pest of corn in the United States. Scientists are continually investigating new approaches to manage this insect without damaging the environment with chemical insecticides. A fungus that kills insects also forms a relationship (endophytic) within the corn plant so that the fungus protects the plant from feeding by the European corn borer larvae. Research was conducted to determine if the fungus would also colonize genetically transformed plants and if the fungus causes a pathology to the plant. Data from these studies demonstrated that the fungus forms an endophyte equally with transformed and nontransformed plants and is an insect pathogen not a plant pathogen. This research assures seed producers and corn growers with a tool to manage the European corn borer that is environmentally friendly.

Technical Abstract: Beauveria bassiana forms an endophyte with nontransformed inbred and hybrid cultivars of corn (Zea mays). This relationship has the potential to produce season-long suppression of the European corn borer, Ostrinia nubilalis. Field and greenhouse studies were conducted to determine the proclivity of Bacillus thuringiensis (Bt)transgenic corn to form an endophytic relationship with Beauveria bassiana, and to evaluate the corn for possible plant pathological effects associated with this relationship. B. bassiana was applied in a granular formulation to corn expressing two Bt events (MON802 and MON810) and the corresponding isolines. There were no significant differences in levels of endophytism between transgenic events or their near isolines. B. bassiana also was applied to Bt transgenic corn hybrids 34R06 (event MON810) and Ciba Max 454 (event 176) and their near isolines as a liquid seed treatment or a foliar application. In greenhouse estudies, there were no significant differences in germination or presence of root pathogens in transgenic and isoline seeds soaked in a suspension of B. bassiana (2 x 10**10 conidia/ml). The same lines of corn were used in field experiments with treatments of seed soaked in a suspension of B. bassiana, a foliar application of a granular formulation of B. bassiana, and corresponding untreated checks. Plants were sampled throughout the growing season and evaluated for overall plant growth. There were no significant differences in overall plant growth between the B. bassiana treatments or in the amount of plant material making up each plant component. The results of this study indicate that B. bassiana readily forms an endophytic relationship when applied to transgenic corn and acts solely as an insect and not a plant pathogen.

Last Modified: 7/24/2014
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