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United States Department of Agriculture

Agricultural Research Service

Title: Influence of Cry1ac Toxin on Mineralization and Bioavailability of Glyphosate in Soil

Authors
item Accinelli, Cesare - UNIV OF BOLOGNA ITALY
item Koskinen, William
item Sadowsky, Michale - UNIVERSITY OF MINNESOTA

Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 4, 2005
Publication Date: December 8, 2005
Citation: Accinelli, C., Koskinen, W.C., Sadowsky, M.J. 2006. Influence of cry1ac toxin on mineralization and bioavailability of glyphosate in soil. Journal of Agricultural and Food Chemistry. 54:164-169.

Interpretive Summary: The impact of genetically modified plants containing Bacillus thuringiensis (Bt) toxin on soil processes has recently started to receive attention by scientists. In the present studies we produced the insecticidal protein, Cry1Ac toxin, to determine its effect on soil processes affecting the herbicide glyphosate in two different soils. Glyphosate is an effective non-residual herbicide used to control a wide range of annual and perennial weeds. The addition of 0.25 to 1.0 µg/g soil of purified insecticidal protein did not significantly affect glyphosate bioavailability, that is degradation or binding, in either a sandy loam or a sandy soil. In contrast, we found that bioavailable glyphosate decreased over the 28-day incubation period in both soils. Our findings suggest that the reduction in the bioavailabily of glyphosate was not influenced by the presence of insecticidal protein, but rather the results of aging or binding processes. Results from this investigation suggest that the presence of moderate concentrations of insecticidal protein would have no appreciable impact on processes controlling the fate of glyphosate in soils. Farmers can safely use glyphosate to control weeds in crops that have the ability to control insect pests through production of insecticidal proteins. They do not have to worry about an interaction between between the two chemicals having an adverse impact on the crop or the environment.

Technical Abstract: The impact of transgenic plants containing Bacillus thuringiensis (Bt) toxin on soil processes has received recent attention. In these studies we examined the influence of the lepidopterean Bt Cry1Ac toxin on mineralization and bioavailability of the herbicide glyphosate in two different soils. The addition of 0.25 to 1.0 µg/g soil of purified Cry1Ac toxin did not significantly affect glyphosate mineralization and sorption in either a sandy loam or a sandy soil. In contrast, extractable glyphosate decreased over the 28-day incubation period in both soils. Our findings suggest that the reduction in the bioavailabily of glyphosate was not influenced by the presence of Cry1Ac toxin, but rather the results of aging or adsorption processes. Results from this investigation suggest that the presence of moderate concentrations of Bt-derived Cry1AC toxin would have no appreciable impact on processes controlling the fate of glyphosate in soils.

Last Modified: 9/20/2014
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