ARS | Publication request: Mineralization and Sorption of Glyphosate in Two Agricultural Soils: Influence of Cry1ac Toxin

Submitted to: International Symposium On Environmental Aspects Of Pesticide Microbiology
Publication Acceptance Date: June 1, 2004
Publication Date: September 4, 2004
Citation: Accinelli, C., Seebinger, J.D., Koskinen, W.C., Vicari, A., Sadowsky, M.J. 2004. Mineralization And Sorption Of Glyphosate In Two Agricultural Soils: Influence Of Cry1ac Toxin. International Symposium On Environmental Aspects Of Pesticide Microbiology. P. 57.

Technical Abstract: Glyphosate [N-(phosphonomethyl)glycine] is a non-selective herbicide widely used in the weed management of several agricultural crops. Since the introduction of genetically modified crops, mainly represented by glyphosate-tolerant crops, the importance of this herbicide has further increased. Considering the importance of genetically modified crops in the modern agriculture, more information is needed regarding the potential effect of compounds (i.e. insecticidal Cry toxins) coupled with the pest management of these crops on the fate of glyphosate in soil. In a previous experiment, the influence of insecticidal Cry toxins extracted and purified from a commercial formulation of Bacillus thuringiensis subsp. kurstaky on the degradation of glyphosate in soil was studied. The adopted methodology did not permit separating the four Cry toxins contained in the Bt commercial formulation and consequently permitted only roughly simulating a real agricultural scenario with glyphosate-tolerant/Bt-protected (stacked trait crops) or the use of glyphosate in the weed management of Bt-protected crops. In the present experiment, the influence of a single specific Cry toxin, namely CrylAc, on the mineralization and sorption of glyphosate in soil was estimated. CrylAc toxin was obtained from a cloned Bt strain encoding for this specific toxin. The methodology to extract, purify and incorporate the toxin to the soil is discussed. The use of the single CrylAc toxin leads to significantly different results in comparison to the incorporation with the soil of the four different Cry toxins extracted from the Bt commercial formulation. These results confirmed the high specificity of this group of toxins, even in their effects on processes involved in the microbial degradation of pesticides in soil.