CRUCIAL PAPER 14: Transgenic DNA does not significantly degrade in the soil food web
Detection of transgenic cp4 epsps genes in the soil food web
Miranda M. Hart, Jeff R. Powell, Robert H. Gulden, David J. Levy- Booth, Kari E.Dunfield, K. Peter Pauls, Clarence J. Swanton, John N. Klironomos, Jack T. Trevors
Agron. Sustain. Dev. 29 (2009) 497–501 www.agronomy-journal.org http://bit.ly/6gauyk
(Accepted 12 May 2009)
Abstract
The persistence and movement of transgenic DNA in agricultural and natural systems is largely unknown. This movement poses a threat of horizontal gene transfer and possible proliferation of genetically modified DNA into the general environment. To assess the persistence of transgenic DNA in a field of Roundup Ready corn, we quantified the presence of the transgene for glyphosate tolerance within a soil food web. Using quantitative real-time PCR, we identified the cp4 epsps transgene in bulk soil microarthropods, nematodes, macroarthropods and earthworms sampled within the corn cropping system. We found evidence of the transgene at all dates and in all animal groups. Transgenic DNA concentration in animal was significantly higher than that of background soil, suggesting the animals were feeding directly on transgenic plant material. It remains to be tested whether this DNA was still within the plant residues, present as free, extracellular DNA or had already undergone genetic transformation into competent bacterial cells. These results are the first to demonstrate the persistence of transgenic crop DNA residues within a food web.
4. CONCLUSION We found evidence for large concentrations of transgenic DNA in animals from the food web associated with RoundUp Ready corn. This indicates that the transgene does not significantly degrade within the food web. Further, the guts of these animals may provide opportunity for genetic transformation into native soil bacteria. It remains to be determined how far down the food web the transgene is detectable and whether or not the identified gene is available for transformation. It may be that animals associated with the soil food web provide an excellent starting spot for detecting genetic transformation in the natural environment.