Environmental impact of transgenic crops
The large-scale adoption of transgenic crops over the last ten years has led several groups to question the possible impacts of these new plant lines on agricultural and natural ecosystems. In particular, questions have been raised about the impact of the transgenes on the environment, and about an eventual "pollution" of the overall genetic pool of living organisms at the ecosystem level. After an introduction on the possible environmental impacts of transgenic plants, this review summarizes the current knowledge on the fate – or migration – of transgenes in the environment. Hybridization and introgression processes involving transgenic crops and their close relatives are first considered. Transgene integration in non-related organisms by horizontal gene transfer is then considered. A companion review in this same issue addresses the environmental impacts of recombinant proteins encoded by the transgenes (Michaud 2005).