Can transferred genes escape into other plants?
Yes, if the GM plant can breed with wild relatives (hybridisation) and produce offspring that can themselves reproduce. Hybrids could become a problem if they disrupt the ecological balance in the environment, for example by growing faster than their neighbours. No such effects have yet been demonstrated. Engineered genes can be genetically marked so that the frequency of gene transfers can be measured.
Environmental damage isn't inevitable just because hybrids form, but it's possible, so scientists are taking precautions. Researchers across the globe have developed measures that could help prevent hybrids, ranging from isolating GM crops, to using technology to ensure that hybrids either don't germinate or are infertile - called terminator technology. These techniques are highly effective when implemented properly. Scientists are also looking for new ways to introduce traits that restrict gene flow between crops and wild relatives, or make hybrids less able to survive.
Research published in 2010 suggests that a bacterium that is commonly used to transfer new genes into plants may also be able to pass these genes on to other organisms. If the bacteria come into contact with a particular kind of fungus at a wound in a plant's outer skin, the fungus can come away with new genes. If these help the fungus survive, they could become a permanent part of its genetic makeup. Such results show that more research is needed into the topic of gene transfer to ensure that new genetic material does not escape into the wider environment, with potentially unwelcome consequences.