Early in the history of genetically modified crops, there were concerns that foreign genes introduced into plants could jump into their wild relatives through pollen. Sequences in the nuclear DNA of many plants suggest that this has happened a few times throughout natural evolution. To stop this from happening, the foreign DNA is inserted into the genetic machinery of the chloroplast - those elements in the part of the plant cell that makes energy from light. This is in net contrast to the DNA in the cell nucleus that is incorporated into pollen as the cells divide. Jeremy Timmis at the University of Adelaide, working with tobacco plants inserted a marker gene into the chloroplasts and then searched for it in about 250,000 of the offspring of the plants under test. In about 1 in 16,000 of the seedlings, the foreign gene had jumped from chloroplast to nuclues and was being expressed in a heritable manner. Further experiments are required to evaluate this general risk in GM plants. "Nature" Jeremy Timmis E-mail: jeremy.timmis@adelaide.edu.au