Researchers at the Rockefeller University and University of Singapore have developed a method to screen for genetically modified crops without having to insert a gene for antibiotic resistance. Some scientists and environmentalists have voiced concerns that the main way to confirm that a plant has taken up a foreign gene is to include a second which gives antibiotic resistance, a trait they fear might later escape into wild plants and pathogens. The new method, described in Nature , involves using a gene that enhances a plant's use of its own growth hormones.