Combating bioterrorism is no longer the domain of high-tech gadgets alone.
A new breed of genetically engineered plants will soon be capable of functioning as "sentinels," detecting harmful chemical and biological agents in the atmosphere. Designed to turn fluorescent green or a sickly brown within minutes or hours of exposure, the plants could be used along airport runways or around military or industrial sites.
"Plants make good sentinels because they can't run away," says Jack Schultz, a chemical ecologist and professor of entomology at Pennsylvania State University. "Because they are rooted in their environment, they must respond dynamically to environmental changes."
Some of the plants being developed will be able to signal the presence of chemical agents and animal pathogens such as anthrax. Others are being designed to fluoresce upon detecting TNT residues in the soil, aiding in land mine detection. If enough plants are gathered in one place, and if their glow is bright enough, researchers say satellites may be able to detect minefields from space.
Schultz, with Ramesh Raina, heads the Penn State research team conducting the $3.5 million project, which is sponsored by the Defense Advanced Research Projects Agency (DARPA).
By 2006, the scientists hope to have created around 300 lines of sentinel plants to test out in nature. Currently, their work centers on Arabidopsis, or mouse-ear cress, a small flowering plant from the mustard family. Dr. Raina says the plant is the most studied on earth, and the only one whose entire genetic sequence has been mapped and is publicly available.
Engineered to produce one of two consistent responses, the plants will change color, simulating diseased plants, upon exposure to a wide variety of chemical and biological agents. Effects are expected to be temporary, lasting anywhere from a few hours to a few days.