Although such a device does not exist, it's not as far-fetched as it may sound. As concerns grow over the threat of bioterrorism and weapons of mass destruction, university researchers are working on an early warning system -- the figurative canary in the mineshaft -- that could be as unobtrusive and ubiquitous as plants in a landscape.
Under a three-year, $3.5 million grant from the Defense Advanced Research Projects Agency, Penn State scientists are laying the groundwork for genetically engineering plants that can detect and signal the presence of many harmful chemical or biological agents.
"Plants make good sentinels because they can't run away," says Jack Schultz, a chemical ecologist and professor of entomology in the College of Agricultural Sciences. "Because they are rooted in their environment, plants must respond dynamically to environmental changes. And many of these responses can be observed or measured, such as changes in color, shape or growth habit, or the emitting of volatiles into the air.
"In simple terms, if you don't fertilize your houseplant, it may not grow well and may change color," Schultz explains. "The plant is reporting the conditions it's experiencing in its soil. In essence, it's telling you, 'Feed me.' The trick is to design plants that respond in particular ways to particular stimuli, and to amplify these responses so they can be detected readily."
The key to manipulating plant response to environmental stimuli is to understand the role of certain genes, says Ramesh Raina, assistant professor of biology in the Eberly College of Science.