By Changing Color, Plants Can Signal Presence of Explosives
Researchers at Colorado State University are using actual plants — green, leafy organisms — to detect explosives and environmental pollutants.
“We envision these plants enabling ordinary people to know if their air and water are clean, as well as helping to provide security around airports, shopping centers and sports arenas,” said professor, plant biologist and lead researcher June Medford. They could be placed around a home, too, so a family could tell if it had radon in the basement just by looking at a plant, she added.
Research partners at Duke University and the University of Washington used a computer program to redesign naturally occurring proteins called receptors. Medford and her team then modified these receptors to work in the cell walls of plants, which will turn from green to white when they detect certain chemicals in the air or soil. The plants will change back to their normal green when the dangerous substance is removed from the environment.
“The idea to make detector plants comes directly from nature,” Medford said. “Plants can’t run or hide from threats, so they’ve developed sophisticated systems to detect and respond to their environment. We’ve ‘taught’ plants how to detect things we’re interested in and respond in a way anyone can see, to tell us there is something nasty around.”
The initial research was funded in part by the Defense Advanced Research Projects Agency and the Department of Homeland Security. Medford and company recently received an additional three-year, $7.9 million grant from the Defense Threat Reduction Agency to bring their lab success to real world applications. Officials in the Office of Naval Research have said that engineered plant sentinels could help protect troops from improvised explosive devices. Studies so far have shown the plants to possess detection abilities similar to or better than those of dogs, Medford said. Eventually, they will be able to alert people walking by in airports to “the bad guys with the explosives in their bags,” she said.
The next logical step is to shorten the time it takes for a plant to react to the presence of harmful chemicals. Initially, plants that had been rewired with the overhauled receptors took hours to respond to nearby explosives. Work is under way to reduce that to a few minutes.