Imagine a future in which each row of annuals and perennials in the flowerbed outside your house was a line of defense against dangerous chemicals and explosives. Biologist June Medford and her team at Colorado State University made a big step towards turning plants into chemical security guards when they recently inserted a computer-redesigned receptor protein into a living plant — giving it the ability to detect explosives.
Medford described her research to TPM: “Okay. I’m a plant. There is a chemical on the outside, and I’m going to recognize this and do something about it on the inside.”There are many uses for such a discovery. The most obvious use is to assist human screeners at airports by “smelling” explosives and other illegal items. Certainly walking past a row of ferns and other plants would be preferable to full-body, back-scatter x-ray machines. Any building, like schools or government buildings, could be surrounded by a ring of Medford’s plants to detect explosives nearby.
Medford and her team took naturally-occurring proteins, called receptors, and tweaked them. Because plants are naturally stuck in a single location, they have developed these receptors to automatically react to any outside stimulation. Naturally, the receptors Medford used react to sugar, but she used a computer to help redesign the protein so it would react to explosives. With the aid of a computer, the protein can be retooled to react to most chemicals, Medford said.
When the plant comes into contact with explosives, the receptors alert the plant and plant loses its typical green color, turning white.
The possible defense applications attracted the attention of the military, who helped to fund her work. The Defense Advanced Research Projects Agency (DARPA), the Office of Naval Research, and the Department of Homeland Security were some of the organizations who helped fund her research so far.
The next step for Medford and her team to make her laboratory discovery ready for real-world applications. The Department of Defense’s Defense Threat Reduction Agency has given her a three-year, $7.9 million grant to begin the next stage of work. Medford estimates that she still has three to four more years to go before her chemical-detecting plants can be used outside the lab.
Making the plants more reliable is the biggest challenge Medford foresees for her research. Right now, the plant “works right now in laboratory conditions where the sun always comes up at 8 am and always goes down at 11 pm, and it’s always 25 degrees (Celsius), and there is no bugs and no wind, and no people dumping coffee on the plants,” Medford said. In real world conditions, the plant will have to know the difference between natural and human stimuli — like dumped coffee — and dangerous chemicals.
Speeding up the response time of the plants is another goal for Medford. “We need to make sure it’s fast enough to be useful.”
This is not the first time that scientist have tried to co-opt plants to improve security. Since 2005, Danish scientists have been working to develop plants from the mustard family to detect landmines. When the plant’s roots come into contact with nitrous oxide, a byproduct of landmines that leaks into the surrounding soil, the plant turns red.
Medford believes that future applications for the plants extend beyond national security. She hopes for a future where the plants are integral for monitoring many aspects of the environment. “I’d like to empower people. If you give people a cell phone or the internet, look what we’ve been able to do. If we can let just ordinary people know if their air and water is clean just by looking at a plant, I think it would be really quite powerful.”