Plants Go on High Alert

The New York Times writes that new research from Colorado State University indicates progress has been made towards a “plant-kingdom early warning system.” Plants’ ability to sense the slightest chemical changes can be manipulated so they change color when exposed to tiny amounts of airborne TNT molecules. Instead of intrusive scanners, perhaps air passengers will soon be walking past security gardens. In addition, these early warning plants could even be integrated into important public spaces: “How about a defensive line of bomb-sniffing tulips in Central Park in New York, or at the local shopping mall’s indoor waterfall, or lining the streets of Baghdad?”

In a study recently published in the peer-reviewed journal, PloS ONE, the plant reseachers say they are focused on how “computationally re-designed periplasmic binding proteins (PBPs) provide a means to design highly sensitive and specific ligand sensing capabilities in receptors. Input from these proteins can be linked to gene expression through histidine kinase (HK) mediated signaling.” They are in fact manipulating the chemical reactions of plants so their leaves are designed to “drain off chlorophyll” when bomb chemicals are detected. Without chlorophyll, plants turn a much lighter shade. June Medford, a a professor of biology at Colorado State, says the color change must be dramatic if plants are going to work as an early detection system.

Plants have evolved a system of sensors for detecting subtle chemical changes in their environment. This has been used to detect and ward off pests. Their chemical sensory power potentially makes plants an ideal (and sustainable) bomb-sniffer. “Plants in the lab, when modified to sense TNT, the most commonly used explosive, reacted to levels one one-hundredth of anything a bomb-sniffing dog could muster.”

The research, which has been funded by the U.S. Departments of Defense and Homeland Security, is now moving towards improving plants’ response time to threatening chemical compounds. Right now, the plants are responding slowly to chemicals, and take hours to indicate the presence of molecules. “Practical application requires a signal within minutes, and a natural reset system back to healthy green in fairly short order.” In addition, these plants must be kept healthy — an ailing plant could give a false signal. Sean R. Cutler, an associate professor of plant cell biology at the University of California, Riverside, said: “What you want is something that is extreme on-and-off and reliable, and I don’t think they’re there yet.”

Read the article and see the research study.

In another use of plants for security, Agence-France Press writes that a French businessman hopes to replace cement walls and razor wire with thorny security hedges in the cities of Iraq and Afghanistan. “The idea of establishing security barriers made of plants has many benefits, both from the psychological side and for the beauty and attractiveness of the city.” Dense, nearly impenetrable hedges could also be used in combination with high-tech sensors along border regions to slow illegal immigrants. “When you have five or six rows of thorny trees it will take at least an hour to cross, and that is more than enough time to capture [a] guy.”

Image credit: Central Park Flowers, NYC / Bertoco, Panoramio

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