Plants, the sensitivity of which to explosives exceeds that of dogs, are derived by American biologists. To create unusual living sensors, scientists modified the natural plant defense mechanism in such a way that it responds to the desired stimulus by changing the color of the foliage
Almost any plant can be made a sensor: all have one or another protection system and contain proteins suitable for modification. Pictured: Professor Madford (right) and postdoc Peter Bowerman
The protection system, mercilessly exploited by scientists, was "invented" by plants a long time ago. It's simple: if they can't escape from the place where they grow up, then they must learn to protect themselves from external threats. So, tobacco leaves, suffering from the good appetite of a voracious caterpillar, begin to secrete substances that attract predatory insects. Other plants, having detected the attacker's protein receptors, emit terpenoids into the tissues, which tighten the cuticle of the leaves.
Researchers have figured out how to use the latter mechanism for their own purposes. As guinea pigs, a team of geneticists led by Professor June Medford chose Arabidopsis, a biologists' favorite, and tobacco.
Researchers have figured out how to use the latter mechanism for their own purposes. As guinea pigs, a team of geneticists led by Professor June Medford chose Arabidopsis, a biologists' favorite, and tobacco.
As conceived by the scientists, it was necessary to change the receptor protein in the cell walls so that it would turn on a defense mechanism, "feeling" explosive chemicals or pollutants of water and air in the plant environment.
Biologists, using a special computer program, calculated how to change the natural proteins of a plant so that they perform the desired functions. Then the appropriate modifications were made using genetic engineering methods.
As a result, in the presence of a signaling substance (the most common component of bombs, trinitrotoluene), the entire bed of genetically modified plants (both Arabidopsis and tobacco) began to lose their green color, giving a clear signal to researchers.
Promotional video:
The reaction of the modified tobacco to the presence of TNT (23 ppb) in the soil appears within several hours (the time is indicated horizontally). On the left, a change in leaf color is shown, visible to the naked eye. Right: hyperspectral imaging of changes in the efficiency of photosystem II.
In the current study, the soil was saturated with TNT, isolating the leaves from TNT vapor and its decay products. However, a separate experiment showed that tobacco sprouts turned pale in the presence of volatile forms. Bottom: The best response from a plant (CSU illustration).
But, as the developers themselves note, what happens in a research laboratory, where the amount of light is the same during the day, "there is no wind, rain and pests, as well as people splashing out coffee."
It is not yet known whether the frames of metal detectors and other scanners will be covered with plants. According to Madford, it will take at least 5-7 years before the traditional methods of finding explosives are replaced (photo by CSU).
Scientists taught the first generation of tobacco to turn pale within a few hours after the discovery of explosives. Any person can recognize the "answer" of a plant. However, no mechanism has yet been invented to return the leaves to their natural color.
In the future, plants can be tuned to capture environmental pollutants and other chemical compounds.
However, researchers now face another important task: to speed up the process of detecting the required substances. Madford is going to involve all of her employees in solving this problem, and she has a lot of them: about 30 students, graduate students and postdocs. Purpose: change the color of the leaves within a few minutes.
An article by the creators of the snake plants was published in the open access in the journal PLoS ONE. In it, Americans argue that the sensitivity of plants is comparable, and sometimes even higher than that of dogs.
The current work began back in 2003. Several interested organizations provided financial support at once. About $ 3 million was invested in the development of living explosive sensors in grants.
To bring the development to mind, the American Defense Threat Reduction Agency (DTRA), the main player in this field, allocated another $ 8 million to the Madford group. Scientists estimate that it will take another 3-4 years to complete the work.
Plants have already tried to teach mine detection. The Danish company Aresa Biodetection has modified Arabidopsis so that its leaves turn red-brown instead of green in 3-5 weeks (in the pictures) in the presence of nitrogen dioxide from unexploded mines in the soil.
In 2008, the company recognized the development as commercially unprofitable, abandoned further investments in biotechnology and switched to another type of activity (photo gizmag, from the sites technoccult.net, storyofcool.com).
June believes that bloodhound plants can be sold as genetically modified seedlings, and that such greens will cost less than conventional frame scanners.
Previously, bees, rats, moths, brewer's yeast and bacteria were involved in detecting explosives (photo from thehoneybeeconservancy.org).
In the future, plants can also be taught to recognize several pollutants at once, and the color change of foliage can be
monitored even from space, the developers dream.
The New York Times goes a step further and presents what airport audio announcements will sound like in the future: "Please show your ID and boarding pass and walk past the rhododendron wall."