On scrubby flatland outside copenhagen Airport, Jarne Elleholm and Carsten Meier are watching green foliage turn red. This is no autumn leaf-peeping exercise. Rather, they’re keeping an eye on a swath of weeds they’re growing that should turn red in the proximity of land mines. If the weeds change hues as designed, Elleholm and Meier could save thousands of lives and limbs.
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Their company, Aresa, a Copenhagen-based biotech start-up, has genetically modified a common weed called thale-cress so that its leaves turn red when the plant comes in contact with nitrogen dioxide — a compound that naturally leaches into the soil from unexploded land mines made from plastic and held together by leaky rubber seals. Aresa is growing large patches of the stuff on old army shooting ranges that have been seeded with land mines.
The Geneva-based International Campaign to Ban Landmines says there are an average of 15,000 to 20,000 land-mine deaths or injuries annually as innocent victims wander onto the leftover devices. Unknown numbers of unexploded mines are waiting to find victims in Angola, Cambodia, Sudan, Afghanistan, Bosnia and Herzegovina and many other countries.
Unless the mines can be found first. “There are a lot of promises in land-mine detection, but still, what people often come back to is the guy poking around with a stick,” says Elleholm, speaking of technologies such as ground-penetrating radar, infrared devices and thermal neutron activation. Many current methods are slow and cover no more than 1% of the estimated 77,220 sq. mi. of the world’s land-mine-infested territory every year. Elleholm says Aresa’s technique can cover five times as much ground in the same amount of time as other detection techniques.
Aresa uses a seeding hose known as a “hydroseeder” — groundskeepers use such a hose to grow green grass on golf courses — to cover about a football field of territory in a day. After four to five weeks the thale-cress will have sprouted and turned red if it encounters nitrogen dioxide. Normally, plants neutralize nitrogen dioxide, which they recognize as harmful. But Aresa scientists, led by founder Meier, have genetically engineered thale-cress, fusing its nitrogen dioxide neutralizer with an enzyme that creates red pigment (plants naturally produce red pigment, which isn’t visible until the green disappears in autumn).
Aresa has had mixed results. The thale-cress does indeed turn red when it meets nitrogen dioxide. But Aresa can’t get the weed to grow large enough to be easily visible. Aresa has experimented with only one of the more than 1,600 varieties of thale-cress. Following the summer letdown, the company ordered 174 different strains, and is awaiting seeds from Libya, Norway, the Caucasus, Britain, the U.S. and elsewhere.
Elleholm thinks Aresa will have a reliable land-mine-detecting thale-cress in about two years and hopes to apply similar biotech to detect larger, unexploded ordnance and eventually to cull antibodies from plants. But first it will focus on land mines. If it succeeds, Aresa will make thale-cress a weed that will be welcomed.