X-plant: 'Mutant' digests TNT & could be key to contaminated land clean-up, study finds
A team of scientists from Britain's University of York began the study by growing a number of arabidopsis plants (a type of weed) in soil laced with TNT.
Observing plants' progress in the contaminated soil, the researchers noticed that one plant seemed to thrive.
They further discovered that plant was lacking the MDHAR6 gene. The finding - published in the journal Science on Thursday - came as a shock, particularly because the gene is known to boosts plants' immunity by producing vitamin C to fight off toxic molecules.
"It was quite a surprise – we were really quite flummoxed by what we found," said plant biologist Neil Bruce, lead author of the study, as quoted by Popular Mechanics.
To understand more, Bruce and his team investigated what actually takes place when TNT reacts with an ordinary plant with the MDHAR6 gene.
In those plants, "the TNT gets taken up through the plant's roots, where it diffuses across cell membranes into the plant's cells,” Bruce said.
Once the TNT is inside the cells, its molecules make their way into the cells' mitochondria. There, the TNT hijacks the MDHAR6's vitamin C-producing enzymes and hyper-producing the same toxic chemicals that the MDHAR6 was meant to fight off. The TNT also drains the plant's mitochondrial fuel supply. Needless to say, the process is enough to kill a plant.
But none of this happened in the mutant plant with no MDHAR6. None of its enzymes in the mitochondria were hijacked, and no plant fuel was stolen. Instead, the plant's natural immune system – which Bruce says acts like a human liver – gathered the TNT, broke it down, and stored the debris the plant's cell walls.
The 'mutant plant' is not genetically modified, but is rather produced by treating plants with mutagens and screening their offspring for resistance to TNT.
Bruce says the same process could, in theory, be carried out to find similar mutants in grasses and other species, which could then be grown on contaminated land, thereby re-vegetating the area.
The process of degrading TNT without exploding it has stumped scientists for more than a century, as the substance is highly resistant to being broken down. This poses a problem for many parts of the world – including the US, which is estimated to have about “10 million hectares (24 million acres) of military land contaminated with munitions constituents, many of which contain TNT," according to University of York biologist Liz Rylott.