Plants could potentially help solve a global problem: how to clean up land contaminated by explosives, according to biologists at the University of York.
TNT has become an extensive global pollutant over the last 100 years and there are mounting concerns over its toxicity to biological systems. The majority of TNT remains in the roots of plants, where it inhibits growth. Says Neil Bruce, a professor at the University of York who led the research:
“There is a lot of interest in natural mechanisms for the removal of recalcitrant toxic chemicals from the biosphere, and because of the scale of explosives pollution, particularly on military training ranges, the remediation of polluted land and water as a result of military activity is a pressing global issue.”
Bruce and colleagues discovered that a key plant enzyme, MDHAR6, reacts with TNT, generating reactive superoxide, which is highly damaging to cells.
Mutant plants lacking the enzyme, previously implicated in protecting plants from stress, in fact have an enhanced TNT tolerance.
By targeting this enzyme, it may be possible to produce TNT-resistant plants to revegetate and remediate explosives at contaminated sites such as military ranges and manufacturing waste sites.
“Only by eliminating the acute phytotoxicity of TNT can plant-based systems be successfully used to clean-up contaminated sites. Our work is an important step on that journey,” says Liz Rylott, who co-led the research.
The new findings also point to the potential of a new type of herbicide, which could be used sustainably in rotation with other herbicide types, to limit the emergence of herbicide resistance.
Since MDHAR6 is plant specific, compounds that react with the enzyme in the same way as TNT, yet are readily degraded in the environment, could also be screened for herbicide potential.
“This is an important additional finding as it is an increasing concern that although herbicide resistance has been increasing steadily since the 1970s, no new herbicide mode of action has been commercialized since the 1980s,” adds Bruce.
Monodehydroascorbate reductase mediates TNT toxicity in plants
Emily J. Johnston, Elizabeth L. Rylott, Emily Beynon, Astrid Lorenz, Victor Chechik, and Neil C. Bruce
Science 4 September 2015: 349 (6252), 1072-1075. [DOI:10.1126/science.aab3472]