Phytoremediation of explosive

Phytoremediation is one of the best technique to use plants to get rid of hazardous chemicals. Scientists, working on stress biology, are trying to discover the underlyinmolecular mechanism and candidate genes to engineer plants against different heavy metals and hazardous components.

For example, explosive like 2,4,6-trinitrotoluene (TNT) is a worldwide pollutant, contaminating manufacturing waste sites, mines, current and former conflict zones, and military land. The U.S. Department of Defense has an estimated 10 million hectares of operational ranges contaminated with munitions constituents and rated as a class C carcinogen by the Environmental Protection Agency. TNT has toxic effects on all living organisms: in animals, causing hepatitis, anemia, hyperplasia of bone marrow, and cataracts, and in soil, severely affecting microbial diversity and the establishment of vegetation. In plants, the majority of TNT remains in the roots, where growth and development is inhibited, reducing overall biomass. When most plants soak up TNT, a harmful chemical reaction occurs in the energy making mitochondria of the plant’s cells, stunting its growth dramatically and eventually killing it. 

In a recently published article in Science, Johnston et al. has reported that a novel mutation

in the weed Arabidopsis thaliana that shields it from harmful reactions with TNT. The mutation—in the MDHAR6 gene—allows the plant to remove TNT from the soil with little to no damage. Researchers report that MDHAR6 mutant plants have long roots and bushy leaves, compared with other plants exposed to TNT. Their research findings revealed that phytotoxicity is caused by reduction of TNT in the mitochondria, forming a nitro radical that reacts with atmospheric oxygen, generating reactive superoxide. The reaction is catalyzed by monodehydroascorbate reductase 6 (MDHAR6), with Arabidopsis deficient in MDHAR6 displaying enhanced TNT tolerance. This discovery will contribute toward the remediation of contaminated sites. Moreover, in an environment of increasing herbicide resistance, with a shortage in new herbicide classes, our findings reveal MDHAR6 as a valuable plant-specific target.

To read the original research article, please follow the link below:

Monodehydroascorbate reductase mediates TNT toxicity in plants