A mutation has been discovered in several plant lines of Arabidopsis thaliana also known as thale cress and mouse-ear cress that renders the plant immune to the detrimental effects of the explosive trinitrotoluene (TNT). Emily Johnston and colleagues from the University of York in Britain have identified the mutation and the mechanism that the mutation produces to provide immunity to TNT for the plants.
TNT is toxic to most plants because it acts in the plant mitochondria with oxygen to produce an oxygen compound that lacks an electron and is toxic to all known life. The reaction is catalyzed by the gene monodehydroascorbate reductase 6 (MDHAR6) in the plants. The plants that grow naturally around factories that produce TNT have developed a mutation in the gene that produces a single electron that eliminates the activity of the electron deficient oxygen molecule and renders the deadly effects of TNT null.
The mutation did not produce resistance or immunity to any other chemical in the mutant plants. This is the first known mutation in plants that is specific to a man-made chemical and the deadly effects produced by the chemical. The mutation does not produce an elimination of TNT in the area that the plants live in but it simply provides a protection for the plants from the TNT.
The mutation in the Arabidopsis thaliana that are resistant to TNT can be used to clean up manufacturing sites and other areas that have been contaminated by TNT. The MDHAR6 gene is proposed as a target to use in developing natural pesticides that have minimal environmental impact. TNT has been in existence for 152 years and the exact date that the mutation occurred is not known.