Technical Approach

Under SERDP project ER-1318, researchers demonstrated that expression of the rhodococcal gene in the model plant system arabidopsis confers the ability to tolerate and degrade high concentrations of RDX. They also demonstrated that expression of the bacterial nitroreductase XplA gene in tobacco and arabidopsis confers resistance to toxic levels of TNT. Researchers have shown that the nitroreductase TNT transformation products are conjugated to sugars as part of the detoxification process in plants; however, experiments using axenic culture systems suggest that this may be a rate-limiting step to removing TNT from the environment. To investigate this observation and to further improve TNT resistance in the RDX-degrading transgenic plant lines, identification and overexpression of appropriate glycosyltransferases will be carried out. The ability of XplA to degrade RDX and the related nitramine explosive HMX in plants will be further improved through methods of random mutagenesis and directed evolution. Arabidopsis will be used as a model plant system; however, the major objective of this project is to generate transgenic plants that can detoxify TNT and remove and degrade RDX at training ranges. The transformed plants must be appropriate for growth on ranges, in particular, low-growing, fire-resistant, and capable of withstanding and recovering rapidly from disruption by heavy equipment. To meet this requirement, researchers will introduce the genes encoding explosives degrading and detoxifying enzymes into a range of grasses of known utility.