title: Phytotoxicity and phytoremediation of 2,6-dinitrotoluene using a model plant, Arabidopsis thaliana.
abstract: Biochemical and genetic studies of xenobiotic metabolism in the model plant Arabidopsis have significant potential in providing information for phytoremediation. This paper presents the toxicity of 2,6-dinitrotoluene (2,6-DNT) to Arabidopsis under axenic conditions, the fate and transformation of 2,6-DNT after uptake by the plant, and the effect of a putative glutathione S-transferase (GST), which is highly induced by 2,4,6-trinitrotoluene (TNT) in the previous study, on the detoxification of 2,6-DNT. 2,6-DNT had toxic effects on the growth of Arabidopsis based on whole seedling as well as root growth assays. Using [U- 14C]2,6-DNT, the recovery was over 87% and less than 2% accounted for the mineralization of 2,6-DNT in axenic liquid cultures during the 14d of exposure. About half (48.3%) of the intracellular radioactivity was located in the root tissues in non-sterile hydroponic cultures. 2-Amino-6-nitrotoluene (2A6NT) and two unknown metabolites were produced as transformation products of 2,6-DNT in the liquid media. The metabolites were further characterized by proton NMR spectra and the UV-chromatograms when the plant was fed with either 2,6-DNT or 2A6NT. In addition, polar unknown metabolites were detected at short retention times from radiochromatograms of plant tissue extracts. The GST gene of the wild-type of Arabidopsis in response to 2,6-DNT was induced by 4.7-fold. However, the uptake rates and the tolerance at different concentrations of 2,6-DNT and TNT were not significantly different between the wild-type and the gst mutant indicating that induction of the GST gene is not related to the detoxification of 2,6-DNT.
authors: Department of Chemical and Biological Engineering, Iowa State University, Ames, IA 50011, USA.
authors: Jong Moon
authors: JM
authors: Yoon
authors: David J
authors: DJ
authors: Oliver
authors: Jacqueline V
authors: JV
authors: Shanks
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D001673:Biodegradation, Environmental; D002250:Carbon Radioisotopes / Q000378:metabolism; D004269:DNA, Bacterial; D004136:Dinitrobenzenes / Q000493:pharmacokinetics*; D018506:Gene Expression Regulation, Plant; D005856:Germ-Free Life; D005982:Glutathione Transferase / Q000235:genetics / Q000378:metabolism*; D008658:Inactivation, Metabolic; D016254:Mutagenesis, Insertional
chemical_list: D002250:Carbon Radioisotopes; D004269:DNA, Bacterial; D004136:Dinitrobenzenes; C036483:T-DNA; D005982:Glutathione Transferase; C023514:2,6-dinitrotoluene