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First published online May 27, 2005; 10.1104/pp.104.056168 Plant Physiology 138:858-869 (2005) © 2005 American Society of Plant Biologists Gene Expression and Microscopic Analysis of Arabidopsis Exposed to Chloroacetanilide Herbicides and Explosive Compounds. A Phytoremediation Approach1Department of Civil and Environmental Engineering (M.P.M., C.L.J., J.L.S.), Central Microscopy Research Facility (K.W.), and Department of Biological Sciences (M.C.S.), University of Iowa, Iowa City, Iowa 52242; and Institute of Chemical Technology, Prague, Czech Republic (M.J.)
Understanding the function of detoxifying enzymes in plants toward xenobiotics is of major importance for phytoremediation applications. In this work, Arabidopsis (Arabidopsis thaliana; ecotype Columbia) seedlings were exposed to 0.6 mM acetochlor (AOC), 2 mM metolachlor (MOC), 0.6 mM 2,4,6-trinitrotoluene (TNT), and 0.3 mM hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX). In vivo glutathione (GSH) conjugation reactions of AOC, MOC, RDX, and TNT were studied in root cells using a multiphoton microscope. In situ labeling with monochlorobimane, used as a competitive compound for conjugation reactions with GSH, confirmed that AOC and MOC are conjugated in Arabidopsis cells. Reverse transcription-PCR established the expression profile of glutathione S-transferases (GSTs) and nitroreductases enzymes. Genes selected for this study were AtGSTF2, AtGSTU1, AtGSTU24, and two isoforms of 12-oxophytodienoate reductase (OPR1 and OPR2). The five transcripts tested were induced by all treatments, but RDX resulted in low induction. The mRNA level of AtGSTU24 showed substantial increase for all chemicals (23-fold induction for AOC, 18-fold for MOC, 5-fold for RDX, and 40-fold for TNT). It appears that GSTs are also involved in the conjugation reactions with metabolites of TNT, and to a lesser extent with RDX. Results indicate that OPR2 is involved in plant metabolism of TNT (11-fold induction), and in oxidative stress when exposed to AOC (7-fold), MOC (9-fold), and RDX (2-fold). This study comprises gene expression analysis of Arabidopsis exposed to RDX and AOC, which are considered significant environmental contaminants, and demonstrates the importance of microscopy methods for phytoremediation investigations.
1 This work was supported by the Strategic Environmental Research and Development Program, the Center for Health Effects of Environmental Contamination, and Conselho Nacional de Desenvolvimento Científico e Tecnológico of the Ministry for Science and Technology of Brazil (scholarship to M.P.M.). The study was conducted as part of a W.M. Keck Foundation project. 2 Present address: Department of Biochemistry and Cell Biology, Rice University MS140, 6100 Main Street, Houston, TX 77251. Article, publication date, and citation information can be found at www.plantphysiol.org/cgi/doi/10.1104/pp.104.056168. * Corresponding author; e-mail jerald-schnoor{at}uiowa.edu; fax 3193355660. Received November 27, 2004; returned for revision March 7, 2005; accepted March 8, 2005. This article has been cited by other articles:
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