Gene expression and microscopic analysis of Arabidopsis exposed to chloroacetanilide herbicides and explosive compounds. A phytoremediation approach.
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.
Mezzari
Melissa P
MP
Department of Civil and Environmental Engineering , University of Iowa, Iowa City, Iowa 52242, USA.
Walters
Katherine
K
Jelínkova
Marcela
M
Shih
Ming-Che
MC
Just
Craig L
CL
Schnoor
Jerald L
JL
D000081:Acetamides / Q000378:metabolism / Q000494:pharmacology; D017360:Arabidopsis / Q000187:drug effects* / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000378:metabolism; D001673:Biodegradation, Environmental; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D005978:Glutathione / Q000378:metabolism; D006540:Herbicides / Q000378:metabolism / Q000494:pharmacology*; D018613:Microscopy, Confocal; D008969:Molecular Sequence Data; D018517:Plant Roots / Q000166:cytology / Q000378:metabolism; D014052:Toluidines / Q000378:metabolism / Q000494:pharmacology; D014227:Triazines / Q000378:metabolism / Q000494:pharmacology*; D014303:Trinitrotoluene / Q000378:metabolism / Q000494:pharmacology*
D000081:Acetamides; D029681:Arabidopsis Proteins; D006540:Herbicides; D014052:Toluidines; D014227:Triazines; D014303:Trinitrotoluene; C043377:acetochlor; D005978:Glutathione; C009160:cyclonite; C051786:metolachlor