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Abstract
Serial Analysis of Gene Expression (SAGE) was used to profile transcript levels in Arabidopsis thaliana roots and assess their responses to 2,4,6-trinitrotoluene (TNT) and 1,3,5-hexahydro-1,3,5-triazine (RDX) exposure. SAGE libraries representing control, TNT, and RDX-exposed seedling root transcripts were constructed, and each was sequenced to a depth of roughly 30,000 tags. More than 19,000 unique tags were identified overall. Upon TNT exposure, the second most highly induced tag (27-fold increase) represented a glutathione S-transferase. Several cytochrome P450 enzymes, as well as an ABC transporter, were also highly induced by TNT exposure. These analyses also revealed an oxidative stress response upon TNT exposure. RDX exposure also induced a number of transcripts including: molecular chaperones and transcription factors, as well as vacuolar proteins and peroxidases. Comparison of these transcripts to those induced by TNT, identified significant differences, suggesting drastically different mechanisms for the metabolism of these two compounds. Preliminary DNA microarray analyses were also used to verify the expression levels of transcripts affected by TNT as identified previously by SAGE. Identification of transcriptome-level responses to TNT and RDX exposure will better define the metabolic pathways plants use to detoxify these xenobiotic compounds, which should help us improve phytoremediation strategies directed at these and other nitroaromatic compounds.