Gene Expression Changes in Arabidopsis thaliana Seedling Roots Exposed to the Munition Hexahydro-1,3,5-trinitro-1,3,5-triazine

Arabidopsis thaliana root transcriptome responses to the munition, hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), were assessed using serial analysis of gene expression (SAGE). Sequencing of SAGE libraries from control and RDX-exposed root tissues revealed induction of genes known to respond to a variety of general stresses. Among the highly induced genes were several encoding molecular chaperones and transcription factors as well as vacuolar proteins and peroxidases. Strongly repressed transcripts included ones encoding ribosomal proteins, a cyclophilin, a katanin, and a peroxidase. Comparison of the transcriptional profile for the RDX response to a profile previously described for Arabidopsis roots exposed to trinitrotoluene (TNT) revealed significant differences in the inferred gene expression patterns. This suggests that Arabidopsis employs drastically different mechanisms for coping with these two compounds. With respect to the goal of engineering plants to better tolerate and degrade explosives at contaminated sites, these results suggest that enhancement of different genes and metabolic pathways may be required to deal effectively with each type of explosive. This has ramifications for phytoremediation efforts since many contaminated sites harbor both compounds.