Genetic modification of western wheatgrass (Pascopyrum smithii) for the phytoremediation of RDX and TNT
- 87 Downloads
Transgenic western wheatgrass degrades the explosive RDX and detoxifies TNT.
Contamination, from the explosives, hexahydro-1, 3, 5-trinitro-1, 3, 5-triazine (RDX), and 2, 4, 6-trinitrotoluene (TNT), especially on live-fire training ranges, threatens environmental and human health. Phytoremediation is an approach that could be used to clean-up explosive pollution, but it is hindered by inherently low in planta RDX degradation rates, and the high phytotoxicity of TNT. The bacterial genes, xplA and xplB, confer the ability to degrade RDX in plants, and a bacterial nitroreductase gene nfsI enhances the capacity of plants to withstand and detoxify TNT. While the previous studies have used model plant species to demonstrate the efficacy of this technology, trials using plant species able to thrive in the challenging environments found on military training ranges are now urgently needed. Perennial western wheatgrass (Pascopyrum smithii) is a United States native species that is broadly distributed across North America, well-suited for phytoremediation, and used by the US military to re-vegetate military ranges. Here, we present the first report of the genetic transformation of western wheatgrass. Plant lines transformed with xplA, xplB, and nfsI removed significantly more RDX from hydroponic solutions and retained much lower, or undetectable, levels of RDX in their leaf tissues when compared to wild-type plants. Furthermore, these plants were also more resistant to TNT toxicity, and detoxified more TNT than wild-type plants. This is the first study to engineer a field-applicable grass species capable of both RDX degradation and TNT detoxification. Together, these findings present a promising biotechnological approach to sustainably contain, remove RDX and TNT from training range soil and prevent groundwater contamination.
KeywordsPhytoremediation RDX TNT Western wheatgrass Transformation Monocot promoters Stacked genes
The authors declare no conflict of interest. This work was funded by US DoD SERDP ER-1498 and ESTCP ER-201436. We thank Mr. Ryan Routsong for his work of maintaining the HPLC system and advice for preparing HPLC samples.
- Gunning V, Tzafestas K, Sparrow H, Johnston EJ, Brentnall AS, Potts JR, Rylott EL, Bruce NC (2014) Arabidopsis glutathione transferases U24 and U25 exhibit a range of detoxification activities with the environmental pollutant and explosive, 2,4,6-trinitrotoluene. Plant Physiol 165:854–865CrossRefGoogle Scholar
- Mann DG, Lafayette PR, Abercrombie LL, King ZR, Mazarei M, Halter MC, Poovaiah CR, Baxter H, Shen H, Dixon RA, Parrott WA, Neal Stewart C Jr (2012) Gateway-compatible vectors for high-throughput gene functional analysis in switchgrass (Panicum virgatum L.) and other monocot species. Plant Biotechnol J 10:226–236CrossRefGoogle Scholar
- Ramasahayam S, Jaligama S, Atwa SM, Salley JT, Thongdy M, Blaylock BL, Meyer SA (2017) Megakaryocyte expansion and macrophage infiltration in bone marrow of rats subchronically treated with MNX, N-nitroso environmental degradation product of munitions compound RDX (hexahydro-1,3,5-trinitro-1,3,5-triazine). J Appl Toxicol 37:913–921CrossRefGoogle Scholar
- United States Department of Agriculture (2002) Plant fact sheet-western wheatgrass (Pascopyrum smithii) https://plants.usda.gov/factsheet/pdf/fs_pasm.pdf
- United States Environmental Protection Agency (2014) Technical fact sheet –hexahydro-1,3,5-trinitro- 1,3,5-triazine (RDX) https://www.epa.gov/sites/production/files/2014-03/documents/ffrrofactsheet_contaminant_rdx_january2014_final.pdf and technical fact sheet—2,4,6-trinitrotoluene (TNT) https://www.epa.gov/sites/production/files/2014-03/documents/ffrrofactsheet_contaminant_tnt_january2014_final.pdf
- United States General Accounting Office (2004) Department of Defense operational ranges, more reliable cleanup cost estimates and a proactive approach to identifying contamination are needed. http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA435939&Location=U2&doc=GetTRDoc.pdf