Genetic modification of western wheatgrass (Pascopyrum smithii) for the phytoremediation of RDX and TNT

Abstract

Contamination, from the explosives, hexahydro-1, 3, 5-trinitro-1, 3, 5-triazine (RDX) and 2, 4, 6trinitrotoluene (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 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, and remove, RDX and TNT from training range soil and prevent groundwater contamination.

Roadmap for Accelerated Domestication of an Emerging Perennial Grain Crop

“…Few genetic transformation protocols and no genome editing studies have been reported for T. intermedium [66]. To increase the gene transformation efficiency, both Agrobacteriummediated and biolistic transformation methods need to be optimized and established in T. intermedium.…”

Implementation of Omics Research to Enhance Phytoremediation Efficiency - a Review

“…Phytoremediation can be a reliable, cost-efficient and vastly socially acceptable technology for dealing with contaminated lands. To increase its efficiency new omics approaches has gained a lot of interest in recent years [34]. Our review shows, that such large omics data sets have already identified specific environmental conditions that shape the quantity and quality of microbial communities in soil.…”

“…Study showed that transformed plants removed significantly more RDX when compared to wild-type plants. Furthermore, these plants were also more resistant to TNT toxicity, and detoxified more TNT than wild-type plants [34].…”

“…Sedum alfredii cadmium 2016 [8] Populus nigra boron 2016 [9] Phytolacca americana cadmium 2018 [6] Medicago sativa atrazine 2016 [5] Landoltia punctata cadmium 2018 [34] Zea mays PAHs 2018 [4] Festuca arundinacea cadmium 2018 [15] Nicotiana tabacum thorium 2018 [30] Sorghum bicolor cadmium 2017 [14] 3.3. The use of omics for designing new transgenic species…”

Right on target: using plants and microbes to remediate explosives

“…Etroploe) expressing a bacterial TNT-detoxifying nitroreductase . Further progress has since been made with RDX-degrading switchgrass (Panicum virgatum), wheatgrass (Pascopyrum smithii) and creeping bentgrass (Agrostis stolonifera) transformed with xplA, xplB and nfsI Zhang et al 2018Zhang et al , 2016. The next steps now require the development of transformation protocols for a broader range of plant species such as vetiver and miscanthus.…”