Glyphosate-remediation potential of selected plant species in artificial wetlands

Glyphosate is a systemic herbicide with an important environmental impact due to its adverse effect on non-target organisms. Its removal can be accomplished by wild (native) plants which, together with their associated microbiota, have acquired tolerance against glyphosate or are able to degrade it. Little is known, however, about these plants' potential for glyphosate remediation and the role that plant-microbe interactions play in this process. The objective of the present study was to evaluate plant species from locations with a history of glyphosate exposure - drainage ditches of banana plantations (Musa sp.), or riparian areas - to determine which, in combination with their microbiota, promote the removal of glyphosate. Five plant species were selected to evaluate their response to inundated growing conditions and exposure to 20 mg glyphosate acid equivalent/L for 47 days. Parameters affecting plant growth and glyphosate removal were recorded. Rhizosphere bacterial strains were identified and their tolerance to different glyphosate concentrations determined. Also, the activity of 19 rhizospheric enzymes associated with the phosphorus, carbon and nitrogen cycles were analyzed. Glyphosate-treated Panicum maximum exhibited the highest removal efficiency (87%), followed by Typha domingensis and Heliconia latispatha. All plants were associated with glyphosate-tolerant bacteria, and in the cases of Xanthosoma sagittifolium and Fimbristylis dichotoma, strains were recovered that even succeeded in growing in a medium containing 40 g glyphosate ae/L. Processes involved in carbon, nitrogen and phosphorus metabolism in the rhizosphere were affected by glyphosate exposure, and the importance of plant-microbe-substrate interactions in the elimination of glyphosate was evinced. Although all plants contributed to the removal of glyphosate, their use in phytoremediation projects will depend on the location and nature of the environmental problem to be resolved. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

The study evaluated five plant species from locations with a history of glyphosate exposure and found that Panicum maximum exhibited the highest glyphosate removal efficiency. The plant-microbe-substrate interactions played a significant role in the elimination of glyphosate.