Consequences of phosphate application on glyphosate uptake by roots: Impacts for environmental management practices.
Phosphate (PO4(3-)) fertilization is a common practice in agricultural fields also targets for glyphosate application. Due to their chemical similarities, PO4(3-) and glyphosate compete for soil adsorbing sites, with PO4(3-) fertilization increasing glyphosate bioavailability in the soil solution. After PO4(3-) fertilization, its concentration will be elevated in the soil solution and both PO4(3-) and glyphosate will be readily available for runoff into aquatic ecosystems. In this context, man-made riparian buffer strips (RBS) at the interface of agricultural lands and waterways can be used as a green technology to mitigate water contamination. The plants used in RBS form a barrier to agricultural wastes that can limit runoff, and the ability of these plants to take up these compounds through their roots plays an important role in RBS efficacy. However, the implications of PO4(3-) for glyphosate uptake by roots are not yet clearly demonstrated. Here, we addressed this problem by hydroponically cultivating willow plants in nutrient solutions amended with glyphosate and different concentrations of PO4(3-), assuring full availability of both chemicals to the roots. Using a phosphate carrier inhibitor (phosphonophormic acid-PFA), we found that part of the glyphosate uptake is mediated by PO4(3-) transporters. We observed, however, that PO4(3-) increased glyphosate uptake by roots, an effect that was related to increased root cell membrane stability. Our results indicate that PO4(3-) has an important role in glyphosate physiological effects. Under agricultural conditions, PO4(3-) fertilization can amplify glyphosate efficiency by increasing its uptake by the roots of undesired plants. On the other hand, since simultaneous phosphate and glyphosate runoffs are common, non-target species found near agricultural fields can be affected.
Université du Québec à Montréal, Department of Biological Sciences, TOXEN, Ecotoxicology of Aquatic Microorganisms Laboratory, Succ. Centre-Ville, H3C 3P8 Montréal, Québec, Canada; Université du Québec à Montréal, Institut des Sciences de l'environnement, Succ. Centre-Ville, C.P. 8888, H3C 3P8 Montréal, Québec, Canada.
Marcelo Pedrosa
MP
Gomes
Université du Québec à Montréal, Institut des Sciences de l'environnement, Succ. Centre-Ville, C.P. 8888, H3C 3P8 Montréal, Québec, Canada.
Sophie
S
Maccario
Université du Québec à Montréal, Institut des Sciences de l'environnement, Succ. Centre-Ville, C.P. 8888, H3C 3P8 Montréal, Québec, Canada.
Marc
M
Lucotte
Institut de Recherche en Biologie Végétale, Montreal Botanical Garden, 4101 Sherbrooke East, H1X 2B2 Montréal, Québec, Canada.
Michel
M
Labrecque
Université du Québec à Montréal, Department of Biological Sciences, TOXEN, Ecotoxicology of Aquatic Microorganisms Laboratory, Succ. Centre-Ville, H3C 3P8 Montréal, Québec, Canada; Université du Québec à Montréal, Institut des Sciences de l'environnement, Succ. Centre-Ville, C.P. 8888, H3C 3P8 Montréal, Québec, Canada. Electronic address: juneau.philippe@uqam.ca.
Philippe
P
Juneau
D005998:Glycine / Q000031:analogs & derivatives* / Q000378:metabolism; D006540:Herbicides / Q000378:metabolism; D010710:Phosphates / Q000378:metabolism*; D018517:Plant Roots / Q000378:metabolism*; D032108:Salix; D012987:Soil / Q000737:chemistry; D012989:Soil Pollutants / Q000378:metabolism*; D000097797:Glyphosate
D005998:Glycine; D006540:Herbicides; D010710:Phosphates; D012987:Soil; D012989:Soil Pollutants; D000097797:Glyphosate
Contamination; Herbicide; Phosphate carriers; Phytoremediation; Riparian buffer strips; Transport