Unravelling the Phytotoxic Effects of Glyphosate on Sensitive and Resistant Amaranthus palmeri Populations by GC–MS and LC–MS Metabolic Profiling

Abstract

Glyphosate, the most successful herbicide in history, specifically inhibits the activity of the enzyme 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS; EC 2.5.1.19), one of the key enzymes in the shikimate pathway. Amaranthus palmeri is a driver weed in agriculture today that has evolved glyphosate-resistance through increased EPSPS gene copy number and other mechanisms. Non-targeted GC–MS and LC–MS metabolomic profiling was conducted to examine the innate physiology and the glyphosate-induced perturbations in one sensitive and one resistant (by EPSPS amplification) population of A. palmeri. In the absence of glyphosate treatment, the metabolic profile of both populations was very similar. The comparison between the effects of sublethal and lethal doses on sensitive and resistant populations suggests that lethality of the herbicide is associated with an amino acid pool imbalance and accumulation of the metabolites of the shikimate pathway upstream from EPSPS. Ferulic acid and its derivatives were accumulated in treated plants of both populations, while quercetin and its derivative contents were only lower in the resistant plants treated with glyphosate.

Yeast of Eden: microbial resistance to glyphosate from a yeast perspective

“…Glyphosate is a broad-spectrum herbicide that inhibits EPSP synthase, an enzyme that converts shikimate 3-phosphate to 5-enolpyruvylshik i mate 3-phosphate (EPSP), a key step, in the shikimate pathway (also called the chorismate pathway) in plants, bacteria, and fungi. This leads to the depletion of chorismate, the precursor for all compounds containing aromatic rings, such as tryptophan, tyrosine, phenylalanine, pABA, and ubiquinone (Marbois et al 2010 ) as well as metabolites from the TCA cycle (Zulet-Gonzalez et al 2023 ). At lower doses, glyphosate itself does not kill plants but reduces their ability to grow and mount an effective immune response to infections, due to the aromatic precursors being building blocks for important molecules such as auxin, salicylic acid, and melatonin (Sauer et al 2013 ; Pérez-Llorca et al 2019 ), as well as structural compounds like lignin (Jalal et al 2021 ).…”

“…A side effect of glyphosate inhibiting shikimate is increased levels of PEP, one of the necessary components to build shikimate. Citric acid cycle intermediates increase in glyphosate-resistant Amaranthus palmeri in a dose-dependent manner while increased levels were detected in sublethal exposed glyphosate-resistant varieties (Zulet-Gonzalez et al 2023 ). The glyphosate-resistant A. palmeri have amplified the EPSP loci; however, the entire genome was not sequence so it is unknown what other compensatory mutations occurred (Fernández-Escalada et al 2016 ).…”

Comprehensive insights into herbicide resistance mechanisms in weeds: a synergistic integration of transcriptomic and metabolomic analyses

“…They didn’t find any differences in the metabolic profiles in the absence of herbicide treatment. However, upon treatment with glyphosate, they detected reduced concentrations of quercetin and its derivatives only in the resistant plants ( Zulet-Gonzalez et al., 2023 ). In another study conducted by Tafoya-Razo et al., the authors conducted metabolic fingerprinting of susceptible and resistant common Avena fatua L. populations using Desorption Electrospray Ionization-Mass Spectrometry (DIESI-MS).…”

Pollutants, including Organophosphorus and Organochloride Pesticides, May Increase the Risk of Cardiac Remodeling and Atrial Fibrillation: A Narrative Review

“…The chemical structure of glyphosate includes monobasic (carboxylic) and dibasic (phosphonic) acidic sites and an amino acid glycine [ 69 ] ( Figure 4 ). The primary target of glyphosate is the shikimate pathway, which produces the aromatic amino acids phenylalanine, tyrosine, and tryptophan in plants and microorganisms [ 70 ]. When glyphosate started to be commercialized, due to its specific effects on vegetables, its toxicity on mammals, including animals and humans was minimized or unsuspected [ 66 ].…”