Profiling and fingerprinting strategies to assess exposure of edible plants to herbicides

Metabolomic evaluation of selenium seed priming on mitigating lead stress toxicity in Vicia faba plants

BACKGROUND

Persistent lead contamination and the absence of natural remediation elements exacerbate the long-term toxicity of plants. Nevertheless, it has been consistently shown that selenium has a protective effect against heavy metal toxicity in plants. Consequently, it is imperative to identify the metabolic pathways that selenium employs to enhance the resistance of plants to lead stress. This study aimed to investigate the metabolomic alterations induced by selenium priming of Vicia faba seeds to enhance their tolerance to lead stress.

RESULTS

Selenium seed priming significantly improved the growth parameter and mitigated the adverse growth consequences observed under lead stress. Nuclear magnetic resonance-based metabolomic analysis identified 58 metabolites in the polar extracts of the shoots, with the metabolites composed of amino acids (40%), carboxylic acids (12%), fatty acids (11%), carbohydrates (5%), alkaloids (5%), and phenols (4%). The addition of Pb facilitated the biosynthesis of unique metabolites, including 2-methylglutarate, 3-methyladipate, and epinephrine, which were absent in control and selenium-treated samples. Conversely, 4-aminobutyrate and 2-methylglutarate were entirely absent in Pb samples. Selenium-treated plants accumulated trigonelline and AMP at levels 1.4 and 6.0 times, respectively, more than the control samples. Selenium-primed plants exposed to lead stress exhibited higher levels of asparagine, tryptophan, and xanthine compared to other treatments. As determined by both enrichment analysis and pathway analysis, the most significantly altered pathways were alanine, aspartate, and glutamate metabolism; aminoacyl-tRNA biosynthesis; and valine, leucine, and isoleucine biosynthesis pathways.

CONCLUSION

The results demonstrate the crucial role of selenium priming in enhancing the growth and lead stress resistance of Vicia faba plants by significantly altering the concentrations of key metabolites and metabolic pathways, particularly those involved in amino acid metabolism, offering a promising strategy for improving plant resilience to heavy metal contamination.

Non-target metabolomics approach for the investigation of the hidden effects induced by atrazine and its degradation products on plant metabolism

Japanese radish (Raphanus sativus var. longipinnatus) plants grown under laboratory conditions were individually exposed to the same doses of atrazine (2-chloro-4-ethylamino-6-isopropylamino-1,3,5-triazine, ATR) or its main degradation products: either 2-amino-4-chloro-6-isopropylamino-1,3,5-triazine (DEA) or 2-amino-4-chloro-6-ethylamino-1,3,5-triazine (DIA) or desethyl-desisopropyl-atrazine (DEDIA) or 4-(ethylamino)-2-hydroxy-6-(isopropylamino)-1,3,5-triazine (HA), respectively. One week after treatment in plants exposed to ATR, DIA, and DEA, their concentrations were 7.8 μg/g, 9.7 μg/g, and 14.5 μg/g, respectively, while those treated with DEDIA and HA did not contain these compounds. These results were correlated with plant amino acid profile obtained by suspect screening analysis and metabolomic "fingerprint" based on non-target analysis, obtained by liquid chromatography coupled with QTRAP triple quadrupole mass spectrometer. In all cases, both ATR and its by-products were found to interfere with the plant's amino acid profile and modify its metabolic "fingerprint". Therefore, we proved that the non-target metabolomics approach is an effective tool for investigating the hidden effects of pesticides and their transformation products, which is particularly important as these compounds may reduce the quality of edible plants.

The metabolic processes of selected pesticides and their influence on plant metabolism. A case study of two field-cultivated wheat varieties

Pesticides that are absorbed by plants undergo biotransformation and might affect plant metabolic processes. The metabolisms of two cultivated wheat varieties, Fidelius and Tobak, treated with commercially available fungicides (fluodioxonil, fluxapyroxad, and triticonazole) and herbicides (diflufenican, florasulam, and penoxsulam) were studied under field conditions. The results provide novel insights regarding the effects of these pesticides on plant metabolic processes. Plants (roots and shoots) were sampled six times during the six-week experiment. Pesticides and pesticide metabolites were identified using GC-MS/MS, LC-MS/MS, and LC-HRMS, while root and shoot metabolic fingerprints were determined using non-targeted analysis. Fungicide dissipation kinetics were analyzed according to the quadratic mechanism (R²: 0.8522-0.9164) for Fidelius roots, and zero-order for Tobak roots (R²: 0.8455-0.9194); shoot dissipation kinetics were analyzed according to first-order (R²: 0.9593-0.9807) and quadratic (R²: 0.8415-0.9487) mechanisms for Fidelius and Tobak, respectively. The fungicide degradation kinetics were different compared to reported literature values, most likely due to differences in pesticide application methods. The following metabolites were respectively identified in shoot extracts of both wheat varieties for fluxapyroxad, triticonazole, and penoxsulam: 3-(difluoromethyl)-N-(3',4',5'-trifluorobiphenyl-2-yl)-1H pyrazole-4-carboxamide, 2-chloro-5-{(E)-[2-hydroxy-3,3-dimethyl-2-(1H-1,2,4-triazol-1-ylmethyl)-cyclopentylidene]-methyl}phenol, and N-(5,8-dimethoxy[1,2,4]triazolo[1,5-c]pyrimidin-2-yl)-2,4-dihydroxy-6 (trifluoromethyl)benzene sulfonamide. Metabolite dissipation kinetics varied depending on the wheat variety. These compounds were more persistent than parent compounds. Despite having the same cultivation conditions, the two wheat varieties varied in their metabolic fingerprints. The study revealed that pesticide metabolism has a greater dependence on plant variety and method of administration compared to the physicochemical properties of the active substance. This highlights the necessity of conducting research on pesticide metabolism under field conditions.