Perfluorooctanoic acid (PFOA) changes nutritional compositions in lettuce (Lactuca sativa) leaves by activating oxidative stress

PFOA accumulation in the leaves of basil (Ocimum basilicum L.) and its effects on plant growth, oxidative status, and photosynthetic performance

BACKGROUND

Perfluoroalkyl substances (PFASs) are emerging contaminants of increasing concern due to their presence in the environment, with potential impacts on ecosystems and human health. These substances are considered "forever chemicals" due to their recalcitrance to degradation, and their accumulation in living organisms can lead to varying levels of toxicity based on the compound and species analysed. Furthermore, concerns have been raised about the possible transfer of PFASs to humans through the consumption of edible parts of food plants. In this regard, to evaluate the potential toxic effects and the accumulation of perfluorooctanoic acid (PFOA) in edible plants, a pot experiment in greenhouse using three-week-old basil (Ocimum basilicum L.) plants was performed adding PFOA to growth substrate to reach 0.1, 1, and 10 mg Kg- 1 dw.

RESULTS

After three weeks of cultivation, plants grown in PFOA-added substrate accumulated PFOA at different levels, but did not display significant differences from the control group in terms of biomass production, lipid peroxidation levels (TBARS), content of α-tocopherol and activity of ascorbate peroxidase (APX), catalase (CAT) and guaiacol peroxidase (POX) in the leaves. A reduction of total phenolic content (TPC) was instead observed in relation to the increase of PFOA content in the substrate. Furthermore, chlorophyll content and photochemical reflectance index (PRI) did not change in plants exposed to PFAS in comparison to control ones. Chlorophyll fluorescence analysis revealed an initial, rapid photoprotective mechanism triggered by PFOA exposure, with no impact on other parameters (Fv/Fm, ΦPSII and qP). Higher activity of glutathione S-transferase (GST) in plants treated with 1 and 10 mg Kg- 1 PFOA dw (30 and 50% to control, respectively) paralleled the accumulation of PFOA in the leaves of plants exposed to different PFOA concentration in the substrate (51.8 and 413.9 ng g- 1 dw, respectively).

CONCLUSION

Despite of the absorption and accumulation of discrete amount of PFOA in the basil plants, the analysed parameters at biometric, physiological and biochemical level in the leaves did not reveal any damage effect, possibly due to the activation of a detoxification pathway likely involving GST.

Perfluorobutanoic acid triggers metabolic and transcriptional reprogramming in wheat seedlings

The environmental risks of fluorinated alternatives are of great concern with the phasing out of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate. Here, multi-omics (i.e., metabolomics and transcriptomics) coupled with physiological and biochemical analyses were employed to investigate the stress responses of wheat seedings (Triticum aestivum L.) to perfluorobutanoic acid (PFBA), one of the short-chain per- and polyfluoroalkyl substances (PFAS) and PFOA alternatives, at environmentally relevant concentrations (0.1-100 ng/g). After 28 days of soil exposure, PFBA boosted the generation of OH and O2- in wheat seedlings, resulting in lipid peroxidation, protein perturbation and impaired photosynthesis. Non-enzymatic antioxidant defense systems (e.g., glutathione, phenolics, and vitamin C) and enzymatic antioxidant copper/zinc superoxide dismutase were strikingly activated (p < 0.05). PFBA-triggered oxidative stress induced metabolic and transcriptional reprogramming, including carbon and nitrogen metabolisms, lipid metabolisms, immune responses, signal transduction processes, and antioxidant defense-related pathways. Down-regulation of genes related to plant-pathogen interaction suggested suppression of the immune-response, offering a novel understanding on the production of reactive oxygen species in plants under the exposure to PFAS. The identified MAPK signaling pathway illuminated a novel signal transduction mechanism in plant cells in response to PFAS. These findings provide comprehensive understandings on the phytotoxicity of PFBA to wheat seedlings and new insights into the impacts of PFAS on plants.

Perfluoroalkyl substances exposure alters stomatal opening and xylem hydraulics in willow plants

Climate change and pollution are increasingly important stress factors for life on Earth. Dispersal of poly- and perfluoroalkyl substances (PFAS) are causing worldwide contamination of soils and water tables. PFAS are partially hydrophobic and can easily bioaccumulate in living organisms, causing metabolic alterations. Different plant species can uptake large amounts of PFAS, but little is known about its consequences for the plant water relation and other physiological processes, especially in woody plants. In this study, we investigated the fractionation of PFAS bioaccumulation from roots to leaves and its effects on the conductive elements of willow plants. Additionally, we focused on the stomal opening and the phytohormonal content. For this purpose, willow cuttings were exposed to a mixture of 11 PFAS compounds and the uptake was evaluated by LC-MS/MS. Stomatal conductance was measured and the xylem vulnerability to air embolism was tested and further, the abscisic acid and salicylic acid contents were quantified using LC-MS/MS. PFAS accumulated from roots to leaves based on their chemical structure. PFAS-exposed plants showed reduced stomatal conductance, while no differences were observed in abscisic acid and salicylic acid contents. Interestingly, PFAS exposure caused a higher vulnerability to drought-induced xylem embolism in treated plants. Our study provides novel information about the PFAS effects on the xylem hydraulics, suggesting that the plant water balance may be affected by PFAS exposure. In this perspective, drought events may be more stressful for PFAS-exposed plants, thus reducing their potential for phytoremediation.

α-Galactosidase interacts with persistent organic pollutants to induce oxidative stresses in rice (Oryza sativa L.)

Persistent organic pollutants (POPs) in agricultural soil often triggered metabolic alterations and phytotoxicity in plants, ultimately threatening crop quality. Unraveling the phytotoxic mechanisms of POPs in crops is critical for evaluating their environmental risks. Herein, the molecular mechanism of POP-induced phytotoxicity in rice (Oryza sativa L.) was analyzed using metabolic profile, enzyme activity, and gene expression as linkages, including polycyclic aromatic hydrocarbons, polybrominated diphenyl ethers, polychlorinated biphenyls, and phthalate esters. Despite no observable changes in phenotypic traits (e.g., biomass and length of aboveground), the levels of reactive oxygen species (ROS) were promoted under stresses of the tested POPs, particularly 2,2',4,4'-tetrabromodiphenyl ether (BDE-47), dibutyl phthalate (DBP), and di(2-ethylhexyl) phthalate (DEHP). Metabolomics analysis revealed that ROS contents positively correlated with metabolic perturbation levels (r = 0.83), among which the galactose metabolism was significantly inhibited when exposed to DBP, DEHP, or BDE-47. The α-Galactosidase (α-Gal) involved in galactose metabolism was targeted as the key enzyme for the phytotoxicity of DBP, DEHP, and BDE-47, which was revealed by the inhibition of saccharide levels (45.5-82.1%), the catalytic activity of α-Gal (18.5-24.3%), and the gene expression (28.5-34.5%). Molecular docking simulation suggested that the three POPs occupied the active sites of α-Gal and formed a stable protein-ligand complex, thus inhibiting the catalytic activity of α-Gal. Partial least-squares regression analysis indicated that α-Gal activity was negatively associated with hydrogen bond acceptor, rotatable bond, and topological polar surface area of POPs. The results offered novel insights into the molecular mechanisms of phytotoxicity of POPs and provided important information for evaluating the environmental risk of POPs.

Joint effects of CuO nanoparticles and perfluorooctanoic acid on cabbage (Brassica pekinensis L.)

Coexisting nanoparticles (NPs) may change plant accumulation and toxicity of perfluorooctanoic acid (PFOA) in soil, but research is very scarce. In this study, cabbage (Brassica pekinensis L.) was exposed to single or combined treatments of PFOA (2 mg/kg and 4 mg/kg) and copper oxide NPs (nCuO, 200 mg/kg and 400 mg/kg) for 40 days. At harvest, biomass, photosynthesis index, and nutrient composition of cabbage, as well as plant accumulation of PFOA and Cu, were measured. Results showed that nCuO and PFOA were adverse to cabbage growth by decreasing chlorophyll contents, inhibiting photosynthesis and transpiration, and interfering with the utilization of nutrient components. Besides, they also affected each other's plant utilization and transmission. Especially, nCuO at a high dose (400 mg/kg) significantly increased the transport of coexisting PFOA (4 mg/kg) content (by 124.9% and 118.2%) to cabbage shoots. The interaction mechanism between nCuO and PFOA is unknown, and more research is needed to evaluate their composite phytotoxicity.

Bioavailability, phytotoxicity and plant uptake of per-and polyfluoroalkyl substances (PFAS): A review

Per- and polyfluoroalkyl substances (PFAS) are a group of legacy and emerging contaminants containing at least one aliphatic perfluorocarbon moiety. They display rapid and extensive transport in the environment due to their generally high water-solubility and weak adsorption onto soil particles. Because of their widespread presence in the environment and known toxicity, PFAS has become a serious threat to the ecosystem and public health. Plants are an essential component of the ecosystem and their uptake and accumulation of PFAS affect the fate and transport of PFAS in the ecosystem and has strong implications for human health. It is therefore imperative to investigate the interactions of plants with PFAS. This review presents a detailed discussion on the mechanisms of the bioavailability and plant uptake of PFAS, and essential factors affecting these processes. The phytotoxic effects of PFAS at physiological, biochemical, and molecular level were also carefully reviewed. At the end, key research gaps were identified, and future research needs were proposed.

Effects of physicochemical properties and co-existing zinc agrochemicals on the uptake and phytotoxicity of PFOA and GenX in lettuce

Even though the potential toxicity and treatment methods for per- and polyfluoroalkyl substances (PFAS) have attracted extensive attention, the plant uptake and accumulation of PFAS in edible plant tissues as a potential pathway for human exposure received little attention. Our study in a hydroponic system demonstrated that perfluorooctanoic acid (PFOA) and its replacing compound, 2,3,3,3-tetrafluoro-2-(heptafluoropropoxy) propanoic acid (GenX) displayed markedly different patterns of plant uptake and accumulation. For example, the root concentration factor (RCF) of PFOA in lettuce is almost five times of that of GenX while the translocation factor (TF) of GenX is about 66.7% higher than that for PFOA. The co-presence of zinc amendments affected the phyto-effect of these two compounds and their accumulation in plant tissues, and the net effect on their plant accumulation depended on both the properties of Zn amendments and PFAS. Zinc oxide nanoparticles (ZnONPs) at 100 mg/L did not affect the uptake of PFOA in either lettuce roots or shoots; however, Zn2+ at the same concentration significantly increased PFOA accumulation in both tissues. In contrast, both Zn amendments significantly lowered the accumulation of GenX in lettuce roots, but only ZnONPs significantly hindered the GenX accumulation in lettuce shoots. The co-exposure to ZnONPs and PFOA/GenX resulted in lower oxidative stress than the plants exposed to PFOA or GenX alone. However, both zinc agrochemicals with or without PFAS led to lower root dry biomass. The results shed light on the property-dependent plant uptake of PFAS and the potential impact of co-existing nanoagrochemicals and their dissolved ions on plant uptake of PFOA and GenX.

Removal of Per-, Poly-fluoroalkyl substances (PFASs) and multi-biosphere community dynamics in a bacteria-algae symbiotic aquatic ecosystem

The presence of Per-, Poly-fluoroalkyl substances (PFASs) in aquatic ecosystems has drawn broad concerns in the scientific community due to their biological toxicity. However, little has been explored regarding PFASs' removal in phytoplankton-dominated environments. This study aimed to create a simulated bacteria-algae symbiotic ecosystem to observe the potential transportation of PFASs. Mass distributions showed that sand (63-2000 μm), silt & clay (0-63 μm), the phycosphere (>3 μm plankton), and the free-living biosphere (0.22-3 μm plankton) contained 19.00, 7.78, 5.73 and 2.75% PFASs in their total mass, respectively. Significant correlations were observed between carbon chain lengths and removal rates (R² = 0.822, p < 10^-4). Structural equation models revealed potential PFAS transportation pathways, such as water-phycosphere- free-living biosphere-sand-silt&clay, and water-sand-silt&clay (p < 0.05). The presence of PFASs decreased the bacterial density but increased algal density (p < 0.01) in the planktonic environment, and PFASs with longer carbon chain lengths showed a stronger enhancement in microbial community successions (p < 0.05). In algal metabolisms, chlorophyll-a and carotenoids were the key pigments that resisted reactive oxygen species caused by PFASs. PFBA (perfluorobutyric acid) (10.38-14.68%) and PFTeDA (perfluorotetradecanoic acid) (10.33-15.96%) affected bacterial metabolisms in phycosphere the most, while in the free-living biosphere was most effected by PFPeA (perfluorovaleric acid) (13.21-13.99%) and PFDoA (perfluorododecanoic acid) (10.04-10.50%). The results of this study provide new guidance measures for PFAS removal and management in aquatic environments.

Effects of trace PFOA on microbial community and metabolisms: Microbial selectivity, regulations and risks

Perfluorooctanoic acid (PFOA), a "forever chemical", is continuously discharged and mitigated in the environment despite its production and use being severely restricted globally. Due to the transformation, attachment, and adsorption of PFOA in aquatic environments, PFOA accumulates in the porous media of sediments, soils, and vadose regions. However, the impact of trace PFOA in the porous media on interstitial water and water safety is not clear. In this work, we simulated a porous media layer using a sand column and explored the effects of µg-level PFOA migration on microbial community alternation, microbial function regulation, and the generation and spread of microbial risks. After 60 days of PFOA stimulation, Proteobacteria became the dominant phylum with an abundance of 91.8%, since it carried 71% of the antibiotic resistance genes (ARGs). Meanwhile, the halogen-related Dechloromonas abundance increased from 0.4% to 10.6%. In addition, PFOA significantly stimulated protein (more than 1288%) and polysaccharides (more than 4417%) production by up-regulating amino acid metabolism (p< 0.001) and membrane transport (p < 0.001) to accelerate the microbial aggregation. More importantly, the rapidly forming biofilm immobilized and blocked PFOA. The more active antioxidant system repaired the damaged cell membrane by significantly up-regulating glycerophospholipid metabolism and peptidoglycan biosynthesis. It is worth noting that PFOA increased the abundance of antibiotic resistance genes (ARGs) and human bacterial pathogens (HBPs) in porous media by 30% and 106%. PFOA increased the proportion of vertical transmission ARGs (vARGs), and co-occurrence network analysis (r ≥ 0.8, p ≤ 0.01) verified that vARGs were mainly mediated by HBPs. A comprehensive understanding of PFOA interactions with its microecological environment is provided.

β-Glucosidases as dominant dose-dependent regulators of Oryza sativa L. in response to typical organic pollutant exposures

Understanding the metabolic defense and compensation to maintain homeostasis is crucial for assessing the potential health risk of organic pollutants in crops. Currently, limited understanding is available regarding the targeted metabolic pathways and response mechanism under contaminant stress. This study showed that ciprofloxacin (CIP) at the environmental concentrations (1, 5, 25, 50 mg/L) did not significantly inhibit growth or cause severe oxidative damage to rice (Oryza sativa L.). Instead, the increment in CIP concentration induced a series of sequential metabolic disorders, which were characterized predominantly by primary and secondary metabolic disturbances, including phenylpropanoid biosynthesis, the carbohydrate, lipid and amino acid metabolism. After CIP in vivo exceeded a certain threshold level (>0.29 mg/g dry weight), β-glucosidases (BGLUs) mediated the transition from the activation of the genes related to phenylpropanoid biosynthesis to the inhibition of the genes related to carbohydrate metabolism in rice. In particular, starch and sucrose metabolism showed the most profound perturbation stressed by environmental concentrations of CIP (5 mg/L) and other tested organic pollutants (10 μg/L of tricyclazole, thiamethoxam, polybrominated diphenyl ethers, and polychlorinated biphenyls). Besides, the key genes encoding endoglucanase and BGLU were significantly downregulated (|log₂FC| > 3.0) under 100 μg/L of other tested organic pollutants, supporting the transition from the activation of secondary defense metabolism to the disruption of primary energy metabolism. Thus, in addition to bioaccumulation, changes in BGLU activity and starch and sucrose metabolism can reflect the potential adverse effects of pollutants on rice. This study explained the stepwise metabolic and transcriptional responses of rice to organic pollutants, which provided a new reference for the comprehensive evaluation of their environmental risks.

Perfluorobutanoic Acid (PFBA) Induces a Non-Enzymatic Oxidative Stress Response in Soybean (Glycine max L. Merr.)

Short-chain perfluoroalkyl substances (PFAS) are generally considered to be of less environmental concern than long-chain analogues due to their comparatively shorter half-lives in biological systems. Perfluorobutanoic acid (PFBA) is a short-chain PFAS with the most root–shoot transfer factor of all PFAS. We investigated the impact of extended exposure of soybean plants to irrigation water containing environmentally relevant (100 pg–100 ng/L) to high (100 µg–1 mg/L) concentrations of PFBA using phenotypical observation, biochemical characterization, and transcriptomic analysis. The results showed a non-monotonous developmental response from the plants, with maximum stimulation and inhibition at 100 ng/L and 1 mg/L, respectively. Higher reactive oxygen species and low levels of superoxide dismutase (SOD) and catalase (CAT) activity were observed in all treatment groups. However transcriptomic analysis did not demonstrate differential expression of SOD and CAT coding genes, whereas non-enzymatic response genes and pathways were enriched in both groups (100 ng/L and 1 mg/L) with glycine betaine dehydrogenase showing the highest expression. About 18% of similarly downregulated genes in both groups are involved in the ethylene signaling pathway. The circadian rhythm pathway was the only differentially regulated pathway between both groups. We conclude that, similar to long chain PFAS, PFBA induced stress in soybean plants and that the observed hormetic stimulation at 100 ng/L represents an overcompensation response, via the circadian rhythm pathway, to the induced stress.

Evaluation of the ecological impacts of short- and long-chain perfluoroalkyl acids on constructed wetland systems: Perfluorobutyric acid and perfluorooctanoic acid

Perfluoroalkyl substances (PFASs) contamination of aquatic system has attracted widespread attention in recent years. From both plant and microbial perspectives, the ecological risk of CWs by comparing PFASs with different chain lengths have not been fully understood. In this study, the influences of perfluorobutyric acid (PFBA) and perfluorooctanoic acid (PFOA) as typical of short- and long-chains on the ecological effect of CWs have been specifically studied. The results showed that plants produced oxidative stress response and the activities of superoxide dismutase (SOD) and peroxidase (POD) in leaves were stimulated by 17.23-28.13% and 10.49-14.17% upon 10 mg/L PFBA and PFOA exposure. Under the high level of PFBA and PFOA stress, the chlorophyll content was reduced by 15.20-39.40% and lipid peroxidation was observed in leaves with the accumulation of malondialdehyde (MDA) at 1.20-1.22 times of the control. Dehydrogenase (DHA) exhibited the most sensitivity in the presence of PFBA and PFOA with an inhibition ratio of over 90%. The biotoxicity of PFOA was higher than that of PFBA in terms of the inhibition degree of several substrate enzymes. The information of Illumina Miseq sequencing indicated that the diversity and structure of microbial community in CWs were significantly altered by PFBA and PFOA addition and led to an enrichment of more PFASs-tolerant bacteria.

Ecotoxicological responses and removal of submerged macrophyte Hydrilla verticillate to multiple perfluoroalkyl acid (PFAA) pollutants in aquatic environments

The ubiquitous existence of perfluoroalkyl acids (PFAAs) in aquatic environments might pose toxic potential to ecosystems. To assess the ecotoxicological responses and removal of submerged macrophyte to multiple PFAA pollutants in aquatic environments, a typical submerged macrophyte, Hydrilla verticillate, was exposed to solutions with 12 typical PFAAs in the present study. The results showed that PFAAs at concentrations higher than 10 μg/L had significantly passive effects on biomass, relative growth rates, chlorophyll contents, and chlorophyll autofluorescence. PFAAs could induce the accumulation of hydrogen peroxide and lipid peroxidation in H. verticillate. Significant upregulation of CAT was observed in treatments with more than 10 μg/L PFAAs (p < 0.05). The results also showed that 13.53-20.01% and 19.73-37.72% of PFAAs could be removed in treatments without plants and with H. verticillate, respectively. The removal rates of PFAAs were significantly correlated with perfluoroalkyl chain length in treatments with H. verticillate. The removal of PFAAs was suggested to be related to the uptake of plant tissues and biosorption of microbiota. Furthermore, the dominant microbiota and biomarkers were identified in water and biofilm. Betaproteobacteriales was the most dominant microbiota at the order level. The presence of PFAAs could significantly increase the relative abundance of Micrococcales, Verrucomicrobiales, Rhizobiales, Sphingomonadales, Roseomonas, Cyanobium_PCC_6307, and Synechococcales. Our results provide scientific basis for evaluating the ecotoxicological responses and removal of submerged macrophytes in response to multiple PFAA pollutants at environmentally relevant levels, thereby providing insights into PFAA management and removal.

Long-term effect of perfluorooctanoic acid on the anammox system based on metagenomics: Performance, sludge characteristic and microbial community dynamic

The effects of PFOA on the nitrogen removal performance, microbial community and functional genes of anaerobic ammonium oxidation (anammox) sludge in an anaerobic baffled reactor (ABR) were investigated. The removal efficiencies of ammonia nitrogen (NH₄⁺-N) and nitrite (NO₂^--N) decreased from 93.90 ± 3.64% and 98.6 ± 1.84% to 77.81 ± 6.86% and 77.96 ± 1.88% when PFOA increased from 5 mg/L to 50 mg/L, respectively. X-ray photoelectron spectra analysis of the anammox sludge showed the presence of both C-F and CaF₂ forms of F. Metagenomics analysis of the anammox sludge in the first compartment illustrated that the relative abundance of Ca.Brocadia and Ca.Kuenenia decreased from 22.21% and 5.61% to 2.11% and 2.84% at 50 mg/L PFOA compared with that without PFOA. In addition, the nitrogen metabolism pathway showed that adding 50 mg/L PFOA decreased the expression of HzsB, HzsC, and Hdh (anammox genes) by 0.096%, 0.05% and 0.062%, respectively.

Removal potential of multiple perfluoroalkyl acids (PFAAs) by submerged macrophytes in aquatic environments: Tolerance of Vallisneria natans and PFAA removal in submerged macrophyte-microbiota systems

Perfluoroalkyl acids (PFAAs) have emerged as a global concern in aquatic environment remediation due to their abundance, persistence, bioaccumulation, and toxicity. To comprehensively understand the removal potential of multiple PFAAs by submerged macrophytes in aquatic environments, systematic investigations into the tolerance of the typical submerged macrophyte Vallisneria natans to 12 typical PFAAs and the removal capacity to PFAAs in V. natans-microbiota systems were carried out. Results showed that although PFAAs could induce the accumulation of hydrogen peroxide and malondialdehyde, V. natans was overall resistant to multiple PFAAs with natural concentrations. Catalase is one of the main strategies of V. natans to alleviate PFAA stress. Microbiota can remove 18.10-30.84% of the PFAAs from the water column. 24.35-73.45% of PFAAs were removed from water in V. natans-microbiota systems. The uptake of plant tissues and the bioaccumulation of microbiota were proposed as the main removal processes. The removal rates were significantly correlated with the perfluorinated carbon atoms numbers (p < 0.05). PFAAs and V. natans increased the relative abundance of Betaproteobacteria, Nostocales, Microscillaceae, Sphingobacteriales, SBR1031, Chlamydiales, Phycisphaerae, Caldilineales, Rhodobacterales, and Verrucomicrobiales. The present study suggested that V. natans can be a potential species to remove multiple PFAAs in aquatic environments, and further providing insights into the PFAAs' remediation.

Exposure routes, bioaccumulation and toxic effects of per- and polyfluoroalkyl substances (PFASs) on plants: A critical review

Per- and polyfluoroalkyl substances (PFASs) are artificial persistent organic pollutants ubiquitous in ecosystem, and their bioaccumulation and adverse outcomes in plants have attracted extensive concerns. Here, we review the toxic effects of PFASs encountered by various plants from physiological, biochemical and molecular perspectives. The exposure routes and bioaccumulation of PFASs in plants from contaminated sites are also summarized. The bioaccumulation of PFASs in plants from contaminated sites varied between ng/g and μg/g levels. The 50% inhibition concentration of PFASs for plant growth is often several orders of magnitude higher than the environmentally relevant concentrations (ERCs). ERCs of PFASs rarely lead to obvious phenotypic/physiological damages in plants, but markedly perturb some biological activities at biochemical and molecular scales. PFAS exposure induces the over-generated reactive oxygen species and further damages plant cell structure and organelle functions. A number of biochemical activities in plant cells are perturbed, such as photosynthesis, gene expression, protein synthesis, carbon and nitrogen metabolisms. To restore the desire states of cells exposed to PFASs, plants initiate several detoxifying mechanisms, including enzymatic antioxidants, non-enzymatic antioxidants, metallothionein genes and metabolic reprogramming. Future challenges and opportunities in PFAS phytotoxicity studies are also proposed in the review.