Cytogenotoxic potential of a hazardous material, polystyrene microparticles on Allium cepa L

Microplastics in the soil-water-food nexus: Inclusive insight into global research findings

Nuisance imposed by biotic and abiotic stressors on diverse agroecosystems remains an area of focus for the scientific fraternity. However, emerging contaminants such as microplastics (MP) have imposed additional dimension (alone or in combinations with other stressors) in agroecosystems and keep escalating the challenges to achieve sustainability. MP are recognized as persistent anthropogenic contaminants, fetch global attention due to their unique chemical features that keeps themselves unresponsive to the decaying process. This review has been theorized to assess the current research trends (along with possible gap areas), widespread use of MP, enhancement of the harshness of heavy metals (HMs), complex interactions with physico-chemical constituents of arable soil, accumulation in the edible parts of field crops, dairy products, and other sources to penetrate the food web. So far, the available review articles are oriented to a certain aspect of MP and lack a totality when considered from in soil-water-food perspective. In short, a comprehensive perspective of the adverse effects of MP on human health has been assessed. Moreover, an agro-techno-socio-health prospective-oriented critical assessment of policies and remedial measures linked with MP has provided an extra edge over other similar articles in influential future courses of research.

Polyvinyl chloride and polybutylene adipate microplastics affect peanut and rhizobium symbiosis by interfering with multiple metabolic pathways

Microplastics (MPs), widely presented in cultivated soil, have caused serious stresses on crop growth. However, the mechanism by which MPs affect legumes and rhizobia symbiosis is still unclear. Here, peanut seedlings were inoculated with Bradyrhizobium zhanjiangense CCBAU 51778 and were grown in vermiculite with 3 %/5 % (w/w) addition of PVC (polyvinyl chloride)-MPs/PBAT (polybutylene adipate)-MPs. PVC-MPs and PBAT-MPs separately decreased nodule number by 33-100 % and 2.62-80.91 %. Transcriptome analysis showed that PVC-MPs affected more DEGs (differentially expressed genes) than PBAT-MPs, indicating PVC-MPs were more devastating for the symbiosis than PBAT-MPs. Functional annotation revealed that PVC-MPs and PBAT-MPs enriched DEGs related to biosynthesis pathways such as flavonoid, isoflavonoid, and phenylpropanoid, in peanut. And when the dose increased from 3 % to 5 %, PVC-MPs mainly enriched the pathways of starch and sucrose metabolism, alanine, aspartate and glutamate metabolism, diterpenoid biosynthesis, etc.; PBAT-MPs enriched cysteine and methionine metabolism, photosynthesis, MAPK signaling, and other pathways. These significantly enriched pathways functioned in reducing nodule number and promoting peanut tolerance to MPs stresses. This study reveals the effect of PVC-MPs and PBAT-MPs on peanut and rhizobium symbiosis, and provides new perspectives for legume production and environmental safety.

Multiomics analysis reveals a substantial decrease in nanoplastics uptake and associated impacts by nano zinc oxide in fragrant rice (Oryza sativa L.)

Nanoplastics (NPs) have emerged as global environmental pollutants with concerning implications for sustainable agriculture. Understanding the underlying mechanisms of NPs toxicity and devising strategies to mitigate their impact is crucial for crop growth and development. Here, we investigated the nanoparticles of zinc oxide (nZnO) to mitigate the adverse effects of 80 nm NPs on fragrant rice. Our results showed that optimized nZnO (25 mg L-1) concentration rescued root length and structural deficits by improving oxidative stress response, antioxidant defense mechanism and balanced nutrient levels, compared to seedlings subjected only to NPs stress (50 mg L-1). Consequently, microscopy observations, Zeta potential and Fourier transform infrared (FTIR) results revealed that NPs were mainly accumulated on the initiation joints of secondary roots and between cortical cells that blocks the nutrients uptake, while the supplementation of nZnO led to the formation of aggregates with NPs, which effectively impedes the uptake of NPs by the roots of fragrant rice. Transcriptomic analysis identified a total of 3973, 3513 and 3380 differentially expressed genes (DEGs) in response to NPs, nZnO and NPs+nZnO, respectively, compared to the control. Moreover, DEGs were significantly enriched in multiple pathways including biosynthesis of secondary metabolite, phenylpropanoid biosynthesis, amino sugar and nucleotide sugar metabolism, carotenoid biosynthesis, plant-pathogen interactions, MAPK signaling pathway, starch and sucrose metabolism, and plant hormone signal transduction. These pathways could play a significant role in alleviating NPs toxicity and restoring fragrant rice roots. Furthermore, metabolomic analysis demonstrated that nZnO application restored 2-acetyl-1-pyrroline (2-AP) pathways genes expression, enzymatic activities, and the content of essential precursors related to 2-AP biosynthesis under NPs toxicity, which ultimately led to the restoration of 2-AP content in the leaves. In conclusion, this study shows that optimized nZnO application effectively alleviates NPs toxic effects and restores both root structure and aroma production in fragrant rice leaves. This research offers a sustainable and practical strategy to enhance crop production under NPs toxicity while emphasizing the pivotal role of essential micronutrient nanomaterials in agriculture.

Micro and nanoplastics pollution: Sources, distribution, uptake in plants, toxicological effects, and innovative remediation strategies for environmental sustainability

Microplastics and nanoplastics (MNPs), are minute particles resulting from plastic fragmentation, have raised concerns due to their widespread presence in the environment. This study investigates sources and distribution of MNPs and their impact on plants, elucidating the intricate mechanisms of toxicity. Through a comprehensive analysis, it reveals that these tiny plastic particles infiltrate plant tissues, disrupting vital physiological processes. Micro and nanoplastics impair root development, hinder water and nutrient uptake, photosynthesis, and induce oxidative stress and cyto-genotoxicity leading to stunted growth and diminished crop yields. Moreover, they interfere with plant-microbe interactions essential for nutrient cycling and soil health. The research also explores the translocation of these particles within plants, raising concerns about their potential entry into the food chain and subsequent human health risks. The study underscores the urgency of understanding MNPs toxicity on plants, emphasizing the need for innovative remediation strategies such as bioremediation by algae, fungi, bacteria, and plants and eco-friendly plastic alternatives. Addressing this issue is pivotal not only for environmental conservation but also for ensuring sustainable agriculture and global food security in the face of escalating plastic pollution.

Microplastics in agroecosystems: Soil-plant dynamics and effective remediation approaches

Increasing microplastic (MP) pollution, primarily from anthropogenic sources such as plastic film mulching, waste degradation, and agricultural practices, has emerged as a pressing global environmental concern. This review examines the direct and indirect effects of MPs on crops, both in isolation and in conjunction with other contaminants, to elucidate their combined toxicological impacts. Organic fertilizers predominantly contain 78.6% blue, 9.5% black, and 8.3% red MPs, while irrigation water in agroecosystems contains 66.2% white, 15.4% blue, and 8.1% black MPs, ranging from 0-1 mm to 4-5 mm in size. We elucidate five pivotal insights: Firstly, soil MPs exhibit affinity towards crop roots, seeds, and vascular systems, impeding water and nutrient uptake. Secondly, MPs induce oxidative stress in crops, disrupting vital metabolic processes. Thirdly, leachates from MPs elicit cytotoxic and genotoxic responses in crops. Fourthly, MPs disrupt soil biotic and abiotic dynamics, influencing water and nutrient availability for crops. Lastly, the cumulative effects of MPs and co-existing contaminants in agricultural soils detrimentally affect crop yield. Thus, we advocate agronomic interventions as practical remedies. These include biochar input, application of growth regulators, substitution of plastic mulch with crop residues, promotion of biological degradation, and encouragement of crop diversification. However, the efficacy of these measures varies based on MP type and dosage. As MP volumes increase, exploring alternative mitigation strategies such as bio-based plastics and environmentally friendly biotechnological solutions is imperative. Recognizing the persistence of plastics, policymakers should enact legislation favoring the mitigation and substitution of non-degradable materials with bio-derived or compostable alternatives. This review demonstrates the urgent need for collective efforts to alleviate MP pollution and emphasizes sustainable interventions for agricultural ecosystems.

Toxicological effects of nodularin on the reproductive endocrine system of female zebrafish (Danio rerio)

Nodularin is a potent cyanotoxin that has been detected in aquatic environments as well as in the body of aquatic organisms throughout the world, but its effects on the reproductive system are yet to be explored. The present study investigated the toxic effects of environmentally relevant concentrations of nodularin on the reproductive endocrine system of female zebrafish (Danio rerio). After exposure to nodularin for 14 days, decreased gonadosomatic Index (GSI), germinal vesicle breakdown (GVBD), and decreased level of follicle-stimulating hormone (FSH), luteinizing hormone (LH), 17β-estradiol (E2) level and increased testosterone (T) content in female zebrafish suggested that nodularin may disrupt both oocyte growth and maturation. In support of this data, alteration in different marker gene expression on the hypothalamic-pituitary-gonadal-liver (HPGL) axis was observed. Transcriptional levels of genes related to steroidogenesis including cytochrome P450 aromatase (cyp19a1a) in the ovary and primary vitellogenin genes (vtg1, vtg2, and vtg3) in the liver were down-regulated and marker genes for oxidative stress (sod, cat, and gpx) were up-regulated on HPGL axis. These findings revealed for the first time that nodularin is a potent endocrine-disrupting compound posing oxidative stress and causes reproductive endocrine toxicity in female zebrafish, emphasizing the importance of assessing its environmental risks.

Evaluating the role of soil EPS in modifying the toxicity potential of the mixture of polystyrene nanoplastics and xenoestrogen, Bisphenol A (BPA) in Allium cepa L

The coexistence of emerging pollutants like nanoplastics and xenoestrogen chemicals such as Bisphenol A (BPA) raises significant environmental concerns. While the individual impacts of BPA and polystyrene nanoplastics (PSNPs) on plants have been studied, their combined effects are not well understood. This study examines the interactions between eco-corona formation, physicochemical properties, and cyto-genotoxic effects of PSNPs and BPA on onion (Allium cepa) root tip cells. Eco-corona formation was induced by exposing BPA-PSNP mixtures to soil extracellular polymeric substances (EPS), and changes were analyzed using 3D-EEM, TEM, FTIR, hydrodynamic diameter, and contact angle measurements. Onion roots were treated with BPA (2.5, 5, and 10 mgL-1) combined with plain, aminated, and carboxylated PSNPs (100 mgL-1), with and without EPS interaction. Toxicity was assessed via cell viability, oxidative stress markers (superoxide radical, total ROS, hydroxyl radical), lipid peroxidation, SOD and catalase activity, mitotic index, and chromosomal abnormalities. BPA alone increased cytotoxic and genotoxic parameters in a dose-dependent manner. BPA with aminated PSNPs exhibited the highest toxicity among the pristine mixtures, revealing increased chromosomal abnormalities, oxidative stress, and cell mortality with rising BPA concentrations. In-silico experiments demonstrated the relationship between superoxide dismutase (SOD), catalase enzymes, PSNPs, BPA, and their mixtures. EPS adsorption notably reduced cyto-genotoxic effects, lipid peroxidation, and ROS levels, mitigating the toxicity of BPA-PSNP mixtures.

Time dependent release of microplastics from disposable face masks poses cyto-genotoxic risks in Allium cepa

The use of disposable face masks (DFMs) increased during the COVID-19 pandemic and has become a threat to the environment due to the release of microplastics (MPs). Although many reports have characterized and explored the release of MPs from DFMs and their effects in aquatic ecosystems, there is a lack of investigation into the effects in terrestrial plants. This report aims to fill this research gap by characterizing whole mask leachates (WMLs) collected at different time points and examining their toxicity on Allium cepa, a terrestrial model plant. Various analytical techniques including FE-SEM, FT-IR, and Raman spectroscopy were used to identify MPs in WMLs. The MPs are composed of polypropylene mostly and the concentration of smaller-sized MPs increased with leachate release time. The WMLs showed a MP concentration-dependent cytogenotoxic effect (72 %, 50 %, and 31 %, on 1, 5, and 11-day WMLs, respectively) on A. cepa root cells due to elevated oxidative stress (19 %, 45 %, and 70 %, on 1, 5, and 11-day WMLs, respectively). Heavy metal content of the WMLs was negligible and, thus, not a significant contributor to toxicity in the plant. Overall, this report highlights the fate of DFMs in the environment and their biological impacts in a model plant.

Comparative analysis of the effects of microplastics and nitrogen on maize and wheat: Growth, redox homeostasis, photosynthesis, and AsA-GSH cycle

Microplastics (MPs) pose a significant threat to the function of agro-ecosystems. At present, research on MPs has mainly focused on the effects of different concentrations or types of MPs on a crop, while ignoring other environmental factors. In agricultural production, the application of nitrogen (N) fertilizer is an important means to maintain the high yield of crops. The effects of MPs and N on growth parameters, photosynthetic system, active oxygen metabolism, nutrient content, and ascorbate-glutathione (AsA-GSH) cycle of maize and wheat were studied in order to explicit whether N addition could effectively alleviate the effects of MPs on maize and wheat. The results showed that MPs inhibited the plant height of both maize and wheat, and MPs effects on physiological traits of maize were more severe than those of wheat, reflecting in reactive oxygen metabolism and restriction of photosynthetic capacity. Under the condition of N supply, AsA-GSH cycle of two plants has different response strategies to MPs: Maize promoted enzyme activity and co-accumulation of AsA and GSH, while wheat tended to consume AsA and accumulate GSH. N application induced slight oxidative stress on maize, which was manifested as an increase in hydrogen peroxide and malonaldehyde contents, and activities of polyphenol oxidase and peroxidase. The antioxidant capacity of maize treated with the combination of MPs + N was better than that treated with N or MPs alone. N could effectively alleviate the adverse effects of MPs on wheat by improving the antioxidant capacity.

Tracking and imaging nano-plastics in fresh plant using cryogenic laser ablation inductively coupled plasma mass spectrometry

Tracking and imaging of nano-plastics are extremely challenging, especially in fresh biological samples. Here, we propose a new strategy in which polystyrene (PS) was doped with the europium chelate Eu (DBM)3bpy to quantify, track, and in situ image nano-plastics in fresh cucumber based on inherent metals using cryogenic laser ablation inductively coupled plasma mass spectrometry (cryo-LA-ICP-MS). The cryogenic conditions provide a stable condition for imaging fresh cucumber, suppressing the evaporation of water in fresh plants, and maintaining the original structure of plants with respect to room temperature imaging in LA-ICP-MS. The plants were cultivated in two types of nano-plastics solutions with low (50 mg/L) and high (200 mg/L) concentrations for 9 days. The results showed that nano-plastics mainly enrich the roots and have negative effects, which decrease the trace elements of Zn, Mn, and Cu in cucumber. Smaller PS particles are able to penetrate the plant more easily and inflict serious damage. Novel imaging method provides a novel insight into the tracking and imaging of nano-plastics in fresh plant samples. The results illustrated that nano-plastics deposition on plants has the potential to have direct ecological effects as well as consequences for potential health.

The effects of Micro/Nano-plastics exposure on plants and their toxic mechanisms: A review from multi-omics perspectives

In recent years, plastic pollution has become a global environmental problem, posing a potential threat to agricultural ecosystems and human health, and may further exacerbate global food security problems. Studies have revealed that exposure to micro/nano-plastics (MPs/NPs) might cause various aspects of physiological toxicities, including plant biomass reduction, intracellular oxidative stress burst, photosynthesis inhibition, water and nutrient absorption reduction, cellular and genotoxicity, seed germination retardation, and that the effects were closely related to MP/NP properties (type, particle size, functional groups), exposure concentration, exposure duration and plant characteristics (species, tissue, growth stage). Based on a brief review of the physiological toxicity of MPs/NPs to plant growth, this paper comprehensively reviews the potential molecular mechanism of MPs/NPs on plant growth from perspectives of multi-omics, including transcriptome, metabolome, proteome and microbiome, thus to reveal the role of MPs/NPs in plant transcriptional regulation, metabolic pathway reprogramming, protein translational and post-translational modification, as well as rhizosphere microbial remodeling at multiple levels. Meanwhile, this paper also provides prospects for future research, and clarifies the future research directions and the technologies adopted.

Micro/nanoplastics: Critical review of their impacts on plants, interactions with other contaminants (antibiotics, heavy metals, and polycyclic aromatic hydrocarbons), and management strategies

Microplastic/nanoplastics (MPs/NPs) contamination is not only emerging threat to the agricultural system but also constitute global hazard to the environment worldwide. Recent review articles have addressed the environmental distribution of MPs/NPs and their single-exposure phytotoxicity in various plant species. However, the mechanisms of MPs/NPs-induced phytotoxicity in conjunction with that of other contaminants remain unknown, and there is a need for strategies to ameliorate such phytotoxicity. To address this, we comprehensively review the sources of MPs/NPs, their uptake by and effects on various plant species, and their phytotoxicity in conjunction with antibiotics, heavy metals, polycyclic aromatic hydrocarbons (PAHs), and other toxicants. We examine mechanisms to ameliorate MP/NP-induced phytotoxicity, including the use of phytohormones, biochar, and other plant-growth regulators. We discuss the effects of MPs/NPs -induced phytotoxicity in terms of its ability to inhibit plant growth and photosynthesis, disrupt nutrient metabolism, inhibit seed germination, promote oxidative stress, alter the antioxidant defense system, and induce genotoxicity. This review summarizes the novel strategies for mitigating MPs/NPs phytotoxicity, presents recent advances, and highlights research gaps, providing a foundation for future studies aimed at overcoming the emerging problem of MPs/NPs phytotoxicity in edible crops.

Discrepancy of Growth Toxicity of Polystyrene Nanoplastics on Soybean (Glycine max) and Mung Bean (Vigna radiata)

Nanoplastics, as a hot topic of novel contaminants, lack extensive concern in higher plants; especially the potential impact and mechanism of nanoplastics on legume crops remains elusive. In this study, the toxicity of polystyrene nanoplastics (PS-NPs, 200 nm) with diverse doses (control, 10, 50, 100, 200, 500 mg/L) to soybean and mung bean plants grown hydroponically for 7 d was investigated at both the macroscopic and molecular levels. The results demonstrated that the root length of both plants was markedly suppressed to varying degrees. Similarly, mineral elements (Fe, Zn) were notably decreased in soybean roots, consistent with Cu alteration in mung bean. Moreover, PS-NPs considerably elevated malondialdehyde (MDA) levels only in soybean roots. Enzyme activity data indicated mung bean exhibited significant damage only at higher doses of PS-NPs stress than soybean, implying mung bean is more resilient. Transcriptome analysis showed that PS-NPs stimulated the expression of genes associated with the antioxidant system in plant roots. Furthermore, starch and sucrose metabolism might play a key role in coping with PS-NPs to enhance soybean resistance, but the MAPK pathway was enriched in mung bean. Our findings provide valuable perspectives for an in-depth understanding of the performance of plants growing in waters contaminated by nanoplastics.

Growth, physiological parameters and DNA methylation in Spirodela polyrhiza (L.) Schleid exposed to PET micro-nanoplastic contaminated waters

The effects of polyethylene terephthalate micro-nanoplastics (PET-MNPs) were tested on the model freshwater species Spirodela polyrhiza (L.) Schleid., with focus on possible particle-induced epigenetic effects (i.e. alteration of DNA methylation status). MNPs (size ∼ 200-300 nm) were produced as water dispersions from PET bottles through repeated cycles of homogenization and used to prepare N-medium at two environmentally relevant concentrations (∼0.05 g L-1 and ∼0.1 g L-1 of MNPs). After 10 days of exposure, a reduction in fresh and dry weight was observed in treated plants, even if the average specific growth rate for both frond number and area was not altered. Impaired growth was coupled with a MNP-induced decrease of chlorophyll fluorescence parameters (i.e. ΨETo and Piabs, indicators of photochemical efficiency) and starch concentration, as well as with alterations in plant ionomic profile and oxidative status. The methylation-sensitive amplification polymorphism (MSAP) technique was used to assess possible changes in DNA methylation levels induced by plastic particles. The analysis showed unusual hypermethylation in 5'-CCGG sites that could be implicated in DNA protection from dangerous agents (i.e. reactive oxygen species) or in the formation of new epialleles. This work represents the first evidence of MNP-induced epigenetic modifications in the plant world.

Microplastics in soils: Production, behavior process, impact on soil organisms, and related toxicity mechanisms

In recent years, microplastics (MPs) pollution has become a hot ecological issue of global concern and MP pollution in soil is becoming increasingly serious. Studies have shown that MPs have adverse effects on soil biology and ecological functions. Although MPs are evident in soils, identifying their source, abundance, and types is difficult because of the complexity and variability of soil components. In addition, the effects of MPs on soil physicochemical properties (PCP), including direct effects such as direct interaction with soil particles and indirect effects such as the impact on soil organisms, have not been reported in a differentiated manner. Furthermore, at present, the soil ecological effects of MPs are mostly based on biological toxicity reports of their exudate or size effects, whereas the impact of their surface-specific properties (such as environmentally persistent free radicals, surface functional groups, charge, and curvature) on soil ecological functions is not fully understood. Considering this, this paper reviews the latest research findings on the production and behavioral processes of MPs in soil, the effects on soil PCP, the impacts on different soil organisms, and the related toxic mechanisms. The above discussion will enhance further understanding of the behavioral characteristics and risks of MPs in soil ecosystems and provide some theoretical basis for further clarification of the molecular mechanisms of the effects of MPs on soil organisms.

Internalization, physiological responses and molecular mechanisms of lettuce to polystyrene microplastics of different sizes: Validation of simulated soilless culture

Microplastics (MPs) exists widely in the environment, and the resulting pollution of MPs has become a global environmental problem. Plants can absorb MPs through their roots. However, studies on the mechanism of the effect of root exposure to different size MPs on vegetables are limited. Here, we use Polystyrene (PS) MPs with different particle sizes to investigate the internalization, physiological response and molecular mechanism of lettuce to MPs. MPs may accumulate in large amounts in lettuce roots and migrate to the aboveground part through the vascular bundle, while small particle size MPs (SMPs, 100 nm) have stronger translocation ability than large particle size MPs (LMPs, 500 nm). MPs can cause physiological and biochemical responses and transcriptome changes in lettuce. SMPs and LMPs resulted in reduced biomass (38.27 % and 48.22 % reduction in fresh weight); caused oxidative stress (59.33 % and 47.74 % upregulation of SOD activity in roots) and differential gene expression (605 and 907 DEGs). Signal transduction, membrane transport and alteration of synthetic and metabolic pathways may be the main causes of physiological toxicity of lettuce. Our study provides important information for understanding the behavior and fate of MPs in edible vegetables, especially the physiological toxicity of MPs to edible vegetables, in order to assess the potential threat of MPs to food safety and agricultural sustainable development.

Phytochemical characterization, isolation, antioxidant and cytogenotoxic activity of leaves of Heliotropium elongatum (Lehm) I.M. Johnst

Heliotropium elongatum is used to treat inflammation, cough, and flu. This study aimed to characterize the phytochemical profile and determine the total phenolic content (TPC), antioxidant and cytogenotoxic activity of the ethanolic extract (EE), and fractions of H. elongatum leaves. In the phytochemical profile analysis, organic acids, reducing sugars, flavonoids, saponins, anthraquinones, steroids/triterpenes, and depsides/depsidones were detected in the EE and/or fractions (hexanic/FH, chloroformic/FC, ethyl acetate/FAE, and hydromethanolic/FHM). The highest TPC and highest antioxidant activity (DPPH and ABTS) was detected in FHM. In FH, 16 compounds were identified by GC-MS, and ursolic acid was isolated by 1H NMR and 13C NMR. HPLC-DAD from EE, FAE, and FHM demonstrated characteristic wavelengths for flavonoids, flavonols, flavones, and anthraquinones. ESI-IT/MSn analysis of EE, FC, FAE, and FHM revealed alkaloids, steroids, terpenoids, flavonoids, and phenolic acids. In Allium cepa assay there was no significant cytotoxic effect initiated by EE (62.5 to 1,000 µg/ml), FHM (1,000 µg/ml), and FAE (62.5 µg/ml). Genotoxicity was evidenced only with EE at 500 and 1,000 µg/ml, and FHM (62.5 to 1,000 µg/ml) as evidenced by presence of micronuclei (MN) and nuclear buds (NB). Our results identified compounds of medicinal interest with antioxidant activity; however observed cytogenotoxic changes indicated the need for caution when using these compounds for therapeutic purposes.

Dose-dependent toxicity of polyethylene microplastics (PE-MPs) on physiological and biochemical response of blackgram and its associated rhizospheric soil properties

Microplastic contamination in terrestrial ecosystem is emerging as a global threat due to rapid production of plastic waste and its mismanagement. It affects all living organisms including plants. Hence, the current study aims at understanding the effect of polyethylene microplastics (PE-MPs) at different concentrations (0, 0.25, 0.50, 0.75, and 1.00% w/w) on the plant growth and yield attributes. With blackgram as a test crop, results revealed that a maximum reduction in physiological traits like photosynthetic rate; chlorophyll a, b; and total chlorophyll by 5, 14, 10, and 13% at flowering stage; and an increase in biochemical traits like ascorbic acid, malondialdehyde, proline, superoxide dismutase, and catalase by 11, 29.7, 16, 22, and 30% during vegetative stage was observed with 1% PE-MP application. Moreover, a reduction in growth and yield attributes was also observed with increasing concentration of microplastics. Additionally, application of 1% PE-MPs decreased the soil bulk density, available phosphorus, and potassium, whereas the EC, organic carbon, microbial biomass carbon, NO3-N, and NH4-N significantly increased. Moreover, the presence of PE-MPs in soil also had a significant influence on the soil enzyme activities. Metagenomic analysis (16 s) reveals that at genus level, Bacillus (19%) was predominant in control, while in 1% PE-MPs, Rubrobacter (28%) genus was dominant. Microvirga was found exclusively in T5, while the relative abundance of Gemmatimonas declined from T1 to T5. This study thus confirms that microplastics exert a dose-dependent effect on soil and plant characteristics.

Biomarkers of oxidative stress, inflammation, and genotoxicity to assess exposure to micro- and nanoplastics. A literature review

The increased awareness about possible health effects arising from micro- and nanoplastics (MNPs) pollution is driving a huge amount of studies. Many international efforts are in place to better understand and characterize the hazard of MNPs present in the environment. The literature search was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) methodology in two different databases (PubMed and Embase). The selection of articles was carried out blind, screening titles and abstracts according to inclusion and exclusion criteria. In general, these studies rely on the methodology already in use for assessing hazard from nanomaterials and particles of concern. However, only a limited number of studies have so far directly measured human exposure to MNPs and examined the relationship between such exposure and its impact on human health. This review aims to provide an overview of the current state of research on biomarkers of oxidative stress, inflammation, and genotoxicity that have been explored in relation to MNPs exposure, using human, cellular, animal, and plant models. Both in-vitro and in-vivo models suggest an increased level of oxidative stress and inflammation as the main mechanism of action (MOA) leading to adverse effects such as chronic inflammation, immunotoxicity and genotoxicity. With the identification of such biological endpoints, representing critical key initiating events (KIEs) towards adaptive or adverse outcomes, it is possible to identify a panel of surrogate biomarkers to be applied and validated especially in occupational settings, where higher levels of exposure may occur.

Unveiling the effect of microplastics on agricultural crops - a review

Microplastics (MPs), ever since they were identified as a potential and widely distributed persistent contaminant, the number of studies highlighting their impacts on various terrestrial ecosystems have been increasing. Recently, the effect of MPs on the agricultural ecosystem has gained momentum. Hence, the present review examines the impact of microplastics on agricultural crop systems and the mechanism underlying its toxicity. The current review revealed that most of the studies were conducted at a laboratory scale and under controlled conditions. Additionally, it was observed that polystyrene (PS) followed by polyethylene (PE) are the most studied polymer type, while the most studied plants are wheat and maize. Hitherto, literature studies suggest that the microplastics' influence on plant growth can be negative or sometimes neutral; while in some cases it exerts a hormetic effect which depends on other factors determining plant growth. Notably, the main mechanisms through which microplastics influence plant growth are mechanical damage, alteration of soil properties, or by leaching of additives. Overall, with burgeoning research interest in this aspect, the current review has significant implications for the toxicity of MPs on plants and throws light on the need to develop novel guidelines toward the sustainable use of plastics in agricultural sector. However, realistic field-level studies and estimating the MPs concentration at various region are essential to develop remediation approaches. Future studies should also focus on translocation and accumulation of micron sized MPs in edible portion of crops and their effect on food safety.

Eco-corona formation diminishes the cytogenotoxicity of graphene oxide on Allium cepa: Role of soil extracted-extracellular polymeric substances in combating oxidative stress

Graphene oxide (GO) is widely acknowledged for its exceptional biological and industrial applications. However, its discharge into the environment negatively impacts the ecosystem. This study aimed to investigate the toxicity of GO in Allium cepa root tip cells and the role of extracellular polymeric substances (EPS) in modulating its toxic effects. To evaluate toxicity, various endpoints like cell viability using Evans blue dye, cytotoxicity (mitotic index), genotoxicity (chromosomal aberrations), and oxidative stress assessments (total ROS, superoxide, hydroxyl radical production, and lipid peroxidation) were considered. The results suggest that pristine GO caused a dose-dependent increase in various toxicity parameters, especially the genotoxic effects. Oxidative stress generation by GO is proposed to be the principal mode of action. The EPS-corona formed on GO could potentially counteract the toxic effects, substantially reducing the oxidative stress within the cells.

Plastic in the Environment: A Modern Type of Abiotic Stress for Plant Physiology

In recent years, plastic pollution has become a growing environmental concern: more than 350 million tons of plastic material are produced annually. Although many efforts have been made to recycle waste, a significant proportion of these plastics contaminate and accumulate in the environment. A central point in plastic pollution is demonstrated by the evidence that plastic objects gradually and continuously split up into smaller pieces, thus producing subtle and invisible pollution caused by microplastics (MP) and nanoplastics (NP). The small dimensions of these particles allow for the diffusion of these contaminants in farmlands, forest, freshwater, and oceans worldwide, posing serious menaces to human, animal, and plant health. The uptake of MPs and NPs into plant cells seriously affects plant growth, development, and photosynthesis, finally limiting crop yields and endangering natural environmental biodiversity. Furthermore, nano- and microplastics-once adsorbed by plants-can easily enter the food chain, being highly toxic to animals and humans. This review addresses the impacts of MP and NP particles on plants in the terrestrial environment. In particular, we provide an overview here of the detrimental effects of photosynthetic injuries, oxidative stress, ROS production, and protein damage triggered by MN and NP in higher plants and, more specifically, in crops. The possible damage at the physiological and environmental levels is discussed.

Impacts of Micro(nano)plastics on Terrestrial Plants: Germination, Growth, and Litter

Micro(nano)plastics (MNP) are pervasive in various environmental media and pose a global environmental pollution issue, particularly in terrestrial ecosystems, where they exert a significant impact on plant growth and development. This paper builds upon prior research to analyze and consolidate the effects of MNP on soil properties, seed germination, plant growth, and litter decomposition. The objective is to elucidate the environmental behavior of MNP and their mechanisms of influence on the plant life cycle. The unique physicochemical and electrical properties of MNP enable them to modify soil structure, water retention capacity, and pH. They can potentially act as "electron shuttles" or disrupt natural "electron shuttles" in litter decomposition, thereby interfering with nutrient transport and availability in the soil. Furthermore, MNP can physically obstruct nutrient and water channels within plants, impacting nutrient and water absorption. Once infiltrating plant tissues, MNP can form eco-coronas with plant proteins. Together with MNP adsorbed on the plant's surface and within its tissues, they disrupt normal physiological processes, leading to changes in photosynthesis, biomass, cellular toxicity, genetics, nutrient uptake, and gene expression. These changes, in turn, influence seed germination and plant growth and development. As a burgeoning research field, future studies should delve deeper into various aspects of these changes, such as elucidating the pathways and mechanisms through which MNP enter plant tissues, assessing their intensity and mechanisms of toxicity on different plant species, and exploring the relationship between micro(nano)plastics and "electron shuttles". These endeavors will contribute to establishing a more comprehensive theoretical framework for understanding the environmental behavior of MNP and their impact on plants.

Exposure pathways, environmental processes and risks of micro (nano) plastics to crops and feasible control strategies in agricultural regions

Micro/nanoplastics (MPs/NPs) pollution may adversely impact agricultural ecosystems, threatening the sustainability and security of agricultural production. This drives an urgent need to comprehensively understand the environmental behavior and effects of MPs/NPs in soil and atmosphere in agricultural regions, and to seek relevant pollution prevention strategies. The rhizosphere and phyllosphere are the interfaces where crops are exposed to MPs/NPs. The environmental behavior of MPs/NPs in soil and atmosphere, especially in the rhizosphere and phyllosphere, determines their plant accessibility, bioavailability and ecotoxicity. This article comprehensively reviews the transformation and migration of MPs/NPs in soil, transportation and deposition in the atmosphere, environmental behavior and effects in the rhizosphere and phyllosphere, and plant uptake and transportation pathways. The article also summarizes the key factors controlling MPs/NPs environmental processes, including their properties, biotic and abiotic factors. Based on the sources, environmental processes and intake risks of MPs/NPs in agroecosystems, the article offers several feasible pollution prevention and risk management options. Finally, the review highlights the need for further research on MPs/NPs in agro-systems, including developing quantitative detection methods, exploring transformation and migration patterns in-situ soil, monitoring long-term field experiments, and establishing pollution prevention and control systems. This review can assist in improving our understanding of the biogeochemistry behavior of MPs/NPs in the soil-plant-atmosphere system and provide a roadmap for future research.

Nitrogen fertilization and arbuscular mycorrhizal fungi do not mitigate the adverse effects of soil contamination with polypropylene microfibers on maize growth

Soil contamination with microplastics may adversely affect soil properties and functions and consequently crop productivity. In this study, we wanted to verify whether the adverse effects of microplastics in the soil on maize plants (Zea mays L.) are due to a reduction in nitrogen (N) availability and a reduced capacity to establish symbiotic relationships with arbuscular mycorrhizal (AM) fungi. To do this, we performed a pot experiment in which a clayey soil was exposed to two environmentally relevant concentrations of polypropylene (PP; one of the most used plastic materials) microfibers (0.4% and 0.8% w/w) with or without the addition of N fertilizer and with or without inoculation with AM fungi. The experiment began after the soil had been incubated at 23 °C for 5 months. Soil contamination with PP considerably reduced maize root and shoot biomass, leaf area, N uptake, and N content in tissue. The adverse effects increased with the concentration of PP in the soil. Adding N to the soil did not alleviate the detrimental effects of PP on plant growth, which suggests that other factors besides N availability played a major role. Similarly, although the presence of PP did not inhibit root colonization by AM fungi (no differences were observed for this trait between the uncontaminated and PP-contaminated soils), the addition of the fungal inoculum to the soil failed to mitigate the negative impact of PP on maize growth. Quite the opposite: mycorrhization further reduced maize root biomass accumulation. Undoubtedly, much research remains to be done to shed light on the mechanisms involved in determining plant behavior in microplastic-contaminated soils, which are most likely complex. This research is a priority given the magnitude of this contamination and its potential implications for human and environmental health.

Impact and mitigation of lead, cadmium and micro/nano plastics in fragrant rice

Heavy metals (HMs) and micro(nano)plastics (MNPs), represent a significant risk to global food supply as well as a potential risk to humankind. Over 50% of the worldwide population eat rice every day, and rice aroma is a significant qualitative trait that is highly valued by consumers and fetches premium prices in the global market. Despite the huge commercial importance of fragrant rice, limited studies were directed to investigate the influence of HMs and MNPs on yield related traits and 2-Acetyl-1-pyrroline (2-AP) compound, mainly responsible for aroma production in fragrant rice. In this review, we found that the interaction of HMs and MNPs in fragrant rice is complex and accumulation of HMs and MNPs was higher in root as compared to the grains. Nutrients and phytohormones mediated mitigation of HMs and MNPs were most effective sustainable strategies. In addition, monitoring the checkpoints of 2-AP biosynthesis and its interaction with HMs and MNPs is challenging. Finally, we explained the potential challenges that fragrant rice faces considering the continuous rise in environmental pollutants and discussed the future avenues of research to improve fragrant rice's yield and qualitative traits.

Phytotoxicity assessment of dandelion exposed to microplastics using membership function value and integrated biological response index

Microplastic (MP) pollution is a critical environmental issue. Dandelions could be used as a biomonitor of environmental pollution. However, the ecotoxicology of MPs in dandelions remains unclear. Therefore, the toxic effects of polyethylene (PE), polystyrene (PS), and polypropylene (PP) at concentrations of 0, 10, 100, and 1000 mg L-1 on the germination and early seedling growth of dandelion were investigated. PS and PP inhibited seed germination and decreased root length and biomass while promoting membrane lipid peroxidation, increasing O2•-, H2O2, SP, and proline contents, and enhancing the activities of SOD, POD, and CAT. Principal component analysis (PCA) and membership function value (MFV) analysis indicated that PS and PP could be more harmful than PE in dandelion, especially at 1000 mg L-1. In addition, according to the integrated biological response (IBRv2) index analysis, O2•-, CAT, and proline were sensitive biomarkers of dandelion contamination by MPs. Here we provide evidence that dandelion has the potential to be a biomonitor to assess the phytotoxicity of MPs pollution, especially PS with high toxicity. Meanwhile, we believe that if dandelion is to be used as a biomonitor for MPs, attention should also be paid to the practical safety of dandelion.

Microplastic stress in plants: effects on plant growth and their remediations

Microplastic (MP) pollution is becoming a global problem due to the resilience, long-term persistence, and robustness of MPs in different ecosystems. In terrestrial ecosystems, plants are exposed to MP stress, thereby affecting overall plant growth and development. This review article has critically analyzed the effects of MP stress in plants. We found that MP stress-induced reduction in plant physical growth is accompanied by two complementary effects: (i) blockage of pores in seed coat or roots to alter water and nutrient uptake, and (ii) induction of drought due to increased soil cracking effects of MPs. Nonetheless, the reduction in physiological growth under MP stress is accompanied by four complementary effects: (i) excessive production of ROS, (ii) alteration in leaf and root ionome, (iii) impaired hormonal regulation, and (iv) decline in chlorophyll and photosynthesis. Considering that, we suggested that targeting the redox regulatory mechanisms could be beneficial in improving tolerance to MPs in plants; however, antioxidant activities are highly dependent on plant species, plant tissue, MP type, and MP dose. MP stress also indirectly reduces plant growth by altering soil productivity. However, MP-induced negative effects vary due to the presence of different surface functional groups and particle sizes. In the end, we suggested the utilization of agronomic approaches, including the application of growth regulators, biochar, and replacing plastic mulch with crop residues, crop diversification, and biological degradation, to ameliorate the effects of MP stress in plants. The efficiency of these methods is also MP-type-specific and dose-dependent.

Analyzing the impacts of cadmium alone and in co-existence with polypropylene microplastics on wheat growth

Heavy metals typically coexist with microplastics (MPs) in terrestrial ecosystems. Yet, little is known about how the co-existence of heavy metals and MPs affect crops. Therefore, this study aimed to evaluate the impact of cadmium (Cd; 40 mg/L) alone and its co-existence with polypropylene (PP)-MPs (50 and 100 µm) on seed germination, root and shoot growth, seedling dry weight (DW), and antioxidant enzyme activities of wheat. The study demonstrated that the germination rate of wheat did not vary significantly across treatment groups. Yet, the inhibitory impact on wheat seed germination was strengthened under the co-existence of Cd and PP-MPs, as the effect of a single treatment on seed germination was non-significant. The germination index and mean germination time of wheat seeds were not affected by single or combined toxicity of Cd and PP-MPs. In contrast, Cd and PP-MPs showed synergistic effects on germination energy. Wheat root and shoot length were impeded by Cd alone and in combination with PP-MPs treatments. The DW of wheat seedlings showed significant change across treatment groups until the third day, but on the seventh day, marginal differences were observed. For example, on third day, the DW of the Cd treatment group increased by 6.9% compared to CK, whereas the DW of the 100 µm PP-MPs+Cd treatment group decreased by 8.4% compared to CK. The co-occurrence of Cd and PP-MPs indicated that 50 μm PP-MPs+Cd had an antagonistic impact on wheat seedling growth, whereas 100 μm PP-MPs+Cd had a synergistic impact due to the larger size of PP-MPs. The antioxidant enzyme system of wheat seeds and seedlings increased under single Cd pollution, while the activities of superoxide dismutase, catalase, and peroxidase were decreased under combined pollution. Our study found that Cd adversely affects wheat germination and growth, while the co-existence of Cd and PP-MPs have antagonistic and synergistic effects depending on the size of the PP-MPs.

Indole-3-acetic acid and zinc synergistically mitigate positively charged nanoplastic-induced damage in rice

Recent research has shown that polystyrene nanoplastics (PS-NPs) can inhibit plant growth and the development of crops, such as rice. In this study, we aimed to investigate the effects of PS-NPs of different particle sizes (80 nm, 200 nm, and 2 µm) and charges (negative, neutral, and positive) on rice growth, and to explore the underlying mechanisms and potential strategies for mitigating their impacts. Two-week-old rice plants were planted in a standard ½ Murashige-Skoog liquid medium holding 50 mg/L of different particle sizes and/or charged PS-NPs for 10 days, and the liquid medium without PS-NPs was used as control. The results showed that positively charged PS-NPs (80 nm PS-NH2) had the greatest impact on plant growth and greatly reduced the dry biomass, root length, and plant height of rice by 41.04%, 46.34%, and 37.45%, respectively. The positively charged NPs with a size of 80 nm significantly decreased the zinc (Zn) and indole-3-acetic acid (IAA, auxin) contents by 29.54% and 48.00% in roots, and 31.15% and 64.30% in leaves, respectively, and down-regulated the relative expression level of rice IAA response and biosynthesis genes. Moreover, Zn and/or IAA supplements significantly alleviated the adverse effects of 80 nm PS-NH2 on rice plant growth. Exogenous Zn and/or IAA increased seedlings' growth, decreased PS-NPs distribution, maintained redox homeostasis, and improved tetrapyrrole biosynthesis in rice treated with 80 nm PS-NH2. Our findings suggest that Zn and IAA synergistically alleviate positively charged NP-induced damage in rice.

Effect of polypropylene microplastics on seed germination and nutrient uptake of tomato and cherry tomato plants

Although microplastic (MP) pollution in farmland increased, the effect of MPs on plant growth was not clearly explained. Therefore, the object of the study was to evaluate the effect of polypropylene microplastics (PP-MPs) on plant germination, growth, and nutrient uptake under hydroponic conditions. The effect of PP-MPs on seed germination, shoot and root length, and nutrient uptake were assessed using tomato (Solanum lycopersicum L.) and cherry tomato (Solanum lycopersicum var. cerasiforme) seeds grown in half-strength Hoagland solution. The results showed that PP-MPs did not significantly affect seed germination, but positively affected the shoot and root elongation. In cherry tomato, the root elongation was significantly increased by 34%. Microplastics also affected nutrient uptake by plants, however, the effect varied depending on elements and plant species. The Cu concentration was substantially increased in tomato shoot while it decreased in cherry tomato root. Nitrogen uptake decreased in MP treated plants compared to the control and phosphorus uptake was significantly decreased in the shoot of cherry tomato. However, the root-to-shoot translocation rate of most macro nutrients decreased following exposure to PP-MPs indicating that long-term exposure to MPs may lead to a nutritional imbalance in plants.

Visual tracking of label-free microplastics in wheat seedlings and their effects on crop growth and physiology

The effects of microplastics on crop plants have attracted growing attention. However, little is known about the effects of microplastics and their extracts on the growth and physiology of wheat seedlings. In this study, hyperspectral-enhanced dark field microscopy and scanning electron microscopy were used to accurately track the accumulation of 200 nm label-free polystyrene microplastics (PS) in wheat seedlings. The PS accumulated along the root xylem cell wall and in the xylem vessel member and then moved toward to the shoots. In addition, lower concentration (≤ 5 mg·L^-1) of microplastics increased root hydraulic conductivity by 80.6 %- 117.0 %. While higher PS treatment (200 mg·L^-1) considerably decreased plant pigments content (chlorophyll a, b, and total chlorophyll) by 14.8 %, 19.9 %, and 17.2 %, respectively, and decreased root hydraulic conductivity by 50.7 %. Similarly, catalase activity was reduced by 17.7 % in root and 36.8 % in shoot. However, extracts from the PS solution showed no physiological effect on wheat. The result confirmed that it was the plastic particle, rather than the chemical reagents added in the microplastics, contributed to the physiological variation. These data will benefit to better understanding on the behavior of microplastics in soil plants, and to providing of convincing evidence for the effects of terrestrial microplastics.

Assessing phytotoxicity of microplastics on aquatic plants using fluorescent microplastics

Although studies on microplastics are increasing every year, still very little is known about their toxicity. Especially for plant species, even studies of uptake of microplastics are only few, not to mention phytotoxicity of microplastics. Therefore, we conducted a pilot study on the phytotoxicity of 1-μm-sized fluorescent microplastics (FMPs) on the free-floating aquatic plants Spirodela polyrhiza and Salvinia natans and the emergent aquatic plant Phragmites australis using 0.1% and 0.01% FMP treatment. Furthermore, uptake of FMPs by plants was verified by detecting fluorescence of FMPs by laser. A free-floating aquatic plant S. polyrhiza and emergent aquatic plant P. australis showed significantly decreased harvested biomass after 3 weeks indicating phytotoxicity of FMPs, but S. natans did not show any differences of harvested biomass or chlorophyll contents among treatments. Detection of fluorescence from plant leaves provided evidence of active FMPs uptake by plants. The emission spectra of plant leaves in 0.1% FMP treatment showed similar peaks to those of free fluorescent microplastics, providing a firm evidence of FMPs uptake by plants. This study is one of the pioneering studies to explore fluorescent microplastic uptake and toxicity in aquatic plants and therefore provides a baseline for further studies.

Polystyrene nanoplastics' accumulation in roots induces adverse physiological and molecular effects in water spinach Ipomoea aquatica Forsk

The ubiquity of plastic pollution has emerged as a perplexing issue for aquatic and terrestrial plants. To assess the toxic effects of polystyrene NPs (PS-NPs, 80 nm), we conducted a hydroponic experiment in which water spinach (Ipomoea aquatica Forsk) was subjected to low (0.5 mg/L), medium (5 mg/L), and high (10 mg/L) concentrations of fluorescent PS-NPs for 10 days to examine their accumulation and transportation in water spinach and associated impacts on growth, photosynthesis, antioxidant defense systems. Laser confocal scanning microscopy (LCSM) observations at 10 mg/L PS-NPs exposure indicated that PS-NPs only adhered to the root surface of water spinach and were not transported upward, indicating that short-term exposure to high concentrations of PS-NPs (10 mg/L) did not cause the internalization of PS-NPs in the water spinach. However, this high concentration of PS-NPs (10 mg/L) discernibly inhibited the growth parameters (fresh weight, root length and shoot length), albeit failed to induce any significant impact on chlorophyll a and chlorophyll b concentrations. Meanwhile, high concentration of PS-NPs (10 mg/L) significantly decreased the SOD and CAT activities in leaves (p < 0.05). At the molecular level, low and medium concentrations of PS-NPs (0.5, 5 mg/L) significantly promoted the expression of photosynthesis (PsbA and rbcL) and antioxidant-related (SIP) genes in leaves (p < 0.05), and high concentration of PS-NPs (10 mg/L) significantly increased the transcription levels of antioxidant-related (APx) genes (p < 0.01). Our results imply that PS-NPs accumulate in the roots of water spinach, compromising the upward transport of water and nutrients and undermining the antioxidant defense system of the leaves at the physiological and molecular levels. These results provide a fresh perspective to examine the implications of PS-NPs on edible aquatic plants, and future efforts should be focused intensively on the impacts of PS-NPs on agricultural sustainability and food security.

Transcriptomic and physiological effects of polyethylene microplastics on Zea mays seedlings and their role as a vector for organic pollutants

The widespread employment of plastics in recent decades has resulted in the accumulation of plastic residues in all ecosystems. Their presence and degradation into small particles such as microplastics (MPs) may have a negative effect on plant development and therefore on crop production. In this study, the effects of two types of polyethylene MPs on Zea mays seedlings cultured in vitro were analysed. In addition, four organic pollutants (ibuprofen, simazine, sertraline, and amoxicillin) were adsorbed by the MPs to evaluate their capacity as other contaminant vectors. The development of the plants was negatively affected by MPs alone or with the organic compounds. The strongest effect was observed in the W-MPs treatments, with a reduction in leaf and root length near 70%. Chlorophyll content was also differentially affected depending on the treatment. Transcriptome analysis showed that MPs affected gene expression in the roots of maize seedlings. As observed in the physiological parameters analysed, some gene expression changes were associated with specific treatments, such as changes in sugar transport genes in the B-MIX treatment. These results contribute to a better understanding of the molecular mechanisms of plants in regard to plastic stress responses.

Nanoparticles in Plants: Uptake, Transport and Physiological Activity in Leaf and Root

Due to their unique characteristics, nanoparticles are increasingly used in agricultural production through foliage spraying and soil application. The use of nanoparticles can improve the efficiency of agricultural chemicals and reduce the pollution caused by the use of agricultural chemicals. However, introducing nanoparticles into agricultural production may pose risks to the environment, food and even human health. Therefore, it is crucial to pay attention to the absorption migration, and transformation in crops, and to the interaction with higher plants and plant toxicity of nanoparticles in agriculture. Research shows that nanoparticles can be absorbed by plants and have an impact on plant physiological activities, but the absorption and transport mechanism of nanoparticles is still unclear. This paper summarizes the research progress of the absorption and transportation of nanoparticles in plants, especially the effect of size, surface charge and chemical composition of nanoparticle on the absorption and transportation in leaf and root through different ways. This paper also reviews the impact of nanoparticles on plant physiological activity. The content of the paper is helpful to guide the rational application of nanoparticles in agricultural production and ensure the sustainability of nanoparticles in agricultural production.

Optimize lettuce washing methods to reduce the risk of microplastics ingestion: The evidence from microplastics residues on the surface of lettuce leaves and in the lettuce washing wastewater

Airborne microplastics have been identified as an emerging contaminant that can adhere to the surface of leafy vegetables, and if not completely removed by washing, there is a high risk that human consumption of these plastics may cause harm to humans. In this study, we simulated atmospheric pollution by spraying microplastic particles (MPs) with particle sizes of 100 nm and 500 nm to determine whether MPs particles would adhere to the lettuce surface and whether different common cleaning methods (water rinsing, ultrasonic vibration cleaning, and edible detergent cleaning) would be effective in removing MPs from the leaf surfaces. We scanned the leaf surface with a laser confocal microscope and examined the wash water with a flow cytometer and found that simple rinsing was not effective in removing plastic particles from lettuce leaves. In comparison, ultrasonic vibratory cleaning showed a better efficiency, 4 times higher than more MPs being washed from the leaves. The most effective method was detergent washing, with the washing efficiency increased by 6.9 times. Ultrasonic vibrations can partially break the chemical bonds between MPs and plant surfaces, and detergents' surfactants can enhance MPs' hydrophilicity. MPs with a particle size of 100 nm were more difficult to clean than those with a particle size of 500 nm. This finding has important implications for the interaction of MPs contamination with vegetables and the cleaning of vegetables.

Phytoremediation of fluoroalkylethers (ether-PFASs): A review on bioaccumulation and ecotoxilogical effects

Fluoroalkylethers (ether-PFASs), as alternatives to phased-out per- and perfluoroalkyl substances (PFASs), have attracted mounting attention due to their ubiquitous detection in aquatic environment and their similarity to legacy PFASs in terms of persistence and toxicity. In this review, the sources and distribution of ether-PFASs in soil ecosystem as well as their toxic impacts on soil microbial community are summarized. The plant uptake and bioaccumulation potential of ether-PFASs are presented, and a wide range of the influencing factors for their uptake and translocation is discussed. In response to ether-PFASs, the corresponding phytotoxic effects, such as seed germination, plant growth, photosynthesis, oxidative damage, antioxidant enzymes activities, and genotoxicity, are systematically elucidated. Finally, the current knowledge gaps and future research prospective are highlighted. The findings of this review will advance our understanding for the environmental behavior and implications ether-PFASs in soil-plant systems and help explore the strategies for ether-PFASs remediation to minimize their adverse toxicity.

Physiological Toxicity and Antioxidant Mechanism of Photoaging Microplastics on Pisum sativum L. Seedlings

Recent studies have confirmed that changes in the physical properties of microplastics (MPs) trigger toxicological effects and ecological risks. To explore the toxicity of different types of MPs on plants, and the influence of MP photoaging, this study investigated the toxicity mechanisms of pristine, 7 and 14 d photoaged polystyrene (PS), polyamide (PA), polyethylene (PE), and polyethylene terephthalate (PET) MPs on seed germination, root growth, nutrient fraction, oxidative stress, and antioxidant systems of Pisum sativum L. (pea) seedlings. The results showed that pristine PS and 14 d photoaged PET inhibited seed germination. Compared to the pristine MPs, photoaged MPs had negative effects on root elongation. Moreover, photoaged PA and PE impeded the nutrient transport of soluble sugars from roots to stems. Notably, the production of superoxide anion radicals (•O₂^-) and hydroxyl radicals (•OH) through the photoaging of MPs exacerbated oxidative stress and reactive oxygen species formation in roots. Antioxidant enzyme data revealed that the activities of superoxide dismutase and catalase were significantly activated in photoaged PS and PE, respectively, in order to scavenge •O₂^- and hydrogen peroxide (H₂O₂) accumulation and alleviate lipid peroxidation levels in cells. These findings provide a new research perspective on the phytotoxicity and ecological risk of photoaged MPs.

Advances in transport and toxicity of nanoparticles in plants

In recent years, the rapid development of nanotechnology has made significant impacts on the industry. With the wide application of nanotechnology, nanoparticles (NPs) are inevitably released into the environment, and their fate, behavior and toxicity are indeterminate. Studies have indicated that NPs can be absorbed, transported and accumulated by terrestrial plants. The presence of NPs in certain edible plants may decrease harvests and threaten human health. Understanding the transport and toxicity of NPs in plants is the basis for risk assessment. In this review, we summarize the transportation of four types of NPs in terrestrial plants, and the phytotoxicity induced by NPs, including their impacts on plant growth and cell structure, and the underlying mechanisms such as inducing oxidative stress response, and causing genotoxic damage. We expect to provide reference for future research on the effects of NPs on plants.

Responses of individual and combined polystyrene and polymethyl methacrylate nanoplastics on hormonal content, fluorescence/photochemistry of chlorophylls and ROS scavenging capacity in Lemna minor under arsenic-induced oxidative stress

Nanoplastics alter the adverse impacts of hazardous contaminants such as heavy metals by changing their adsorption and accumulation. Few findings are available on the interaction between nanoplastic and heavy metals in plants. However, there is no report on the mechanisms for removing metal stress-mediated oxidative damage by the combination treatments of nanoplastics. To address this lack of information, polystyrene nanoplastic (PS, 100 mg L^-1) and polymethyl methacrylate (PMMA, 100 mg L^-1) were hydroponically applied to Lemna minor exposed to arsenate (As, 100 μM) for 7 days. PS or PMMA caused a reduction in the contents of N, P, K, Ca, Mg and Mn, but the improved contents were detected in the presence of PS or PMMA plus As stress. The hormone contents (auxin, gibberellic acid, cytokinin, salicylic acid and jasmonic acid) reduced by stress were re-arranged through PS or PMMA applications. Based on chlorophyll efficiency, fluorescence kinetics and performance of PSII, the impaired photosynthesis by As stress was improved via PS or PMMA applications. This alleviation did not continue under the combined form of PS and PMMA in As-applied plants. All analyzed antioxidant activity (superoxide dismutase (SOD), catalase (CAT), peroxidase (POX), ascorbate peroxidase (APX), glutathione reductase (GR), glutathione S-transferase (GST), glutathione peroxidase (GPX), monodehydroascorbate reductase (MDHAR) and dehydroascorbate reductase (DHAR)) decreased or unchanged under As, PS or PMMA. Due to the inactivation of the defense system, L. minor had high levels of hydrogen peroxide (H₂O₂) and thiobarbituric acid reactive substances (TBARS), showing lipid peroxidation. After As toxicity, induvial applications of PS or PMMA indicated the activated enzyme capacity (SOD, POX, GST and GPX) and upregulated AsA/DHA, GSH/GSSG and redox state of GSH, which facilitated the removal of radical accumulation. The efficiency of the antioxidant system in As + PS + PMMA-applied L. minor was not enough to remove damage induced by As stress; hereby, TBARS and H₂O₂ contents were similar to the As-treated group. Our findings from alone or combined application of PS and PMMA provide new information to advance the tolerance mechanism against As exposure in L. minor.

Phytotoxic Effects of Polystyrene and Polymethyl Methacrylate Microplastics on Allium cepa Roots

Plastic contamination has become one of the most pressing environmental issues due to rapidly increasing production of disposable plastic products, their fragmentation into smaller pieces, and long persistence in the environment, which affects all living organisms, including plants. In this study, Allium cepa roots were exposed to 0.01, 0.1, and 1 g L^-1 of commercial polystyrene (PS-MPs) and polymethyl methacrylate microparticles (PMMA-MPs) for 72 h. Dynamic light scattering (DLS) analyses showed high stability of both types of MPs in ultrapure water used for A. cepa treatment. Morphometric analysis revealed no significant change in root length compared to control. Pyrolysis hyphenated to gas chromatography and mass spectrometry (Py-GC-MS) has proven PS-MPs uptake by onion roots in all treatments, while PMMA-MPs were recorded only upon exposure to the highest concentration. Neither MPs induced any (cyto)toxic effect on root growth and PMMA-MPs even had a stimulating effect on root growth. ROS production as well as lipid and protein oxidation were somewhat higher in PS-MP treatments compared to the corresponding concentrations of PMMA-MP, while neither of the applied MPs induced significant damage to the DNA molecule assayed with a Comet test. Significantly elevated activity of H₂O₂ scavenging enzymes, catalase, and peroxidases was measured after exposure to both types of MPs. Obtained results suggest that onion roots take up PS-MPs more readily in comparison to PMMA-MPs, while both types of MPs induce a successful activation of antioxidant machinery in root cells that prevented the occurrence of toxic effects.

A discussion of microplastics in soil and risks for ecosystems and food chains

Microplastics are among the major contaminations in terrestrial and marine environments worldwide. These persistent organic contaminants composed of tiny particles are of concern due to their potential hazards to ecosystem and human health. Microplastics accumulates in the ocean and in terrestrial ecosystems, exerting effects on living organisms including microbiomes, fish and plants. While the accumulation and fate of microplastics in marine ecosystems is thoroughly studied, the distribution and biological effects in terrestrial soil call for more research. Here, we review the sources of microplastics and its effects on soil physical and chemical properties, including water holding capacity, bulk density, pH value as well as the potential effects to microorganisms and animals. In addition, we discuss the effects of microplastics in combination with other toxic environmental contaminants including heavy metals and antibiotics on plant growth and physiology, as well as human health and possible degradation and remediation methods. This reflect is an urgent need for monitoring projects that assess the toxicity of microplastics in soil and plants in various soil environments. The prospect of these future research activities should prioritize microplastics in agro-ecosystems, focusing on microbial degradation for remediation purposes of microplastics in the environment.

Environmental microplastics: Classification, sources, fates, and effects on plants

Microplastic (MP) pollution has become a global concern due to the generation of extensive plastic waste and products (370 million metric tons in 2020) that are difficult to biodegrade. Therefore, MPs have attracted a great deal of research attention, and many new findings regarding MPs (over 9000 papers published in the last 3 years) have been reported. MPs generally exert adverse effects on plants. As MPs accumulate in agricultural ecosystems, many studies have sought to understand the sources and fates of MPs and their effects on various plants. However, there have been few reviews of the properties of MPs, their effects on plants, and their interactions with other factors (e.g., drought, heat, ultraviolet light, plant hormones, heavy metals, and other pollutants) remain poorly understood. In this review, we performed scientometrics analyses of research papers (January 1, 2019, to September 30, 2022) in this field. We focused on the recent progress in the classification of MPs and their sources, circulation, and deposition in agricultural ecosystems. We review MP uptake and transport in plants, as well as factors (size, type, and environmental factors) that affect MP uptake, the positive and negative effects of MPs on plants, and the mechanisms of MP impacts on plants. We discuss current issues and future perspectives concerning research into plant interactions with MPs, along with some promising methods to manage the MP issue.

Genotoxicity of organic contaminants in the soil: A review based on bibliometric analysis and methodological progress

Organic contaminants (OCs) are ubiquitous in the environment, posing severe threats to human health and ecological balance. In particular, OCs and their metabolites could interact with genetic materials to induce genotoxicity, which has attracted considerable attention. In this review, bibliometric analysis was executed to analyze the publications on the genotoxicity of OCs in soil from 1992 to 2021. The result indicated that significant contributions were made by China and the United States in this field and the research hotspots were biological risks, damage mechanisms, and testing methods. Based on this, in this review, we summarized the manifestations and influencing factors of genotoxicity of OCs to soil organisms, the main damage mechanisms, and the most commonly utilized testing methods. OCs can induce genotoxicity and the hierarchical response of soil organisms, which could be influenced by the physicochemical properties of OCs and the properties of soil. Specific mechanisms of genotoxicity can be classified into DNA damage, epigenetic toxicity, and chromosomal aberrations. OCs with different molecular weights lead to genetic material damage by inducing the generation of ROS or forming adducts with DNA, respectively. The micronucleus test and the comet test are the most commonly used testing methods. Moreover, this review also pointed out that future studies should focus on the relationships between bioaccessibilities and genotoxicities, transcriptional regulatory factors, and potential metabolites of OCs to elaborate on the biological risks and mechanisms of genotoxicity from an overall perspective.

Toxicity effects of nanoplastics on soybean (Glycine max L.): Mechanisms and transcriptomic analysis

Microplastic (MP) pollution has become a major concern in recent years. In agricultural production, MPs can not only affect the growth of crops but also affect yield. Compared with micron-sized MPs, nanoplastics (NPs) may be more harmful to plants. However, the effects of NPs on plant growth and development have attracted relatively little attention. As such, research has currently plateaued at the level of morphology and physiology, and the molecular mechanisms are still unclear. In this study, soybeans (Glycine max L.) were treated with polystyrene nanoplastics (PS-NPs) to observe phenotypic changes and measure the effects of PS-NPs on diverse aspects of soybeans. Compared to the control group, the soybean stem and root lengths were inhibited by 11.78% and 12.58%, respectively. The reactive oxygen species content and the antioxidant enzyme activities changed significantly (p < 0.05). The accumulation of manganese (Mn) and magnesium (Mg) in the roots revealed that root transmembrane transport was affected by PS-NPs stress. The content of salicylic acid 2-O-β-glucoside was inhibited whereas the accumulation of l-tryptophan, the precursor of auxin synthesis, was significantly increased (p < 0.05) in leaves. Transcriptomic analysis showed that PS-NPs could affect soybean DNA repair, membrane protein transport, and hormone synthesis and response. This study revealed the toxicity of NPs to soybeans and that NPs affected a variety of biological processes through transcriptome and hormone metabolome analysis, which provides a theoretical basis to further study the molecular mechanism of the effects on plants.

Organosilicon and inorganic silica inhibit polystyrene nanoparticles uptake in rice

Nanoplastics (NPs) have become an emerging global environmental problem, and the toxicity of polystyrene nanoplastics (PS-NPs) in rice plants has received widespread attention. However, few studies have focused on silicon (Si)-mediated interactions between PS-NPs and rice. Thus, two forms of Si (organosilicon/inorganic silica) treated rice cells were exposure of positively or negatively charged NPs, PS-NH₂ and PS-COOH, to evaluate the effects of Si for defense against PS-NPs toxicity in rice. The result showed PS-NH₂ nanoparticles were accumulated at relatively low levels in cells compared with that of PS-COOH, but induced a higher accumulation of hydrogen peroxide (H₂O₂) and superoxide radicals (O₂^•-). However, both organosilicon and inorganic silica can generate more negative potential on the surfaces of cell wall to absorb large numbers of positively charged PS-NH₂. In addition, they can prevent the uptake of both PS-NH₂ and PS-COOH through reducing the porosity on the surface of the cell walls. These finally alleviated the toxicity of oxidative stress caused by PS-NPs and improved the viability of rice cells. Our findings demonstrated the significant contribution of Si in combating PS-NPs in rice.

Mechanism of Cr(VI) reduction by an indigenous Rhizobium pusense CR02 isolated from chromite mining quarry water (CMQW) at Sukinda Valley, India

Toxicological assessment of CMQW generated due to chromite mining activities at Sukinda Valley has revealed high chromium contamination along with Zn and Fe. The present study focused on the mechanism of chromate reduction by an indigenous multi-metal tolerant bacterium, Rhizobium pusense CR02, isolated from CMQW. The isolated strain has shown resistance up to 520 mg/L of Cr(VI) with an IC50 value of 385.4 mg/L. The highest reduction rate 8.6 × 10^-2/h was recorded with 20 mg/L of initial concentration of Cr(VI). Extracellular (3.06 ± 0.012 U/mL), intracellular (3.60 ± 0.13 U/mL), and membrane (1.89 ± 0.01 U/mL) associated chromate reductases were found to be involved for reduction. The extracellular polymeric substances (EPS) produced by the isolate also enhanced reduction activity of 46.32 ± 1.69 mg/L after 72 h with an initial concentration of 50 mg/L. FTIR analysis revealed the involvement of functional groups -OH, -CO, and -NH for Cr(VI) biosorption whereas P=O, -CO-NH- and -COOH interacted with Cr(III). Zeta potential with less negative surface charge favored reduction of Cr(VI). Treatment of CMQW by bacterial isolate detoxified Cr(VI) minimizing chromosomal aberrations in root cells of Allium cepa L., suggesting the role of Rhizobium pusense CR02 as a promising bio-agent for Cr(VI) detoxification.

High doses of nano-polystyrene aggravate the oxidative stress, DNA damage, and the cell death in onions

Plastic pollution has been reported to negatively impact global biodiversity and ecosystem health. However, the molecular mechanisms of nano-plastics in plants are unidentified, especially their negative impacts on genomic stability. This study for the first time showed that nano-polystyrene leads to cell death in plants by subjugating the cellular antioxidant defence mechanisms through the aggravated production of ROS, which in turn could induce the DNA damage impairing the genetic regulation of the corresponding DNA repair pathway. To validate the proposed hypothesis, the DNA damage potential of nano-polystyrene and the expression levels of key genetic regulators of the DNA damage repair pathway (such as - CYCA/B, CDKA, SOG1, MYB transcription factors, and RAD51) have been assessed in onion roots after 72 h exposure with three ecologically relevant concentrations (25, 50, and 100 μg ml^-1) of 100 nm nano-polystyrene. In addition, imbalance in redox homeostasis (oxidative stress), cell viability, and nuclear aberrations such as - the frequency of micronucleus and bi-nucleate cells that are directly linked to the DNA damages have been checked to point out the cause and effect of nano-polystyrene-induced DNA damage. Results showed a significant increase in oxidative stress in each treatment concentrations of nano-polystyrene. However, ROS generated at 100 μg ml^-1 nano-polystyrene dose subdues the antioxidant defence system and induces cell death. These observations may be ascribed to the accumulation damaged DNA and the down-regulation of repair pathway-associated genes, as observed in this treatment group. Conversely, the observed DNA damage and the reduced expressions of genes would be a mere consequence of reduced cellular viability.

Micro(nano)plastic pollution in terrestrial ecosystem: emphasis on impacts of polystyrene on soil biota, plants, animals, and humans

Pollution with emerging microscopic contaminants such as microplastics (MPs) and nanoplastics (NPs) including polystyrene (PS) in aquatic and terrestrial environments is increasingly recognized. PS is largely used in packaging materials and is dumped directly into the ecosystem. PS micro-nano-plastics (MNPs) can be potentially bioaccumulated in the food chain and can cause human health concerns through food consumption. Earlier MP research has focused on the aquatic environments, but recent researches show significant MP and NP contamination in the terrestrial environments especially agricultural fields. Though PS is the hotspot of MPs research, however, to our knowledge, this systematic review represents the first of its kind that specifically focused on PS contamination in agricultural soils, covering sources, effects, and ways of PS mitigation. The paper also provides updated information on the effects of PS on soil organisms, its uptake by plants, and effects on higher animals as well as human beings. Directions for future research are also proposed to increase our understanding of the environmental contamination of PS in terrestrial environments.