Impact of polystyrene nanoplastics (PSNPs) on seed germination and seedling growth of wheat (Triticum aestivum L.)

Tracking the translocation of nanoplastics from soil to plant: Comparison of different analytical techniques

Nanoplastics (NPs) are increasingly prevalent in the environment, posing potential risks to agricultural systems and the food web. Despite this, currently it lacks comprehensive evaluation on NPs detection and quantification techniques, which is critical for quantitatively understanding the fate and transport of NPs. To address this gap, our study systematically assesses and compares advanced analytical tools for tracking different types of NPs (derived from both top-down and bottom-up approaches) from soil to plants. For identifying and quantifying NPs from environmental samples, pyrolysis - gas chromatography - mass spectrometry (Py-GC-MS) and confocal-Raman spectroscopy demonstrate promise. For laboratory study, inductively coupled plasma mass spectrometry (ICP-MS) along with metal doped NPs enables good sensitivity for tracking NPs in plant system. Our results demonstrated a substantial NPs internalization, 1.09 × 10 ¹ ¹ NPs per gram in shoots and 1.52 × 10 ¹ ¹ NPs per gram in roots, by wheat seedlings after five days of exposure, leading to a notable 77.26 % reduction in biomass. This study highlights the importance of integrating multiple techniques to overcome the limitations of each individual technique and provides quantitative insight into the detection of NPs within plant systems, contributing to the improvement of methodology for NPs related research in environmental and agricultural fields.

Exploring omics solutions to reduce micro/nanoplastic toxicity in plants: A comprehensive overview

The proliferation of plastic waste, particularly in the form of microplastics (MPs) and nanoplastics (NPs), has emerged as a significant environmental challenge with profound implications for agricultural ecosystems. These pervasive pollutants accumulate in soil, altering its physicochemical properties and disrupting microbial communities. MPs/NPs can infiltrate plant systems, leading to oxidative stress and cytotoxic effects, which in turn compromise essential physiological functions such as water uptake, nutrient absorption, and photosynthesis. This situation threatens crop yield and health, while also posing risks to human health and food security through potential accumulation in the food chain. Despite increasing awareness of this issue, substantial gaps still remain in our understanding of the physiological and molecular mechanisms that govern plant responses to MP/NP stress. This review employs integrative omics techniques including genomics, transcriptomics, proteomics, metabolomics, and epigenomics to elucidate these responses. High-throughput methodologies have revealed significant genetic and metabolic alterations that enable plants to mitigate the toxicity associated with MPs/NPs. The findings indicate a reconfiguration of metabolic pathways aimed at maintaining cellular homeostasis, activation of antioxidant mechanisms, and modulation of gene expression related to stress responses. Additionally, epigenetic modifications suggest that plants adapt to prolonged plastics exposure, highlighting unexplored avenues for targeted research. By integrating various omics approaches, a comprehensive understanding of molecular interactions and their effects on plant systems can be achieved. This review underscores potential targets for biotechnological and agronomic interventions aimed at enhancing plant resilience by identifying key stress-responsive genes, proteins, and metabolites. Ultimately, this work addresses critical knowledge gaps and highlights the importance of multi-omics strategies in developing sustainable solutions to mitigate the adverse effects of MP/NP pollution in agriculture, thereby ensuring the integrity of food systems and ecosystems.

Effects of polyethylene microplastics on seed germination, growth performance, biomass production and physiological function of cowpea (Vigna unguiculata) young seedlings

Microplastics (MPs) in terrestrial ecosystems have recently raised concerns; here, we performed a pot experiment and investigated the growth and development by different doses of polyethylene microplastics (PE MPs) in a net house under natural conditions and tested the effects of PE MPs on seed germination, growth performance, physiological function and biomass production of cowpea (Vigna unguiculata) for 25 days. According to the hypothesis, a significant dose-dependent inhibition of cowpea seedling's growth and development was observed depicting the phytotoxicity of PE MPs. Results indicate that high concentrations of PE MPs have antagonistic effects on the growth of plant such as plant height, leaf length and root length within a short period of time. Plants grown in PE MPs show less nutritional characters and exhibit a significant drop in leghemoglobin content as the concentration of MP increases which is one of the novel findings. The results showed a significantly increased antioxidant enzyme activity indicating the stress condition of plants due to exposure to PE MPs. PE MPs undergo initial stage of partial disintegration when it contacts with soil which were detected through SEM analysis when compared to control. Comprehensive field study involving MPs at different concentrations throughout the cowpea's whole life cycle until harvest is needed to better clarify the effects of PE MPs and produce reliable results.

Tiny pollutants, big consequences: investigating the influence of nano- and microplastics on soil properties and plant health with mitigation strategies

The impact of nanoplastics (NPs) and microplastics (MPs) on ecosystems and human health has recently emerged as a significant challenge within the United Nations Agenda 2030, drawing global attention. This paper provides a critical analysis of the influence of plastic particles on plants and soils, with the majority of data collected from recent studies, primarily over the past five years. The absorption and translocation mechanisms of NPs/MPs in plants are first described, followed by an explanation of their effects-especially particles like PE, PS, PVC, PLA, and PES, as well as those contaminated with heavy metals-on plant growth, physiology, germination, oxidative stress, and nutrient uptake. The study also links the characteristics of plastics (size, shape, concentration, type, degradability) to changes in the physical, chemical, and microbial properties of soils. Various mitigation strategies, including physical, chemical, and biological processes, are explored to understand how they address these changes. However, further research, including both laboratory and field investigations, is urgently needed to address knowledge gaps, particularly regarding the long-term effects of MPs, their underlying mechanisms, ecotoxicological impacts, and the complex interactions between MPs and soil properties. This research is crucial for advancing sustainability from various perspectives and should contribute significantly toward achieving sustainable development goals (SDGs).

Organic fertilizer mitigated the oxidative stress of tomato induced by nanoplastics through affecting rhizosphere soil microorganisms and bacteriophage functions

Nanoplastics (NPs), which are widely present in agricultural soils, are difficult to remove and are potentially harmful to plant growth and development. However, few studies have focused on how to mitigation the oxidative stress in plants induced by soil NPs exposure. Therefore, in this study, the effects of organic and chemical fertilizers on the oxidative stress of tomato under exposure to polystyrene nanoplastics (PS-NPs) in soil were investigated. Compared with chemical fertilizer under exposure to PS-NPs, the organic fertilizer reduced the reactive oxygen species (ROS) content by 25.63 % and the H2O2 content by 34.58 % in tomato stems, whereas no significant effects were observed with respect to the amount of PS-NP internalized in tomato. Additionally, organic fertilizer increased the accumulation of the phytohormones salicylic acid (SA) and abscisic acid (ABA) by 76.53 % and 22.54 %, respectively, and these factors are key for reducing the ROS and H2O2 contents in stems. In the rhizosphere microbiome of organic fertilizer group under exposure to PS-NPs, enrichment in Actinomycetes and an increased abundance of terpenoids and polyketides metabolism were the main factors affecting the accumulation of ABA and SA. Moreover, bacteriophage activity in the rhizosphere indirectly contributed to the increase in this function. These changes ultimately resulted in a reduction in oxidative stress in tomato stems and protected tomato growth. The results of this study will provide a better understanding of the interaction between plants and nanoplastics in soil and provide a new reference for alleviating the oxidative stress caused by nanoplastics in plants.

Biodegradable microplastics affect tomato (Solanum lycopersicum L.) growth by interfering rhizosphere key phylotypes

Biodegradable microplastics (BMPs), which form as biodegradable plastics degrade in agricultural settings, may influence plant growth and soil health. This study investigates the effects of BMPs on tomato growth and the microbial mechanisms involved. A greenhouse experiment applied BMPs-polyhydroxyalkanoate (PHA), polylactic acid (PLA), poly(butylene succinate-co-butylene adipate) (PBSA), and poly(butylene-adipate-co-terephthalate) (PBAT)-to tomato plants. The study analyzed their effects on plant growth, soil properties, and rhizosphere microbial communities. BMP treatments significantly reduced tomato biomass, height, and chlorophyll content compared to the control. PLA0.1 decreased the chlorophyll a/b ratio, while PLA1 increased it. Elemental analysis showed PLA1 increased phosphorus, calcium, and potassium in leaves, whereas all BMPs reduced nitrogen levels. BMPs also altered soil nitrogen and DOC levels, significantly shifting rhizosphere microbial communities, with a notable increase in Betaproteobacteria abundance. Ecological network analysis revealed that BMPs disrupted key microbial modules linked to plant growth. Beneficial modules positively associated with biomass and nutrient uptake were reduced under BMP treatments, whereas harmful microbial taxa in module 3, associated to poor plant health, were promoted. These shifts suggest that BMPs disrupt microbial ecological relationships critical for optimal plant growth. The findings highlight the potential negative impacts of BMPs on tomato growth through changes in microbial dynamics and soil properties.

Effects of nanoplastics and compound pollutants containing nanoplastics on plants, microorganisms and rhizosphere systems: A review

Nanoplastics (NPs) are the most widespread and least detectable type of plastic pollutant due to their extremely small particle size. The root system of plants has become an important pathway for NPs to enter the food chain from the natural environment. By combining with heavy metals or organic pollutants, NPs can exhibit greater biological toxicity compared to single pollutants. Although many studies have focused on the phytotoxicity and microbial toxicity of NPs separately, to the best of our knowledge, no review summarizes the toxicity of NPs from the perspective of the plant rhizosphere system with a combination of pollutants. By summarizing samples from 2015 to 2025, this review highlights that NPs can affect photosynthesis, gene transcription, and enzyme activity in both plants and microorganisms. NPs with large particle size can also disrupt the chemical balance of the rhizosphere environment and intensify competition for nutrients between plants and microorganisms, ultimately affecting the geochemical cycle. NPs of different particle sizes and concentrations can poison various biological structures, from surface layers to genetic material. In compound pollutants, where NPs combine with other contaminants, they can further disrupt elemental cycles in plants, reduce microbial community diversity, and increase the accumulation of other pollutants in the rhizosphere system compared to single pollutants. These findings provide new insights into the biotoxicity of NPs and the degradation of compound pollutants containing NPs. In addition, combined with the research results of this review, some research prospects on the relationship between NPs and rhizosphere systems are given.

Foliar exposure to microplastics disrupts lettuce metabolism and negatively interferes with symbiotic microbial communities

Plant leaves are considered an important sink for atmospheric microplastics (MPs) because they serve as a vital interface between the atmosphere and terrestrial ecosystems. However, there is still a dearth of information regarding how plant-symbiotic microbe-soil systems are affected by foliar exposure to MPs. In this study, MPs (polystyrene (PS), polyethylene (PE), and polypropylene (PP)) were sprayed over soil-cultivated lettuce (Lactuca sativa L.) four occasions, with final sprays containing 0.4 and 4 μg of MPs per plant. MPs had no discernible impact on lettuce growth as compared to the control group. However, MPs led to reductions in relative chlorophyll content from 16.91 to 30.64 % and net photosynthetic rate from 6.64 to 81.41 %. These results validate the phytotoxicity linked to MP exposure through foliar application. The presence of MPs triggered interspecific competition among phyllosphere microbial species and reduced microbial network complexity by forming ecological niches and regulating carbon- and nitrogen-related metabolic pathways. Furthermore, MPs inhibited the growth of beneficial bacteria in the rhizosphere soil, including a variety of plant growth-promoting bacteria (PGPR) such as Rhizobiales, Pseudomonadales, and Bacillales. This study identifies the ecological health risks associated with atmospheric MPs, which may have a detrimental impact on crop production and further compromise soil ecosystem security.

Micro/Nanoplastics in plantation agricultural products: behavior process, phytotoxicity under biotic and abiotic stresses, and controlling strategies

With the extensive utilization of plastic products, microplastics/nanoplastics (MPs/NPs) contamination not only poses a global hazard to the environment, but also induces a new threat to the growth development and nutritional quality of plantation agricultural products. This study thoroughly examines the behavior of MPs/NPs, including their sources, entry routes into plants, phytotoxicity under various biotic and abiotic stresses (e.g., salinity, polycyclic aromatic hydrocarbons, heavy metals, antibiotics, plasticizers, nano oxide, naturally occurring organic macromolecular compounds, invasive plants, Botrytis cinerea mycorrhizal fungi.) and controlling strategies. MPs/NPs in agricultural systems mainly originate from mulch, sewage, compost fertilizer, municipal solid waste, pesticide packaging materials, etc. They enter plants through endocytosis, apoplast pathways, crack-entry modes, and leaf stomata, affecting phenotypic, metabolic, enzymatic, and genetic processes such as seed germination, growth metabolism, photosynthesis, oxidative stress and antioxidant defenses, fruit yield and nutrient quality, cytotoxicity and genotoxicity. MPs/NPs can also interact with other environmental stressors, resulting in synergistic, antagonistic, or neutral effects on phytotoxicity. To address these challenges, this review highlights strategies to mitigate MPs/NPs toxicity, including the development of novel green biodegradable plastics, plant extraction and immobilization, exogenous plant growth regulator interventions, porous nanomaterial modulation, biocatalysis and enzymatic degradation. Finally, the study identifies current limitations and future research directions in this critical field.

Effect of polystyrene micro/nanoplastics on PCBs removal in constructed wetlands planted with Myriophyllum aquaticum

The co-occurrence of microplastics (MPs) and nanoplastics (NPs) with polychlorinated biphenyls (PCBs) is an emerging environmental concern. Wetland plants, with their unique anaerobic-aerobic environments, offer a promising approach for PCBs removal. However, the impact of MPs and NPs on PCBs dynamics in constructed wetlands is not well understood. This study examined the influence of polystyrene MPs and NPs of two different sizes on PCBs fate in constructed wetlands featuring Myriophyllum aquaticum. Results showed that although there was no significant difference in overall PCBs removal rates, the presence of MPs increased residues of highly chlorinated PCBs from 331 μg/kg to 379 μg/kg, while the presence of NPs increased residues of lightly chlorinated PCBs from 125 μg/kg to 153 μg/kg. Additionally, MPs and NPs increased plant uptake of PCBs from 0.08% to 0.10-0.14%, despite potential inhibition of plant growth. While MPs/NPs elevated microorganism counts, they did not affect microbial diversity or community structure. Importantly, MPs significantly inhibited the main PCB-dechlorinating bacteria (Dehalococcoidia) and had a greater impact on PCB-degrading enzymes (dioxygenase, K03381) compared to NPs. This study highlights the complex interactions between MPs/NPs and PCBs in wetland environments and their implications for bioremediation strategies.

Bipartite trophic levels cannot resist the interference of microplastics: A case study of submerged macrophytes and snail

Some studies frequently focus on the toxic effects of compound pollution formed by microplastics and other pollutants on individual organisms, but it is still unclear how multi-trophic level organisms in compound communities resist the stress of microplastics. Thus, this research used a dose-response experiment (0, 0.1, 0.2, 0.5, 1 mg L-1) to illustrate the influences that microplastics might have on two symbiotic freshwater organisms Vallisneria natans and Sinotaia quadrata. The results showed the reduction of V. natans biomass in 0.5 and 1 mg L-1 groups (28-38 %), and disturbances on the photosynthetic system, reduced the chlorophyll content (15-85 %) and maximum quantum yields (10-31 %). In the case of S. quadrata, which subsisted by scraping leaf biofilms, there was a disruption in the functioning of the antioxidant system. Concurrently, the activities of digestive and neurotransmitter enzymes were affected, potentially leading to detrimental impacts on the organism's essential physiological processes. The introduction of microplastics significantly enhanced the relative abundance of specific microbial taxa, such as Proteobacteria within the biofilm of V. natans leaves and chloroflexi in the rhizosphere, thereby altering the microbial community assembly process. This means the potential ecological functions with microbes as the carrier was influenced. These results indicated that microplastic in aquatic environments can impact the metabolism, autotrophic, and heterotrophic behavior of double-end trophic organisms through symbiotic activities. Therefore, our study reveals how polystyrene microplastics affect the growth of submerged aquatic plants and snails, and from the perspective of community integrity and health, the introduction of these pollutants into freshwater environments may cause disruptive effects.

Translocation, Transformation, and Phytotoxicity of Sulfadiazine and N4-Acetylsulfadiazine in Rice Plants

This study investigates the uptake, biotransformation, and phytotoxicity of sulfadiazine (SDZ) and its acetyl derivative N4-acetylsulfadiazine (NASDZ) in rice. Results showed that rice was more tolerant to NASDZ, with lower malondialdehyde and reactive oxygen species levels but higher antioxidant enzyme activities (SOD, POD, and CAT). The maximum accumulations of SDZ in roots and shoots were 19.3 ± 1.0 and 3.6 ± 1.1 μg/g, while NASDZ were 18.6 ± 2.5 and 3.5 ± 1.4 μg/g, respectively. SDZ exposure generated more metabolic intermediates, including deamination, hydroxylation, glycosylation, acetylation, and formylation products, while NASDZ metabolism was documented for the first time. Key genes involved in biotransformation include cytochrome P450, acetyltransferase, glycosyltransferases, and methyltransferase. Density functional theory calculations showed structural differences affecting reactive sites and intermediates. SDZ disrupted lipid metabolism, while NASDZ altered carbohydrate and amino acid pathways, highlighting their selective effects on rice metabolism. Our data help understand sulfonamide biotransformation and phytotoxicity in rice.

Coding and non-coding transcripts modulated by transparent and blue PET micro-nanoplastics in Arabidopsis thaliana

To get further insights on the micro-nanoplastic (MNP) effects on plants, the aim of this study was to evaluate the response of hydroponically cultivated Arabidopsis thaliana to the presence of differentially colored polyethylene terephthalate (PET) particles. MNP impacts on the root organ were studied at a molecular level, with a special focus on the role of long non-coding RNAs (lncRNAS) in the regulation of gene expression after PET exposure. MNPs of transparent (Tr-PET) and blue (Bl-PET) material at environmentally realistic concentration caused a significant reduction in root length, while only Bl-PET significantly reduced rosette area. MNPs induced oxidative stress markers. Tr-PET upregulated genes involved in signaling of xenobiotics, whereas Bl-PET scarcely affected root transcriptomic profile, activating few gene categories for abiotic stresses. Regarding hormones, genes involved in ABA response were repressed, while brassinosteroid-related genes were differentially regulated by Tr-PET. Both MNPs, but especially Tr-PET, upregulated major latex protein-related genes. Plant molecular response to MNPs was linked to differential abundance of lncRNAs on both comparisons. Tr-PET affected the expression of much more lncRNAs than bl-PET (80 and 11 respectively). These lncRNAs were predicted to interact with several repressed protein-coding genes (i.e. glucosyltransferase UGT2, oxidative stress genes etc.), with possible effects on their regulation. A lncRNA (AT1G09297) interacted with CYP81D8, a key gene of cytochrome P450 gene family involved in xenobiotics detoxification. Two lncRNAs interacted with two members of repressed HSP (HSP90 and HSP17.4) family. Finally, genes involved in redox detoxification and stress responses were inhibited by the interaction with two microplastics-regulated lncRNAs. These data highlighted the need of investigating non-coding RNAs in the future in addition to the mostly studied protein coding transcriptome.

Physiological and oxidative status of soybean seedlings exposed to short term treatment with polystyrene nanoparticles

Plastic is widely used worldwide due to its durability and relatively low production costs. However, its durability also has significant drawbacks - plastic is a slowly degrading material and greatly contributes to the environmental pollution. Increasing body of evidence shows that contamination of the environment with plastic negatively affects plants and other living organisms. The aim of present research was to determine whether short-term exposure to polystyrene nanoparticles (PSNP) has toxic effect on soybean seedlings (Glycine max L). In the first stage of the research, the effect of two hour long incubation in PSNP solutions (10 and 100 mgl-1) on the germination of soybean seeds was determined. In the second part of the study, the potential cytotoxic effect of PSNP on young seedlings was measured. The results indicate that incubation in PSNP solutions inhibits the germination of soybean seeds by approx. 10% (at p = 0.05). However, this effect was only observed after 48 and 72 h of germination and by lower PSNP concentrations, 10 mgl-1. In turn, in young soybean seedlings exposure to PSNP had no effect on growth, cell viability or oxidative status by p = 0.05. The results indicate that germination is a PSNP-sensitive process. In turn, already germinated seedlings are relatively resistant to the short-term exposure to this stressor.

The wheel of time: The environmental dance of aged micro- and nanoplastics and their biological resonance

The aging of micro- and nanoplastics (MNPs) significantly affects their environmental behavior and ecological impacts in both aquatic and terrestrial ecosystems. This review explored the known effects of aging on MNPs and identified several key perspectives. Firstly, aging can alter the environmental fate and transport of MNPs due to changes in their surface properties. This alteration accelerates their accumulation in specific habitats like oceans and soils, resulting in increased bioaccumulation by organisms. In addition, aged MNPs interact differently with living organisms than their pristine counterparts by influencing the attachment of biofilms and other microorganisms in aquatic ecosystems. Moreover, the aging processes of MNPs exhibit adverse effects on aquatic and terrestrial organisms via increasing the bioavailability and potential toxicity of MNPs as degradation products are released. Last but not least, the biodegradation potential of MNPs can be altered by the aging process, thus affecting their degradation rates and pathways in the environment. However, there are still knowledge gaps regarding the natural aging behaviors of MNPs, such as the aging mechanisms of different types of plastic, the influence of environmental factors, the release of pollutants, and even the effects of aging on their transformation in different ecosystems. Therefore, a great contribution can be made to sustainable plastic use and environmental preservation by studying the natural aging of common MNPs and their subsequent biological effects.

Polyethylene nanoplastics affected morphological, physiological, and molecular indices in tomato (Solanum lycopersicum L.)

This study explored morphological, physiological, molecular, and epigenetic responses of tomatoes (Solanum lycopersicum) to soil contamination with polyethylene nanoplastics (PENP; 0.01, 0.1, and 1 gkg-1 soil). The PENP pollution led to severe changes in plant morphogenesis. The PENP treatments were associated with decreased plant biomass, reduced internode length, delayed flowering, and prolonged fruit ripening. Abnormal inflorescences, flowers, and fruits observed in the PENP-exposed seedlings support genetic changes and meristem dysfunction. Exposure of seedlings to PENP increased H2O2 accumulation and damaged membranes, implying oxidative stress. The PENP treatments induced activities of catalase (EC1.11.1.6), peroxidase (EC1.11.1.7), and phenylalanine ammonia-lyase (EC4.3.1.24) enzymes. Soil contamination with PENP also decreased the net photosynthesis, maximum photosystem efficiency, stomatal conductance, and transpiration rate. The nano-pollutant upregulated the expression of the histone deacetylase (HDA3) gene and R2R3MYB transcription factor. However, the AP2a gene was down-regulated in response to the PENP treatment. Besides, EPNP epigenetically contributed to changes in DNA methylation. The concentrations of proline, soluble phenols, and flavonoids also displayed an upward trend in response to the applied PENP treatments. The long-term exposure of seedlings to PENP influenced fruit biomass, firmness, ascorbate, lycopene, and flavonoid content. These findings raise concerns about the hazardous aspects of PENP to agricultural ecosystems and food security.

Polypropylene microplastic exposure modulates multiple metabolic pathways in tobacco leaves, impacting lignin biosynthesis

The adverse effects of microplastics (MPs) and nanoplastics (NPs) on plant growth have gained significant attention. However, the response of tobacco plants to polypropylene microplastics (PP-MPs) remains poorly understood. To address this, a microcosm experiment was conducted in which tobacco seedlings were exposed to PP-MPs at varying concentrations (100 and 1000 mg/kg) and particle sizes (20 nm and 100 µm) for 48 days in red soil. The physicochemical, transcriptomic, and metabolic responses of tobacco plants to PP-MP treatments were assessed. Our findings indicate that the effect of PP-MP exposure on tobacco growth was dose-dependent, with the higher doses (1000 mg/kg) inducing significantly stronger responses. Further, a significant accumulation of key metabolites in the phenylpropanoid and flavonoid biosynthesis pathways such as quercetin, phloretin, kaempferol, liquiritigenin, naringin, myricetin, ferulic acid, formaldehyde, and methyl eugenol was observed in response to PP-MPs. Additionally, the transcriptomic analysis revealed that higher doses enriched more DEGs than lower. KEGG pathway analysis identified significant enrichment in phenylpropanoid biosynthesis, flavonoid biosynthesis, sesquiterpenoid and triterpenoid biosynthesis, and plant hormone signal transduction. The notable variation in the expression of key enzyme-related genes such as PAL, CHI, CSE, C4H, 4CL, COMT, and CYP indicates the substantial impact on lignin synthesis. Lastly, large-sized PPMPs alter the activity of key lignin-degrading enzymes, affecting the lignin content. This study offers valuable insights into the responses of tobacco plants to varying concentrations and sizes of PP-MPs, integrating both physicochemical and molecular perspectives.

The fate of biodegradable polylactic acid microplastics in maize: impacts on cellular ion fluxes and plant growth

The widespread application of biodegradable microplastics (MPs) in recent years has resulted in a significant increase in their accumulation in the environment, posing potential threats to ecosystems. Thus, it is imperative to evaluate the distribution and transformation of biodegradable MPs in crops due to the utilization of wastewater containing MPs for irrigation and plastic films, which have led to a rising concentration of biodegradable MPs in agricultural soils. The present study analyzed the uptake and transformation of polylactic acid (PLA) MPs in maize. Seed germination and hydroponic experiments were conducted over a period of 5 to 20 days, during which the plants were exposed to PLA MPs at concentrations of 0, 1, 10, and 100 mg L-1. Low concentrations of PLA MPs (1 mg L-1 and 10 mg L-1) significantly enhanced maize seed germination rate by 52.6%, increased plant shoot height by 16.6% and 16.9%, respectively, as well as elevated aboveground biomass dry weight by 133.7% and 53.3%, respectively. Importantly, depolymerization of PLA MPs was observed in the nutrient solution, resulting in the formation of small-sized PLA MPs (< 2 μm). Interestingly, further transformation occurred within the xylem sap and apoplast fluid (after 12 h) with a transformation rate reaching 13.1% and 27.2%, respectively. The enhanced plant growth could be attributed to the increase in dissolved organic carbon resulting from the depolymerization of PLA MPs. Additionally, the transformation of PLA MPs mediated pH and increase in K+ flux (57.2%, 72 h), leading to acidification of the cell wall and subsequent cell expansion. Our findings provide evidence regarding the fate of PLA MPs in plants and their interactions with plants, thereby enhancing our understanding of the potential impacts associated with biodegradable plastics.

The coexistence characteristics of microplastics and heavy metals in rhizomes of traditional Chinese medicine in mulch planting area

Rhizomatous traditional Chinese medicines (RTCMs) are widely crushed into powder and swallowed directly as medicine and food or health products to treat various diseases; however, they may contain toxic microplastics (MPs) and heavy metals. Currently, there are no reports on the detection of MPs and MP-heavy metal synergies in RTCMs. In this study, we selected eight representative RTCMs to investigate the abundance, types, sizes, and polymers of MP and heavy metals and to assess the level of contamination of MPs and synergies between MPs and heavy metals in RTCMs. The abundance of MPs in different RTCM ranged from 20.83 to 43.65 items/g. The dominant type was fragment (95.43%), and the dominant particle size was < 0.5 mm (73.72%) in MPs. Polyurethane (PU) (29.21%) and acrylics (ACR 13.53%) were the dominant polymers of MP. MP polymers showed obvious correlations with type and particle size: PU was enriched in 0-50-mm and 100-300-mm fragments, whereas ethylene vinyl acetate and ACR were enriched in 0-30-mm fibers. The heavy metals arsenic (As), lead (Pb), and chromium (Cr) were found to be more susceptible to synergistic contamination with MPs in RTCMs compared to other heavy metals. The estimated daily intake (EDI) of the MPs and heavy metals for RG (Rehmannia glutinosa) and RAY (Rhizoma atractylodis) were higher than others. The results showed that MP pollution is common in RTCMs and carries the potential risk of heavy metal or MP poisoning in humans who consume RTCMs.

Bacillus subtilis, a promising bacterial candidate for trapping nanoplastics during water treatment

As a probiotic, Bacillus subtilis (B. subtilis) has a wide range of application values. In this study, the trap by B. subtilis and the effect of NPs on its growth physiology were studied. Confocal laser scanning microscopy (LCSM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) confirmed that PS-NPs were trapped by B. subtilis when they were exposed to PS-NPs. At this point, most of the PS-NPs are clustered around B. subtilis. Flow cytometry showed that at 10 mg/L, 73.7 % of PS-NPs' environmental state changed. The complexity of 9.73 %, 23.77 %, 43.27 %, and 65.13 % of B. subtilis increased at PS-NP concentrations of 10, 20, 50, and 200 mg/L, respectively. The increase in overall EPS secretion ranged from 0.51 ∼ 7.13 μg/mL after adding different concentrations of PS-NPs. The effect of different concentrations of PS-NPs on NAR activity ranged from -11.38 ∼ 16.2 %, on NIR activity from -17.90 ∼ 7.22 %, on NOR activity from -15.10 ∼ 7.69 % and on NO2R activity from -14.01 ∼ 17.03 %. These results indicated that B. subtilis can process nitrogen compounds in water while capturing NPs in the environment. They have the potential to be candidate bacteria in the water treatment process, and specific applications are needed to research further.

Toxicological effects and molecular metabolic of polystyrene nanoplastics on soybean (Glycine max L.): Strengthening defense ability by enhancing secondary metabolisms

Nanoplastics, as emerging pollutants, have attracted worldwide concern for their possible environmental dangers. The ingestion and accumulation of nanoplastics in crops can contaminate the food chain and have unintended consequences for human health. In this study, we revealed the effects of polystyrene nanoplastics (PS-NPs; 80 nm) at different concentrations (0, 10, 100 mg L-1) on soybean (Glycine max L.) seedling growth, antioxidant enzyme system and secondary metabolism. Using laser confocal microscopy, we demonstrated that the absorption and translocation of PS-NPs in soybean. Plant growth inhibition was observed by changes in plant height, root length, and leaf area after 7 days of exposure to PS-NPs. The effect of PS-NPs on photosynthetic characteristics was reflected by a significant reduction in total chlorophyll content at 10 mg L-1. Activation of the antioxidant system was observed with increased malondialdehyde (MDA) content, and elevated activities of superoxide dismutase (SOD) and catalase (CAT). Non-targeted metabolomics analysis identified a total of 159 secondary metabolites, and exposure to 10 and 100 mg L-1 PS-NPs resulted in the production of 61 and 62 differential secondary metabolites. Metabolomics analysis showed that PS-NPs treatment altered the secondary metabolic profile of soybean leaves through the biosynthesis pathways of flavonoid, flavone flavonol, and isoflavones, which is expected to provide new insights into the tolerance mechanisms of plants to nanoplastics. Overall, the results of this study deepen our understanding of the negative impacts of nanoplastics in agricultural systems, which is crucial for assessing the risks of nanoplastics to ecological security.

Environmental impact of microplastics and potential health hazards

Microscopic plastic (microplastic) pollutants threaten the earth's biodiversity and ecosystems. As a result of the progressive fragmentation of oversized plastic containers and products or manufacturing in small sizes, microplastics (particles of a diameter of 5 mm with no lower limit) are used in medicines, personal care products, and industry. The incidence of microplastics is found everywhere in the air, marine waters, land, and even food that humans and animals consume. One of the greatest concerns is the permanent damage that is created by plastic waste to our fragile ecosystem. The impossibility of the complete removal of all microplastic contamination from the oceans is one of the principal tasks of our governing body, research scientists, and individuals. Implementing the necessary measures to reduce the levels of plastic consumption is the only way to protect our environment. Cutting off the plastic flow is the key remedy to reducing waste and pollution, and such an approach could show immense significance. This review offers a comprehensive exploration of the various aspects of microplastics, encompassing their composition, types, properties, origins, health risks, and environmental impacts. Furthermore, it delves into strategies for comprehending the dynamics of microplastics within oceanic ecosystems, with a focus on averting their integration into every tier of the food chain.

Microplastic-induced changes in Cd and Cr behavior in the agricultural soil-wheat system: Insights into metal bioavailability and phytotoxicity

Microplastics (MPs) and heavy metals widely coexist in agricultural soils, posing significant risks to soil-plant ecosystems. This study explores the effects of five common MPs-polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), polystyrene (PS), and polylactic acid (PLA)-and environmental-simulating microplastics (EMPs), composed based on the composition of local MPs in agricultural soils, on the bioavailability and phytotoxicity of Cd and Cr in soils. Pot experiments demonstrated that MPs, particularly PE and EMPs at a 5 % dosage, markedly decreased soil pH, water-holding capacity, and soil organic carbon content. This decrease in pH led to enhanced Cd and Cr mobility and bioavailability, especially with PE and EMPs increasing Cr bioavailability in 15 cm depth soil by up to 43.9 % and 37.8 %, respectively. In soils with 2.1 mg/kg of Cd and 390 mg/kg of Cr, both 1 % and 5 % doses of MPs inhibited wheat growth while enhancing the uptake and translocation of Cd and Cr in wheat. Notably, PE, PS, PLA, and EMPs exposure significantly elevated levels of oxidative stress markers (SOD, POD, CAT, and MDA) in wheat. These findings highlight the importance of further research on the combined impacts of MPs and heavy metals on soil health and plant safety.

Unveiling the mechanism of micro-and-nano plastic phytotoxicity on terrestrial plants: A comprehensive review of omics approaches

Micro-and-nano plastics (MNPs) are pervasive in terrestrial ecosystems and represent an increasing threat to plant health; however, the mechanisms underlying their phytotoxicity remain inadequately understood. MNPs can infiltrate plants through roots or leaves, causing a range of toxic effects, including inhibiting water and nutrient uptake, reducing seed germination rates, and impeding photosynthesis, resulting in oxidative damage within the plant system. The effects of MNPs are complex and influenced by various factors including size, shape, functional groups, and concentration. Recent advancements in omics technologies such as proteomics, metabolomics, transcriptomics, and microbiomics, coupled with emerging technologies like 4D omics, phenomics, spatial transcriptomics, and single-cell omics, offer unprecedented insight into the physiological, molecular, and cellular responses of terrestrial plants to MNPs exposure. This literature review synthesizes current findings regarding MNPs-induced phytotoxicity, emphasizing alterations in gene expression, protein synthesis, metabolic pathways, and physiological disruptions as revealed through omics analyses. We summarize how MNPs interact with plant cellular structures, disrupt metabolic processes, and induce oxidative stress, ultimately affecting plant growth and productivity. Furthermore, we have identified critical knowledge gaps and proposed future research directions, highlighting the necessity for integrative omics studies to elucidate the complex pathways of MNPs toxicity in terrestrial plants. In conclusion, this review underscores the potential of omics approaches to elucidate the mechanisms of MNPs-phytotoxicity and to develop strategies for mitigating the environmental impact of MNPs on plant health.

Titanium dioxide nanoparticles seed priming as a remedy for nickel-induced stress in maize through antioxidant enhancement and ultrastructural optimization

Heavy metals (HMs) have emerged as a critical global concern, not only limiting crop productivity but also posing risks to public health. Among them, nickel (Ni) is an essential micronutrient for plant growth; however, it becomes toxic at higher concentrations. Nano-enabled approaches, on the other hand, have emerged as promising eco-friendly alternatives for mitigating the negative impact associated with HMs. Here, we investigated the potential of titanium dioxide nanoparticles (TiO2 NPs) against Ni-induced stress in maize. Our results showed that Ni stress caused negative changes in maize by the excessive production of reactive oxygen species (ROS), inhibiting photosynthetic attributes, and damaging cellular ultrastructure. In contrast, TiO2 NPs priming significantly enhanced the antioxidant mechanism, photosynthetic efficacy, and nutrient uptake while reducing ultrastructural damage caused by Ni stress. Furthermore, TiO2 NPs efficiently reduced Ni accumulation, MDA (28%/32%), H2O2 (23%/26%), and O2•‒ (31%/34%) levels in shoot/root tissues, respectively, compared to Ni treatment. Moreover, TiO2 NPs priming has modulated the expression of antioxidant and defense-related genes, thereby restoring cellular redox homeostasis. Collectively, this is the first piece of evidence demonstrating the potential of TiO2 NPs as an efficient and sustainable alternative for enhancing crop tolerance in Ni-contaminated areas.

Microplastics in Agricultural Crops and Their Possible Impact on Farmers' Health: A Review

The indiscriminate use of plastic products and their inappropriate management and disposal contribute to the increasing presence and accumulation of this material in all environmental zones. The chemical properties of plastics and their resistance to natural degradation lead over time to the production of microplastics (MPs) and nanoplastics, which are dispersed in soil, water, and air and can be absorbed by plants, including those grown for food. In agriculture, MPs can come from many sources (mulch film, tractor tires, compost, fertilizers, and pesticides). The possible effects of this type of pollution on living organisms, especially humans, increase the need to carry out studies to assess occupational exposure in agriculture. It would also be desirable to promote alternative materials to plastic and sustainable agronomic practices to protect the safety and health of agricultural workers.

Polyethylene terephthalate nanoplastics affect potassium accumulation in foxtail millet (Setaria italica) seedlings

BACKGROUND

As modern industrial activities have advanced, the prevalence of microplastics and nanoplastics in the environment has increased, thereby impacting plant growth. Potassium is one of the most crucial nutrient cations for plant biology. Understanding how polyethylene terephthalate (PET) treatment affects potassium uptake will deepen our understanding of plant response mechanisms to plastic pollution.

RESULTS

In this study, we examined the impact of PET micro- and nanoplastics on foxtail millet seedling growth and potassium accumulation. Additionally, we measured reactive oxygen species (ROS) production, antioxidant enzyme activities, and the expression levels of the corresponding enzyme-encoding genes. Our findings indicated that the germination and seedling growth of foxtail millet were not significantly affected by exposure to PET plastics. However, the ROS levels in foxtail millet increased under these conditions. This increase in ROS led to the upregulation of several genes involved in K+ uptake and transport (SiHAK1, SiHAK2, SiAKT2/3, SiHKT2;2, SiHKT1;1, SiGORK, and SiSKOR), thereby increasing K+ accumulation in foxtail millet leaves. Further research revealed that higher K+ concentrations in plant leaves were correlated with increased expression of the antioxidant-related genes SiCAT1, SiPOD1, and SiSOD3, as well as increased activities of the corresponding antioxidant enzymes. This response helps mitigate the excessive accumulation and damage caused by ROS in plant cells after PET nanoplastic treatment, suggesting a potential stress response mechanism in foxtail millet against nanoplastic pollution.

CONCLUSIONS

Our research indicates that PET nanoplastic treatment induces the expression of genes related to K+ uptake in foxtail millet through ROS signaling, leading to increased K+ accumulation in the leaves. This process mitigates the ROS damage caused by PET nanoplastic treatment by increasing the expression and activity of genes encoding antioxidant enzymes. The present research has unveiled the K+ accumulation-related response mechanism of foxtail millet to PET nanoplastic treatment, contributing significantly to our understanding of both the potassium absorption regulation mechanism in plants and the broader impact of plastic pollution on agricultural crops. This discovery not only highlights the complexity of plant responses to environmental stressors but also underscores the importance of considering such responses when evaluating the ecological and agricultural implications of plastic pollution.

Understanding the possible cellular responses in plants under micro(nano)-plastic (MNPs): Balancing the structural harmony with functions

The harmful impacts of micro(nano)-plastics (MNPs) on plants have gained significant attention in the last decades. Plants have a greater tendency to aggregate positively charged (+ve) MNPs on leaf surfaces and root tips, and it can be more challenging to enter the plant body than the negatively charged (-ve) MNPs. MNPs <20 nm can directly cross the cell wall and enter mainly via leaf stomata and root crack portion. Additionally, plants with aerenchyma tissue or higher water requirement might be more vulnerable to MNPs as well as environmental factors also affected MNPs uptake like porosity and structure (i.e. crack of soil) of soil, wind speed, etc. The subsequent translocation of MNPs hamper regular morphological, physiological, and biochemical functions by causing oxidative stress, altering several plant metabolic pathways, reducing the rate of photosynthesis and nutrient intake, etc. These induce cellular toxicity and chromosomal alteration; as a result, the total biomass and productivity reduce vigorously. However, there is a knowledge gap regarding MNPs' uptake by plants and related variables affecting phytotoxicity at the omics levels. So, the present literature review represents a comprehensive theoretical framework that includes genomics, transcriptomics, miRNAomics, proteomics, metabolomics, and ionomics/metallomics, which is established to understand the effects of MNPs on plants at the molecular level. As well as it will also help in further studies of the research community in the future because this field is still in the preliminary stages due to a lack of study.

Effects of nanoplastics on the growth, transcription, and metabolism of rice (Oryza sativa L.) and synergistic effects in the presence of iron plaque and humic acid

Nanoplastics (NPs) can adversely affect living organisms. However, the uptake of NPs by plants and the physiological and molecular mechanisms underlying NP-mediated plant growth remain unclear, particularly in the presence of iron minerals and humic acid (HA). In this study, we investigated NP accumulation in rice (Oryza sativa L.) and the physiological effects of exposure to polystyrene NPs (0, 20, and 100 mg L-1) in the presence of iron plaque (IP) and HA. NPs were absorbed on the root surface and entered cells, and confocal laser scanning microscopy confirmed NP uptake by the roots. NP treatments decreased root superoxide dismutase (SOD) activity (28.9-44.0%) and protein contents (31.2-38.6%). IP and HA (5 and 20 mg L-1) decreased the root protein content (20.44-58.3% and 44.2-45.2%, respectively) and increased the root lignin content (22.3-27.5% and 19.2-29.6%, respectively) under NP stress. IP inhibited the NP-induced decreasing trend of SOD activity (19.2-29.5%), while HA promoted this trend (48.7-50.3%). Transcriptomic and metabolomic analysis (Control, 100NPs, and IP-100NPs-20HA) showed that NPs inhibited arginine biosynthesis, and alanine, aspartate, and glutamate metabolism and activated phenylpropanoid biosynthesis related to lignin. The coexistence of IP and HA had positive effects on the amino acid metabolism and phenylpropanoid biosynthesis induced by NPs. Regulation of genes and metabolites involved in nitrogen metabolism and secondary metabolism significantly altered the levels of protein and lignin in rice roots. These findings provide a scientific basis for understanding the environmental risk of NPs under real environmental conditions.

Impact of microplastics on plant physiology: A meta-analysis of dose, particle size, and crop type interactions in agricultural ecosystems

The increasing prevalence of plastic pollution has led to widespread environmental concerns, particularly with microplastics (MPs) that persist in various ecosystems. As MPs accumulate in terrestrial environments, their potential impact on plant health and agricultural productivity has become a growing area of focus. This study presents a comprehensive meta-analysis evaluating the effects of MPs on plant physiological and biochemical parameters, synthesizing data from 37 studies comprising 2886 observations. Our findings indicate that MPs significantly decrease plant biomass by 13 % (95 % CI: 7-19 %) and chlorophyll content by 28 % (95 % CI: 23-34 %), impairing crop growth and quality. Notably, higher doses and smaller MP particle sizes exert more pronounced inhibitory effects, particularly on root activity and biomass, while larger MPs predominantly damage plant roots. Furthermore, MPs were found to significantly increase oxidative stress in plants, evidenced by a 20 % rise in oxidative damage (95 % CI: 15-25 %) and a 14 % increase in antioxidant capacity (95 % CI: 8-19 %). This study highlights intricate interactions between MP type, particle size, dose, and plant species, with particle size having a greater impact than dose. This study emphasizes the importance of accounting for crop diversity and environmental factors to fully elucidate the potential risks posed by MP pollution to agricultural ecosystems.

Assessing the combined impacts of microplastics and nickel oxide nanomaterials on soybean growth and nitrogen fixation potential

The excessive presence of polystyrene microplastic (PS-MPx) and nickel oxide nanomaterials (NiO-NPs) in agriculture ecosystem have gained serious attention about their effect on the legume root-nodule symbiosis and biological nitrogen fixation (BNF). However, the impact of these contaminants on the root-nodule symbiosis and biological N2-fixation have been largely overlooked. The current findings highlighted that NiO-NMs at 50 mg kg-1 improved nodule formation and N2-fixation potential, leading to enhanced N2 uptake by both roots and shoots, resulting in increased plant growth and development. While single exposure of PS-MPx (500 mg kg-1) significantly reduced the photosynthetic pigment (8-14 %), phytohormones (9-25 %), nodules biomass (24 %), N2-related enzymes (12-17 %) that ultimately affected the N2-fixation potential. Besides, co-exposure of MPx and NiO at 100 mg kg-1 altered the nodule morphology. Additionally, single and co-exposure of MPx and NiO-NMs at 100 mg kg-1 reduced the relative abundance of Proteobacteria, Gemmatimonadota, Actinobacteria, Firmicutes, and Bacteroidetes is associated with N2-cycling and N2-fixation potential. The findings of this study will contribute to understanding the potential risks posed by MPx and NiO-NMs to leguminous crops in the soil environment and provide scientific insights into the soybean N2-fixation potential.

Human exposure to micro/nano-plastics through vegetables, fruits, and grains - A predictive modelling approach

The emergence of human exposure (HE) to micro/nano-plastics (MN-P) via the food chain is a significant public health concern. This study aimed to evaluate HE from ingesting vegetables, fruits, and grains using linear regression models to analyse MN-P size-concentration relationships and bioaccumulation factors (BF). For Irish adults, the Estimated Daily Intake (EDI) of MN-Ps was calculated, considering potential internalisation in these foods, with a sensitivity analysis addressing variability and uncertainty. The simulated mean (SM) root stomatal diameter in selected plants was 620 nm, indicating the potential uptake of MN-Ps smaller than this size. The SM BF for vegetables was 24.24 for nanoplastics (NP). Limited NP data led to the use of metal nanoparticle (MNP) data, yielding an overall BF of 3.22 for pooled vegetables, fruits, and grains. Potential HE levels of MN-Ps in agricultural soil were simulated at 6.05 × 104 n/kg (SM), with predicted MN-P levels in edible plants at 1.47 × 106 n/kg of food products. The simulated EDI of MN-Ps through all crops was 1.62 × 103 n/kg bw/day, with vegetables contributing the most to MN-P exposure, followed by fruits and grains. Sensitivity parameters are ranked as MN-P abundance in soil > bioaccumulation factor > food consumption.

Polyethylene nanoplastics, tebuconazole and cadmium affect soil-wheat system by altering rhizosphere microenvironment under single or combined exposure

Microplastics and nanoplastics (NPs) are pollutants of global concern. However, the understanding of the combined effects of NPs and other pollutants in the soil-plant system remains limited, particularly for polyethylene (PE), the primary component of agricultural films. This study investigated the effects of PE NPs (0.5 %, w/w), fungicide tebuconazole (Te, 10 mg·kg-1), and cadmium (Cd, 4.0 mg·kg-1) on the soil-wheat system under single and combined exposures. The synergistic toxicity observed between NPs and Te impacted the nutritional conditions and antioxidant mechanisms of the soil-wheat system. The NPs increased the concentration of Cd in roots and the proportion of bioavailable Cd, exacerbating oxidative stress in wheat and inhibiting biomass. The soil-wheat system responded to stress by upregulating or downregulating pathways related to carbohydrate, amino acid, and sugar metabolism under various treatments. Sixteen functional genes associated with carbohydrate metabolism, amino acid metabolism, energy utilization, and gene repair at KEGG level 3 were employed to sustain microenvironmental homeostasis. Correlation analysis between microorganisms and environmental factors showed that various PGPG played roles in maintaining the health of the soil-wheat system. These results help to elucidate the comprehensive effects of NPs with other pollutants on the soil-plant system and provide new perspectives for toxic mechanisms.

Polystyrene microplastics facilitate the chemical journey of phthalates through vegetable and aggravate phytotoxicity

Polystyrene microplastics (PS) and dibutyl phthalate (DBP) are emerging pollutants widely coexisting in agroecosystems. However, the efficacies of PS as carriers for DBP and their interactive mechanisms on crop safety remain scarce. Here, this study investigated the combined exposure effects and the interacting mechanisms of PS laden with DBP on choy sum (Brassica parachinensis L.). Results showed that PS could efficiently adsorb and carry DBP, with a maximum carrying capacity of 9.91 %, facilitating the chemical translocation of DBP in choy sum and exacerbating phytotoxicity. Due to the changes in the properties of PS, DBP loading aggravated the phytotoxicity of choy sum, exhibiting synergistically toxic effects compared with individual exposure. The Trojan-horse-complexes formed by PS+DBP severely delayed the seed germination process and altered spatial growth patterns, causing disruptions in oxidative stress, osmoregulation, photosynthetic function, and elemental reservoirs of choy sum. Combined pollutants enhanced the uptake and translocation of both PS and DBP by 8.90-31.94 % and 136.81-139.37 %, respectively; while the accumulation processes for PS were more complex than for DBP. Visualization indicated that PS was intensively sequestered in roots with a strong fluorescent signal after loading DBP. This study comprehensively investigated the efficacies of PS carrying DBP on phytotoxicity, bioavailability, and their interactive mechanisms, providing significant evidence for food safety assessment of emerging contaminant interactions.

Accumulation modes and effects of differentially charged polystyrene nano/microplastics in water spinach (Ipomoea aquatica F.)

There is widespread concern about the risk of nano/microplastics (N/MPs) entering the food chain through higher plants. However, the primary factors that influence the absorption of N/MPs by higher plants remain largely unclear. This study examined the impact of Europium-doped N/MPs with different particle sizes and surface charges by water spinach (Ipomoea aquatica F.) to address this knowledge gap. N/MPs were visualized and quantitatively analyzed using laser confocal microscopy, scanning electron microscopy, and inductively coupled plasma-mass spectrometry. N/MPs with different surface charges were absorbed by the roots, with the apoplastic pathway as the major route of transport. After 28 days of exposure to 50 mg L-1 N/MPs, N/MPs-COOH caused the highest levels of oxidative stress and damage to the roots. The plants accumulated NPs-COOH the most (average 1640.16 mg L-1), while they accumulated NPs-NH2 the least (average 253.70 mg L-1). Particle size was the main factor influencing the translocation of N/MPs from the root to the stem, while the Zeta potential mainly influenced particle entry into the roots from the hydroponic solution as well as stem-to-leaf translocation. Different charged N/MPs induced osmotic stress in the roots. A small amount of N/MPs in the leaves significantly stimulated the production of chlorophyll, while excessive N/MPs significantly reduced its content. These results provide new insights into the mechanism of interaction between N/MPs and plants.

Revealing the bioavailability and phytotoxicity of different particle size microplastics on diethyl phthalate (DEP) in rye (Secale cereale L.)

Understanding how widely distributed microplastics (MPs) and diethyl phthalate (DEP) interact with crops remains limited, despite their significant implications for human exposure. We used physiology, transcriptomics, adsorption kinetics, and computational chemistry to assess rye's molecular response to two sizes of MPs (200 nm and 5 µm) and DEP, both individually and in combination. Findings systematically highlight potential ecological risks from MPs and DEP, with ecotoxicity ranking as follows: CK (Control Check) < LMPs < SMPs < DEP < LMPs+DEP < SMPs+DEP. Fluorescence and scanning electron microscopy revealed SMP's translocation ability in rye and its potential to disrupt leaf cells. DEP increased the electronegativity on MPs, which enhanced their uptake by rye. DEP adsorption by MPs in hydroponics reduced DEP bioavailability in rye (18.17-46.91 %). Molecular docking studies showed DEP interacted with chlorophyll, superoxide dismutase, and glutathione S-transferases proteins' active sites. Transcriptomic analysis identified significant up-regulation of genes linked to mitogen-activated protein kinase signaling, phytohormones, and antioxidant systems in rye exposed to MPs and DEP, correlating with physiological changes. These findings deepen the understanding of how MPs can accumulate and translocate within rye, and their adsorption to DEP raises crop safety issues of greater environmental risk.

Accumulation of nanoplastics by wheat seedling roots: Both passive and energy-consuming processes

Nanoplastics can transfer from the environment to plants and potentially harm organisms. However, the mechanisms on how crop root systems absorb and transport nanoplastics are still unclear. Here, original and fluorescent labeled polystyrene and polyvinyl chloride nanoparticles (PS-NPs, PVC-NPs; 30 nm; 10 mg L-1) were employed to study the distribution and internalization pathways in wheat seedling roots. In the study, nanoplastics accumulated more in the root tip and surface, with PVC-NPs more prevalent than PS-NPs. After being treated with inhibitors (Na3VO4, chlorpromazine and amiloride), the nanoplastics mean fluorescence intensities were reduced by 4.0-51.1 %. During the uptake, both passive and energy-consuming pathways occurred. For the energy-consuming uptake pathway, macropinocytosis contributed more to cytoplasm than clathrin-mediated endocytosis. H+ influx was observed during nanoplastic transport into the cytoplasm, and the reduction in plasma membrane ATPase activity led to a decrease in nanoplastic internalization. These results elucidate the pathways of nanoplastics absorption and transport in wheat roots, provide crucial evidence for assessing nanoplastics' ecological risks and support the development of technologies to block nanoplastics absorption by crop roots, ensuring agricultural and ecosystem safety.

Effects of co-exposure of antibiotic and microplastic on the rhizosphere microenvironment of lettuce seedlings

Antibiotics and microplastics (MPs) often coexist in facility agriculture soils due to the prevalent use of animal manure and plastic films. However, their combined impacts on the rhizosphere environment of lettuce remain unclear. This study assessed the effects of individual and combined exposure to polyethylene (PE) MPs (2 g·kg-1) and oxytetracycline (OTC) (0, 5, 50, and 150 mg·kg-1) on the growth of lettuce seedlings and enzyme activities, physicochemical properties, metabolite profiles and bacterial communities of rhizosphere soil of lettuce. Exposure to 150 mg·kg-1 OTC, either individually or combined, significantly increased lettuce seedling shoot biomass. All treatments decreased chlorophyll and carotenoid contents. Combined exposure notably increased the Simpson's index of rhizosphere bacterial communities and altered community composition. The number of differential genera of rhizosphere was less than that of non-rhizosphere. Combined exposure significantly changed both rhizosphere and non-rhizosphere metabolite profiles. Soil organic matter emerged as the key environmental factor influencing bacterial community variation. Mantel tests revealed strong positive associations between total potassium and rhizosphere bacterial communities under combined exposure. The correlation network identified stearic acid and palmitic acid as the core metabolites in the rhizosphere. These findings offer valuable insights into the impact of OTC combined with PE MPs on lettuce rhizosphere environment.

Multifaceted effects of microplastics on soil-plant systems: Exploring the role of particle type and plant species

Microplastics have emerged as a global environmental concern, yet their impact on terrestrial environments, particularly agricultural soils, remains underexplored. Agricultural soils, due to intensive farming, may serve as significant sinks for microplastics. This study investigated the effects of different types of microplastics-polyester microfibers, polyethylene terephthalate microfragments, and polystyrene microspheres-on soil properties and radish growth, while a complementary experiment examined the impact of polyester microfibers on the growth of lettuce and Chinese cabbage. Through both horizontal and vertical comparisons, this research comprehensively evaluated the interactions between microplastic particles and plant species in soil-plant systems. The results showed that polyester microfibers significantly affected soil bulk density, with effects varying based on planting conditions (p < 0.01). Polyethylene terephthalate microfragments and polystyrene microspheres reduced the proportion of small soil macroaggregates under radish cultivation (p < 0.01). Additionally, polystyrene microspheres significantly altered the total organic carbon stock in radish-growing soil, potentially affecting the microclimate (p < 0.01). Interestingly, polyester microfibers promoted lettuce seed germination and significantly enhanced the root biomass of Chinese cabbage (p < 0.05). Overall, the environmental effects of microplastic exposure varied depending on the type of particle and plant species, suggesting that microplastics are not always harmful to soil-plant systems and may even offer benefits in certain scenarios. Given the crucial role of soil-plant systems in terrestrial ecosystems, and their direct connection to food safety, human health, and global change, further research should explore both the positive and negative impacts of microplastics on agricultural practices.

Microplastics in soil: A comprehensive review of occurrence, sources, fate, analytical techniques and potential impacts

Through their accumulation in soils, microplastics have recently become a matter of concern. The aim of this review is to assemble and investigate the recent studies about microplastics in soil by focusing on their sources, occurrence, fate in soil, and analytical methods. The objective is also to clarify and elucidate their potential impacts on soil fauna, plants and microorganisms. In this paper, articles reporting the quantity of microplastics and their characteristics in soil at 62 sites situated across 17 countries were reviewed. The land type, microplastic abundances, types and sizes were compared. We summarized and discussed the sampling and analytical methods used and the variation of microplastic concentration according to their sources. The data showed that microplastic in soil from available global studies ranged from 0 to 3573×103 particles kg-1, with major dominance of polyethylene, polystyrene and polypropylene found in 50, 37 and 32 studies, respectively. The data analysis showed the high migration of small particles, spherical shape with high polymer density in the major studies. We also described the mechanisms controlling the vertical transport of microplastics: agricultural activity (plowing: at a depth between 10 cm (very shallow plowing) and 40 cm (deeper soil tillage)), bioturbation by soil organisms and plants, and leaching that can lead to the contamination of the groundwater. This review elucidated the behavior and fate of microplastics within the soil, serving as a reference for upcoming studies aimed at devising solutions to mitigate the toxicity associated with microplastics in soil.

Combined effects of polyamide microplastic and sulfamethoxazole in modulating the growth and transcriptome profile of hydroponically grown rice (Oryza sativa L.)

The use of reclaimed water from wastewater treatment plants for irrigation has a risk of introducing micropollutants such as microplastics (MPs) and antimicrobials (AMs) into the agroecosystem. This study was conducted to investigate the effects of single and combined treatment of 0.1 % polyamide (PA ∼15 μm), and varying sulfamethoxazole (SMX) levels 0, 10, 50, and 150 mg/L on rice seedlings (Oryza sativa L.) for 12 days. The study aimed to assess the impact of these contaminants on the morphological, physiological, and biochemical parameters of the rice plants. The findings revealed that rice seedlings were not sensitive to PA alone. However, SMX alone or in combination with PA, significantly inhibited shoot and root growth, total biomass, and affected photosynthetic pigments. Higher concentrations of SMX increased antioxidant enzyme activity, indicating oxidative stress. The roots had a higher SMX content than the shoots, and the concentration of minerals such as iron, copper, and magnesium were reduced in roots treated with SMX. RNA-seq analysis showed changes in the expression of genes related to stress, metabolism, and transport in response to the micropollutants. Overall, this study provides valuable insights on the combined impacts of MPs and AMs on food crops, the environment, and human health in future risk assessments and management strategies in using reclaimed water.

Unveiling the impacts of microplastic pollution on soil health: A comprehensive review

Soil contamination by microplastics (MPs) has emerged as a significant global concern. Although traditionally associated with crop production, contemporary understanding of soil health has expanded to include a broader range of factors, including animal safety, microbial diversity, ecological functions, and human health protection. This paradigm shifts underscores the imperative need for a comprehensive assessment of the effects of MPs on soil health. Through an investigation of various soil health indicators, this review endeavors to fill existing knowledge gaps, drawing insights from recent studies conducted between 2021 and 2024, to elucidate how MPs may disrupt soil ecosystems and compromise their crucial functions. This review provides a thorough analysis of the processes leading to MP contamination in soil environments and highlights film residues as major contributors to agricultural soils. MPs entering the soil detrimentally affect crop productivity by hindering growth and other physiological processes. Moreover, MPs hinder the survival, growth, and reproductive rates of the soil fauna, posing potential health risks. Additionally, a systematic evaluation of the impact of MPs on soil microbes and nutrient cycling highlights the diverse repercussions of MP contamination. Moreover, within soil-plant systems, MPs interact with other pollutants, resulting in combined pollution. For example, MPs contain oxygen-containing functional groups on their surfaces that form high-affinity hydrogen bonds with other pollutants, leading to prolonged persistence in the soil environment thereby increasing the risk to soil health. In conclusion, we succinctly summarize the current research challenges related to the mediating effects of MPs on soil health and suggest promising directions for future studies. Addressing these challenges and adopting interdisciplinary approaches will advance our understanding of the intricate interplay between MPs and soil ecosystems, thereby providing evidence-based strategies for mitigating their adverse effects.

Comparative toxic effect of tire wear particle-derived compounds 6PPD and 6PPD-quinone to Chlorella vulgaris

N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD), a widely used antioxidant in rubber products, and its corresponding ozone photolysis product N-(1,3-Dimethylbutyl)-N'-phenyl-p-phenylenediamine-quinone (6PPD-Q), have raised public concerns due to their environmental toxicity. However, there is an existing knowledge gap on the toxicity of 6PPD and 6PPD-Q to aquatic plants. A model aquatic plant, Chlorella vulgaris (C. vulgaris), was subjected to 6PPD and 6PPD-Q at concentrations of 50, 100, 200, and 400 μg/L to investigate their effects on plant growth, photosynthetic, antioxidant system, and metabolic behavior. The results showed that 6PPD-Q enhanced the photosynthetic efficiency of C. vulgaris, promoting growth of C. vulgaris at low concentrations (50, 100, and 200 μg/L) while inhibiting growth at high concentration (400 μg/L). 6PPD-Q induced more oxidative stress than 6PPD, disrupting cell permeability and mitochondrial membrane potential stability. C. vulgaris responded to contaminant-induced oxidative stress by altering antioxidant enzyme activities and active substance levels. Metabolomics further identified fatty acids as the most significantly altered metabolites following exposure to both contaminants. In conclusion, this study compares the toxicity of 6PPD and 6PPD-Q to C. vulgaris, with 6PPD-Q demonstrating higher toxicity. This study provides valuable insight into the risk assessment of tire wear particles (TWPs) derived chemicals in aquatic habitats and plants.

Microplastics and nanoplastics in soil: Sources, impacts, and solutions for soil health and environmental sustainability

The present review discusses the growing concern of microplastics (MPs) and nanoplastics (NPs) in soil, together with their sources, concentration, distribution, and impact on soil microorganisms, human health, and ecosystems. MPs and NPs can enter the soil through various pathways, such as agricultural activities, sewage sludge application, and atmospheric deposition. Once in the soil, they can accumulate in the upper layers and affect soil structure, water retention, and nutrient availability. The presence of MPs and NPs in soil can also have ecological consequences, acting as carriers for pollutants and contaminants, such as heavy metals and persistent organic pollutants. Additionally, the leaching of chemicals and additives from MPs and NPs can pose public health risks through the food web and groundwater contamination. The detection and analyses of MPs and NPs in soil can be challenging, and methods involve spectroscopic and microscopy techniques, such as Fourier-transform infrared spectroscopy and scanning electron microscopy. To mitigate the presence and effects of MPs and NPs in soil, it is essential to reduce plastic waste production, improve waste management practices, and adopt sustainable agricultural practices. Effective mitigation measures include implementing stricter regulations on plastic use, promoting biodegradable alternatives, and enhancing recycling infrastructure. Additionally, soil amendments, such as biochar and compost, can help immobilize MPs and NPs, reducing their mobility and bioavailability. This review article aims to provide a comprehensive understanding of these emerging environmental issues and identify potential solutions to alleviate their impact on soil health, ecosystem functioning, and community health.

A critical review of co-pollution of microplastics and heavy metals in agricultural soil environments

The soil environment is a primary destination for contaminants such as microplastics (MPs) and heavy metals (HMs), which are frequently detected simultaneously. The long-term coexistence of MPs and HMs in the soil necessitates unavoidable interactions, affecting their environmental chemical behavior and bioavailability. These co-contaminants pose potential threats to soil organism growth and reproduction, crop productivity, food security, and may jeopardize human health via the food chain. This paper summarizes the sources and trends of MPs in the soil environment, along with the mechanisms and current research status of MP adsorption or desorption of HMs. Additionally, this paper reviews factors affecting HM adsorption on MPs, including MP properties, HM chemical properties, and other environmental factors. Lastly, the effects of MPs and HMs on soil ecology and human health are summarized. The interaction mechanisms and potential biological effects of their co-contamination require further exploration. Future research should delve deeper into the ecotoxic effects of MP-HM co-contamination at cellular and molecular levels, to provide a comprehensive reference for understanding the environmental behavior of their co-contamination in soil.

The addition of humic acid into soil contaminated with microplastics enhanced the growth of black gram (Vigna mungo L. Hepper) and modified the rhizosphere microbial community

Microplastics have polluted agricultural soils, posing a substantial risk to crop productivity. Moreover, the presence of microplastic pollution has caused a disturbance in the composition of the microbial community in the soil surrounding plant roots, therefore impacting the growth of beneficial bacteria. A study was conducted to examine if humic acid (HA) can counteract the harmful effects of microplastics (MPs) on the growth of black gram crops and the composition of the rhizosphere soil microbial community, to reduce the negative impacts of microplastics on these microorganisms and crops. The research was carried out using mud pots and the plastic utilized for the experiment consisted of 60% high-density polyethylene (HDPE) and 40% polypropylene (PP). The soil was enriched with lignite-based potassium humate, which had a pH range of 8.0-9.5 and with 65% humic acid. The experiment consisted of six treatments: T1, which served as the control without HA and MP; T2, which involved the use of HA at a concentration of 0.15% w/w; T3, which involved the use of MP at a concentration of 0.2% w/w; T4, which involved the use of MP at a concentration of 0.4% w/w; T5, which involved the combination of HA at a concentration of 0.15% w/w and MP at a concentration of 0.2% w/w; and T6, which involved the combination of HA at a concentration of 0.15% w/w and MP at a concentration of 0.4% w/w. The plant growth characteristics, including germination percentage, nodule number, and chlorophyll content, were measured. In addition, the DNA obtained from the rhizosphere soil was analyzed using metagenomics techniques to investigate the organization of the microbial population. Seedlings in soil polluted with MP exhibited delayed germination compared to seedlings in uncontaminated soil. Following 60 days of growth, the soil samples treated with T5 (0.2% MP and 0.15% HA w/w) had the highest population of bacteria and rhizobium, with counts 5.58 ± 0.02 and 4.90 ± 0.02 CFU g-1 soil. The plants cultivated in T5 had the most elevated chlorophyll-a concentration (1.340 ± 0.06 mg g-1), and chlorophyll-b concentration (0.62 ± 0.02 mg g-1) while those cultivated in T3 displayed the lowest concentration of chlorophyll-a (0.59 ± 0.02 mg g-1) and chlorophyll-b (0.21 ± 0.04 mg g-1). Within the phylum, Proteobacteria had the highest prevalence in all treatments. However, when the soil was polluted with MPs, its relative abundance was reduced by 8.4% compared to the control treatment (T1). Conversely, treatment T5 had a 3.76% rise in relative abundance when compared to treatment T3. The predominant taxa found in soil polluted with MP were Sphingomonas and Bacillus, accounting for 19.3% of the total. Sphingomonas was the predominant genus (21.2%) in soil polluted with MP and supplemented with humic acid. Humic acid can be used as a soil amendment to mitigate the negative effects of MPs and enhance their positive advantages. Research has demonstrated that incorporating humic acid into soil is a viable method for maintaining the long-term integrity of soil's physical, chemical, and biological characteristics.

Microplastic accumulation and oxidative stress in sweet pepper (Capsicum annuum Linn.): Role of the size effect

Microplastics (MPs), which are widely dispersed in terrestrial environments, threaten crop growth and human food security. However, plant accumulation and phytotoxicity related to the size effects of MPs remain insufficiently explored. This study investigated the accumulation and toxicity of two sizes of MPs on Capsicum annuum Linn. (C. annuum) through fluorescence tracing and antioxidant defense system assessment. The results revealed that the size of MPs significantly impacts their accumulation characteristics in C. annuum roots, leading to variations in toxic mechanisms, including oxidative stress and damage. Smaller MPs and higher exposure concentrations result in more pronounced growth inhibition. C. annuum roots have a critical size threshold for the absorption of MPs of approximately 1.2 μm. MPs that enter the root tissue exhibit an aggregated form, with smaller-sized MPs displaying a greater degree of aggregation. MP exposure induces oxidative stress in root tissues, with high concentrations of smaller MPs causing lipid peroxidation. Analysis of the IBR values revealed that C. annuum roots utilize ascorbic acid (ASA) to prevent oxidative damage caused by larger MPs. Conversely, smaller MPs primarily induce superoxide dismutase (SOD) and glutathione (GSH). These results emphasize the significant impact of MP size on plant antioxidant defense response mechanisms, laying the foundation for further investigating the implications for human health.

Optimization of a rapid, sensitive, and high throughput molecular sensor to measure canola protoplast respiratory metabolism as a means of screening nanomaterial cytotoxicity

Nanomaterial-mediated plant genetic engineering holds promise for developing new crop cultivars but can be hindered by nanomaterial toxicity to protoplasts. We present a fast, high-throughput method for assessing protoplast viability using resazurin, a non-toxic dye converted to highly fluorescent resorufin during respiration. Protoplasts isolated from hypocotyl canola (Brassica napus L.) were evaluated at varying temperatures (4, 10, 20, 30 ˚C) and time intervals (1-24 h). Optimal conditions for detecting protoplast viability were identified as 20,000 cells incubated with 40 µM resazurin at room temperature for 3 h. The assay was applied to evaluate the cytotoxicity of silver nanospheres, silica nanospheres, cholesteryl-butyrate nanoemulsion, and lipid nanoparticles. The cholesteryl-butyrate nanoemulsion and lipid nanoparticles exhibited toxicity across all tested concentrations (5-500 ng/ml), except at 5 ng/ml. Silver nanospheres were toxic across all tested concentrations (5-500 ng/ml) and sizes (20-100 nm), except for the larger size (100 nm) at 5 ng/ml. Silica nanospheres showed no toxicity at 5 ng/ml across all tested sizes (12-230 nm). Our results highlight that nanoparticle size and concentration significantly impact protoplast toxicity. Overall, the results showed that the resazurin assay is a precise, rapid, and scalable tool for screening nanomaterial cytotoxicity, enabling more accurate evaluations before using nanomaterials in genetic engineering.

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.

Effects of polystyrene microplastic composite with florfenicol on photosynthetic carbon assimilation of rice (Oryza sativa L.) seedlings: Light reactions, carbon reactions, and molecular metabolism

The effects of co-exposure to antibiotics and microplastics in agricultural systems are still unclear. This study investigated the effects of florfenicol (FF) and polystyrene microplastics (PS-MPs) on photosynthetic carbon assimilation in rice seedlings. Both FF and PS-MPs inhibited photosynthesis, while PS-MPs can alleviate the toxicity of FF. Chlorophyll synthesis genes (HEMA, HEMG, CHLD, CHLG, CHLM, and CAO) were down-regulated, whereas electron transport chain genes (PGR5, PGRL1A, PGRL1B, petH, and ndhH) were up-regulated. FF inhibited linear electron transfer (LET) and activated cyclic electron transfer (CET), which was consistent with the results of the chlorophyll fluorescence parameters. The photosynthetic carbon assimilation pathway was altered, the C3 pathway enzyme Ribulose1,5-bisphosphatecarboxylase/oxygenase (RuBisCO) was affected, C4 enzyme ((phosphoenolpyruvate carboxykinase (PEPCK), pyruvate orthophosphate dikinase (PPDK), malate dehydrogenase (MDH), and phosphoenolpyruvate carboxylase (PEPC))) and related genes were significantly up-regulated, suggesting that the C3 pathway is converted to C4 pathway for self-protection. The key enzymes involved in photorespiration, glycolate oxidase (GO) and catalase (CAT), responded positively, photosynthetic phosphorylation was inhibited, and ATP content and H+-ATPase activity were suppressed, nutrient content (K, P, N, Ca, Mg, Fe, Cu, Zn, Mn, and Ni) significantly affected. Transcriptomic analysis showed that FF and PS-MPs severely affected the photosynthetic capacity of rice seedlings, including photosystem I, photosystem II, non-photochemical quenching coefficients, and photosynthetic electron transport.