TiO2 nanoparticles may alleviate cadmium toxicity in co-treatment experiments on the model hydrophyte Azolla filiculoides

The impact of polystyrene nanoplastics on plants in the scenario of increasing temperatures: The case of Azolla filiculoides Lam

There are great concerns for the accumulation in the environment of small dimension plastics, such as micro- and nanoplastics. Due to their small size, which facilitates their uptake by organisms, nanoplastics are of particular concern. The toxic effects of nanoplastics on plants are already reported in the literature, however nothing is known, to date, about the possible effects of climate change, in particular of increasing temperatures, on their toxicity for plants. To address this issue, plants of the water fern Azolla filiculoides were grown at optimal (25 °C) or high (35 °C) temperature, with or without polystyrene nanoplastics, and the effects of these stressors were assessed using a multidisciplinary approach. Green fluorescent polystyrene nanoplastics were used to track their possible uptake by A. filiculoides. The development and physiology of our model plant was adversely affected by both nanoplastics and high temperatures. Overall, histological, morphological, and photosynthetic parameters worsened under co-treatment, in accordance with the increased uptake of nanoplastics under higher temperature, as observed by fluorescence images. Based on our findings, the concern regarding the potential for increased toxicity of pollutants, specifically nanoplastics, at high temperatures is well-founded and warrants attention as a potential negative consequence of climate change. Additionally, there is cause for concern regarding the increase in nanoplastic uptake at high temperatures, particularly if this phenomenon extends to food and feed crops, which could lead to greater entry into the food chain.

Titanium dioxide nanoparticles enhance the detrimental effect of polystyrene nanoplastics on cell and plant physiology of Vicia lens (L.) Coss. & Germ. seedlings

Polystyrene nanoplastics and titanium dioxide nanoparticles are widely spread in all environments, often coexisting within identical frameworks. Both these contaminants can induce negative effects on cell and plant physiology, giving concerns on their possible interaction which could increase each other's harmful effects on plants. Despite the urgency of this issue, there is very little literature addressing it. To evaluate the potential risk of this co-contamination, lentil seeds were treated for five days with polystyrene nanoplastics and titanium dioxide nanoparticles (anatase crystalline form), alone and in co-presence. Cytological analyses, and histochemical and biochemical evaluation of oxidative stress were carried out on isolated shoots and roots. TEM analysis seemed to indicate the absence of physical/chemical interactions between the two nanomaterials. Seedlings under cotreatment showed the greatest cytotoxic and genotoxic effects and high levels of oxidative stress markers associated with growth inhibition. Even if biochemical data did not evidence significant differences between materials treated with polystyrene nanoplastics alone or in co-presence with titanium dioxide nanoparticles, histochemical analysis highlighted a different pattern of oxidative markers, suggesting a synergistic effect by the two nanomaterials. In accordance, the fluorescence signal linked to nanoplastics in root and shoot was higher under cotreatment, perhaps due to the well-known ability of titanium dioxide nanoparticles to induce root tissue damage, in this way facilitating the uptake and translocation of polystyrene nanoplastics into the plant body. In the antioxidant machinery, peroxidase activity showed a significant increase in treated roots, in particular under cotreatment, probably more associated with stress-induced lignin synthesis than with hydrogen peroxide detoxification. Present results clearly indicate the worsening by metal nanoparticles of the negative effects of nanoplastics on plants, underlining the importance of research considering the impact of cotreatments with different nanomaterials, which may better reflect the complex environmental conditions.

Nano-enabled agrochemicals: mitigating heavy metal toxicity and enhancing crop adaptability for sustainable crop production

The primary factors that restrict agricultural productivity and jeopardize human and food safety are heavy metals (HMs), including arsenic, cadmium, lead, and aluminum, which adversely impact crop yields and quality. Plants, in their adaptability, proactively engage in a multitude of intricate processes to counteract the impacts of HM toxicity. These processes orchestrate profound transformations at biomolecular levels, showing the plant's ability to adapt and thrive in adversity. In the past few decades, HM stress tolerance in crops has been successfully addressed through a combination of traditional breeding techniques, cutting-edge genetic engineering methods, and the strategic implementation of marker-dependent breeding approaches. Given the remarkable progress achieved in this domain, it has become imperative to adopt integrated methods that mitigate potential risks and impacts arising from environmental contamination on yields, which is crucial as we endeavor to forge ahead with the establishment of enduring agricultural systems. In this manner, nanotechnology has emerged as a viable field in agricultural sciences. The potential applications are extensive, encompassing the regulation of environmental stressors like toxic metals, improving the efficiency of nutrient consumption and alleviating climate change effects. Integrating nanotechnology and nanomaterials in agrochemicals has successfully mitigated the drawbacks associated with traditional agrochemicals, including challenges like organic solvent pollution, susceptibility to photolysis, and restricted bioavailability. Numerous studies clearly show the immense potential of nanomaterials and nanofertilizers in tackling the acute crisis of HM toxicity in crop production. This review seeks to delve into using NPs as agrochemicals to effectively mitigate HM toxicity and enhance crop resilience, thereby fostering an environmentally friendly and economically viable approach toward sustainable agricultural advancement in the foreseeable future.

Effect and mechanism of nano-materials on plant resistance to cadmium toxicity: A review

Cadmium (Cd), one of the most toxic heavy metals, has been extensively studied by environmental scientists because of its detrimental effects on plants, animals, and humans. Increased industrial activity has led to environmental contamination with Cd. Cadmium can enter the food chain and pose a potential human health risk. Therefore, reducing the accumulation of Cd in plant species and enhancing their detoxification abilities are crucial for remediating heavy metal pollution in contaminated areas. One innovative technique is nano-phytoremediation, which employs nanomaterials ranging from 1 to 100 nm in size to mitigate the accumulation and detrimental effects of Cd on plants. Although extensive research has been conducted on using nanomaterials to mitigate Cd toxicity in plants, it is important to note that the mechanism of action varies depending on factors such as plant species, level of Cd concentration, and type of nanomaterials employed. This review aimed to consolidate and organize existing data, providing a comprehensive overview of the effects and mechanisms of nanomaterials in enhancing plant resistance to Cd. In particular, its deep excavation the mechanisms of detoxification heavy metals of nanomaterials by plants, including regulating Cd uptake and distribution, enhancing antioxidant capacity, regulating gene expression, and regulating physiological metabolism. In addition, this study provides insights into future research directions in this field.

Trade-off of abiotic stress response in floating macrophytes as affected by nanoplastic enrichment

Nanoparticles have been found in large-scale environmental media in recent years, causing toxic effects in various organisms and even humans through food chain transmission. The ecotoxicological impact of microplastics on specific organisms is currently receiving much attention. However, relatively little research to date has examined the mechanisms through which nanoplastic residue may exert an interference effect on floating macrophytes in constructed wetlands. In our study, the aquatic plant Eichhornia crassipes was subjected to 100 nm polystyrene nanoplastics at concentrations of 0.1, 1 and 10 mg L^-1 after 28 days of exposure. E. crassipes can decrease the concentration of nanoplastics in water by 61.42∼90.81% through phytostabilization. The abiotic stress of nanoplastics on the phenotypic plasticity (morphological and photosynthetic properties and antioxidant systems as well as molecular metabolism) of E. crassipes was assessed. The presence of nanoplastics reduced the biomass (10.66%∼22.05%), and the functional organ (petiole) diameters of E. crassipes decreased by 7.38%. The photosynthetic efficiency was determined, showing that the photosynthetic systems of E. crassipes are very sensitive to stress by nanoplastics at a concentration of 10 mg L^-1. Oxidative stress and imbalance of antioxidant systems in functional organs are associated with multiple pressure modes from nanoplastic concentrations. The catalase contents of roots increased by 151.19% in the 10 mg L^-1 treatment groups compared with the control group. Moreover, 10 mg L^-1 concentrations of the nanoplastic pollutant interfere with purine and lysine metabolism in the root system. The hypoxanthine content was reduced by 6.58∼8.32% under exposure to different concentrations of nanoplastics. In the pentose phosphate pathway, the phosphoric acid content was decreased by 32.70% at 10 mg L^-1 PS-NPs. In the pentose phosphate pathway, the phosphoric acid content was decreased by 32.70% at 10 mg L^-1 PS-NPs. Nanoplastics disturb the efficiency of water purification by floating macrophytes, which reduces the chemical oxygen demand (COD) removal efficiency (from 73% to 31.33%) due to various abiotic stresses. This study provided important information for further clarifying the impact of nanoplastics on the stress response of floating macrophytes.

The combination of graphene oxide and preservatives can further improve the preservation of cut flowers

It is reported that the use of nanomaterials can extend the vase life of fresh-cut flowers. Graphene oxide (GO) is one of these nanomaterials that aid in promoting water absorption and antioxidation during the preservation of fresh-cut flowers. In this investigation, the three mainstream brands of preservatives commercially available on the market ("Chrysal," "Floralife," and "Long Life") in combination with low concentrations of GO (0.15 mg/L) were used to preserve fresh-cut roses. The results showed that the three brands of preservatives had different degrees of freshness retention. Compared to the preservatives used alone, the combination of low concentrations of GO with the preservatives, especially in the L+GO group (with 0.15 mg/L GO added in the preservative solution of "Long life"), further improved the preservation of cut flowers. L+GO group showed less level of antioxidant enzyme activities, lower ROS accumulation and cell death rate, and higher relative fresh weight than the other groups, implying a better antioxidant and water balance abilities. GO attached to the xylem duct of flower stem, and reduced the blockage of xylem vessels by bacteria, which were determined by SEM (scanning electron microscopy) and FTIR (Fourier transform infrared) analysis. XPS (X-ray photoenergy spectra) analysis results proved that GO could enter the interior of flower stem through xylem duct, and when combined with "Long Life," the anti-oxidation protection ability of GO was enhanced, thus delaying ageing, and greatly extending the vase life of fresh-cut flowers. The study provides new insights into cut flower preservation using GO.

Nano-selenium Alleviates Cadmium-Induced Mouse Leydig Cell Injury, via the Inhibition of Reactive Oxygen Species and the Restoration of Autophagic Flux

Cadmium (Cd) is a well-known environmental pollutant that can contribute to male reproductive toxicity through oxidative stress. Nano-selenium (Nano-se) is an active single body of selenium with strong antioxidant properties and low toxicity. Some studies have addressed the potential ameliorative effect of Nano-se against Cd-induced testicular toxicity; however, the underlying mechanisms remain to be investigated. This study aimed to explore the protective effect of Nano-se on Cd-induced mouse testicular TM3 cell toxicity by regulating autophagy process. We showed that cadmium exposure to TM3 cells inhibited cell viability and elevated the level of reactive oxygen species (ROS) generation. Morphology observation by transmission electron microscope and the presence of mRFP-GFP-LC3 fluorescence puncta demonstrated that cadmium increased autophagosome formation and accumulation in TM3 cells, resulting in blocking the autophagic flux of TM3 cells. Meanwhile, cadmium remarkably increased the ratio of LC3-II to LC3-I protein expression (2.07 ± 0.31) and the Beclin-1 protein expression (1.97 ± 0.40) in TM3 cells (P < 0.01). Pretreatment with Nano-se significantly reduced Cd-induced TM3 cell toxicity (P < 0.01). Furthermore, Nano-se treatment reversed Cd-induced ROS production and autophagosome accumulation, and autophagy as evidenced by the ratio of LC3-II to LC3-I and Beclin-1 expression. In addition, ROS scavenger, N-acetyl-L-cysteine (NAC) or autophagy inhibitor, 3-methyladenine (3-MA) reversed cadmium-induced ROS generation, autophagosome accumulation, and autophagy-related protein expression levels, which confirmed that cadmium induced TM3 cell injury via ROS signal pathway and blockage of autophagic flux. Collectively, our results reveal that Nano-se attenuates Cd-induced TM3 cell toxicity through the inhibition of ROS production and the amelioration of autophagy disruption.

Bisphenol-A incite dose-dependent dissimilitude in the growth pattern, physiology, oxidative status, and metabolite profile of Azolla filiculoides

Bisphenol-A (BPA) is a ubiquitous environmental pollutant affecting the growth and development of aquatic macrophytes. The present study was designed to evaluate the toxic effect of BPA on Azolla filiculoides. The plants were exposed to different concentrations of BPA and the effect was evaluated in terms of plant growth, physiological and oxidative status, responses of the antioxidative system, and changes in key metabolites. The results have shown that BPA (≥ 20 mg L^-1) incites a significant reduction in frond number, frond surface area, and growth rate of the plants along with severe frond damage, membrane peroxidation, and electrolyte leakage. Moreover, at higher concentrations, a significant reduction in the content of chlorophylls and carotenoids was observed, which was further amplified with the duration of treatments. Furthermore, excessive generation of O₂^•- and H₂O₂ invoked the antioxidative machinery under BPA exposure. However, sufficient activity of the antioxidative enzymes was observed in plants treated with ≤ 10 mg L^-1 of BPA. The untargeted metabolome profile revealed modulation of 29 metabolites including amino acids, sugar alcohols, organic acids, and phenolics in response to BPA. An increased amount of asparagine, lysine, serine, tryptophan, tyrosine, and valine after 3 days of BPA exposure indicates their role in providing better stress tolerance. Therefore, the experimental findings suggest that A. filiculoides responds differently to BPA exposure. Higher BPA concentrations (≥ 20 mg L^-1) documented a greater impact in terms of plant physiology and metabolism whereas, the effect was minimal at lower concentrations (≤ 10 mg L^-1).

Early evidence of the impacts of microplastic and nanoplastic pollution on the growth and physiology of the seagrass Cymodocea nodosa

Microplastics (MPs) and nanoplastics (NPs) are ubiquitous in natural habitats and the risks their presence poses to marine environments and organisms are of increasing concern. There is evidence that seagrass meadows are particularly prone to accumulate plastic debris, including polystyrene particles, but the impacts of this pollutant on seagrass performance are currently unknown. This is a relevant knowledge gap as seagrasses provide multiple ecosystem services and are declining globally due to anthropogenic impact and climate-change-related stressors. Here, we explored the potential effects of a 12 day-exposure of seagrasses to one concentration (68 μg/L) of polystyrene MPs and NPs on the growth, oxidative status, and photosynthetic efficiency of plants using the foundation species Cymodocea nodosa as a model. Among plant organs, adventitious roots were particularly affected by MPs and NPs showing complete degeneration. The number of leaves per shoot was lower in MPs- and NPs-treated plants compared to control plants, and leaf loss exceeded new leaf production in MPs-treated plants. MPs also reduced photochemical efficiency and increased pigment content compared to control plants. Shoots of NPs-treated plants showed a greater oxidative damage and phenol content than those of control plants and MPs-treated plants. Biochemical data about oxidative stress markers were consistent with histochemical results. The effects of MPs on C. nodosa could be related to their adhesion to plant surface while those of NPs to entering tissues. Our study provides the first experimental evidence of the potential harmful effects of MPs/NPs on seagrass development. It also suggests that the exposure of seagrasses to MPs/NPs in natural environments could have negative consequences on the functioning of seagrass ecosystems. This stresses the importance of implementing cleaning programs to remove all plastics already present in marine habitats as well as of undertaking specific actions to prevent the introduction of these pollutants within seagrass meadows.

Low levels of TiO2-nanoparticles interact antagonistically with Al and Pb alleviating their toxicity

The contamination and bioavailability of deleterious metals in arable soils significantly limits crop development and yield. Aiming at mitigating Pb- and Al-induced phytotoxicity, this work explores the use of P25 titanium dioxide nanoparticles (nTiO₂) in soil amendments. For that, Lactuca sativa L. plants were germinated and grown in the presence of 10 ppm Pb or 50 ppm Al, combined or not with 5 ppm nTiO₂. Growth parameters, as well as endpoints of the redox state [cell relative membrane permeability (RMP), thiobarbituric acid reactive substances content, total phenolic content and photosynthesis (sugars and pigments levels, chlorophyll a fluorescence and gas exchange), were evaluated. Concerning Al, nTiO₂ treatment alleviated the impairments induced in germination rate, seedling length, water content, RMP, stomatal conductance (g_s), intercellular CO₂ (C_i), and net CO₂ assimilation rate (P_N). It increased anthocyanins contents and effective efficiency of photosystem II (Φ_PSII). In Pb-exposed plants, nTiO₂ amendment mitigated the effects in RMP, P_N, g_s, and C_i. It also increased the pigment contents and the transpiration rate (E) comparatively to the control without nTiO₂. These results clearly highlight the high potential of low doses of nTiO₂ in alleviating metal phytotoxicity, particularly the one of Pb. Additionally, further research should explore the use of these nanoparticles in agricultural soil amendments.

Application of Polypodiopsida Class in Nanotechnology-Potential towards Development of More Effective Bioactive Solutions

The area of phytosynthesized nanomaterials is rapidly developing, with numerous studies being published yearly. The use of plant extracts is an alternative method to reduce the toxic potential of the nanomaterials and the interest in obtaining phytosynthesized nanoparticles is usually directed towards accessible and common plant species, ferns not being explored to their real potential in this field. The developed nanoparticles could benefit from their superior antimicrobial and antioxidant properties (compared with the nanoparticles obtained by other routes), thus proposing an important alternative against health care-associated and drug-resistant infections, as well as in other types of applications. The present review aims to summarize the explored application of ferns in nanotechnology and related areas, as well as the current bottlenecks and future perspectives, as emerging from the literature data.

Effect of Zinc Priming on Salt Response of Wheat Seedlings: Relieving or Worsening?

In an attempt to alleviate salt-induced damage, the application of ZnO nanoparticles has been suggested. As the use of these particles has also been associated with phytotoxicity, to better clarify the effect of zinc and its possible mitigation of salt stress, we treated wheat seedlings with ZnO (nanoparticles or their bulk-scale counterparts, amended either in the growth medium, NPs and B, or sprayed on the leaves, SPNPs and SPB) with or without subsequent treatment with salt. Growth, photosynthetic parameters, zinc and ion concentration, and in situ and biochemical determination of oxidative stress in wheat leaves and/or in roots were considered. Both Zn and NaCl significantly inhibited growth and induced severe alterations in root morphology. Oxidative stress and damage decreased or increased under ZnO treatment and in saline conditions depending on the organ and on the size and mode of application of particles. In spite of the higher stress conditions often recorded in treated leaves, neither pigment concentration nor photochemical efficiency were decreased. A large variability in the effects of ZnO treatment/priming on seedling salt response was recorded; however, the presence of a cumulative negative effect of priming and salt stress sometimes observed calls for caution in the use of ZnO in protection from saline stress.