X-ray Spectroscopy Uncovering the Effects of Cu Based Nanoparticle Concentration and Structure on Phaseolus vulgaris Germination and Seedling Development

An assessment of nanotechnology-based interventions for cleaning up toxic heavy metal/metalloid-contaminated agroecosystems: Potentials and issues

Heavy metals (HMs) are among the most dangerous environmental variables for a variety of life forms, including crops. Accumulation of HMs in consumables and their subsequent transmission to the food web are serious concerns for scientific communities and policy makers. The function of essential plant cellular macromolecules is substantially hampered by HMs, which eventually have a detrimental effect on agricultural yield. Among these HMs, three were considered, i.e., arsenic, cadmium, and chromium, in this review, from agro-ecosystem perspective. Compared with conventional plant growth regulators, the use of nanoparticles (NPs) is a relatively recent, successful, and promising method among the many methods employed to address or alleviate the toxicity of HMs. The ability of NPs to reduce HM mobility in soil, reduce HM availability, enhance the ability of the apoplastic barrier to prevent HM translocation inside the plant, strengthen the plant's antioxidant system by significantly enhancing the activities of many enzymatic and nonenzymatic antioxidants, and increase the generation of specialized metabolites together support the effectiveness of NPs as stress relievers. In this review article, to assess the efficacy of various NP types in ameliorating HM toxicity in plants, we adopted a 'fusion approach', in which a machine learning-based analysis was used to systematically highlight current research trends based on which an extensive literature survey is planned. A holistic assessment of HMs and NMs was subsequently carried out to highlight the future course of action(s).

Impact of nanopollution on plant growth, photosynthesis, toxicity, and metabolism in the agricultural sector: An updated review

Nanotechnology provides distinct benefits to numerous industrial and commercial fields, and has developed into a discipline of intense interest to researchers. Nanoparticles (NPs) have risen to prominence in modern agriculture due to their use in agrochemicals, nanofertilizers, and nanoremediation. However, their potential negative impacts on soil and water ecosystems, as well as plant growth and physiology, have caused concern for researchers and policymakers. Concerns have been expressed regarding the ecological consequences and toxicity effects associated with nanoparticles as a result of their increased production and usage. Moreover, the accumulation of nanoparticles in the environment poses a risk, not only because of the possibility of plant damage but also because nanoparticles may infiltrate the food chain. In this review, we have documented the beneficial and detrimental effects of NPs on seed germination, shoot and root growth, plant biomass, and nutrient assimilation. Nanoparticles exert toxic effects by inducing ROS generation and stimulating cytotoxic and genotoxic effects, thereby leading to cell death in several plant species. We have provided possible mechanisms by which nanoparticles induce toxicity in plants. In addition to the toxic effects of NPs, we highlighted the importance of nanomaterials in the agricultural sector. Thus, understanding the structure, size, and concentration of nanoparticles that will improve plant growth or induce plant cell death is essential. This updated review reveals the multifaceted connection between nanoparticles, soil and water pollution, and plant biology in the context of agriculture.

CeO2NP priming enhances the seed vigor of alfalfa (Medicago sativa) under salt stress

Soil salinization is a common environmental problem that seriously threatens crop yield and food security, especially through its impact on seed germination. Nanoparticle priming, an emerging seed treatment method, is receiving increasing attention in improving crop yield and stress resistance. This study used alfalfa seeds as materials to explore the potential benefits of cerium oxide nanoparticle (CeO2NP) priming to promote seed germination and improve salt tolerance. CeO2NPs at concentrations up to 500 mg/L were able to significantly alleviate salt stress in alfalfa seeds (200 mM), with 50 mg/L of CeO2NP having the best effect, significantly (P< 0.05) increasing germination potential (from 4.0% to 51.3%), germination rate (from 10.0% to 62.7%), root length (from 8.3 cm to 23.1 cm), and seedling length (from 9.8 cm to 13.7 cm). Priming treatment significantly (P< 0.05) increased seed water absorption by removing seed hardness and also reducing abscisic acid and jasmonic acid contents to relieve seed dormancy. CeO2NP priming increased α-amylase activity and osmoregulatory substance level, decreased reactive oxygen species and malonaldehyde contents and relative conductivity, and increased catalase enzyme activity. Seed priming regulated carotenoid, zeatin, and plant hormone signal transduction pathways, among other metabolic pathways, while CeO2NP priming additionally promoted the enrichment of α-linolenic acid and diterpenoid hormone metabolic pathways under salt stress. In addition, CeO2NPs enhanced α-amylase activity (by 6.55%) in vitro. The optimal tested concentration (50 mg/L) of CeO2NPs was able to improve the seed vigor, enhance the activity of α-amylase, regulate the osmotic level and endogenous hormone levels, and improve the salt tolerance of alfalfa seeds. This study demonstrates the efficacy of a simple seed treatment strategy that can improve crop stress resistance, which is of great importance for reducing agricultural costs and promoting sustainable agricultural development.

Unleashing the potential of nanoparticles on seed treatment and enhancement for sustainable farming

The foremost challenge in farming is the storage of seeds after harvest and maintaining seed quality during storage. In agriculture, studies showed positive impacts of nanotechnology on plant development, seed storage, endurance under various types of stress, detection of seed damages, and seed quality. Seed's response varies with different types of nanoparticles depending on its physical and biochemical properties and plant species. Herein, we aim to cover the impact of nanoparticles on seed coating, dormancy, germination, seedling, nutrition, plant growth, stress conditions protection, and storage. Although the seed treatment by nanopriming has been shown to improve seed germination, seedling development, stress tolerance, and seedling growth, their full potential was not realized at the field level. Sustainable nano-agrochemicals and technology could provide good seed quality with less environmental toxicity. The present review critically discusses eco-friendly strategies that can be employed for the nanomaterial seed treatment and seed enhancement process to increase seedling vigor under different conditions. Also, an integrated approach involving four innovative concepts, namely green co-priming, nano-recycling of agricultural wastes, nano-pairing, and customized nanocontainer storage, has been proposed to acclimatize nanotechnology in farming.

Use of metal nanoparticles in agriculture. A review on the effects on plant germination

Agricultural nanotechnology has become a powerful tool to help crops and improve agricultural production in the context of a growing world population. However, its application can have some problems with the development of harvests, especially during germination. This review evaluates nanoparticles with essential (Cu, Fe, Ni and Zn) and non-essential (Ag and Ti) elements on plant germination. In general, the effect of nanoparticles depends on several factors (dose, treatment time, application method, type of nanoparticle and plant). In addition, pH and ionic strength are relevant when applying nanoparticles to the soil. In the case of essential element nanoparticles, Fe nanoparticles show better results in improving nutrient uptake, improving germination, and the possibility of magnetic properties could favor their use in the removal of pollutants. In the case of Cu and Zn nanoparticles, they can be beneficial at low concentrations, while their excess presents toxicity and negatively affects germination. About nanoparticles of non-essential elements, both Ti and Ag nanoparticles can be helpful for nutrient uptake. However, their potential effects depend highly on the crop type, particle size and concentration. Overall, nanotechnology in agriculture is still in its early stages of development, and more research is needed to understand potential environmental and public health impacts.

Recent Advances in Nano-Enabled Seed Treatment Strategies for Sustainable Agriculture: Challenges, Risk Assessment, and Future Perspectives

Agro seeds are vulnerable to environmental stressors, adversely affecting seed vigor, crop growth, and crop productivity. Different agrochemical-based seed treatments enhance seed germination, but they can also cause damage to the environment; therefore, sustainable technologies such as nano-based agrochemicals are urgently needed. Nanoagrochemicals can reduce the dose-dependent toxicity of seed treatment, thereby improving seed viability and ensuring the controlled release of nanoagrochemical active ingredients However, the applications of nanoagrochemicals to plants in the field raise concerns about nanomaterial safety, exposure levels, and toxicological implications to the environment and human health. In the present comprehensive review, the development, scope, challenges, and risk assessments of nanoagrochemicals on seed treatment are discussed. Moreover, the implementation obstacles for nanoagrochemicals use in seed treatments, their commercialization potential, and the need for policy regulations to assess possible risks are also discussed. Based on our knowledge, this is the first time that we have presented legendary literature to readers in order to help them gain a deeper understanding of upcoming nanotechnologies that may enable the development of future generation seed treatment agrochemical formulations, their scope, and potential risks associated with seed treatment.

Nanopriming of Barley Seeds-A Shotgun Approach to Improve Germination under Salt Stress Conditions by Regulating of Reactive Oxygen Species

Abiotic stresses are the most important environmental factors affecting seed germination, and negatively affect crop production worldwide. Water availability is essential for proper seed imbibition and germination. The mechanism by which seeds can germinate in areas with high soil salinity is, however, still unclear. The present study aims to investigate the protective roles of AgNPs in alleviating stress symptoms caused by salinity exposure in barley seeds. For this purpose, different treatment combinations of seed priming with PVP-AgNPs in salinity stress conditions were used. Salt stress (150 and 200 mM) was found to reduce seed germination by 100% when compared to the control. Under NaCl concentrations, seed priming with PVP-AgNPs (40 mg L^-1) only for 2 h, reduced salinity effects. Salinity resulted in increased reactive oxygen species (ROS) generation compared to the control. However, increased antioxidants in the NPs treatments, such as SOD, CAT, GR, GPX (expression at both genes, such as HvSOD, HvCAT, HvGR or HvGPX, and protein levels) and glutathione content, scavenged these ROS. Considering all of the parameters under study, priming alleviated salt stress. To summarize, seed priming with AgNPs has the potential to alleviate salinity stress via reduced ROS generation and activation of the antioxidant enzymatic system during germination.

Seed nanopriming: How do nanomaterials improve seed tolerance to salinity and drought?

Salt and drought stress are major environmental issues world-widely. These stresses can result in failures of seed germination, limiting agricultural production. New approaches are needed to increase crop production, ensuring food safety, quality, and agriculture sustainability. Nanopriming (priming seeds with nanomaterials) is an emerging seed technology improving crop production under the drastic climate change associated with stress factors. The present review not only provided an overview of nanopriming achieved salt and drought tolerance but also tried to discuss the behind mechanisms. We argued that the physico-chemical properties of the nanomaterials are key factors affecting their negative or positive effects on seed germination in terms of seed nanopriming. Furthermore, we highlighted the possible critical role of seed coat anatomy in effective nanopriming, in terms of saving costs and reducing biosafety issues. This review aims to help researchers to better understand and follow this fast-developing, cost-effective, and environmentally friendly research area.

Mitotic effects of copper oxide nanoparticle on root development and root tip cells of Phaseolus vulgaris L. seeds

Copper oxide nanoparticle (CuO NP) is used widely in many fields in nanotechnology. For this reason, both production, use, and release to the environment are increasing with each passing day. With the increased use of products that contain nanoparticles (NP) (<100 nm), plants and organisms that constitute the food chain are at risk. In the present study, Phaseolus vulgaris L., a very common food plant, was exposed to metal-based CuO NPs. The anomalies that were caused by CuO NP in germination and mitosis of P. vulgaris were investigated. In the trials, a total of 4 groups (Control, 50, 150, and 300 ppm) were formed and examined in three replications. The determination of the accumulation and elimination rate because of NPs in P. vulgaris that was used in the study was made through X-ray diffraction (XRD), scanning electron microscope (SEM), mapping image, and EDX characteristic spectrum analysis. Also, the mitotic effects on germination, root development, and root tip cells of seeds that were grown by treatment with control, 50, 150, and 300 ppm concentrations were investigated. The study was conducted in three replications in a laboratory setting. All concentrations of CuO NPs caused significant decreases in the mitotic index in the root tip cells of P. vulgaris when compared to the control. The mitotic index reached the lowest level, especially at the highest concentration. Multiple analyzes in the study showed that CuO NPs cause abnormalities in cell division such as C-metaphase, distorted metaphase, distorted anaphase and telophase, chromosome breakage, asynchronous division, advanced chromosomes, micronucleus, and loss of genetic material. These findings also support that the Cytogenetic Test of P. vulgaris can be used to evaluate the genotoxicity of new nanomaterials that are used in many consumer products. In this respect, NPs that are taken up by the organisms in the food chain may pose a danger to higher consumer organisms when they accumulate in the tissue. A control mechanism must be established for the use and contamination of these particles and wider studies must be conducted regarding their effects. HIGHLIGHTS: The effects of CuO nanoparticle, which has a very wide usage area, on root development and mitosis of Phaseolus vulgaris L. plant were investigated in the study. The abnormalities of mitotic division on interphase, prophase, metaphase, anaphase, and telophase were visualized. Evaluation was made considering scanning electron microscopy (SEM) and X-ray diffraction (XRD) results as well.

Green synthesis of metal-based nanoparticles for sustainable agriculture

The large-scale use of conventional pesticides and fertilizers has put tremendous pressure on agriculture and the environment. In recent years, nanoparticles (NPs) have become the focus of many fields due to their cost-effectiveness, environmental friendliness and high performance, especially in sustainable agriculture. Traditional NPs manufacturing methods are energy-intensive and harmful to environment. In contrast, synthesizing metal-based NPs using plants is similar to chemical synthesis, except the biological extracts replace the chemical reducing agent. This not only greatly reduces the used of traditional chemicals, but also produces NPs that are more economical, efficient, less toxic, and less polluting. Therefore, green synthesized metal nanoparticles (GS-MNPs) are widely used in agriculture to improve yields and quality. This review provides a comprehensive and detailed discussion of GS-MNPs for agriculture, highlights the importance of green synthesis, compares the performance of conventional NPs with GS-MNPs, and highlights the advantages of GS-MNPs in agriculture. The wide applications of these GS-MNPs in agriculture, including plant growth promotion, plant disease control, and heavy metal stress mitigation under various exposure pathways, are summarized. Finally, the shortcomings and prospects of GS-MNPs in agricultural applications are highlighted to provide guidance to nanotechnology for sustainable agriculture.

Effects of Iron Oxide Nanoparticles (Fe3O4) on Growth, Photosynthesis, Antioxidant Activity and Distribution of Mineral Elements in Wheat (Triticum aestivum) Plants

Engineered nanoparticles (NPs) are considered potential agents for agriculture as fertilizers and growth enhancers. However, their action spectrum differs strongly, depending on the type of NP, its concentrations, and plant species per se, ranging from growth stimulation to toxicity. This work aimed to investigate effects of iron oxide (Fe3O4) NPs on growth, photosynthesis, respiration, antioxidant activity, and leaf mineral content of wheat plants. Wheat seeds were treated with NP for 3 h and plants were grown in the soil at two light intensities, 120 and 300 μmol (photons) m−2·s−1, followed by physiological assessment at several time points. High NP treatment (200 and 500 mg·L−1) enhanced plant growth, photosynthesis and respiration, as well as increasing the content of photosynthetic pigments in leaves. This effect depended on both the light intensity during plant growth and the age of the plants. Regardless of concentration and light intensity, an effect of NPs on the primary photochemical processes was not observed. Seed treatment with NP also led to increased activity of ascorbate peroxidase and reduced malondialdehyde (MDA) content in roots and leaves. Treatment with Fe3O4 also led to noticeable increases in the leaf Fe, P, and K content. It is concluded that iron oxide (Fe3O4)-based NP could enhance plant growth by improving photosynthetic performance and the availability of Fe and P.

Surface-enhanced Raman scattering labeled nanoplastic models for reliable bio-nano interaction investigations

Nanoplastics (NPs) have attracted great attention as an emerging pollution. To date, their interaction with biological systems has been studied mostly by using fluorescent-labeled NPs, which suffered from serious drawbacks such as biological autofluorescence interference and false-positive results. Reliable optically labeled NP models are eagerly desired until now. Herein, a novel near-infrared (NIR) surface-enhanced Raman scattering (SERS) labeled NP model was proposed, which gained single-particle ultra-sensitivity, deep tissue detection, multiplex labeling ability, and anti-interference property. More importantly, the NP demonstrated satisfactory in vivo signal stability which completely prevented the positive-false problems. The advantages of the NPs enabled direct, dynamic in vivo behavior imaging study in living zebrafish embryo, adult zebrafish and green vegetable Brassica rapa. It was found for the first time that NPs entered blood circulation system of zebrafish larva via dermal uptake route, which only occurred in a short 48 h-window post-hatch. NPs widely distributed in roots, shoots and leaves of Brassica rapa seedlings germinating and growing in the NP-containing hydroponic culture. Different depths of one root showed varied adsorption capabilities towards NPs with fulvic acid, lipid and sodium dodecyl sulfate eco-coronas. This work provided an ideal tool for reliable bio-NP interaction study for a variety of organisms, which could promote the research of NPs.

Sustainable Agriculture through Multidisciplinary Seed Nanopriming: Prospects of Opportunities and Challenges

The global community decided in 2015 to improve people's lives by 2030 by setting 17 global goals for sustainable development. The second goal of this community was to end hunger. Plant seeds are an essential input in agriculture; however, during their developmental stages, seeds can be negatively affected by environmental stresses, which can adversely affect seed vigor, seedling establishment, and crop production. Seeds resistant to high salinity, droughts and climate change can result in higher crop yield. The major findings suggested in this review refer nanopriming as an emerging seed technology towards sustainable food amid growing demand with the increasing world population. This novel growing technology could influence the crop yield and ensure the quality and safety of seeds, in a sustainable way. When nanoprimed seeds are germinated, they undergo a series of synergistic events as a result of enhanced metabolism: modulating biochemical signaling pathways, trigger hormone secretion, reduce reactive oxygen species leading to improved disease resistance. In addition to providing an overview of the challenges and limitations of seed nanopriming technology, this review also describes some of the emerging nano-seed priming methods for sustainable agriculture, and other technological developments using cold plasma technology and machine learning.

Biogenic copper nanoparticles from Avicennia marina leaves: Impact on seed germination, detoxification enzymes, chlorophyll content and uptake by wheat seedlings

Biogenic copper nanoparticles (Cu NPs) were synthesized using the aqueous crude extract of mangrove leaves, Avicennia marina (CE). GC-MS metabolite profiling of CE showed that their carbohydrates are mainly composed of D-mannose (29.21%), D-fructose, (18.51%), L-sorbose (12.91%), D-galactose (5.47%) and D-Talose (5.21%). Ultra-fine nanoparticles of 11.60 ±4.65 nm comprising Cu2O and Cu(OH)2 species were obtained with a carbohydrate and phenolic content of 35.6±3.2% and 3.13±0.05 mgGA/g, respectively. The impact of the biogenic Cu NPs on wheat seedling growth was dose-dependent. Upon treatment with 0.06 mg/mL of Cu NPs, the growth was promoted by 172.78 ± 23.11 and 215.94 ± 37.76% for wheat root and shoot, respectively. However, the lowest relative growth % of 81.94 ± 11.70 and 72.46 ± 18.78% were recorded for wheat root and shoot, respectively when applying 0.43 mg/mL of Cu NPs. At this concentration, peroxidase activity (POX) of the germinated wheat seeds also decreased, while ascorbic acid oxidase (AAO) and polyphenol oxidase (PPO) activities increased. Higher uptake of copper was observed in the root relative to the shoot implying the accumulation of the nanoparticles in the former. The uptake was also higher than that of the commercial Cu NPs, which showed an insignificant effect on the seedling growth. By treating the wheat leaves in foliar application with 0.06 mg/mL of Cu NPs, their contents of Chlorophyll a, Chlorophyll b, and total chlorophyll were enhanced after 21 days of application. Meanwhile, the high concentration (0.43 mg/mL) of Cu NPs was the most effective in reducing the leaf content of chlorophyll (a, b, and total) after the same time of application. The findings of this study manifest the potential of utilizing controlled doses of the prepared biogenic Cu NPs for inhibition or stimulation of seedling growth.

Nanotechnology Potential in Seed Priming for Sustainable Agriculture

Our agriculture is threatened by climate change and the depletion of resources and biodiversity. A new agriculture revolution is needed in order to increase the production of crops and ensure the quality and safety of food, in a sustainable way. Nanotechnology can contribute to the sustainability of agriculture. Seed nano-priming is an efficient process that can change seed metabolism and signaling pathways, affecting not only germination and seedling establishment but also the entire plant lifecycle. Studies have shown various benefits of using seed nano-priming, such as improved plant growth and development, increased productivity, and a better nutritional quality of food. Nano-priming modulates biochemical pathways and the balance between reactive oxygen species and plant growth hormones, resulting in the promotion of stress and diseases resistance outcoming in the reduction of pesticides and fertilizers. The present review provides an overview of advances in the field, showing the challenges and possibilities concerning the use of nanotechnology in seed nano-priming, as a contribution to sustainable agricultural practices.

Impact of copper oxide nanoparticles on the germination, seedling growth, and physiological responses in Brassica pekinensis L

Wide application of nanoparticles causes considerable environmental, health, and safety problems. However, their potential impact and mechanisms on plant growth are not completely clear. In the present study, the effects of different concentration of copper oxide nanoparticles (nCuO) on seed germination and seedling growth, as well as physiological parameters of Brassica pekinensis L., were investigated. The seeds were exposed to 10-, 100-, and 1000-mg L-1 nCuO suspensions and 0.8-mg L-1 Cu2+ released from 1000-mg L-1 nCuO for 7 day. The results showed that nCuO did not affect the germination rate, germination potential, and germination index of B. pekinensis but significantly affected the vitality index. The growth of roots and shoots of B. pekinensis was promoted at 10-mg L-1 nCuO, while they were inhibited under 1000-mg L-1 nCuO and Cu2+ ion treatments, and roots suffered more damage than shoots. Cu content in shoots and roots of B. pekinensis increased with increasing concentrations of nCuO, which is significantly higher in roots as compared with shoots. Roots and shoots accumulated more Cu under nCuO treatments compared with Cu2+ ion treatment. nCuO treatments led to significant lignification in roots of B. pekinensis. Furthermore, nCuO increased in the contents of soluble sugar and protein in shoots, while nCuO at 1000 mg L-1 significantly inhibited the content of soluble protein in roots. In addition, concentration-dependent augmentation of lipid peroxidation, hydrogen peroxide and superoxide generation, and antioxidant enzyme activity were noticed in shoots and roots of B. pekinensis seedlings under nCuO and Cu2+ ion treatments. Altogether, the results strongly suggested that the phytotoxicity of nCuO in B. pekinensis was caused by both the nanoparticles itself and the released Cu2+ ions.

Phyllosphere bacterial assembly in citrus crop under conventional and ecological management

Divergences between agricultural management can result in different types of biological interactions between plants and microorganisms, which may affect food quality and productivity. Conventional practices are well-established in the agroindustry as very efficient and lucrative; however, the increasing demand for sustainable alternatives has turned attention towards agroecological approaches. Here we intend to explore microbial dynamics according to the agricultural management used, based on the composition and structure of these bacterial communities on the most environmentally exposed habitat, the phyllosphere. Leaf samples were collected from a Citrus crop (cultivated Orange) in Mogi-Guaçu (SP, Brazil), where either conventional or ecological management systems were properly applied in two different areas. NGS sequencing analysis and quantitative PCR allowed us to comprehend the phyllosphere behavior and µ-XRF (micro X-ray fluorescence) could provide an insight on agrochemical persistence on foliar tissues. Our results demonstrate that there is considerable variation in the phyllosphere community due to the management practices used in the citrus orchard, and it was possible to quantify most of this variation. Equally, high copper concentrations may have influenced bacterial abundance, having a relevant impact on the differences observed. Moreover, we highlight the intricate relationship microorganisms have with crop production, and presumably with crop yield as well.

X-ray fluorescence spectroscopy (XRF) applied to plant science: challenges towards in vivo analysis of plants

X-ray fluorescence spectroscopy (XRF) is an analytical tool used to determine the elemental composition in a myriad of sample matrices. Due to the XRF non-destructive feature, this technique may allow time-resolved plant tissue analyses under in vivo conditions, and additionally, the combination with other non-destructive techniques. In this study, we employed handheld and benchtop XRF to evaluate the elemental distribution changes in living plant tissues exposed to X-rays, as well as real-time uptake kinetics of Zn(aq) and Mn(aq) in soybean (Glycine max (L.) Merrill) stem and leaves, for 48 hours, combined with transpiration rate assessment on leaves by an infrared gas analyzer (IRGA). We found higher Zn content than Mn in stems. The latter micronutrient, in turn, presented higher concentration in leaf veins. Besides, both micronutrients were more concentrated in the first trifolium (i.e., youngest leaf) of soybean plants. Moreover, the transpiration rate was more influenced by circadian cycles than Zn and Mn uptake. Thus, XRF represents a convenient tool for in vivo nutritional studies in plants, and it can be coupled successfully to other analytical techniques.

Interaction of Copper-Based Nanoparticles to Soil, Terrestrial, and Aquatic Systems: Critical Review of the State of the Science and Future Perspectives

In the past two decades, increased production and usage of metallic nanoparticles (NPs) have inevitably increased their discharge into the different compartments of the environment, which ultimately paved the way for their uptake and accumulation in various trophic levels of the food chain. Due to these issues, several questions have been raised on the usage of NPs in everyday life and have become a matter of public health concern. Among the metallic NPs, Cu-based NPs have gained popularity due to their cost-effectiveness and multifarious promising uses. Several studies in the past represented the phytotoxicity of Cu-based NPs on plants. However, comprehensive knowledge is still lacking. Additionally, the impact of Cu-based NPs on soil organisms such as agriculturally important microbes, fungi, mycorrhiza, nematode, and earthworms is poorly studied. This review article critically analyses the literature data to achieve a more comprehensive knowledge on the toxicological profile of Cu-based NPs and increase our understanding of the effects of Cu-based NPs on aquatic and terrestrial plants as well as on soil microbial communities. The underlying mechanism of biotransformation of Cu-based NPs and the process of their penetration into plants have also been discussed herein. Overall, this review could provide valuable information to design rules and regulations for the safe disposal of Cu-based NPs into a sustainable environment.

Nanomaterials in Plants: A Review of Hazard and Applications in the Agri-Food Sector

Agricultural food crop plants interact with engineered nanomaterials (ENMs) from the application of agri-food nanotechnologies and from unintentional emissions originating from other nanotechnologies. Both types of exposure present implications for agricultural yield and quality, food chain transfer, and environmental and human health. In this review, the most recent findings from agricultural plant-ENM studies published in 2017 and 2018 are summarized. The aim of this is to identify the current hazard potential of ENMs for plants grown under typical field conditions that originate from both intentional and unintentional exposures and to contribute to knowledge-based decisions on the application of ENMs in food-agriculture. We also address recent knowledge on ENM adsorption, internalization, translocation, and bioaccumulation by plants, ENM impacts on agricultural crop yield and nutrition, and ENM biotransformation. Using adverse effect level concentrations and data on ENM accumulation in environmental matrices, the literature analyses revealed that C-, Ag-, Ce-, and Ti-based ENMs are unlikely to pose a risk to plants grown under typical field conditions, whereas Cu- and Zn-based ENMs require surveillance. Since multiple factors (e.g., ENM concentration, route of exposure, and plant type) influence the effects of ENMs on plants, biomonitoring is recommended for tracking ENM environmental exposure in the future.

A new glance on root-to-shoot in vivo zinc transport and time-dependent physiological effects of ZnSO4 and ZnO nanoparticles on plants

Understanding nanoparticle root uptake and root-to-shoot transport might contribute to the use of nanotechnology in plant nutrition. This study performed time resolved experiments to probe Zn uptake, biotransformation and physiological effects on Phaseolus vulgaris (L.). Plants roots were exposed to ZnO nanoparticles (40 and 300 nm) dispersions and ZnSO_4(aq) (100 and 1000 mg Zn L⁻¹) for 48 h. Near edge X-ray absorption spectroscopy showed that 40 nm ZnO was more easily dissolved by roots than 300 nm ZnO. It also showed that in the leaves Zn was found as a mixture Zn₃(PO₄)₂ and Zn-histidine complex. X-ray fluorescence spectroscopy showed that root-to-shoot Zn-translocation presented a decreasing gradient of concentration and velocity, it seems radial Zn movement occurs simultaneously to the axial xylem transport. Below 100 mg Zn L⁻¹, the lower stem tissue section served as a buffer preventing Zn from reaching the leaves. Conversely, it was not observed for 1000 mg Zn L⁻¹ ZnSO_4(aq). Transcriptional analysis of genes encoding metal carriers indicated higher expression levels of tonoplast-localized transporters, suggesting that the mechanism trend to accumulate Zn in the lower tissues may be associated with an enhanced of Zn compartmentalization in vacuoles. The photosynthetic rate, transpiration, and water conductance were impaired by treatments.

Bean Seedling Growth Enhancement Using Magnetite Nanoparticles

Advanced fertilizers are one of the top requirements to address rising global food demand. This study investigates the effect of bare and polyethylene glycol-coated Fe₃O₄ nanoparticles on the germination and seedling development of Phaseolus vulgaris L. Although the germination rate was not affected by the treatments (1 to 1 000 mg Fe L^-1), seed soaking in Fe₃O₄-PEG at 1 000 mg Fe L^-1 increased radicle elongation (8.1 ± 1.1 cm vs 5.9 ± 1.0 cm for the control). Conversely, Fe²⁺/Fe³⁺_(aq) and bare Fe₃O₄ at 1 000 mg Fe L^-1 prevented the growth. X-ray spectroscopy and tomography showed that Fe penetrated in the seed. Enzymatic assays showed that Fe₃O₄-PEG was the least harmful treatment to α-amylase. The growth promoted by the Fe₃O₄-PEG might be related to water uptake enhancement induced by the PEG coating. These results show the potential of using coated iron nanoparticles to enhance the growth of common food crops.

Laboratory Microprobe X-Ray Fluorescence in Plant Science: Emerging Applications and Case Studies

In vivo and micro chemical analytical methods have the potential to improve our understanding of plant metabolism and development. Benchtop microprobe X-ray fluorescence spectroscopy (μ-XRF) presents a huge potential for facing this challenge. Excitation beams of 30 μm and 1 mm in diameter were employed to address questions in seed technology, phytopathology, plant physiology, and bioremediation. Different elements were analyzed in several situations of agronomic interest: (i) Examples of μ-XRF yielding quantitative maps that reveal the spatial distribution of zinc in common beans (Phaseolus vulgaris) primed seeds. (ii) Chemical images daily recorded at a soybean leaf (Glycine max) infected by anthracnose showed that phosphorus, sulfur, and calcium trended to concentrate in the disease spot. (iii) In vivo measurements at the stem of P. vulgaris showed that under root exposure, manganese is absorbed and transported nearly 10-fold faster than iron. (iv) Quantitative maps showed that the lead distribution in a leaf of Eucalyptus hybrid was not homogenous, this element accumulated mainly in the leaf border and midrib, the lead hotspots reached up to 13,400 mg lead kg^-1 fresh tissue weight. These case studies highlight the ability of μ-XRF in performing qualitative and quantitative elemental analysis of fresh and living plant tissues. Thus, it can probe dynamic biological phenomena non-destructively and in real time.