Accumulation, translocation and impact of TiO2 nanoparticles in wheat (Triticum aestivum spp.): influence of diameter and crystal phase

Size-dependent uptake of chromium colloids in rice (Oryza sativa L.)

Chromium (Cr) contamination in agricultural soils poses a significant threat to food safety. In paddy soil, Cr tends to exist as colloidal Cr, instead of soluble Cr. However, little is known regarding the absorption capability of colloidal Cr in rice. Therefore, this study explores the differential absorption of soluble and colloidal Cr in rice through hydroponic experiments, further investigating size-dependent uptake of Cr colloids, focusing on the role of endocytosis and the effects of adding endocytosis inhibitors. The results demonstrate the accumulation of Cr in rice roots for treatments with 100 μM soluble Cr (Cr-EDTA), 28 nm Cr colloid, and 62 nm Cr colloid were 40.0, 797, and 2033 mg/kg, respectively. The reason for this phenomenon is that colloidal Cr is more likely to be adsorbed onto the cell wall, which increases the potential for rice to absorb colloidal Cr, particularly the larger Cr colloids. When endocytosis in rice was inhibited by wortmannin, the absorption of Cr colloid with small size was reduced by 7.30%-26.6%, thereby highlighting the important role of endocytosis in the uptake of 28 nm particles in rice. In contrast, the uptake of soluble Cr and larger colloids were less affected by endocytosis inhibition. This study underscores the importance of considering colloidal Cr and its particle size when assessing the risks associated with heavy metal pollution in agriculture. The findings have significant implications for managing soil contamination and ensuring food safety.

Elucidating the phytotoxic endpoints of sub-chronic exposure to titanium dioxide nanoparticles in Endemic Persian Dracocephalum species

This study was designed to investigate the dichotomous effects of titanium dioxide nanoparticles (TiO2NPs) at varying concentrations (0, 50, 100, 1000, and 2500 ppm) on the physiological, biochemical, and antioxidative defense responses of Persian dragonhead plants cultivated in hydroponic conditions. Over 21 days of treatment, an increase in fresh shoot biomass by 26.2% and plant height by 18.2% was observed at exposure to 50 ppm TiO2NPs. Exposure to 100 ppm NPs negatively affected the biosynthesis of carotenoids, chlorophyll pigments (a, b, and total), and protein content. Field Emission Scanning Electron Microscopy (FE-SEM) and Transmission Electron Microscopy (TEM) analysis revealed TiO2NPs deposition within intercellular spaces and cell walls of root tissues. The physiological stress was prominent in response to 2500 ppm NPs as evidenced by a significant increase in proline and sugar content compared to the control. The enzymatic antioxidative defense was significantly upregulated by the enhanced activity of catalase (CAT) across exposure ranges 100-2500 ppm NPs, ascorbate peroxidase (APX) at 100 and 2500 ppm NPs, and peroxidase (POD) at 100 ppm NPs in plant roots. The antioxidant proficiency was further corroborated by increases in total flavonoids by 30.43% at 2500 ppm, saponins by 253.7%, and iridoids by 22.3% at 100 ppm NPs, relative to control. The results suggest that TiO2NPs fostered growth promotion at sub-lethal doses, and induced adverse biochemical changes at elevated concentrations, prompting the activation of intrinsic defense mechanisms to enhance plant resilience against NPs stresses. The optimal nano-stimulation performance was observed at 50 ppm TiO2NPs, which was suggested for the high yield targets, signifying a potential boon for agricultural productivity.

Nano-assisted delivery tools for plant genetic engineering: a review on recent developments

Conventional approaches like Agrobacterium-mediated transformation, viral transduction, biolistic particle bombardment, and polyethylene glycol (PEG)-facilitated delivery methods have been optimized for transporting specific genes to various plant cells. These conventional approaches in genetically modified crops are dependent on several factors like plant types, cell types, and genotype requirements, as well as numerous disadvantages such as time-consuming, untargeted distribution of genes, and high cost of cultivation. Therefore, it is suggested to develop novel techniques for the transportation of genes in crop plants using tailored nanoparticles (NPs) of manipulative and controlled high-performance features synthesized using green and chemical routes. It is observed that site-specific delivery of genes exhibits high efficacy in species-independent circumstances which leads to an increased level of productivity. Therefore, to achieve these outcomes, NPs can be utilized as gene nano-carriers for excellent delivery inside crops (i.e., cotton, tobacco, rice, wheat, okra, and maize) for desired genetic engineering modifications. As outcomes, this review provides an outline of the conventional techniques and current application of numerous nano-enabled gene delivery needed for crop gene manipulation, the benefits, and drawbacks associated with state-of-the-art techniques, which serve as a roadmap for the possible applicability of nanomaterials in plant genomic engineering as well as crop improvement in the future.

Molecular mechanisms of plant productivity enhancement by nano fertilizers for sustainable agriculture

Essential plant nutrients encapsulated or combined with nano-dimensional adsorbents define nano fertilizers (NFs). Nanoformulation of non-essential elements enhancing plant growth and stress tolerance also comes under the umbrella of NFs. NFs have an edge over conventional chemical fertilizers, viz., higher plant biomass and yield using much lesser fertilization, thereby reducing environmental pollution. Foliar and root applications of NFs lead to their successful uptake by the plant, depending on the size, surface charge, and other physicochemical properties of NFs. Smaller NFs can pass through channels on the waxy cuticle depending on the hydrophobicity, while larger NFs pass through the stomatal conduits of leaves. Charge-based adsorption, followed by apoplastic movement and endocytosis, translocates NFs through the root, while the size of NFs influences passage into vascular tissues. Recent transcriptomic, proteomic, and metabolomic studies throw light on the molecular mechanisms of growth promotion by NFs. The expression levels of nutrient transporter genes are regulated by NFs, controlling uptake and minimizing excess nutrient toxicity. Accelerated growth by NFs is brought about by their extensive regulation of cell division, photosynthesis, carbohydrate, and nitrogen metabolism, as well as the phytohormone-dependent signaling pathways related to development, stress response, and plant defense. NFs mimic Ca,2+ eliciting second messengers and associated proteins in signaling cascades, reaching transcription factors and finally orchestrating gene expression to enhance growth and stress tolerance. Developing advanced nano fertilizers of the future must involve exploring molecular interactions with plants to reduce toxicity and improve effectiveness.

Green synthesis and characterization of Fe2O3, ZnO and TiO2 nanoparticles and searching for their potential use as biofertilizer on sunflower

Nanoparticles, thanks to their superior properties such as large surface area and high reactivity, can be an alternative to traditional fertilizers for improving nutrient uptake. Furthermore, considering that chemical and physical synthesis methods require high energy consumption and cause environmental pollution, plant-mediated green synthesis of NPs has attracted great attention since it provides eco-friendly, biocompatible, and inexpensive solutions. In this present study, plant mediated green synthesis of Iron Oxide (Fe2O3), Zinc Oxide (ZnO) and Titanium Dioxide (TiO2) nanoparticles by using Laurus nobilis leaves (bay leaves) were carried out and their structural properties were characterized by UV visible spectra, Dynamic Light Scattering (DLS), Fourier Transform Infrared (FTIR), X-Ray Diffraction (XRD) and Transmission Electron Microscopy (TEM). UV spectrum and FTIR analysis exhibited characteristic peaks indicating the presence of the desired NPs, while DLS analysis and TEM images confirmed that synthesized particles are in nano-scale. The potential of nanoparticles as biofertilizer in agricultural uses were assessed by investigating their effects on sunflower growth in hydroponic system. TEM images of the NP applied plant tissues proved the uptake and translocation of NPs from root to leaf. Furthermore, Fe2O3, ZnO and TiO2 NP applications on sunflower up to 5 ppm generally improved physiological growth parameters such as root length, fresh weight and leaf surface area while 20 ppm of Fe2O3 and ZnO NPs application cause a significant decrease.

Graphical abstract

The fate and impact of Co3O4 nanoparticles in the soil environment: Observing the dose effect of nanoparticles on soybeans

The widespread presence and distribution of metal-based nanoparticles (NPs) in soil is threatening crop growth and food security. However, little is known about the fate of Co3O4 NPs in the soil-soybean system and their phytotoxicity. The study demonstrated the effects of Co3O4 NPs on soybean growth and yield in soil after 60 days and 140 days, and compared them with the phytotoxic effects of Co2+. The results showed that Co3O4 NPs (10-500 mg/kg) had no significant toxic effect on soybeans. Soil available Co content was significantly increased under 500 mg/kg Co3O4 NPs treatment. Compared with Co2+, Co3O4 NPs mainly accumulated in roots and had limited transport to the shoots, which was related to the particle size, surface charge and chemical stability of Co3O4 NPs. The significant accumulation of Co3O4 NPs in roots further led to a significant decrease in root antioxidant enzyme activity and changes in functional gene expression. Co3O4 NPs reduced soybean yield after 140 days, but interestingly, at specific doses, it increased grain nutrients (Fe content increased by 17.38% at 100 mg/kg, soluble protein and vitamin E increased by 14.34% and 16.81% at 10 mg/kg). Target hazard quotient (THQ) assessment results showed that consuming soybean seeds exposed to Co3O4 NPs (≥100 mg/kg) and Co2+ (≥10 mg/kg) would pose potential health risks. Generally, Co3O4 NPs could exist stably in the environment and had lower environmental risks than Co2+. These results help to better understand the environmental behavior and plant effect mechanisms of Co3O4 NPs in soil-plant systems.

In planta synthesis of silver nanoparticles and its effect on adventitious shoot growth and withanolide production in Withania somnifera (L.) Dunal

Silver (Ag) is a non-essential heavy metal with substantial environmental toxicity but an excellent promotor for plant organogenesis. It is used as an elicitor for secondary metabolite production and for in planta synthesis of metal nanoparticles (MNPs). In the present study, the Ag accumulation and reduction capability of in vitro shoots of Withania somnifera and the toxicity and elicitation effect of Ag on in vitro shoots were explored. In vitro shoot cultures of W. somnifera were treated with different concentrations of silver nitrate for a specific treatment period. Growth index, withaferin A, elemental and electron microscopy analyses were done on silver-treated in vitro shoots of W. somnifera. 1 mM silver nitrate treatment for 12 days period was found to give increased growth index (1.425 ± 0.05c) and withaferin A (2.568 ± 0.08e mg g-1) content. The concentration of bioaccumulated Ag in 1 mM silver nitrate treated in vitro shoot was found to be 50.8 ppm. The presence of nano-Ag was also found in the leaves of 1 mM silver nitrate-treated in vitro shoots. In summary, this is the first report portraying the bioaccumulation and in planta reduction capability of the in vitro shoot system of W. somnifera, which makes it a potential medicinal plant of commercial value for silver contaminated soils.

Effect of CeO2, TiO2 and SiO2 nanoparticles on the growth and quality of model medicinal plant Salvia miltiorrhiza by acting on soil microenvironment

In this study, a six-month pot experiment was conducted to explore the effects of nanoparticles (NPs), including CeO2, TiO2 and SiO2 NPs at 200 and 800 mg/kg, on the growth and quality of model medicinal plant Salvia miltiorrhiza. A control group was implemented without the application of NPs. Results showed that NPs had no significant effect on root biomass. Treatment with 200 mg/kg of SiO2 NPs significantly increased the total tanshinone content by 44.07 %, while 200 mg/kg of CeO2 NPs were conducive to a 22.34 % increase in salvianolic acid B content. Exposure to CeO2 NPs induced a substantial rise in the MDA content in leaves (176.25 % and 329.15 % under low and high concentration exposure, respectively), resulting in pronounced oxidative stress. However, TiO2 and SiO2 NPs did not evoke a robust response from the antioxidant system. Besides, high doses of CeO2 NP-amended soil led to reduced nitrogen, phosphorus and potassium contents. Furthermore, the NP amendment disturbed the carbon and nitrogen metabolism in the plant rhizosphere and reshaped the rhizosphere microbial community structure. The application of CeO2 and TiO2 NPs promoted the accumulation of metabolites with antioxidant functions, such as D-altrose, trehalose, arachidonic acid and ergosterol. NPs displayed a notable suppressive effect on pathogenic fungi (Fusarium and Gibberella) in the rhizosphere, while enriching beneficial taxa with disease resistance, heavy metal antagonism and plant growth promotion ability (Lysobacter, Streptomycetaceae, Bacillaceae and Hannaella). Correlation analysis indicated the involvement of rhizosphere microorganisms in plant adaptation to NP amendments. NPs regulate plant growth and quality by altering soil properties, rhizosphere microbial community structure, and influencing plant and rhizosphere microbe metabolism. These findings were beneficial to deepening the understanding of the mechanism by which NPs affect medicinal plants.

The role of iron materials in the abiotic transformation and biotransformation of polybrominated diphenyl ethers (PBDEs): A review

Polybrominated diphenyl ethers (PBDEs), widely used as flame retardants, easily enter the environment, thus posing environmental and health risks. Iron materials play a key role during the migration and transformation of PBDEs. This article reviews the processes and mechanisms of adsorption, degradation, and biological uptake and transformation of PBDEs affected by iron materials in the environment. Iron materials can effectively adsorb PBDEs through hydrophobic interactions, π-π interactions, hydrogen/halogen bonds, electrostatic interactions, coordination interactions, and pore filling interactions. In addition, they are beneficial for the photodegradation, reduction debromination, and advanced oxidation degradation and debromination of PBDEs. The iron material-microorganism coupling technology affects the uptake and transformation of PBDEs. In addition, iron materials can reduce the uptake of PBDEs in plants, affecting their bioavailability. The species, concentration, and size of iron materials affect plant physiology. Overall, iron materials play a bidirectional role in the biological uptake and transformation of PBDEs. It is necessary to strengthen the positive role of iron materials in reducing the environmental and health risks caused by PBDEs. This article provides innovative ideas for the rational use of iron materials in controlling the migration and transformation of PBDEs in the environment.

Unravelling the effects of nano SiO2, nano TiO2 and their nanocomposites on Zea mays L. growth and soil health

Amidst the challenges posed by climate change, exploring advanced technologies like nanotechnology is crucial for enhancing agricultural productivity and food security. Consequently, this study investigated the impact of nano SiO2 (nSiO2), nano TiO2 (nTiO2) and SiO2/TiO2 nanocomposites (NCs) on 30-day-old Zea mays L. plants and soil health at concentrations of 100 and 200 ppm. Results showed that nSiO2 and nTiO2 at 100 ppm and SiO2/TiO2 NCs at both concentrations, positively influenced plant growth, with the best stimulation observed at 200 ppm of SiO2/TiO2 NCs. Improved plant growth was associated with higher chlorophyll content, photosynthetic rate, transpiration rate, stomatal conductance, rhizospheric N-fixing and phosphate solubilizing bacterial population and plant nutrient uptake. Additionally, treated plants exhibited increased cellulose and starch levels. Malondialdehyde (MDA) content was lower or similar to that of the control, except at 200 ppm of nTiO2-treated shoots. Antioxidant enzyme activities fluctuated, indicating physiological adjustments. Overall, 100 ppm of nTiO2 as well as nSiO2 and 100 and 200 ppm of SiO2/TiO2 NCs improved soil fertility and Z. mays growth, suggesting potential benefits for sustainable agriculture. The findings lay the foundation for more comprehensive investigations into the long-term fate of nanomaterials in soil and their intricate molecular-level interactions with Z. mays.

Studying the impact of titanium dioxide nanoparticles on the expression of pivotal genes related to menthol biosynthesis and certain biochemical parameters in peppermint plants (Mentha Piperita L.)

BACKGROUND

This study examines the impact of titanium dioxide nanoparticles (TiO2NPs) on gene expression associated with menthol biosynthesis and selected biochemical parameters in peppermint plants (Mentha piperita L.). Menthol, the active ingredient in peppermint, is synthesized through various pathways involving key genes like geranyl diphosphate synthase, menthone reductase, and menthofuran synthase. Seedlings were treated with different concentrations of TiO2NPs (50, 100, 200, and 300 ppm) via foliar spray. After three weeks of treatment, leaf samples were gathered and kept at -70 °C for analysis.

RESULTS

According to our findings, there was a significant elevation (P ≤ 0.05) in proline content at concentrations of 200 and 300 ppm in comparison with the control. Specifically, the highest proline level was registered at 200 ppm, reaching 259.64 ± 33.33 µg/g FW. Additionally, hydrogen peroxide and malondialdehyde content exhibited a decreasing trend following nanoparticle treatments. Catalase activity was notably affected by varying TiO2NP concentrations, with a significant decrease observed at 200 and 300 ppm compared to the control (P ≤ 0.05). Conversely, at 100 ppm, catalase activity significantly increased (11.035 ± 1.12 units/mg of protein/min). Guaiacol peroxidase activity decreased across all nanoparticle concentrations. Furthermore, RT-qPCR analysis indicated increased expression of the studied genes at 300 ppm concentration.

CONCLUSIONS

Hence, it can be inferred that at the transcript level, this nanoparticle exhibited efficacy in influencing the biosynthetic pathway of menthol.

Critical Review: Uptake and Translocation of Organic Nanodelivery Vehicles in Plants

Nanodelivery vehicles (NDVs) are engineered nanomaterials (ENMs) that, within the agricultural sector, have been investigated for their ability to improve uptake and translocation of agrochemicals, control release, or target specific tissues or subcellular compartments. Both inorganic and organic NDVs have been studied for agrochemical delivery in the literature, but research on the latter has been slower to develop than the literature on the former. Since the two classes of nanomaterials exhibit significant differences in surface chemistry, physical deformability, and even colloidal stability, trends that apply to inorganic NDVs may not hold for organic NDVs, and vice versa. We here review the current literature on the uptake, translocation, biotransformation, and cellular and subcellular internalization of organic NDVs in plants following foliar or root administration. A background on nanomaterials and plant physiology is provided as a leveling ground for researchers in the field. Trends in uptake and translocation are examined as a function of NDV properties and compared to those reported for inorganic nanomaterials. Methods for assessing fate and transport of organic NDVs in plants (a major bottleneck in the field) are discussed. We end by identifying knowledge gaps in the literature that must be understood in order to rationally design organic NDVs for precision agrochemical nanodelivery.

Proteomic insights to decipher nanoparticle uptake, translocation, and intercellular mechanisms in plants

Advent of proteomic techniques has made it possible to identify a broad spectrum of proteins in living systems. Studying the impact of nanoparticle (NP)-mediated plant protein responses is an emerging field. NPs are continuously being released into the environment and directly or indirectly affect plant's biochemistry. Exposure of plants to NPs, especially crops, poses a significant risk to the food chain, leading to changes in underlying metabolic processes. Once absorbed by plants, NPs interact with cellular proteins, thereby inducing changes in plant protein patterns. Based on the reactivity, properties, and translocation of nanoparticles, NPs can interfere with proteins involved in various cellular processes in plants such as energy regulation, redox metabolism, and cytotoxicity. Such interactions of NPs at the subcellular level enhance ROS scavenging activity, especially under stress conditions. Although higher concentrations of NPs induce ROS production and hinder oxidative mechanisms under stress conditions, NPs also mediate metabolic changes from fermentation to normal cellular processes. Although there has been lots of work conducted to understand the different effects of NPs on plants, the knowledge of proteomic responses of plants toward NPs is still very limited. This review has focused on the multi-omic analysis of NP interaction mechanisms with crop plants mainly centering on the proteomic perspective in response to both stress and non-stressed conditions. Furthermore, NP-specific interaction mechanisms with the biological pathways are discussed in detail.

Unraveling the plethora of toxicological implications of nanoparticles on living organisms and recent insights into different remediation strategies: A comprehensive review

Increased use of nanoscale particles have benefited many industries, including medicine, electronics, and environmental cleaning. These particles provide higher material performance, greater reactivity, and improved drug delivery. However, the main concern is the generation of nanowastes that can spread in different environmental matrices, posing threat to our environment and human health. Nanoparticles (NPs) have the potential to enter the food chain through a variety of pathways, including agriculture, food processing, packaging, and environmental contamination. These particles can negatively impact plant and animal physiology and growth. Due to the assessment of their environmental damage, nanoparticles are the particles of size between 1 and 100 nm that is the recent topic to be discussed. Nanoparticles' absorption, distribution, and toxicity to plants and animals can all be significantly influenced by their size, shape, and surface chemistry. Due to their absorptive capacity and potential to combine with other harmful substances, they can alter the metabolic pathways of living organisms. Nevertheless, despite the continuous research and availability of data, there are still knowledge gaps related to the ecotoxicology, prevalence and workable ways to address the impact of nanoparticles. This review focuses on the impact of nanoparticles on different organisms and the application of advanced techniques to remediate ecosystems using hyperaccumulator plant species. Future considerations are explored around nano-phytoremediation, as an eco-friendly, convenient and cost effective technology that can be applied at field scales.

The combined contamination of nano-polystyrene and nanoAg: Uptake, translocation and ecotoxicity effects on willow saplings

Nanoplastics (NPLs) and nanoAg (AgNPs) are emerging contaminants commonly detected in aquatic and terrestrial environments due to their widespread use in various domains. However, their uptake, translocation, and toxic effects on plants in cooccurrence environments remain largely unexplored. Therefore, a hydroponic experiment was conducted using 100 nm NPLs (1 mg/L and 10 mg/L), AgNPs (100 μg/L and 1000 μg/L) and saplings of willow (Salix matsudana 'J172') to investigate absorption, translocation and the physio-biochemical responses of the plants. The results indicated that NPLs and AgNPs were agglomerated with each other in solutions. NPLs not only penetrated the roots of the saplings but also translocated to the branches and leaves through xylem ducts. However, AgNPs was only detected in the roots, suggesting that the internalization of nanoparticles in plants depends on the properties and types of particles themselves. The combined exposure to NPLs and AgNPs selectively affected the absorption and distribution of K, Ca, Mg and Fe, resulting in inhibited saplings growth and photosynthesis. Furthermore, the presence of NPLs and AgNPs induced oxidative damage and stimulated the antioxidant stress system in the plants. This study provides novel insights into the internalization and ecotoxicological mechanisms of NPLs and AgNPs in woody vascular plants.

Quantitative biodistribution of nanoparticles in plants with lanthanide complexes

The inefficient distribution of fertilizers, nutrients, and pesticides on crops is a major challenge in modern agriculture that leads to reduced productivity and environmental pollution. Nanoformulation of agrochemicals is an attractive approach to enable the selective delivery of agents into specific plant organs, their release in those tissues, and improve their efficiency. Already commercialized nanofertilizers utilize the physiochemical properties of metal nanoparticles such as size, charge, and the metal core to overcome biological barriers in plants to reach their target sites. Despite their wide application in human diseases, lipid nanoparticles are rarely used in agricultural applications and a systematic screening approach to identifying efficacious formulations has not been reported. Here, we developed a quantitative metal-encoded platform to determine the biodistribution of different lipid nanoparticles in plant tissues. In this platform lanthanide metal complexes were encapsulated into four types of lipid nanoparticles. Our approach was able to successfully quantify payload accumulation for all the lipid formulations across the roots, stem, and leaf of the plant. Lanthanide levels were 20- to 57-fold higher in the leaf and 100- to 10,000-fold higher in the stem for the nanoparticle encapsulated lanthanide complexes compared to the unencapsulated, free lanthanide complex. This system will facilitate the discovery of nanoparticles as delivery carriers for agrochemicals and plant tissue-targeting products.

Translocation of CdS nanoparticles in maize (Zea mays L.) plant and its effect on metabolic response

Cadmium sulfide nanomaterials are of great concern because of their potential toxicity and unavoidable releases due to multiple commercial applications of nanoparticles (NPs). Commercial NPs act as mediators of damage to plant cells and pose potential toxicity to plants and human health. In the current study, investigated the phytotoxicology, absorption, translocation, antioxidant enzyme activity, and metabolic profiles of maize (Zea mays L.) seedlings exposed to different hydroponic treatments for fifteen days. The different concentrations of CdS NPs (3, 15, 30, 50, and 100 mg/L), 0.3 mg/L Cd ions, and unexposed control were performed in treatments. The results indicated that CdS NPs could present phytotoxic effects on seed germination and root elongation. Compared to the control, the CdS NPs dramatically reduced the shoots and root biomass, as well as the shape of the roots. Transmission electron microscopy and energy-dispersive mapping confirmed that CdS NPs could penetrate the maize root epidermis and bioaccumulate in the shoots with high concentrations. According to metabolomics studies, exposure to CdS NPs and Cd ions would result in metabolic disruption. Based on the statistical analysis, 290 out of 336 metabolites (86.30%) were obviously inhibited. The findings of this study demonstrated possible risks of emerging potential toxic NPs, and the release of these NPs to environment is a serious concern for agricultural activities.

Translocation of TiO2 nanoparticles enhances phosphorus uptake by wetland plants: Evidence from Pistia stratiotes and Alisma plantago-aquatica

Titanium dioxide nanoparticles (nTiO2) and phosphorus (P) are widely present in sewages. To verify the hypothesis and the associated mechanisms that root-to-shoot translocation of nTiO2 can enhance plant P uptake thus P removal during sewage treatment, two wetland plants (Pistia stratiotes and Alisma plantago-aquatica) with different lateral root structures were used to examine the effect of nTiO2 (89.7% anatase and 10.3% rutile) on plant growth and P uptake in a hydroponic system. Inductively coupled plasma-optical emission spectroscopy and transmission electron microscopy-energy dispersive spectroscopy showed that P. stratiotes with well-developed lateral roots translocated 1.4-16 fold higher nTiO2 than A. plantago-aquatica with poorly developed roots, indicating P. stratiotes is efficient in nTiO2 uptake. In addition, nTiO2 root-to-shoot translocation in P. stratiotes increased with increasing nTiO2 concentration, while the opposite occurred in A. plantago-aquatica. Corresponding to the stronger nTiO2 translocation in P. stratiotes, its P uptake efficiency (Imax) and P accumulation were greater than that in A. plantago-aquatica, with Imax being increased by 35.8% and -16.4% and shoot P concentrations being increased by 16.2-64.6% and 11.4%, respectively. The strong positive correlation between Ti and P concentrations in plant tissues (r = 0.72-0.89, P < 0.01) indicated that nTiO2 translocation enhanced P uptake. Moreover, nTiO2-enhanced P uptake promoted plant growth and photosynthetic pigment synthesis. Therefore, wetland plants with well-developed lateral roots like P. stratiotes have potential to be used in P removal from nTiO2-enriched sewages.

Particle Size Determines the Phytotoxicity of ZnO Nanoparticles in Rice (Oryza sativa L.) Revealed by Spatial Imaging Techniques

To understand the nanotoxicity effects on plants, it is necessary to systematically study the distribution of NPs in vivo. Herein, elemental and particle-imaging techniques were used to unravel the size effects of ZnO NPs on phytotoxicity. Small-sized ZnO NPs (5, 20, and 50 nm) showed an inhibitory effect on the length and biomass of rice (Oryza sativa L.) used as a model plant. ZnO NP nanotoxicity caused rice root cell membrane damage, increased the malondialdehyde content, and activated antioxidant enzymes. As a control, the same dose of Zn2+ salt did not affect the physiological and biochemical indices of rice, suggesting that the toxicity is caused by the entry of the ZnO NPs and not the dissolved Zn2+. Laser ablation inductively coupled plasma optical emission spectroscopy analysis revealed that ZnO NPs accumulated in the rice root vascular tissues of the rhizodermis and procambium. Furthermore, transmission electron microscopy confirmed that the NPs were internalized to the root tissues. These results suggest that ZnO NPs may exist in the rice root system and that their particle size could be a crucial factor in determining toxicity. This study provides evidence of the size-dependent phytotoxicity of ZnO NPs.

Recent trends and perspectives in the application of metal and metal oxide nanomaterials for sustainable agriculture

Sustainable ecosystem management leads to the use of eco-friendly agricultural techniques for crop production. One of them is the use of metal and metal oxide nanomaterials and nanoparticles, which have proven to be a valuable option for the improvement of agricultural food systems. Moreover, the biological synthesis of these nanoparticles, from plants, bacteria, and fungi, also contributes to their eco-friendly and sustainable characteristics. Nanoparticles, which vary in size from 1 to 100 nm have a variety of mechanisms that are safer and more efficient than conventional fertilizers. Their usage as fertilizers and insecticides in agriculture is gaining favor in the scientific community to maximize crop output. More studies in this field will increase our understanding of this new technology and its broad acceptance in terms of performance, affordability, and environmental protection, as certain nanoparticles may outperform conventional fertilizers and insecticides. Accordingly, to the information gathered in this review, nanoparticles show remarkable potential for enhancing crop production, improving soil quality, and protecting the environment, however, metal and metal oxide NPs are not widely employed in agriculture. Many features of nanoparticles are yet left over, and it is necessary to uncover them. In this sense, this review article provides an overview of various types of metal and metal oxide nanoparticles used in agriculture, their characterization and synthesis, the recent research on them, and their possible application for the improvement of crop productivity in a sustainable manner.

Uptake, accumulation, toxicity, and interaction of metallic-based nanoparticles with plants: current challenges and future perspectives

The rapid development of industrialization is causing several fundamental problems in plants due to the interaction between plants and soil contaminated with metallic nanoparticles (NPs). Numerous investigations have been conducted to address the severe toxic effects caused by nanoparticles in the past few decades. Based on the composition, size, concentration, physical and chemical characteristics of metallic NPs, and plant types, it enhances or lessens the plant growth at various developmental stages. Metallic NPs are uptaken by plant roots and translocated toward shoots via vascular system based on composition, size, shape as well as plant anatomy and cause austere phytotoxicity. Herein, we tried to summarize the toxicity induced by the uptake and accumulation of NPs in plants and also we explored the detoxification mechanism of metallic NPs adopted by plants via using different phytohormones, signaling molecules, and phytochelatins. This study was intended to be an unambiguous assessment including current knowledge on NPs uptake, accumulation, and translocation in higher plants. Furthermore, it will also provide sufficient knowledge to the scientific community to understand the metallic NPs-induced inhibitory effects and mechanisms involved within plants.

Uptake of TiO2 Nanoparticles was Linked to Variation in net Cation flux in Wheat Seedlings

Titanium dioxide nanoparticles (TiO₂ NPs) are ubiquitous in the environment and enter the terrestrial food chain via plant uptake. However, plant uptake behaviors of TiO₂ NPs remain elusive. Here, the uptake kinetics of TiO₂ NPs by wheat (Triticum aestivum L.) seedlings and the effects on cation flux in roots were examined in a hydroponic system. Uptake rate of TiO₂ NPs ranged from 119.0 to 604.2 mg kg^- 1 h^- 1 within 8 h exposure. NP uptake decreased by 83% and 47%, respectively, in the presence of sodium azide (NaN₃) and carbonyl cyanide m-chlorophenylhydrazone (CCCP), indicating an energy-dependent uptake of TiO₂ NPs. Moreover, accompanied with TiO₂ NP uptake, net influx of Cd²⁺ decreased by 81%, while Na⁺ flux shifted from inflow to outflow at the meristematic zone of root. These findings provide valuable information for understanding plant uptake of TiO₂ NPs.

Potential Threat of Lead Oxide Nanoparticles for Food Crops: Comprehensive Understanding of the Impacts of Different Nanosized PbOx (x = 1, 2) on Maize (Zea mays L.) Seedlings In Vivo

PbO_x (PbO₂ and PbO, x = 1, 2) nanoparticles are emerging contaminants in dust, soil, and water due to extensive application of commercial lead products. As far as we know, the current studies are first conducted to understand the phytotoxic effects of PbO₂ (10 ± 3 nm) and PbO NPs (20 ± 5 nm) on maize (Zea mays L.) grown in hydroponic treatments. The exposure assays indicated that phytotoxic effects were dose- and size-dependent on PbO_x NPs. Water uptake would be the crucial mechanism to govern the effects of PbO_x on maize seed germination and root elongation, while the nanosize of particles and water transpiration processes would control maize growth and biomass production. PbO_x NPs significantly influenced the macro- and micronutrients in roots and shoots of maize and significantly affected the maize growth and grain development. Our findings provide clear-cut evidence that PbO/PbO₂ NPs can bioaccumulate in maize cell organelles via apoplastic and symplastic routes from the seed and root pathways along with water uptake and transportation. The significance of this research elucidates the impacts of PbO/PbO₂ NPs on food security and indicates the threat of emerging PbO/PbO₂ NPs to human dietary health.

Nanobionics: A Sustainable Agricultural Approach towards Understanding Plant Response to Heavy Metals, Drought, and Salt Stress

In the current scenario, the rising concentration of heavy metals (HMs) due to anthropogenic activities is a severe problem. Plants are very much affected by HM pollution as well as other abiotic stress such as salinity and drought. It is very important to fulfil the nutritional demands of an ever-growing population in these adverse environmental conditions and/or stresses. Remediation of HM in contaminated soil is executed through physical and chemical processes which are costly, time-consuming, and non-sustainable. The application of nanobionics in crop resilience with enhanced stress tolerance may be the safe and sustainable strategy to increase crop yield. Thus, this review emphasizes the impact of nanobionics on the physiological traits and growth indices of plants. Major concerns and stress tolerance associated with the use of nanobionics are also deliberated concisely. The nanobionic approach to plant physiological traits and stress tolerance would lead to an epoch of plant research at the frontier of nanotechnology and plant biology.

Advances in transport and toxicity of nanoparticles in plants

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

Biosynthesis and characterization of nanoparticles, its advantages, various aspects and risk assessment to maintain the sustainable agriculture: Emerging technology in modern era science

The current review aims to gain knowledge on the biosynthesis and characterization of nanoparticles (NPs), their multifactorial role, and emerging trends of NPs utilization in modern science, particularly in sustainable agriculture, for increased yield to solve the food problem in the coming era. However, it is well known that an environment-friendly resource is in excessive demand, and green chemistry is an advanced and rising resource in exploring eco-friendly processes. Plant extracts or other resources can be utilized to synthesize different types of NPS. Hence NPs can be synthesized by organic or inorganic molecules. Inorganic molecules are hydrophilic, biocompatible, and highly steady compared to organic types. NPs occur in numerous chemical conformations ranging from amphiphilic molecules to metal oxides, from artificial polymers to bulky biomolecules. NPs structures can be examined by different approaches, i.e., Raman spectroscopy, optical spectroscopy, X-ray fluorescence, and solid-state NMR. Nano-agrochemical is a unification of nanotechnology and agro-chemicals, which has brought about the manufacture of nano-fertilizers, nano-pesticides, nano-herbicides, nano-insecticides, and nano-fungicides. NPs can also be utilized as an antimicrobial solution, but the mode of action for antibacterial NPs is poorly understood. Presently known mechanisms comprise the induction of oxidative stress, the release of metal ions, and non-oxidative stress. Multiple modes of action towards microbes would be needed in a similar bacterial cell for antibacterial resistance to develop. Finally, we visualize multidisciplinary cooperative methods will be essential to fill the information gap in nano-agrochemicals and drive toward the usage of green NPs in agriculture and plant science study.

A systematic review on bioplastic-soil interaction: Exploring the effects of residual bioplastics on the soil geoenvironment

Growing demand for plastic and increasing plastic waste pollution have led to significant environmental challenges and concerns in today's world. Bioplastics offer exciting new opportunities and possibilities where biodegradable and bio-based plastics are expected to be more eco-friendly and rely on renewable resources. With all its promises, evaluating its real impact and fate on the geoenvironment is paramount for promoting bioplastic use. This paper presents a systematic literature review to understand current bioplastic-soil research and the effects of its residues on the geoenvironment. 632 studies related to bioplastic research in soil since 1973 were identified and categorized into different relevant topics. Publication trend showed bioplastic-soil research grew exponentially after 2010 wherein field studies accounted to 33.1 % of the total studies and only about 9.7 % studied the effects of bioplastic residues on the geoenvironment. Majority of the lab studies were on development and subsequent stability of bioplastics in soil. Short-term studies (in months) dominated the longer-term studies and studies over 4 years were almost non-existent. Lab and field experiments often gave inconsistent results with seasonal, climatic and bio-geographical factors strongly influencing the field results and bioplastic stability in soil. Most existing studies reported significant effects for microbioplastic concentrations at or above 1 % w/w. Bioplastic residues were found to substantially affect soil C/N ratio, impact soil microbial diversity by favouring certain microbial taxa and alter soil physical structure by influencing soil aggregates formation. At higher concentrations, plant health and germination success were also negatively affected. Conclusively, the review found it important to focus more on long-term field experiments to better understand the degree and extent of bioplastic residue impact on soil physico-chemical properties, mechanical properties, soil biology, soil-bioplastic-plant response, nutrients and toxicity. There are also very few studies investigating contaminant transport and migration of micro or nano-bioplastics in soil.

Imaging tools for plant nanobiotechnology

The successful application of nanobiotechnology in biomedicine has greatly changed the traditional way of diagnosis and treating of disease, and is promising for revolutionizing the traditional plant nanobiotechnology. Over the past few years, nanobiotechnology has increasingly expanded into plant research area. Nanomaterials can be designed as vectors for targeted delivery and controlled release of fertilizers, pesticides, herbicides, nucleotides, proteins, etc. Interestingly, nanomaterials with unique physical and chemical properties can directly affect plant growth and development; improve plant resistance to disease and stress; design as sensors in plant biology; and even be used for plant genetic engineering. Similarly, there have been concerns about the potential biological toxicity of nanomaterials. Selecting appropriate characterization methods will help understand how nanomaterials interact with plants and promote advances in plant nanobiotechnology. However, there are relatively few reviews of tools for characterizing nanomaterials in plant nanobiotechnology. In this review, we present relevant imaging tools that have been used in plant nanobiotechnology to monitor nanomaterial migration, interaction with and internalization into plants at three-dimensional lengths. Including: 1) Migration of nanomaterial into plant organs 2) Penetration of nanomaterial into plant tissues (iii)Internalization of nanomaterials by plant cells and interactions with plant subcellular structures. We compare the advantages and disadvantages of current characterization tools and propose future optimal characterization methods for plant nanobiotechnology.

Nanoparticle's uptake and translocation mechanisms in plants via seed priming, foliar treatment, and root exposure: a review

Nanotechnology is one of the promising techniques and shares wide ranges of applications almost in every field of life. Nanomaterials are getting continuous attractions due to specific physical and chemical properties and being applied as multifunctional material. The use of nanomaterials/nanoparticles in agriculture sector for crop improvement and protection against various environmental threats have attained greater significance. Size and nature of nanoparticles, mode of application, environmental conditions, rhizospheric and phyllospheric environment, and plant species are major factors that influence the action of nanoparticles. The mode or method of nanoparticle applications to plants is attaining greater attentions. Recently, different methods for nanoparticle applications (seed priming, foliar, and root application) are being used to improve crop growth. It is of quite worth that which method is suitable for nanoparticle application, and how nanoparticles can possibly translocate to various plant tissues from root to shoot or vice versa. These information's are poorly understood and need more investigations to explore the comprehensive mechanism by which nanoparticles make their possible entry through different plant organs and how they transport to regulate various physiological and molecular functions in plant cells. Therefore, this study comprehensively provides the knowledge of nanoparticles uptake via seed priming, foliar exposure, and root application, and their possible translocation mechanism within plants influenced by various factors that has not clearly presented. This study will provide new insights to find out an actual uptake and translocation mechanism of nanoparticles that may help researchers to develop nanoparticle-based new strategies for plants to cope with various environmental challenges. This study also focuses on different soil factors or above ground factors that are involved in nanoparticles uptake and translocation and ultimately their functioning in plants.

Re-translocation of photoassimilates by Nano-TiO2 spraying in favor of osmotic adjustment in water-stressed sunflower.. [DOI: 10.21203/rs.3.rs-2135004/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

Background Water deficit is one of the main environmental stresses that modifies the biomass allocation patterns between shoots and roots. Any attempt to improve the water status of plants, especially in regions of water scarcity, will be significantly important. In this study, the effect of foliar application of nanoparticles or ordinary TiO2 on water status of Helianthus annuus subjected to water deficit stress was evaluated. Results The water content of H. annuus shoots or roots didn’t change significantly by spraying with different concentrations of Nano- or Ord-TiO2. The dry mass (DM), relative dry mass (RDM) and root / shoot ratio of sunflower sprayed with Nano-TiO2, when averaged across all concentrations, mostly didn’t differ significantly from those sprayed with Ord-TiO2. In roots, the DM and RDM were decreased with increasing concentration of Ord-TiO2 but unchanged significantly by spraying with Nano-TiO2. Under all levels of water availability, total osmotic potential (ψs) and osmotic potential contributed by organic substances (ψorganic) didn’t change significantly by Ord-TiO2. Nano-TiO2 doesn't have any effect on the shoot or root dry mass and osmotic potential contributed by electrolytes (ψelect). Low concentrations of Nano-TiO2 significantly decreased relative water content (RWC) and ψs due to decreasing ψorganic. The ψs and ψelect of the root sap of sunflower were greatly lower than that of leaf sap. The soluble sugars partitioning and re-translocation was mainly in the priority of osmotic adjustment of the roots as a functional equilibrium under water deficit stress. Conclusion The foliar application of Nano-TiO2 didn’t significantly improve the sunflower water status built up by the shortage in water supply, and the quite small effect was via re-translocation of electrolytes and organic substances from shoots to roots.

The potential of bacterial microcompartment architectures for phytonanotechnology

The application of nanotechnology to plants, termed phytonanotechnology, has the potential to revolutionize plant research and agricultural production. Advancements in phytonanotechnology will allow for the time-controlled and target-specific release of bioactive compounds and agrochemicals to alter and optimize conventional plant production systems. A diverse range of engineered nanoparticles with unique physiochemical properties is currently being investigated to determine their suitability for plants. Improvements in crop yield, disease resistance and nutrient and pesticide management are all possible using designed nanocarriers. However, despite these prospective benefits, research to thoroughly understand the precise activity, localization and potential phytotoxicity of these nanoparticles within plant systems is required. Protein-based bacterial microcompartment shell proteins that self-assemble into spherical shells, nanotubes and sheets could be of immense value for phytonanotechnology due to their ease of manipulation, multifunctionality, rapid and efficient producibility and biodegradability. In this review, we explore bacterial microcompartment-based architectures within the scope of phytonanotechnology.

Interaction of the Nanoparticles and Plants in Selective Growth Stages—Usual Effects and Resulting Impact on Usage Perspectives

Nanotechnologies have received tremendous attention since their discovery. The current studies show a high application potential of nanoparticles for plant treatments, where the general properties of nanoparticles such as their lower concentrations for an appropriate effects, the gradual release of nanoparticle-based nutrients or their antimicrobial effect are especially useful. The presented review, after the general introduction, analyzes the mechanisms that are described so far in the uptake and movement of nanoparticles in plants. The following part evaluates the available literature on the application of nanoparticles in the selective growth stage, namely, it compares the observed effect that they have when they are applied to seeds (nanopriming), to seedlings or adult plants. Based on the research that has been carried out, it is evident that the most common beneficial effects of nanopriming are the improved parameters for seed germination, the reduced contamination by plant pathogens and the higher stress tolerance that they generate. In the case of plant treatments, the most common applications are for the purpose of generating protection against plant pathogens, but better growth and better tolerance to stresses are also frequently observed. Hypotheses explaining these observed effects were also mapped, where, e.g., the influence that they have on photosynthesis parameters is described as a frequent growth-improving factor. From the consortium of the used nanoparticles, those that were most frequently applied included the principal components that were derived from zinc, iron, copper and silver. This observation implies that the beneficial effect that nanoparticles have is not necessarily based on the nutritional supply that comes from the used metal ions, as they can induce these beneficial physiological changes in the treated cells by other means. Finally, a critical evaluation of the strengths and weaknesses of the wider use of nanoparticles in practice is presented.

The effect of 100-200 nm ZnO and TiO2 nanoparticles on the in vitro-grown soybean plants

Engineered nanomaterials are increasingly used in everyday life applications and, in consequence, significant amounts are being released into the environment. From soil, water, and air they can reach the organelles of edible plants, potentially impacting the food chain and human health. The potential environmental and health impact of these nanoscale materials is of public concern. TiO2 and ZnO are among the most significant nanomaterials in terms of production amounts. Our study aimed at evaluating the effects of large-scale TiO2 (~100 nm) and ZnO (~200 nm) nanoparticles on soybean plants grown in vitro. The effect of different concentrations of nanoparticles (10, 100, 1000 mg/L) was evaluated regarding plant morphology and metabolic changes. ZnO nanoparticles showed higher toxicity compared to TiO2 in the experimental set-up. Overall, elevated levels of chlorophylls and proteins were observed, as well as increased concentrations of ascorbic and dehydroascorbic acids. Also, the decreasing stomatal conductance to water vapor and net CO2 assimilation rate show higher plant stress levels. In addition, ZnO nanoparticle treatments severely affected plant growth, while TEM analysis revealed ultrastructural changes in chloroplasts and rupture of leaf cell walls. By combining ICP-OES and TEM results, we were able to show that the nanoparticles were metabolized, and their internalization in the soybean plant tissues occurred in ionic forms. This behavior most likely is the main driving force of nanoparticle toxicity.

Overview on Recent Developments in the Design, Application, and Impacts of Nanofertilizers in Agriculture

Nutrient management is always a great concern for better crop production. The optimized use of nutrients plays a key role in sustainable crop production, which is a major global challenge as it depends mainly on synthetic fertilizers. A novel fertilizer approach is required that can boost agricultural system production while being more ecologically friendly than synthetic fertilizers. As nanotechnology has left no field untouched, including agriculture, by its scientific innovations. The use of nanofertilizers in agriculture is in the early stage of development, but they appear to have significant potential in different ways, such as increased nutrient-use efficiency, the slow release of nutrients to prevent nutrient loss, targeted delivery, improved abiotic stress tolerance, etc. This review summarizes the current knowledge on various developments in the design and formulation of nanoparticles used as nanofertilizers, their types, their mode of application, and their potential impacts on agricultural crops. The main emphasis is given on the potential benefits of nanofertilizers, and we highlight the current limitations and future challenges related to the wide-scale application before field applications. In particular, the unprecedent release of these nanomaterials into the environment may jeopardize human health and the ecosystem. As the green revolution has occurred, the production of food grains has increased at the cost of the disproportionate use of synthetic fertilizers and pesticides, which have severely damaged our ecosystem. We need to make sure that the use of these nanofertilizers reduces environmental damage, rather than increasing it. Therefore, future studies should also check the environmental risks associated with these nanofertilizers, if there are any; moreover, it should focus on green manufactured and biosynthesized nanofertilizers, as well as their safety, bioavailability, and toxicity issues, to safeguard their application for sustainable agriculture environments.

Plant elicitation and TiO2 nanoparticles application as an effective strategy for improving the growth, biochemical properties, and essential oil of peppermint

Mentha piperita L., which is an abundant source of essential oils (EO) and phenolic acids, is well known for its medicinal significance. The present research aimed to evaluate the impact of various concentrations of methyl jasmonate (MeJA; 0, 0.1, and 0.5 mM), titanium dioxide nanoparticles (TiO₂ NPs; 0 and 150 mg L^-1), and salicylic acid (SA; 0, 0.1, and 1 mM) on growth, EOs, and phenolic compounds of M. piperita L. The results demonstrated that the simultaneous application of SA (0.1 mM) and TiO₂ NPs (150 mg L^-1) enhanced shoot dry weight, the shoot length, and membrane stability index of peppermint by 56.17, 19.52, and 36%, respectively, compared to control. Moreover, phenolic content (76%), caffeic acid content (78%), rosmarinic acid content (87%), 2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging ability (78%), and catalase (155%), ascorbate peroxidase activities (95%) were further improved by simultaneously applying MeJA (0.1 mM) and TiO₂ NPs (150 mg L^-1) compared to control. The highest menthol production (44.51%) was obtained with exogenous application of MeJA (0.1 mM) with 150 mg L^-1 TiO₂ NPs. The findings of the current study presented an ideal combination of TiO₂ NPs with plant growth regulators for promoting antioxidant activities and increasing major components of EO in peppermint plants.

Nanofertilizer Possibilities for Healthy Soil, Water, and Food in Future: An Overview

Conventional fertilizers and pesticides are not sustainable for multiple reasons, including high delivery and usage inefficiency, considerable energy, and water inputs with adverse impact on the agroecosystem. Achieving and maintaining optimal food security is a global task that initiates agricultural approaches to be revolutionized effectively on time, as adversities in climate change, population growth, and loss of arable land may increase. Recent approaches based on nanotechnology may improve in vivo nutrient delivery to ensure the distribution of nutrients precisely, as nanoengineered particles may improve crop growth and productivity. The underlying mechanistic processes are yet to be unlayered because in coming years, the major task may be to develop novel and efficient nutrient uses in agriculture with nutrient use efficiency (NUE) to acquire optimal crop yield with ecological biodiversity, sustainable agricultural production, and agricultural socio-economy. This study highlights the potential of nanofertilizers in agricultural crops for improved plant performance productivity in case subjected to abiotic stress conditions.

Uptake and Translocation of a Silica Nanocarrier and an Encapsulated Organic Pesticide Following Foliar Application in Tomato Plants

Pesticide nanoencapsulation and its foliar application are promising approaches for improving the efficiency of current pesticide application practices, whose losses can reach 99%. Here, we investigated the uptake and translocation of azoxystrobin, a systemic pesticide, encapsulated within porous hollow silica nanoparticles (PHSNs) of a mean diameter of 253 ± 73 nm, following foliar application on tomato plants. The PHSNs had 67% loading efficiency for azoxystrobin and enabled its controlled release over several days. Thus, the nanoencapsulated pesticide was taken up and distributed more slowly than the nonencapsulated pesticide. A total of 8.7 ± 1.3 μg of the azoxystrobin was quantified in different plant parts, 4 days after 20 μg of nanoencapsulated pesticide application on a single leaf of each plant. In parallel, the uptake and translocation of the PHSNs (as total Si and particulate SiO₂) in the plant were characterized. The total Si translocated after 4 days was 15.5 ± 1.6 μg, and the uptake rate and translocation patterns for PHSNs were different from their pesticide load. Notably, PHSNs were translocated throughout the plant, although they were much larger than known size-exclusion limits (reportedly below 50 nm) in plant tissues, which points to knowledge gaps in the translocation mechanisms of nanoparticles in plants. The translocation patterns of azoxystrobin vary significantly following foliar uptake of the nanosilica-encapsulated and nonencapsulated pesticide formulations.

Response of Saponaria officinalis L. hairy roots to the application of TiO2 nanoparticles in terms of production of valuable polyphenolic compounds and SO6 protein

Saponaria officinalis L. is a perennial plant from the Caryophyllaceae family whose various parts are used in traditional medicine as the treatment agent of skin diseases, blood purifier, diuretic, sudorific, and bile purifier. The cultivation system of hairy roots is a proper alternative for improving the valuable pharmaceutical compounds production compared to other in-vitro methods. The extensive nanotechnology applications in hairy roots cultivation is a sustainable production foundation to produce such active elements. In this study, the effect of various concentrations of titanium dioxide nanoparticles (TiO₂ NPs) (0, 10, 20, 30, 50 mg L^-1) with two treatments (24 and 48 h) was examined on the growth level, antioxidant capacity, total phenol and flavonoid contents, antioxidant enzyme activities, certain polyphenol compounds and SO6 protein in hairy roots of S. officinalis. According to the results, the maximum (3.09 g) and minimum (0.96 g) fresh weight (FW) of hairy roots were observed in treated culture media with 10 and 20 mg L^-1 of TiO₂ NPs after 24 and 48 h of exposure times, respectively. The highest rate of total phenol (9.79 mg GLA g^-1 FW) and total flavonoid contents (1.06 mg QE g^-1 FW) were obtained in the treated hairy roots with 50 and 30 mg L^-1 of nano elicitor in 24 and 48 h of treatments, respectively. The maximum level of most polyphenols, such as rosmarinic acid, cinnamic acid, and rutin, was produced in 24 h of treatment. The use of TiO₂ NP for 48 h with 50 mg L^-1 concentration showed the highest production level of SO6 protein.

Nanofertilizers for agricultural and environmental sustainability

Indiscriminate use of chemical fertilizers in the agricultural production systems to keep pace with the food and nutritional demand of the galloping population had an adverse impact on ecosystem services and environmental quality. Hence, an alternative mechanism is to be developed to enhance farm production and environmental sustainability. A nanohybrid construct like nanofertilizers (NFs) is an excellent alternative to overcome the negative impact of traditional chemical fertilizers. The NFs provide smart nutrient delivery to the plants and proves their efficacy in terms of crop productivity and environmental sustainability over bulky chemical fertilizers. Plants can absorb NFs by foliage or roots depending upon the application methods and properties of the particles. NFs enhance the biotic and abiotic stresses tolerance in plants. It reduces the production cost and mitigates the environmental footprint. Multitude benefits of the NFs open new vistas towards sustainable agriculture and climate change mitigation. Although supra-optimal doses of NFs have a detrimental effect on crop growth, soil health, and environmental outcomes. The extensive release of NFs into the environment and food chain may pose a risk to human health, hence, need careful assessment. Thus, a thorough review on the role of different NFs and their impact on crop growth, productivity, soil, and environmental quality is required, which would be helpful for the research of sustainable agriculture.

Silver and gold nanoparticles induced differential antimicrobial potential in calli cultures of Prunella vulgaris

Background

Prunella vulgaris is medicinally important plant containing high-valued chemical metabolites like Prunellin which belong to family Lamiaceae and it is also known as self-heal. In this research, calli culture were exposed to differential ratios of gold (Au) and silver (Ag) nanoparticles (1:1, 1:2, 1:3, 2:1 and 3:1) along with naphthalene acetic acid (2.0 mg NAA) to investigate its antimicrobial potential. A well diffusion method was used for antimicrobial properties.

Results

Here, two concentrations (1 and 2 mg/6 µl) of all treated calli cultures and wild plants were used against Escherichia coli, Pseudomonas aeruginosa, Salmonella typhi, Bacillus atrophaeus, Bacillus subtilis, Agrobacterium tumefaciens, Erwinia caratovora and Candida albicans. Dimethyl sulfoxide (DMSO) and antibiotics were used as negative and positive controls. Here, the calli exposed to gold (Au) nanoparticles (NPs) and 2.0 mg naphthalene acetic acid (NAA) displayed the highest activity (25.7 mm) against Salmonella typhi than other extracts, which was considered the most susceptible species, while Agrobacterium tumefaciens and Candida albicans was the most resistance species. A possible mechanism of calli induced nanoparticles was also investigated for cytoplasmic leakage.

Conclusion

From the above data it is concluded that Prunella vulgaris is medicinally important plant for the development of anti-microbial drugs using nanotechnology and applicable in various pharmaceutical research.

Fate, bioaccumulation and toxicity of engineered nanomaterials in plants: Current challenges and future prospects

The main focus of this review is to discuss the current advancement in nano-metallic caused phytotoxicity on living organisms and current challenges in crops. Nanostructured materials provide new tools in agriculture to boost sustainable food production, but the main concern is that large-scale production and release of nanomaterials (NMs) into the ecosystem is a rising threat to the surrounding environment that is an urgent challenge to be addressed. The usage of NMs directly influences the transport pathways within plants, which directly relates to their stimulatory/ inhibitory effects. Because of the unregulated nanoparticles (NMs) exposure to soil, they are adsorbed at the root surface, followed by uptake and inter/intracellular mobility within the plant tissue, while the aerial exposure is taken up by foliage, mostly through cuticles, hydathodes, stigma, stomata, and trichomes, but the actual mode of NMs absorption into plants is still unclear. NMs-plant interactions may have stimulatory or inhibitory effects throughout their life cycle depending on their composition, size, concentration, and plant species. Although many publications on NMs interactions with plants have been reported, the knowledge on their uptake, translocation, and bioaccumulation is still a question to be addressed by the scientific community. One of the critical aspects that must be discovered and understood is detecting NMs in soil and the uptake mechanism in plants. Therefore, the nanopollution in plants has yet to be completely understood regarding its impact on plant health, making it yet another artificial environmental influence of unknown long-term consequences. The present review summarizes the uptake, translocation, and bioaccumulation of NMs in plants, focusing on their inhibitory effects and mechanisms involved within plants.

A comprehensive review of impacts of diverse nanoparticles on growth, development and physiological adjustments in plants under changing environment

The application of nanotechnology in agriculture includes the use of nanofertilizers, nanopesticides, and nanoherbicides that enhance plant nutrition without disturbing the soil texture and protect it against microbial infections. Thus, nanotechnology maintains the plant's health by maintaining its soil health. The use of nanoparticles (NPs) in agriculture reduces the chemical spread and nutrient loss and boosts crop yield and productivity. Effect of NPs varies with their applied concentrations, physiochemical properties, and plant species. Various NPs have an impact on the plant to increase biomass productivity, germination rate and their physiology. Also, NPs change the plant molecular mechanisms by altering gene expression. Metal and non-metal oxides of NPs (Au, Ag, ZnO, Fe₂O₃, TiO₂, SiO₂, Al₂O₃, Se, carbon nanotubes, quantum dots) exert an important role in plant growth and development and perform an essential role in stress amelioration. On the other hand, other effects of NPs have also been well investigated by observing their role in growth suppression and inhibition of chlorophyll and photosynthetic efficiency. In this review, we addressed a description of studies that have been made to understand the effects of various kind of NPs, their translocation and interaction with the plants. Also, the phytoremediation approaches of contaminated soil with combined use of NPs for sustainable agriculture is covered.

Co-Application of 24-Epibrassinolide and Titanium Oxide Nanoparticles Promotes Pleioblastus pygmaeus Plant Tolerance to Cu and Cd Toxicity by Increasing Antioxidant Activity and Photosynthetic Capacity and Reducing Heavy Metal Accumulation and Translocation

The integrated application of nanoparticles and phytohormones was explored in this study as a potentially eco-friendly remediation strategy to mitigate heavy metal toxicity in a bamboo species (Pleioblastus pygmaeus) by utilizing titanium oxide nanoparticles (TiO₂-NPs) and 24-epibrassinolide (EBL). Hence, an in vitro experiment was performed to evaluate the role of 100 µM TiO₂ NPs and 10⁻⁸ M 24-epibrassinolide individually and in combination under 100 µM Cu and Cd in a completely randomized design using four replicates. Whereas 100 µM of Cu and Cd reduced antioxidant activity, photosynthetic capacity, plant tolerance, and ultimately plant growth, the co-application of 100 µM TiO₂ NPs and 10⁻⁸ M EBL+ heavy metals (Cu and Cd) resulted in a significant increase in plant antioxidant activity (85%), nonenzymatic antioxidant activities (47%), photosynthetic pigments (43%), fluorescence parameters (68%), plant growth (39%), and plant tolerance (41%) and a significant reduction in the contents of malondialdehyde (45%), hydrogen peroxide (36%), superoxide radical (62%), and soluble protein (28%), as well as the percentage of electrolyte leakage (49%), relative to the control. Moreover, heavy metal accumulation and translocation were reduced by TiO₂ NPs and EBL individually and in combination, which could improve bamboo plant tolerance.

The dichotomy of nanotechnology as the cutting edge of agriculture: Nano-farming as an asset versus nanotoxicity

The unprecedented setbacks and environmental complications, faced by global agro-farming industry, have led to the advent of nanotechnology in agriculture, which has been recognized as a novel and innovative approach in development of sustainable farming practices. The agricultural regimen is the "head honcho" of the world, however presently certain approaches have been imposing grave danger to the environment and human civilization. The nano-farming paradigm has successfully elevated the growth and development of plants, parallel to the production, quality, germination/transpiration index, photosynthetic machinery, genetic progression, and so on. This has optimized the traditional farming into precision farming, utilising nano-based sensors and nanobionics, smart delivery tools, nanotech facets in plant disease management, nanofertilizers, enhancement of plant adaptive potential to external stress, role in bioenergy conservation and so on. These applications portray nanorevolution as "the big cheese" of global agriculture, mitigating the bottlenecks of conventional practices. Besides the applications of nanotechnology, the review identifies the limitations, like possible harmful impact on environment, mankind and plants, as the "Achilles heel" in agro-industry, aiming to establish its defined role in agriculture, while simultaneously considering the risks, in order to resolve them, thus abiding by "technology-yes, but safety-must". The authors aim to provide a significant opportunity to the nanotech researchers, Botanists and environmentalists, to promote judicial use of nanoparticles and establish a secure and safe environment.

The combined effect of water deficit stress and TiO2 nanoparticles on cell membrane and antioxidant enzymes in Helianthus annuus L

Nanotechnology has become one of the several approaches attempting to ameliorate the severe effect of drought on plant's production and to increase the plants tolerance against water deficit for the water economy. In this research, the effect of foliar application of TiO₂, nanoparticles or ordinary TiO₂, on Helianthus annuus subjected to different levels of water deficit was studied. Cell membrane injury increased by increasing the level of water deficit and TiO₂ concentration, and both types of TiO₂ affected the leaves in analogous manner. Ord-TiO₂ increased H₂O₂ generation by 67-240% and lipid peroxidation by 4-67% in leaves. These increases were more than that induced by Nano-TiO₂ and the effect was concentration dependent. Proline significantly increased in leaves by water deficit stress, reaching at 25% field capacity (FC) to more than fivefold compared to that in plants grown on full FC. Spraying plants with water significantly decreased the activities of enzymes in the water deficit stressed roots. The water deficit stress exerted the highest magnitude of effect on the changes of cell membrane injury, MDA, proline content, and activities of CAT and GPX. Nano-TiO₂ was having the highest effect on contents of H₂O₂ and GPX activity. In roots, the level of water deficit causes highest effect on enzyme activities, but TiO₂ influenced more on the changes of MDA and H₂O₂ contents. GPX activity increased by 283% in leaves of plants treated with 50 and 150 ppm Nano-TiO₂, while increased by 170% in those treated with Ord-TiO₂, but APX and CAT activities increased by 17-197%, in average, with Ord-TiO₂. This study concluded that Nano-TiO₂ didn't ameliorate the effects of drought stress on H. annuus but additively increased the stress, so its use in nano-phytotechnology mustn't be expanded without extensive studies.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s12298-022-01153-z.

Uptake, translocation, phytotoxicity, and hormetic effects of titanium dioxide nanoparticles (TiO2NPs) in Nigella arvensis L

The extensive application of titanium dioxide nanoparticles (TiO₂NPs) in agro-industrial practices leads to their high accumulation in the environment or agricultural soils. However, their threshold and ecotoxicological impacts on plants are still poorly understood. In this study, the hormetic effects of TiO₂NPs at a concentration range of 0-2500 mg/L on the growth, and biochemical and physiological behaviors of Nigella arvensis in a hydroponic system were examined for three weeks. The translocation of TiO₂NPs in plant tissues was characterized through scanning and transmission electron microscopy (SEM and TEM). The bioaccumulation of total titanium (Ti) was quantified by inductively coupled plasma atomic emission spectroscopy (ICP-AES). Briefly, the elongation of roots and shoots and the total biomass growth were significantly promoted at 100 mg/L TiO₂NPs. As the results indicated, TiO₂NPs had a hormesis effect on the proline content, i.e., a stimulating effect at the low concentrations of 50 and 100 mg/L and an inhibiting effect in the highest concentration of 2500 mg/L. A biphasic dose-response was observed against TiO₂NPs in shoot soluble sugar and protein contents. The inhibitory effects were detected at ≥1000 mg/L TiO₂NPs, where the synthesis of chlorophylls and carotenoid was reduced. At 1000 mg/ L, TiO₂NPs significantly promoted the cellular H₂O₂ generation, and increased the activities of antioxidant enzymes such as superoxide dismutase (SOD), ascorbate peroxidase (APX), and catalase (CAT). Furthermore, it enhanced the total antioxidant content (TAC), total iridoid content (TIC), and 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activity. Overall, the study revealed the physiological and biochemical alterations in a medicinal plant affected by TiO₂NPs, which can help to use these NPs beneficially by eliminating their harmful effects.

Copper accumulation and physiological markers of soybean (Glycine max) grown in agricultural soil amended with copper nanoparticles

Copper-based nanoparticles (NPs) display a strong potential to replace copper salts (e.g., CuSO4) for application in agricultures as antimicrobial agents or nutritional amendments. Yet, their effects on crop quality are still not comprehensively understood. In this study, the Cu contents in soybeans grown in soils amended with Cu NPs and CuSO4 at 100-500 mg Cu/kg and the subsequent effects on the plant physiological markers were determined. The Cu NPs induced 29-89% at the flowering stage (on Day 40) and 100-165% at maturation stage (on Day 100) more Cu accumulation in soybeans than CuSO4. The presence of particle aggregates in the root cells with deformation upon the Cu NP exposure was observed by transmission electron microscopy. The Cu NPs at 100 and 200 mg/kg significantly improved the plant height and biomass, yet significantly inhibited at 500 mg/kg, compared to the control. In leaves chlorophyll-b was more sensitive than chlorophyll-a and carotenoids to the Cu NP effect. The Cu NPs significantly decreased the root nitrogen and phosphorus contents, while they significantly increased the leaf potassium content in comparison with control. Our results imply that cautious use of Cu NPs in agriculture is warranted due to relatively high uptake of Cu and altered nutrient quality in soybeans.

Trophic Transfer and Toxicity of (Mixtures of) Ag and TiO2 Nanoparticles in the Lettuce-Terrestrial Snail Food Chain

The increasing application of biosolids and agrochemicals containing silver nanoparticles (AgNPs) and titanium dioxide nanoparticles (TiO2NPs) results in their inevitable accumulation in soil, with unknown implications along terrestrial food chains. Here, the trophic transfer of single NPs and a mixture of AgNPs and TiO2NPs from lettuce to snails and their associated impacts on snails were investigated. Both AgNPs and TiO2NPs were transferred from lettuce to snails with trophic transfer factors (defined as the ratio of the Ag/Ti concentration in snail tissues to the Ag/Ti concentration in lettuce leaves) of 0.2-1.1 for Ag and 3.8-47 for Ti. Moreover, the majority of Ag captured by snails in the AgNP-containing treatments was excreted via feces, whereas more than 70% of Ti was distributed in the digestive gland of snails in the TiO2NP-containing treatments. Additionally, AgNP-containing treatments significantly inhibited the activity of snails, while TiO2NP-containing treatments significantly reduced feces excretion of snails. Furthermore, the concurrent application of AgNPs and TiO2NPs did not affect the biomagnification and distribution patterns of Ag and Ti in snails, whereas their co-existence exhibited more severe inhibition of the growth and activity of snails than in the case of applying AgNPs or TiO2NPs alone. This highlights the possibility of nanoparticle transfer to organisms of higher trophic levels via food chains and the associated risks to ecosystem health.