Differential effects of cerium oxide nanoparticles on rice, wheat, and barley roots: a fourier transform infrared (FT-IR) microspectroscopy study

Less is more: The hormetic effect of titanium dioxide nanoparticles on plants

Titanium dioxide nanoparticles have attracted considerable attention due to their extensive applications; however, their multifaceted influence on plant physiology and the broader environment remains a complex subject. This review systematically synthesizes recent studies on the hormetic effects of TiO2 nanoparticles on plants - a phenomenon characterized by dual dose-response behavior that impacts various plant functions. It provides crucial insights into the molecular mechanisms underlying these hormetic effects, encompassing their effects on photosynthesis, oxidative stress response and gene regulation. The significance of this article consists in its emphasis on the necessity to establish clear regulatory frameworks and promote international collaboration to standardize the responsible adoption of nano-TiO2 technology within the agricultural sector. The findings are presented with the intention of stimulating interdisciplinary research and serving as an inspiration for further exploration and investigation within this vital and continually evolving field.

Potential Effects of Metal Oxides on Agricultural Production of Rice: A Mini Review

The extensive usage of metal oxide nanoparticles has aided in the spread and accumulation of these nanoparticles in the environment, potentially endangering both human health and the agroecological system. This research describes in detail the hazardous and advantageous impacts of common metal oxide nanomaterials, such as iron oxide, copper oxide, and zinc oxide, on the life cycle of rice. In-depth analyses are conducted on the transport patterns of nanoparticles in rice, the plant's reaction to stress, the reduction of heavy metal stress, and the improvement of rice quality by metal oxide nanoparticles, all of which are of significant interest in this subject. It is emphasized that from the perspective of advancing the field of nanoagriculture, the next stage of research should focus more on the molecular mechanisms of the effects of metal oxide nanoparticles on rice and the effects of combined use with other biological media. The limitations of the lack of existing studies on the effects of metal oxide nanomaterials on the entire life cycle of rice have been clearly pointed out.

Metabolomics as a Tool to Understand Nano-Plant Interactions: The Case Study of Metal-Based Nanoparticles

Metabolomics is a powerful tool in diverse research areas, enabling an understanding of the response of organisms, such as plants, to external factors, their resistance and tolerance mechanisms against stressors, the biochemical changes and signals during plant development, and the role of specialized metabolites. Despite its advantages, metabolomics is still underused in areas such as nano-plant interactions. Nanoparticles (NPs) are all around us and have a great potential to improve and revolutionize the agri-food sector and modernize agriculture. They can drive precision and sustainability in agriculture as they can act as fertilizers, improve plant performance, protect or defend, mitigate environmental stresses, and/or remediate soil contaminants. Given their high applicability, an in-depth understanding of NPs' impact on plants and their mechanistic action is crucial. Being aware that, in nano-plant interaction work, metabolomics is much less addressed than physiology, and that it is lacking a comprehensive review focusing on metabolomics, this review gathers the information available concerning the metabolomic tools used in studies focused on NP-plant interactions, highlighting the impact of metal-based NPs on plant metabolome, metabolite reconfiguration, and the reprogramming of metabolic pathways.

Effect of gibberellic acid and titanium dioxide nanoparticles on growth, antioxidant defense system and mineral nutrient uptake in wheat

Nanoparticles (NPs), as a novel source of industrial materials, have been extensively used in recent years which ultimately ends up in soils and may cause toxic effects on plants. Gibberellic acid (GA), phytohormone, has ability to minimize abiotic stresses in plants. The role of GA in minimizing titanium dioxide (TiO₂) NPs stress in plants is still unknown. In current study, soil was spiked with TiO₂ NPs (0, 100, 200, 400, 600 mg/kg) while GA was foliar-sprayed at different concentrations during wheat growth. The findings revealed that TiO₂ NPs increased the growth, chlorophyll contents, and nutrient (P, K, Fe, Mn) concentrations in tissues till 400 mg/kg and then decrease was observed at 600 mg/kg level of NPs whereas the values of these parameters were higher compared to control irrespective of NPs levels. The NPs enhanced the antioxidant activities (SOD, POD, CAT, APX) and reduced the oxidative stress (EL, H₂O₂, MDA) in leaves over the control. Foliar GA further improved the growth, yield, nutrients and antioxidant activities while minimized the oxidative stress compared to respective sole NPs- treatments. The interactive effects of NPs and GA were dose dependent. The results proved that studied doses of TiO₂ NPs were not toxic to wheat plants except the highest level (600 mg/kg) used and GA positively affected the yield of wheat under TiO₂ NPs application. The GA can be used to improve crop growth in the presence of NPs which, however, needs further investigation at higher doses of TiO₂ NPs in various crops.

Application of measuring electrochemical characteristics on plant root surfaces in screening Al-tolerant wheat

To explore the relationship between Al phytotoxicity and the electrochemical characteristics of wheat root surfaces, a new chemical mechanism for tolerance of wheat to Al toxicity was initially proposed by conducting acute root elongation experiment, adsorption/desorption experiment, streaming potential determination, and infrared spectroscopy (ATR-FTIR) analysis respectively to classify the grade of Al tolerance of 92 wheat cultivars and quantitatively characterize the electrochemical properties of their root surfaces. Then a pot experiment was conducted with the screened wheat cultivars with different Al resistance grown on acid soils to verify their tolerance to Al toxicity. Results show that zeta potentials of the roots of 67 wheat cultivars at pH4.46 were significantly negatively correlated with Al(Ⅲ) adsorbed on the roots and their relative root elongation (P < 0.05), indicating that wheat roots with less negative charges is more tolerant to Al toxicity. Based on the mechanism, 14 Al-tolerant, 23 medium Al-tolerant and 30 Al-sensitive wheat cultivars were classified. The pot experiment reveals that the relative dry weight of Al-tolerant wheat cultivars was generally greater than that of medium Al-tolerant and Al-sensitive wheat cultivars and Al-tolerant wheat cultivars accumulate less Al in their shoots, which further verifies the relationship among charge characteristics, tolerance of wheat to Al toxicity, and Al uptake by wheat. The negative charges derived from organic functional groups on root surfaces could influence the exchangeable and complexed Al(Ⅲ) adsorbed on wheat roots and thereby affect Al tolerance of wheat cultivars. This finding not only provides a new perspective to screen Al-tolerant wheat cultivars and explain the mechanism of tolerance of wheat to Al toxicity, but is also useful for the prediction of differences in the uptake of Al in the shoots between Al-tolerant and Al-sensitive wheat cultivars, and finally contributes to the prevention of food security risk caused by Al in acid soils.

Effect of nano cerium oxide on soybean (Glycine max L. Merrill) crop exposed to environmentally relevant concentrations

This study evaluated the uptake and translocation of cerium nanoparticles (CeO2 NPs) and soluble Ce(NO3)3 by soybean plants (Glycine max L. Merrill) under the whole plant life-cycle and relevant environmental concentrations, 0.062 and 0.933 mg kg-1, which represent maximal values for 2017 in agricultural soils and sludge treated soils, respectively. The experiments were carried out using a nutrient solution. Cerium was detected in the soybean roots epidermis and cortex, leaves, and grains, but it neither impaired plant development nor grain yield. The concentration of Ce in the shoot increased as a function of time for plants treated with Ce(NO3)3, while it remained constant for plants treated with CeO2 NPs. It means that CeO2 NPs were absorbed in the same rate as biomass production, which suggests that they are taken up and transported by water mass flow. Single-particle inductively coupled plasma mass spectrometry revealed clusters of CeO2 NPs in leaves of plants treated with 25 nm CeO2 NPs (ca. 30-45 nm). The reprecipitation of soluble cerium from Ce(NO3)3 within the plant was not confirmed. Finally, bioconcentration factors above one were found for the lowest concentrated treatments. Since soybean is a widespread source of protein for animals, we draw attention to the importance of evaluating the effects of Ce entrance in the food chain and its possible biomagnification.

Effect of copper oxide nanoparticles on two varieties of sweetpotato plants

Little information is available on the interaction of CuO nanoparticles (nCuO) with tuberous roots. In this study, Beauregard-14 (B-14, low lignin) and Covington (COV, high lignin) sweetpotato varieties were cultivated until maturity in soil amended with nCuO, bulk copper oxide (bCuO) and CuCl2 at 25-125 mg/kg. The Cu treatments had no significant influence on chlorophyll content. Gas exchange parameters were not affected in B-14. In COV, however, at 125 mg/kg treatments, bCuO reduced the intercellular CO2 (11%), while CuCl2 increased it by 7%, compared with control (p ≤ 0.035). At 25 mg/kg nCuO increased the length of COV roots (20.7 ± 2.0 cm vs. 14.6 ± 0.8 cm, p ≤ 0.05). In periderm of B-14, nCuO, at 125 mg/kg, increased Mg by 232%, while the equivalent concentration of CuCl2 reduced P by 410%, compared with control (p ≤ 0.05). The data suggest the potential application of nCuO as nanofertilizer for sweetpotato storage root production.

Spectral characteristics on increasing hydrophilicity of Alfalfa seeds treated with alternating current corona discharge field

In this study, corona discharge at atmospheric pressure under an alternating current (AC) field with a multi-needle plate electrode structure was used as mutagen to study the effects of corona discharge field on the hydrophilicity of alfalfa seeds, especially the effects of non-uniform electric field that is frequently ignored. Alfalfa seed were divided into two groups, one group was covered with 1 mm-thick polypropylene petri dish cover that can be approximated as a single factor effect of non-uniform electric field, the other group was directly irradiated by corona discharge field under different parameters. Fourier transform infrared spectroscopy (FTIR) and dual-index sequence analysis were used to detect and compare the spectra of alfalfa seed coats with different treatments. Results showed that the peaks of the seed coat at 2856 and 1727 cm^-1 in the treatment group changed, indicating that hydrophobic wax, lipid, and cellulose may be cracked or degraded. Corona discharge field treatment can change the chemical structure of alfalfa seed coats, resulting in the changes in their hydrophilicity. The results of the apparent contact angle and scanning electron microscopy (SEM) and other experiments showed that the change in 19 kV non-covered treatment group was greatest, the petri dish cover can effectively reduce the physicochemical etching of ionic wind, the hydrophilicity of alfalfa seeds improved after corona discharge field treatment regardless of whether there is an ionic effect during irradiation, and the ionic wind has a greater influence on the hydrophilicity of alfalfa seeds than the non-uniform electric field. This study revealed the biological effect mechanism of corona discharge field from the perspective of spectral characteristics and provided experimental data support for the analysis of alfalfa seed surface modification and chemical structure after corona discharge field treatment.

Infrared spectroscopy with multivariate analysis to interrogate the interaction of whole cells and secreted soluble exopolimeric substances of Pseudomonas veronii 2E with Cd(II), Cu(II) and Zn(II)

Extracellular polymeric substances (EPS) are bacterial products associated to cell wall or secreted to the liquid media that form the framework of microbial mats. These EPS contain functional groups as carboxyl, amino, hydroxyl, phosphate and sulfhydryl, able to interact with cations. Thus, EPS may be considered natural detoxifying compounds of metal polluted waters and wastewaters. In this work Attenuated Total Reflectance-Fourier Transform Infrared spectroscopy (ATR-FTIR) in combination with multivariate analysis (Principal Component Analysis-PCA-) were used to study the interaction of Cd(II), Cu(II) and Zn(II) and Pseudomonas veronii 2E cells, including bound EPS and cell wall, and its different soluble EPS fractions, previously characterized as Cd(II) ligands of moderate strength. Amino groups present in exopolysaccharide fraction were responsible for Zn(II) and Cu(II) complexation, while carboxylates chelated Cd(II). In lipopolysaccharide fraction, phosphoryl and carboxyl sites were involved in Cd(II) and Cu(II) binding, while Zn(II) interacted with amino groups. Similar results were obtained from cells. These studies confirmed that FTIR-PCA is a rapid analytical tool to provide valuable information regarding the functional groups in biomolecules related to metal interaction. Moreover, a discrimination and identification of functional groups present in both EPS and cells that interacted with Cd(II), Zn(II) and Cu(II) was demonstrated.

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.

Biological Effects of High-Voltage Electric Field Treatment of Naked Oat Seeds

In order to study the mechanism of high-voltage electric field (HVEF) biotechnology, corona discharge produced by a multi-needle-plate HVEF was used to treat naked oat seeds, each treatment dose was divided into two groups, one group was covered with a petri dish cover, the other group was directly exposed to HVEF without a petri dish cover. The scanning electron microscope (SEM) results show that the etching degree of the uncovered group was more serious than that of the covered group, it indicates that ion wind etching has a greater impact on the micro-morphology of seed coat, being covered can effectively reduce the etching degree of discharge plasma on seed. Fourier Transform infrared spectroscopy (FTIR) of the seed coat shows most of the HVEF treatment group can form a new absorption peak at 1740 cm−1, which is closely related to the hydrophilicity of the seed. Comprehensive analysis shows that HVEF treatment can improve the hydrophilicity of seeds, whether they are covered or not. Being covered can reduce the degree of etching of the seed coat, but increase the hydrophilicity of the seed, indicating that the non-uniform electric field has a greater impact on the hydrophilicity of the seed. Our study showed that ion wind had an effect on the micro-morphology of seeds, but this effect didn’t translate into a macroscopic effect. This study provides ideas and experimental data support for the study of the biotechnological mechanism of HVEF.

Liquid assisted pulsed laser ablation synthesized copper oxide nanoparticles (CuO-NPs) and their differential impact on rice seedlings

Hydroponic experiments were conducted to investigate impact of laser ablated copper oxide nanoparticles (CuO-NPs) on rice seedlings. The present work demonstrates that exposure of lower concentrations (5, 10, 20, and 50 µM) of CuO-NPs enhance growth (in terms of fresh and dry weight and length), of rice seedlings. However, at higher concentrations (100, 200, and 500 µM) of CuO-NPs, growth (in terms of length, fresh weight and dry weight) decreased significantly (P < 0.05). Further, photosynthetic pigments (total chlorophyll and carotenoids) and protein contents were also found to be in accordance with the results of growth. This had occurred due to enhanced level of CuO-NPs accumulation at higher doses which also enhanced the level of oxidative stress markers such as hydrogen peroxide (H₂O₂) and malondialdehyde (MDA). Chlorophyll a fluorescence parameters (F_v/F_m and qP and except NPQ) and amount of some minerals (Ca, Mg, Na, and K) increased at lower concentrations of CuO-NPs. In contrast, the levels of F_v/F_m and qP were significantly (P < 0.05) reduced at higher concentration of CuO-NPs, which might be due to enhanced accumulation of Cu and oxidative stresses markers. Our results showed that lower dosages of pulsed laser ablated CuO-NPs (5, 10, 20, and 50 µM) might be beneficial for growth and development of rice seedlings.

Uptake and toxicity studies of magnetic TiO2-Based nanophotocatalyst in Arabidopsis thaliana

Information on the environmental impact of magnetic TiO₂-based nanophotocatalysts is scarce. This study evaluated the potential effects of an innovative magnetic nanophotocatalyst N-TiO₂/Fe₃O₄@SiO₂ (NTFS) on plants using Arabidopsis thaliana grown in a hydroponic system. NTFS was detected in the vascular tissues and mesophyll of plants, thus confirming the uptake and upwards transport of NTFS from roots to leaves. Fourier transform infrared spectroscopy was applied to determine compositional and structural alterations in plant tissues exposed to NTFS, or its two main components (N-TiO₂ and Fe₃O₄@SiO₂), at concentrations ranging from 0 to 1000 mg/L, but no changes were detected in the lipids, pectins, proteins, cellulose, hemicellulose, and carbohydrates. The morphology and biomass of the plants were not affected by the NTFS or its components either. Biosensors for inorganic phosphate (Pi) and MgATP^2- were used to monitor the in vivo Pi and MgATP^2- levels in the plant cells. The results showed that NTFS and its components did not induce any adverse effects on the cytosolic Pi level or ATP synthesis, indicating the energy physiology of Arabidopsis was unaffected. In general, NTFS has inconsequential toxic effects on Arabidopsis, but can be taken up by plants, enter the food chain, and cause potential exposure and bioaccumulation in animals and human beings.

Uptake and Transformation of Silver Nanoparticles and Ions by Rice Plants Revealed by Dual Stable Isotope Tracing

Knowledge on the uptake and transformation of silver nanoparticles (AgNPs) and Ag⁺ ions by organisms is critical for understanding their toxicity. Herein, the differential uptake, transformation, and translocation of AgNPs and Ag⁺ ions in hydroponic rice ( Oryza sativa L.) is assessed in modified Hewitt (with Cl^- ions, HS(Cl)) and Hogland solutions (without Cl^- ions, HS) using dual stable isotope tracing (¹⁰⁷AgNO₃ and ¹⁰⁹AgNPs). After coexposure to ¹⁰⁷Ag⁺ ions and ¹⁰⁹AgNPs at 50 μg L^-1 (as Ag for both) for 14 days, a stimulatory effect was observed on root elongation (increased by 68.8 and 71.9% for HS(Cl) and HS, respectively). Most of the Ag⁺ ions (from ¹⁰⁷Ag⁺ ions and ¹⁰⁹AgNPs) were retained on the root surface, while the occurrence of AgNPs (from ¹⁰⁹AgNPs and ¹⁰⁷Ag⁺ ions) was observed in the root, suggesting the direct uptake of AgNPs and/or reduction of Ag⁺ ions. Higher fractions of Ag⁺ ions in the shoot suggest an in vivo oxidation of AgNPs. These results demonstrated the intertransformation between Ag⁺ ions and AgNPs and the role of AgNPs as carriers and sources of Ag⁺ ions in organisms, which is helpful for understanding the fate and toxicology of Ag.

Spectrochemical analysis of sycamore (Acer pseudoplatanus) leaves for environmental health monitoring

Terrestrial plants are ideal sentinels of environmental pollution, due to their sedentary nature, abundance and sensitivity to atmospheric changes. However, reliable and sensitive biomarkers of exposure have hitherto been difficult to characterise. Biospectroscopy offers a novel approach to the derivation of biomarkers in the form of discrete molecular alterations detectable within a biochemical fingerprint. We investigated the application of this approach for the identification of biomarkers for pollution exposure using the common sycamore (Acer pseudoplatanus) as a sentinel species. Attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectroscopy was used to interrogate leaf tissue collected from three sites exposed to different levels of vehicle exhaust emissions. Following multivariate analysis of acquired spectra, significant biochemical alterations were detected between comparable leaves from different sites that may constitute putative biomarkers for pollution-induced stress. These included differences in carbohydrate and nucleic acid conformations, which may be indicative of sub-lethal exposure effects. We also observed several corresponding spectral alterations in both the leaves of A. pseudoplatanus exposed to ozone pollution under controlled environmental conditions and in leaves infected with the fungal pathogen Rhytisma acerinum, indicating that some stress-induced changes are conserved between different stress signatures. These similarities may be indicative of stress-induced reactive oxygen species (ROS) generation, although further work is needed to verify the precise identity of infrared biomarkers and to identify those that are specific to pollution exposure. Taken together, our data clearly demonstrate that biospectroscopy presents an effective toolkit for the utilisation of higher plants, such as A. pseudoplatanus, as sentinels of environmental pollution.

Toxicity assessment of metal oxide nano-pollutants on tomato (Solanum lycopersicon): A study on growth dynamics and plant cell death

The present study for the first time demonstrated the interactions of metal oxide (MO) nano-pollutants (CuO and Al₂O₃-NPs) with tissues and cellular DNA of tomato plants grown in soil sand: silt: clay (667:190:143) and Hoagland-hydroponic system and assessed the hazardous effects of NPs on cell physiology and biochemistry. Results of SEM equipped with EDX revealed attachment of variably shaped CuO-NPs (18 nm) and Al₂O₃-NPs (21 nm) on roots, and internalization followed by translocation in plants by ICP-MS and TEM. Significant variations in foliage surface area, chlorophyll, proteins, LPO, and antioxidant enzymes were recorded. Roots and shoots accumulated 225.8 ± 8.9 and 70.5 ± 4 μgAl g^-1 DW, whereas Cu accumulation was 341.6 ± 14.3 (roots) and 146.9 ± 8.1 μg g^-1 DW (shoots) which was significant (p ≤ 0.0005) as compared to control. The total soluble protein content in roots, shoots, and leaves collected from Al₂O₃-NPs treated plants increased by 120, 80, and 132%, respectively while in CuO-NPs treatments, the increase was 68 (roots), 36 (shoots), and 86% (leaves) over control. The level of antioxidant enzymes in plant tissues was significantly (p ≤ 0.05) higher at 2000 μg ml^-1 of MONPs over control. A dose-dependent increase in reactive oxygen species (ROS), biphasic change of lower and higher fluorescence in mitochondria due to dissipation of mitochondrial membrane potential (ΔΨm) and membrane defects using propidium iodide were observed. Comparatively, CuO-NPs induced higher toxicity than Al₂O₃-NPs. Perceptible changes in proteins (amide-I & II), cellulose, glucose, galactose and other carbohydrates were observed under FT-IR. The binding studies with TmDNA showed fluorescence quenching of EtBr-TmDNA and acridine orange-TmDNA complex only by CuO-NPs with -ΔG and +ΔH and +ΔS values. However, Al₂O₃-NPs induced lesser change in TmDNA conformation. Conclusively, the results are novel in better demonstrating the mechanistic basis of nano-phyto-toxicity and are important which could be used to develop strategies for safe disposal of Al₂O₃-NPs and CuO-NPs.

Shifts in N and δ15N in wheat and barley exposed to cerium oxide nanoparticles

The effects of cerium oxide nanoparticles (CeO2-NPs) on 15N/14N ratio (δ15N) in wheat and barley were investigated. Seedlings were exposed to 0 and 500 mg CeO2-NPs/L (Ce-0 and Ce-500, respectively) in hydroponic suspension supplied with NH4NO3, NH4 +, or NO3 -. N uptake and δ15N discrimination (i.e. differences in δ15N of plant and δ15N of N source) were measured. Results showed that N content and 15N abundance decreased in wheat but increased in barley. Ce-500 only induced whole-plant δ15N discrimination (-1.48‰, P ≤ 0.10) with a simultaneous decrease (P ≤ 0.05) in whole-plant δ15N (-3.24‰) compared to Ce-0 (-2.74‰) in wheat in NH4 +. Ce-500 decreased (P ≤ 0.01) root δ15N of wheat in NH4NO3 and NH4 + (3.23 and -2.25‰, respectively) compared to Ce-0 (4.96 and -1.27‰, respectively), but increased (P ≤ 0.05) root δ15N of wheat in NO3 - (3.27‰) compared to Ce-0 (2.60‰). Synchrotron micro-XRF revealed the presence of CeO2-NPs in shoots of wheat and barley regardless of N source. Although the longer-term consequences of CeO2-NP exposure on N uptake and metabolism are unknown, the results clearly show the potential for ENMs to interfere with plant metabolism of critical plant nutrients such as N even when toxicity is not observed.

Alleviation of adverse effects of drought stress on wheat seed germination using atmospheric dielectric barrier discharge plasma treatment

Atmospheric dielectric barrier discharge (DBD) was attempted to improve the resistance of wheat seed to drought stress. Effects of DBD plasma on wheat seed germination, seedling growth, osmotic-adjustment products, lipid peroxidation, reactive oxygen species (ROS), antioxidant enzyme activity, abscisic acid, and drought resistant related genes expression under drought stress were investigated. The changes of the wheat seed coat before and after the DBD plasma treatment were explored. Experimental results showed that the DBD plasma treatment could alleviate the adverse effects of drought stress on wheat seed germination and seedling growth; the germination potential and germination rate increased by 27.2% and 27.6%, and the root length and shoot length of the wheat seedlings also increased. Proline and soluble sugar levels under drought stress were improved after the DBD plasma treatment, whereas the malondialdehyde content decreased. ROS contents under drought stress were reduced after the DBD plasma treatment, whereas the activities of superoxide dismutase, catalase, and peroxidase were promoted. DBD plasma treatment promoted abscisic acid generation in wheat seedlings, and it also regulated functional gene LEA1 and stimulated regulation genes SnRK2 and P5CS to resist drought stress. Etching effect and surface modification occurred on the seed coat after the DBD plasma treatment.

Particle-specific toxicity and bioavailability of cerium oxide (CeO2) nanoparticles to Arabidopsis thaliana

The use of manufactured cerium oxide nanoparticles (CeO₂-NPs) in consumer products has increased markedly over the past decade, and their release into natural ecosystems is unavoidable. This study investigated the phytotoxicity and uptake of CeO₂-NPs in Arabidopsis thaliana grown in an agar medium. Although low concentrations of CeO₂-NPs had stimulatory effects on plant growth, at higher concentrations, CeO₂-NPs reduced growth and had adverse effects on the antioxidant systems and photosystem. Importantly, the toxicity resulted from the nanoparticles per se, rather than from the dissolved Ce ions. CeO₂-NPs were taken up and subsequently translocated to shoot tissues, and transmission electron microscopy (TEM) showed the presence of a large number of needle-like particle aggregations in the intercellular regions and the cytoplasm of leaf cells. The up-translocation factor to shoots was independent of the concentrations of Ce in the roots and the supplied forms of Ce (i.e. CeO₂-NPs, CeO₂-bulk, and ionic Ce), suggesting that endocytosis is likely to be a general mechanism responsible for the translocation of these Ce compounds. These findings provide important information regarding the toxicity and uptake of CeO₂-NPs in plants, which needs to be considered in environmental risk assessment for the safe use and disposal of CeO₂-NPs.

Green-synthesised cerium oxide nanostructures (CeO2-NS) show excellent biocompatibility for phyto-cultures as compared to silver nanostructures (Ag-NS)

The use of nanostructures (NS) in plant tissue culture can be beneficial only if we have their complete bio-safety and biocompatibility profile.

Germination and early plant development of ten plant species exposed to titanium dioxide and cerium oxide nanoparticles

Ten agronomic plant species were exposed to different concentrations of nano-titanium dioxide (nTiO2 ) or nano-cerium oxide (nCeO2 ) (0 μg/mL, 250 μg/mL, 500 μg/mL, and 1000 μg/mL) to examine potential effects on germination and early seedling development. The authors modified a standard test protocol developed for soluble chemicals (OPPTS 850.4200) to determine if such an approach might be useful for screening engineered nanomaterials (ENMs) and whether there were differences in response across a range of commercially important plant species to 2 common metal oxide ENMs. Eight of 10 species responded to nTiO2 , and 5 species responded to nCeO2 . Overall, it appeared that early root growth may be a more sensitive indicator of potential effects from ENM exposure than germination. The observed effects did not always relate to the exposure concentration, indicating that mass-based concentration may not fully explain the developmental effects of these 2 ENMs. The results suggest that nTiO2 and nCeO2 have different effects on early plant growth of agronomic species, with unknown effects at later stages of the life cycle. In addition, standard germination tests, which are commonly used for toxicity screening of new materials, may not detect the subtle but potentially more important changes associated with early growth and development in terrestrial plants. Environ Toxicol Chem 2016;35:2223-2229. Published 2016 Wiley Periodicals Inc. on behalf of SETAC. This article is a US Government work and, as such, is in the public domain in the United States of America.

Changes in Physiological and Agronomical Parameters of Barley (Hordeum vulgare) Exposed to Cerium and Titanium Dioxide Nanoparticles

The aims of our experiment were to evaluate the uptake and translocation of cerium and titanium oxide nanoparticles and to verify their effects on the growth cycle of barley (Hordeum vulgare L.). Barley plants were grown to physiological maturity in soil enriched with either 0, 500 or 1000 mg·kg⁻¹ cerium oxide nanoparticles (nCeO₂) or titanium oxide nanoparticles (nTiO₂) and their combination. The growth cycle of nCeO₂ and nTiO₂ treated plants was about 10 days longer than the controls. In nCeO₂ treated plants the number of tillers, leaf area and the number of spikes per plant were reduced respectively by 35.5%, 28.3% and 30% (p ≤ 0.05). nTiO₂ stimulated plant growth and compensated for the adverse effects of nCeO₂. Concentrations of Ce and Ti in aboveground plant fractions were minute. The fate of nanomaterials within the plant tissues was different. Crystalline nTiO₂ aggregates were detected within the leaf tissues of barley, whereas nCeO₂ was not present in the form of nanoclusters.

Effects of Silver Nanoparticles on Radish Sprouts: Root Growth Reduction and Modifications in the Nutritional Value

Reports indicate that silver nanoparticles (nAg) are toxic to vegetation, but little is known about their effects in crop plants. This study examines the impacts of nAg on the physiology and nutritional quality of radish (Raphanus sativus) sprouts. Seeds were germinated and grown for 5 days in nAg suspensions at 0, 125, 250, and 500 mg/L. Seed germination and seedling growth were evaluated with traditional methodologies; the uptake of Ag and nutrients was quantified by inductively coupled plasma-optical emission spectroscopy (ICP-OES) and changes in macromolecules were analyzed by infrared (IR) spectroscopy. None of the nAg concentrations reduced seed germination. However, the water content (% of the total weight) was reduced by 1.62, 1.65, and 2.54% with exposure to 125, 250, and 500 mg/L, respectively, compared with the control. At 500 mg/L, the root and shoot lengths were reduced by 47.7 and 40%, with respect to the control. The seedlings exposed to 500 mg/L had 901 ± 150 mg Ag/kg dry wt and significantly less Ca, Mg, B, Cu, Mn, and Zn, compared with the control. The infrared spectroscopy analysis showed changes in the bands corresponding to lipids (3000-2800 cm(-1)), proteins (1550-1530 cm(-1)), and structural components of plant cells such as lignin, pectin, and cellulose. These results suggest that nAg could significantly affect the growth, nutrient content and macromolecule conformation in radish sprouts, with unknown consequences for human health.

Evidence of Phytotoxicity and Genotoxicity in Hordeum vulgare L. Exposed to CeO2 and TiO2 Nanoparticles

Engineered nanoscale materials (ENMs) are considered emerging contaminants since they are perceived as a potential threat to the environment and the human health. The reactions of living organisms when exposed to metal nanoparticles (NPs) or NPs of different size are not well known. Very few studies on NPs-plant interactions have been published, so far. For this reason there is also great concern regarding the potential NPs impact to food safety. Early genotoxic and phytotoxic effects of cerium oxide NPs (nCeO2) and titanium dioxide NPs (nTiO2) were investigated in seedlings of Hordeum vulgare L. Caryopses were exposed to an aqueous dispersion of nCeO2 and nTiO2 at, respectively 0, 500, 1000, and 2000 mg l(-1) for 7 days. Genotoxicity was studied by Randomly Amplified Polymorphism DNA (RAPDs) and mitotic index on root tip cells. Differences between treated and control plants were observed in RAPD banding patterns as well as at the chromosomal level with a reduction of cell divisions. At cellular level we monitored the oxidative stress of treated plants in terms of reactive oxygen species (ROS) generation and ATP content. Again nCeO2 influenced clearly these two physiological parameters, while nTiO2 were ineffective. In particular, the dose 500 mg l(-1) showed the highest increase regarding both ROS generation and ATP content; the phenomenon were detectable, at different extent, both at root and shoot level. Total Ce and Ti concentration in seedlings was detected by ICP-OES. TEM EDSX microanalysis demonstrated the presence of aggregates of nCeO2 and nTiO2 within root cells of barley. nCeO2 induced modifications in the chromatin aggregation mode in the nuclei of both root and shoot cells.