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Carbon nanotubes in plant dynamics: Unravelling multifaceted roles and phytotoxic implications
Abstract
Carbon nanotubes (CNTs) have emerged as a promising frontier in plant science owing to their unique physicochemical properties and versatile applications. CNTs enhance stress tolerance by improving water dynamics and nutrient uptake and activating defence mechanisms against abiotic and biotic stresses. They can be taken up by roots and translocated within the plant, impacting water retention, nutrient assimilation, and photosynthesis. CNTs have shown promise in modulating plant-microbe interactions, influencing symbiotic relationships and mitigating the detrimental effects of phytopathogens. CNTs have demonstrated the ability to modulate gene expression in plants, offering a powerful tool for targeted genetic modifications. The integration of CNTs as sensing elements in plants has opened new avenues for real-time monitoring of environmental conditions and early detection of stress-induced changes. In the realm of agrochemicals, CNTs have been explored for their potential as carriers for targeted delivery of nutrients, pesticides, and other bioactive compounds. CNTs have the potential to demonstrate phytotoxic effects, detrimentally influencing both the growth and developmental processes of plants. Phytotoxicity is characterized by induction of oxidative stress, impairment of cellular integrity, disruption of photosynthetic processes, perturbation of nutrient homeostasis, and alterations in gene expression. This review aims to provide a comprehensive overview of the current state of knowledge regarding the multifaceted roles of CNTs in plant physiology, emphasizing their potential applications and addressing the existing challenges in translating this knowledge into sustainable agricultural practices.
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Background: The regulatory effects of carbon nanomaterials (CNMs) on plant growth and their potential applications in agriculture have attracted a great deal of attention from researchers. CNMs have been shown to promote nutrient absorption and increase plant growth. However, the mechanisms by which CNMs affect plant growth and nutrient absorption are still unknown.
Methods: The tobacco seedling biomass, potassium (K⁺) concentration, and accumulation in hydroponic were investigated to exposure of carbon nanoparticles (CNPs). To directly observe the effect of CNPs on K⁺ uptake by roots, we employed a noninvasive micro-test technique (NMT) to detect the net flux of K⁺ on the surface of tobacco roots. The K⁺-depletion experiment was carried out to explore the kinetic characteristics of K⁺ absorption, and qRT-PCR was used to monitor the expression levels of the K⁺ channel gene.
Results: The results showed that tobacco seedling biomass significantly improved at 10 mg·L⁻¹ CNP treatments, and K⁺ concentration and accumulation both in roots and shoots increased with 10 and 20 mg·L⁻¹ CNPs. CNP treatments changed the flow rate of K⁺ from efflux to influx in tobacco roots; this was observed both in plants cultivated in a CNP-containing medium and after the addition of CNPs to previously untreated plants. A depletion test also showed that CNPs improved the K⁺ absorption capacity and low-K⁺ tolerance of tobacco seedlings.
Conclusion: CNPs enhanced the K⁺ absorption capacity and low-K⁺ tolerance of tobacco seedlings. The promotion of K⁺ absorption by CNPs was closely related to the activation of K⁺ influx channel genes and inhibition of the K⁺ outflow channel gene. The K⁺ flux response and ion channel gene expression to CNPs in plants reveal the mechanism whereby CNPs promote plant nutrient absorption.
Portable biosensors are emerged as powerful diagnostic tools for analyzing intricately complex biological samples. These biosensors offer sensitive detection capabilities by utilizing biomolecules such as proteins, nucleic acids, microbes or microbial products, antibodies, and enzymes. Their speed, accuracy, stability, specificity, and low cost make them indispensable in forensic investigations and criminal cases. Notably, portable biosensors have been developed to rapidly detect toxins, poisons, body fluids, and explosives; they have proven invaluable in forensic examinations of suspected samples, generating efficient results that enable effective and fair trials. One of the key advantages of portable biosensors is their ability to provide sensitive and non-destructive detection of forensic samples without requiring extensive sample preparation, thereby reducing the possibility of false results. This comprehensive review provides an overview of the current advancements in portable biosensors for the detection of sensitive materials, highlighting their significance in advancing investigations and enhancing sensitive sample detection capabilities.
Carbon nanosol (CNS) is a carbon-based nanomaterial that promotes plant growth; however, its functional mechanisms and effects on the microbiome are not fully understood. Here, we explored the effects of CNS on the relationship between the soil, endophytic microbiomes and plant productivity. CNS treatment increased the fresh biomass of tobacco (Nicotiana tabacum L.) plants by 27.4% ± 9.9%. Amplicon sequencing analysis showed that the CNS treatment significantly affected the composition and diversity of the microbial communities in multiple ecological niches associated with tobacco, especially the bulk soil and stem endophytic microbiome. Furthermore, the application of CNS resulted in enhanced network connectivity and stability of the microbial communities in different niches, particularly in the soil, implying a strengthening of certain microbial interactions. Certain potentially growth-promoting root endophytic bacteria were more abundant under the CNS treatment. In addition, CNS increased the abundance of some endophytic microbial functional genes known to enhance plant growth, such as those associated with nutrient metabolism and the plant hormone biosynthesis pathways. We isolated two bacterial strains (Sphingopyxis sp. and Novosphingobium sp.) that were enriched under CNS treatment, and they were confirmed to promote tobacco plant growth in vitro. These results suggested that CNS might, at least in part, promote plant growth by enriching beneficial bacteria in the microbiome.
Graphical Abstract
Carbon nanomaterials such as single-walled carbon nanotubes (SWCNTs) offer a new possibility for phyto-nanotechnology and biotechnology to improve the quality and quantity of secondary metabolites in vitro . The current study aimed to determine the SWCNTs effects on Thyme (Thymus daenensis celak.) seed germination. The seedlings were further assessed in terms of morphological and phytochemical properties. Sterile seeds were cultured in vitro and treated with various concentrations of SWCNTs. Biochemical analyses were designed on seedling sample extracts for measuring antioxidant activities (AA), total flavonoids (TFC) and phenolic contents, and the main enzymes involved in oxidative reactions under experimental treatments. The results indicated that an increase in SWCNTs concentration can enhance the total percentage of seed germination. The improvement was observed in samples that received SWCNTs levels of up to 125 µg ml ⁻¹ , even though seedling height and biomass accumulation decreased. Seedling growth parameters in the control samples were higher than those of grown in SWCNT-fortified media. This may have happened because of more oxidative damage as well as a rise in POD and PPO activities in tissues. Additionally, secondary metabolites and relevant enzyme activities showed that maximum amounts of TPC, TFC, AA and the highest PAL enzyme activity were detected in samples exposed to 62.5 µg ml ⁻¹ SWCNTs. Our findings reveal that SWCNTs in a concentration-dependent manner has different effects on T. daenensis morphological and phytochemical properties. Microscopic images analysis revealed that SWCNTs pierce cell walls, enter the plant cells and agglomerate in the cellular cytoplasm and cell walls. The findings provide insights into the regulatory mechanisms of SWCNTs on T. daenensis growth, germination and secondary metabolites production.
Drought stress negatively affects the physiology, biochemistry, and morphology of plants. This leads to leaf rolling, leaf scorching, stunning plants, and permanent wilting. Plants adapt different strategies to build stress tolerance by enhancing the production of certain phytohormones. Melatonin is synthesized in plants in response to biotic and abiotic stresses, performing an important role as a plant growth regulator under environmental stresses Melatonin, a natural hormone, is widely found in animals, plants, protists, bacteria, and fungi. It is present in the roots, stems, leaves, fruits, and seeds of the plant in varying concentrations. The presence of melatonin has been revealed in coffee, corn, rice, barley, wheat, and oats. The role of melatonin in plant growth, development, and photosynthesis is well known. Melatonin potentially gives protection to the plants by improving reactive oxygen species (ROS) scavenging efficiency thereby safeguarding photosynthetic apparatus from drought led oxidative stress. In this chapter, the role of melatonin in plant stress tolerance during drought through the cascade of physiological and molecular mechanisms will be discussed.KeywordsMelatoninPlantsDroughtROSPhotosynthesis
Ripening of fruit is a complex physiological process comprising a sequence of events that precipitates the signaling molecules, especially hydrogen peroxide (H2O2), ethylene, melatonin, nitric oxide (NO), auxin, hydrogen sulfide (H2S), and brassinosteroids at different levels of gene and protein expression to initiate activation and/or deactivation of various signaling pathways that ultimately lead to the ripening of the fruit. Although ethylene has been documented as a potent molecule capable of regulating fruit ripening, molecules such as phytomelatonin, NO, H2O2, and H2S have the potential of regulating fruit ripening. However, the interaction of ethylene and these new emerging signaling molecules particularly phytomelatonin, NO, H2O2, and H2S is not fully understood. Therefore, harnessing the phytohormonal functions of phytomelatonin in fruit ripening physiology via crosstalk with ethylene and NO as well as H2O2 and H2S is of biological importance in revealing the free radical scavenging role of phytomelatonin. In this chapter, the interaction of melatonin in fruit ripening in an ethylene-NO- H2O2-H2S -dependent manner via the various signaling pathways will be highlighted and presented.KeywordsEthyleneFruitNitric oxideRipeningMelatoninPhytomelatoninSignaling pathwaysHydrogen peroxideHydrogen sulphide
Nano seed technology is a new platform with endless possibilities and impacts on applied agriculture and forestry research. The implementation of nanotechnology in seed research is in its infancy and needs more pace to meet the needs of current global demand. Carbon nanotubes (CNTs) are allotropes of carbon and engineered nanomaterials. Based on the number of concentric layers of rolled graphene sheets, they are classified into single-walled CNTs (SWCNTs) and multi-walled CNTs (MWCNTs). CNTs exhibit both beneficial and toxic effects on plant species by altering the morphological and physiological properties of plant cells. In most of the studies, low concentrations of CNTs are considered safe. Therefore, there is plenty of room to use these cutting-edge technologies to alleviate seed dormancy, boost vigor, and solves the problem of slow growth in seed propagated species. This chapter summarizes the results of various studies investigating the effects of carbon nanotubes on seed viability, as well as seedling growth and biomass.
The phytotoxicity of synthetic multi-walled carbon nanotubes (MWCNTs) on plant growth has been documented. However, the physiological mechanisms associated with it are not clear. The activity of TOR signaling pathway and phytoregulators balance play key roles in plant growth regulation and their stress response.
Plants respond to a range of abiotic stimuli in nature involving anatomical, cellular, morphological, and physiological changes. The adaptability of plants to acclimatize to different environments is greatly influenced by phytohormones, which mediate growth, development and nutrient partitioning. These signal molecules are biosynthesized by plant itself and are often known as plant growth regulators. Strigolactones (SLs) are a unique class of phytohormones that have an ecological role in overcoming multiple stress circumstances. SLs are originally found in the germinating seeds of parasitic weeds, biosynthesized from precursor carotenoids and perform widespread physiological functions in bud outgrowth, shoot branching, nodulation, and photo-morphogenesis. SLs correspondingly persuade arbuscular mycorrhizal fungi's hyphal branching in germinating spores. Lately, SLs have been drawn to attention as of their role in molecular and physiological adaptations in response to abiotic stresses. The SLs demonstrate crosstalk with other phytohormones and function in mitigating stress conditions through diverse molecular pathways. The present review addresses comprehensive information about the molecular signaling, biosynthesis, and importance of SLs in providing resilience towards stress conditions in diverse plants.
Carbon nanotubes (CNTs) are one of the first examples of nanotechnology, with a history of promising uses and high expectations. This paper uses the recent debate over their future to explore both ethical and value-laden statements which unsettle the notion of CNTs as a value-free nanotechnology and their regulation as purely a technical affair. A point of departure is made with the inclusion of CNTs on the Substitute-It-Now list by the Swedish NGO ChemSec, an assessment process that anticipates and complements the Registration, Evaluation, Authorization and Restriction of Chemicals (REACH) regulation in Europe. An argument map is constructed to illustrate the core contention in the debate—should CNTs be substituted or not—which follows from a systematic literature review and content analysis of sampled journal articles. Nine arguments are articulated that bolster one of two camps: the pro-substitution camp or the contra-substitution camp. Beneath these arguments are a set of three implicit values that animate these two camps in prescribing competing interventions to resolve the dispute: (i) environmental protection and human safety, (ii) good science, and (iii) technological progress. This leads to a discussion around the regulatory problem of safeguarding conflicting values in decision-making under sustained scientific uncertainty. Finally, the study suggests further empirical work on specific nanomaterials in a pivot away from the abstract, promissory nature of nanotechnology and other emerging technologies in science, technology, and innovation policy. The examination of ethics and values is useful for mapping controversies in science and technology studies of regulation, even amongst experts in cognate research fields like nanomedicine and nanotoxicology.
The engineering of carbon nanotubes in the last decades resulted in a variety of applications in electronics, electrochemistry, and biomedicine. A number of reports also evidenced their valuable application in agriculture as plant growth regulators and nanocarriers. In this work, we explored the effect of seed priming with single-walled carbon nanotubes grafted with Pluronic P85 polymer (denoted P85-SWCNT) on Pisum sativum (var. RAN-1) seed germination, early stages of plant development, leaf anatomy, and photosynthetic efficiency. We evaluated the observed effects in relation to hydro- (control) and P85-primed seeds. Our data clearly revealed that seed priming with P85-SWCNT is safe for the plant since it does not impair the seed germination, plant development, leaf anatomy, biomass, and photosynthetic activity, and even increases the amount of photochemically active photosystem II centers in a concentration-dependent manner. Only 300 mg/L concentration exerts an adverse effect on those parameters. The P85 polymer, however, was found to exhibit a number of negative effects on plant growth (i.e., root length, leaf anatomy, biomass accumulation and photoprotection capability), most probably related to the unfavorable interaction of P85 unimers with plant membranes. Our findings substantiate the future exploration and exploitation of P85-SWCNT as nanocarriers of specific substances promoting not only plant growth at optimal conditions but also better plant performance under a variety of environmental stresses.
Introduction
Multi-walled nanotubes (MWCNTs) consist of multiple rolled layers of graphene. Nitrogen plays an important role in apple growth. The effect of MWCNTs on nitrogen utilization in apple needs to be further investigated.
Methods
In this study, the woody plant Malus hupehensis seedlings were used as plant materials, the distribution of MWCNTs in the roots was observed, and the effects of MWCNTs on the accumulation, distribution, and assimilation of nitrate by the seedlings were explored.
Results
The results showed that MWCNTs could penetrate the roots of Malus hupehensis seedlings, and the 50, 100, and 200 µg·mL⁻¹ MWCNTs significantly promoted the root growth of seedlings, increased root number, root activity, fresh weight, and nitrate content of seedlings, and also increased nitrate reductase activity, free amino acid, and soluble protein content of roots and leaves. ¹⁵N tracer experiments indicated that MWCNTs decreased the distribution ratio of ¹⁵N-KNO3 in Malus hupehensis roots but increased its distribution ratio in stems and leaves. MWCNTs improved the utilization ratio of ¹⁵N-KNO3 in Malus hupehensis seedlings, with the values being increased by 16.19%, 53.04%, and 86.44% following the 50, 100, and 200 µg·mL⁻¹ MWCNTs, respectively. The RT-qPCR analysis showed that MWCNTs significantly affected the expression of genes (MhNRTs) related to nitrate uptake and transport in roots and leaves, and MhNRT1.4, MhNRT1.7, MhNRT1.8, MhNRT2.1, MhNRT2.5, and MhNRT2.7 were notably up-regulated in response to 200 µg·mL⁻¹ MWCNTs. Raman analysis and transmission electron microscopy images indicated that MWCNTs could enter the root tissue of Malus hupehensis and were distributed between the cell wall and cytoplasmic membrane. Pearson correlation analysis showed that root tip number, root fractal dimension, and root activity were the main factors affecting root uptake and assimilation of nitrate.
Conclusions
These findings suggest that MWCNTs promoted root growth by entering the root, stimulated the expression of MhNRTs, and increased NR activity, thereby enhancing the uptake, distribution, and assimilation of nitrate by root, and ultimately improved the utilization of ¹⁵N-KNO3 by Malus hupehensis seedlings.
Sugarcane is a tall, stout, perennial grass with fibrous stalks rich in sucrose used for sugar production. Sugarcane is widely used to produce sugar, ethanol, and other bioactive compounds. However, the processing of sugarcane and its byproduct bagasse can result in negative environmental impacts and safety hazards. Therefore, safe, and sustainable processing methods are crucial for the generation of biofuels and bioactive compounds. Sugarcane and its by-products contain high levels of phytochemicals such as phytosterols, terpenoids, flavonoids, fatty acids, and phenolic acids. The phytochemicals and the microbial populations associated with sugarcane that live in the soil (rhizosphere) and on the surface (phyllosphere) contain a wealth of potentially valuable microbes for industrial applications. Using metagenomics and meta-omics techniques, various microbes have been identified and characterized for their role in breaking down sugarcane bagasse, a substantial source of lignocellulosic biomass. Other valuable products of sugarcane include molasses, which offers an intense flavor, whereas bagasse is used to produce paperboard products, reconstituted panelboard, agricultural mulch, and fuel for the kilns. The sugarcane has tremendous applicability in biofuel production, animal feed additive, and electricity production. Furthermore, the paper provides insights into the challenges and opportunities for the safe and sustainable processing of sugarcane and bagasse. Overall, this review highlights the importance of safe and sustainable processing methods for the generation of biofuels and bioactive compounds from sugarcane and its byproduct bagasse.
The extensive use of engineered nanoparticles (ENPs) has raised concerns about their potentially harmful effects on the ecosystem. Despite previous reports of a variety of individual ENPs, the mutual effects of ENPs when used in combination were not well understood. In this study, we first investigated the effects of different sizes and concentrations of ZnO nanoparticles (ZnO NPs) or multi-walled carbon nanotubes (MWCNTs) on the growth performance of Arabidopsis thaliana seedlings. Then, two concentrations of ZnO NP (40 and 50 mg/L) with a diameter of 90 nm and MWCNTs (100 and 500 mg/L) with an outer diameter of 40-60 nm were used to evaluate their respective or simultaneous phytotoxicity to Arabidopsis. The results showed that seedlings exposed to either ZnO NPs or MWCNTs exhibited significant phytotoxic symptoms. ZnO NPs caused stronger inhibitory effects than MWCNTs on several plant growth indices, including reduced root length, chlorophyll content, and increased ROS concentration. When applied together, the concurrent effects of ZnO NPs and MWCNTs on Arabidopsis seedlings appeared to be more negative, as evidenced not only by the further deterioration of several growth indices but also by their synergistic or additive regulation of the activities of several antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT) and glutathione reductase (GR). Moreover, qRT-PCR analysis revealed that in the presence of ZnO NPs and MWCNTs, the expression of genes important for maintaining cellular ROS homeostasis was differentially regulated in shoots and roots of Arabidopsis seedlings. Overall, our data may provide new insights into how plants respond to more than one type of nanomaterial and help us better understand the associated environmental risks.
The recent decade has witnessed remarkable breakthroughs in the use of nano-scaled substances in the field of the cell, tissue, and organ culture of plants. This study investigated how Salvia nemorosa responds to the supplementation of a culture medium with different concentrations of carboxylic acid-functionalized multi-walled carbon nanotubes (COOH-MWCNTs; 0, 40, 80, and 120 mgl⁻¹). The application of COOH-MWCNTs influenced plant growth, morphogenesis, and organogenesis. COOH-MWCNTs, especially at 80 mgl⁻¹, reinforced the shoot and root development. The nano-supplements increased biomass accumulations by 2.3-fold. MWCNTs at 120 mgl⁻¹ contributed to the modification in DNA methylation. Moreover, COOH-MWCNTs contributed to the slight increase in the concentrations of photosynthetic pigments. The COOH-MWCNTs-supplemented seedlings contained higher total protein contents than the control. The activities of peroxidase and catalase enzymes displayed an upward trend (about 2-fold) in response to the COOH-MWCNTs. Likewise, COOH-MWCNTs significantly stimulated the activity of the phenylalanine ammonia-lyase enzyme. The COOH-MWCNTs application enhanced the concentrations of phenylpropanoid derivatives and alkaloids. The nano-scaled material also up-regulated the expression of the tyrosine aminotransferase (TAT) gene. Moreover, the COOH-MWCNTs improved callogenesis performance and callus biomass. The biological assessments support the hypothesis that COOH-MWCNTs can be considered as a highly potent elicitor of plant morphogenesis, organogenesis, cell differentiation, callogenesis, metabolism, transcriptome, and DNA methylome.
Graphical Abstract
Presently, the effects of crop roots on crop root zone thermal characteristics are poorly understood, and new fertilizers are rarely considered from the perspective of changing crop root zone thermal characteristics. This study explored the effect of applying two new fertilizers, multiwalled carbon nanotubes (MWCNTs) and Bacillus atrophaeus (B. atrophaeus), on the crop root zone thermal characteristics of saline farmland soils through in situ measurements. The results showed that MWCNTs and B. atrophaeus could indirectly affect crop root zone thermal characteristics by changing the crop root growth. Combined application of MWCNTs and B. atrophaeus could promote both to induce positive effects, promote crop root growth, and significantly alleviate the adverse effects of soil salinization. The thermal conductivity and heat capacity of the shallow root zone were reduced due to the presence of crop roots, while the opposite was true in the deep root zone. For example, the thermal conductivity of the 0–5 cm rich root zone in the MWCNT treatment was 0.8174 W m−1 ·K−1, and the thermal conductivity of the poor root zone was 13.42% higher than that of the rich root zone. MWCNTs and B. atrophaeus can also change the spatial distribution of soil moisture, soil salt, and soil particle size characteristics by influencing the root-soil interactions and indirectly affecting crop root zone thermal characteristics. In addition, MWCNTs and B. atrophaeus could directly affect the root zone thermal characteristics by changing the soil properties. The higher the soil salt content was, the more obvious the effect of the MWCNTs and B. atrophaeus on the crop root zone thermal characteristics. The thermal conductivity and heat capacity of the crop root zone were positively correlated with the soil moisture content, soil salt content and soil particle specific surface area and negatively correlated with the soil particle size and the fresh and dry root weights. In summary, MWCNTs and B. atrophaeus significantly affected crop root zone thermal characteristics directly and indirectly and could adjust the temperature of the crop root zone.
Plants are continuously challenged by different pathogenic microbes that reduce the quality and quantity of produce and therefore pose a serious threat to food security. Among them bacterial pathogens are known to cause disease outbreaks with devastating economic losses in temperate, tropical and subtropical regions throughout the world. Bacteria are structurally simple prokaryotic microorganisms and are diverse from a metabolic standpoint. Bacterial infection process mainly involves successful attachment or penetration by using extracellular enzymes, type secretion systems, toxins, growth regulators and by exploiting different molecules that modulate plant defence resulting in successful colonization. Theses bacterial pathogens are extremely difficult to control as they develop resistance to antibiotics. Therefore, attempts are made to search for innovative methods of disease management by the targeting bacterial virulence and manipulating the genes in host plants by exploiting genome editing methods. Here, we review the recent developments in bacterial disease management including the bioactive antimicrobial compounds, bacteriophage therapy, quorum-quenching mediated control, nanoparticles and CRISPR/Cas based genome editing techniques for bacterial disease management. Future research should focus on implementation of smart delivery systems and consumer acceptance of these innovative methods for sustainable disease management.
The increasing resistance of bacteria and fungi to antibiotics is one of the health threats facing humanity. Of great importance is the development of new antibacterial agents or alternative approaches to reduce bacterial resistance to available antibacterial drugs. Due to the complexity of their properties, carbon nanomaterials (CNMs) may be of interest for a number of biomedical applications. One of the problems in studying the action of CNMs on microorganisms is the lack of universally standardized methods and criteria for assessing antibacterial and antifungal activity. In this work, using a unified methodology, a comparative study of the antimicrobial properties of the CNM systemic kit against common opportunistic microorganisms, namely Escherichia coli and Staphylococcus aureus, was carried out. Multiwalled carbon nanotubes (MWNTs), catalytic filamentous carbon with different orientations of graphene blocks (coaxial–conical and stacked, CFC), ionic carbon (OLC), and ultrafine explosive nanodiamonds (NDs) were used as a system set of CNMs. The highest antimicrobial activity was shown by NDs, both types of CFCs, and carboxylated hydrophilic MWCNTs. The SEM results point out the difference between the mechanisms of action of UDD and CFC nanotubes.
Recent studies have shown that nanomaterials, including carbon nanotubes, are associated with a wide range of effects on living organisms, from stimulation to toxic effects. Plants are an important object of such research, which is associated with the potential use of carbon nanomaterials in agriculture and environmental protection. At the same time, the specific mechanisms of formation of plant resistance to the effects of carbon nanotubes remain not fully understood, especially in woody plants. Therefore, we studied the effect of aqueous colloids of multi-walled carbon nanotubes (MWCNTs) with an outer diameter of 10–30 nm and a length of about 2 μm at a concentration of 1, 10, 50, and 100 mg/L on morphometric parameters and the level of expression of stress resistance genes in Betula pubescens Ehrh. and B. pendula Roth. plants in greenhouse conditions. The results showed an increase in the length and diameter of the shoot in the studied plants. The dry biomass of the leaf increased by 30%, the stem by 42%, and the root by 49% when using MWCNTs at a concentration of 10 mg/L. The expression of the stress resistance genes DREB2 and PR-10 significantly increased under the influence of 1 mg/L MWCNTs on plants of both species. At the same time, the use of 100 mg/L nanoparticles led to a decrease in the studied parameters in Betula pendula, which may be associated with the negative effect of MWCNTs in high concentrations. The revealed positive effects of low concentrations of MWCNTs on morphometric parameters and stimulation of stress resistance genes by nanotubes open up prospects for their use in woody plant biotechnology.
Diseases induced by phytopathogenic fungi generate considerable economic losses and severe damage to agricultural crops. The objective of this research was to evaluate the inhibitory effect in vitro of carbon nanotubes with extracts of Bacillus amyloliquefaciens on the mycelial development of Rhizoctonia solani (Rs), Fusarium solani (Fs), Colletotrichum acutatum (Ca) and Alternaria alternata (Aa). Data were analyzed using Probit, ANOVA analysis in a completely randomized design of five treatments with 20 repetitions and Tukey test (p ≤ 0.05). B. amyloliquefaciens extracts at high doses, inhibited 100% of mycelial growth but by using carbon nanotubes with extracts at low doses, a similar inhibitory effect of Rs, Fs, Ca and Aa (100, 90, 90 and 60%) respectively. The use of carbon nanotubes with extracts of B. amyloliquefaciens are an efficient alternative in the in vitro control of phytopathogenic fungi.
In this study, the interaction between nanoparticles (0, 50, 100, and 150 mg L−
1) and light intensity (100, 200, and 400 μmol·m−2·s−1) was evaluated for effectiveness in improving stevia shoot induction by measuring morphological traits, nutrient absorption, total carbohydrates, steviol glycosides (SVglys), and DNA damage in two DNA sequence regions (promoter and sequence of the UGT76G1 gene). MWCNTs at a concentration of 50 mg L−1 in interaction with the light intensity of 200 μmol·m−2·s−1 improved the morphological traits and absorption of nutrients such as nitrogen (N), phosphorous (P), potassium (K), calcium (Ca), iron (Fe), and Manganese (Mn), compared to other treatments. Also, under this interaction, the accumulation of total carbohydrates and SVglys was elevated. Moreover, DNA damage in both regions of the DNA sequence under light intensity at low concentrations of MWCNTs (0 and 50 mg L−1) did not show a significant change but increased with increasing MWCNT concentration at high light intensities (200 and 400 μmol·m−2·s−1). These results demonstrate that the advantages and phytotoxicity of MWCNTs in the in vitro culture of stevia are dose-dependent and are affected by light intensity. Based on this, the interaction of 50 mg L−1 of MWCNTs with the light intensity of 200 μmol·m−2·s−1 is recommended to improve stevia micropropagation and subsequent growth and metabolism.
Nanomaterials, including multiwalled carbon nanotubes (MWCNTs), have been recently applied in agriculture to improve stress resistance, leading to contradictory findings for antioxidant responses and mineral nutrient uptake. A pot experiment involving maize in low-salinity sandy loam soils was conducted with the application of different concentrations (0, 20, 50 mg/L) of MWCNTs and the growth-promoting rhizobacterium Bacillus subtilis (B. subtilis). The dose-dependent effects of MWCNTs were confirmed: 20 mg/L MWCNTs significantly promoted the accumulation of osmolytes in maize, particularly K⁺ in the leaves and roots, increased the leaf indoleacetic acid content, decreased the leaf abscisic acid content; but the above-mentioned promoting effects decreased significantly in 50 mg/L MWCNTs-treated plants. We observed a synergistic effect of the combined application of MWCNTs and B. subtilis on plant salt tolerance. The increased lipid peroxidation and antioxidant-like proline, peroxidase (POD), and catalase (CAT) activities suggested that MWCNTs induced oxidative stress in maize growing in low-salinity soils. B. subtilis reduced the oxidative stress caused by MWCNTs, as indicated by a lower content of malondialdehyde (MDA). The MWCNTs significantly increased the leaf Na⁺ content and leaf Na⁺/K⁺ ratio; however, when applied in combination with B. subtilis, the leaf Na⁺/K⁺ ratio decreased sharply to 69% and 44%, respectively, compared to those of the control (CK) group, the contents of which were partially regulated by abscisic acid and nitrate, according to the results of the structural equation model (SEM). Overall, the increased osmolytes and well-regulated Na⁺/K⁺ balance and transport in plants after the combined application of MWCNTs and B. subtilis reveal great potential for their use in combating abiotic stress.
Bioaccumulation is a key factor in understanding the potential ecotoxicity of substances. While there are well-developed models and methods to evaluate bioaccumulation of dissolved organic and inorganic substances, it is substantially more challenging to assess bioaccumulation of particulate contaminants such as engineered carbon nanomaterials (CNMs; carbon nanotubes (CNTs), graphene family nanomaterials (GFNs), and fullerenes) and nanoplastics. In this study, the methods used to evaluate bioaccumulation of different CNMs and nanoplastics are critically reviewed. In plant studies, uptake of CNMs and nanoplastics into the roots and stems was observed. For multicellular organisms other than plants, absorbance across epithelial surfaces was typically limited. Biomagnification was not observed for CNTs and GFNs but were observed for nanoplastics in some studies. However, the reported absorption in many nanoplastic studies may be a consequence of an experimental artifact, namely release of the fluorescent probe from the plastic particles and subsequent uptake. We identify that additional work is needed to develop analytical methods to provide robust, orthogonal methods that can measure unlabeled (e.g., without isotopic or fluorescent labels) CNMs and nanoplastics.
Microorganisms dwell in diverse plant niches as non-axenic biotic components that are beneficial as well pathogenic for the host. They improve nutrients-uptake, stress tolerance, phytohormone synthesis, and strengthening the defense system through phyllosphere, rhizosphere, and endosphere. The negative consequences of the microbial communities are largely in the form of diseases characterized by certain symptoms such as gall, cankers, rots etc. Uncultivable and unspecified nature of different phytomicrobiomes communities is a challenge in the management of plant disease, a leading cause for the loss of the plant products. Metagenomics has opened a new gateway for the exploration of microorganisms that are hitherto unknown, enables investigation of the functional aspect of microbial gene products through metatranscriptomics and metabolomics. Metagenomics offers advantages of characterizing previously unknown microorganisms from extreme environments like hot springs, glaciers, deep seas, animal gut etc. besides bioprospecting gene products such as Taq poly-merase, bor encoded indolotryptoline, hydrolases, and polyketides. This review provides a detailed account of the phyto-microbiome networks and highlights the importance and limitations of metagenomics and other meta-omics approaches for the understanding of plant microbial diversity with special focus on the disease control and its management.
The consumption of food with a high content of bioactive compounds is correlated with the prevention of chronic degenerative diseases. Tomato is a food with exceptional nutraceutical value; however, saline stress severely affects the yield, the quality of fruits, and the agricultural productivity of this crop. Recent studies have shown that seed priming can mitigate or alleviate the negative effects caused by this type of stress. However, the use of carbon nanomaterials (CNMs) in this technique has not been tested for this purpose. In the present study, the effects of tomato seed priming with carbon nanotubes (CNTs) and graphene (GP) (50, 250, and 500 mg L −1) and two controls (not sonicated and sonicated) were evaluated based on the content of photosynthetic pigments in the leaves; the physicochemical parameters of the fruits; and the presence of enzymatic and non-enzymatic antioxidant compounds, carotenoids, and stress biomarkers such as hydrogen peroxide (H2O2) and malondialdehyde (MDA) in the leaves and fruits of tomato plants without saline stress and with saline stress (50 mM NaCl). The results show that saline stress in combination with CNTs and GP increased the content of chlorophylls (9.1-21.7%), ascorbic acid (19.5%), glutathione (≈13%), proteins (9.9-11.9%), and phenols (14.2%) on the leaves. The addition of CNTs and GP increased the activity of enzymes (CAT, APX, GPX, and PAL). Likewise, there was also a slight increase in the content of H2O2 (by 20.5%) and MDA (3.7%) in the leaves. Salinity affected the quality of tomato fruits. The physico-chemical parameters and bioactive compounds in both the stressed and non-stressed tomato plants were modified with the addition of CNTs and GP. Higher contents of total soluble solids (25.9%), phenols (up to 144.85%), flavonoids (up to 37.63%), ascorbic acid (≈28%), and lycopene (12.4-36.2%) were observed. The addition of carbon nanomaterials by seed priming in tomato plants subjected to saline stress modifies the content of bioactive compounds in tomato fruits and improves the antioxidant defense system, suggesting possible protection of the plant from the negative impacts of stress by salinity. However, analysis of the mechanism of action of CNMs through seed priming, in greater depth is suggested, perhaps with the use of omics sciences.
Saffron, a Crocus sativus L. derivative, has been recognized for its medical benefits since ancient times. Besides being an active flavoring and coloring agent in several food items, saffron has primarily been known for its pharmacological properties. Its major metabolites like crocin, picrocrocin, and safranal have been studied in vivo and in vitro as active pharmaceutical agents for inflammation, depression, microbial infections, and cancer-like diseases. These phytochemicals are well known for targeting the etiology of various diseases, making them an essential plant derivative in modern times. Moreover, research has shown saffron with several toxicological consequences as well. Numerous experimental and clinical studies have been conducted to determine the toxicity and safety of saffron. Saffron extract, safranal, and crocin have little or no acute toxicity. Organ toxicity has been detected at high dosages during sub-acute exposure. The teratogenic effects of saffron and its components have been particularly noted at high concentrations. This review provides a comprehensive outlook on the pharmacological attributes of saffron and its derivatives, besides highlighting their associated toxicity.
Sustainable agriculture is an important conception to meet the growing food demand of the global population. The increased need for adequate and safe food, as well as the ongoing ecological destruction associated with conventional agriculture practices are key global challenges. Nanomaterials are being developed in the agriculture sector to improve the growth and protection of crops. Among the various engineered nanomaterials, carbon nanotubes (CNTs) are one of the most promising carbon-based nanomaterials owing to their attractive physiochemical properties such as small size, high surface area, and superior mechanical and thermal strength, offering better opportunities for agriculture sector applications. This review provides basic information about CNTs, including their history; classification; and electrical, thermal, and mechanical properties, with a focus on their applications in the agriculture field. Furthermore, the mechanisms of the uptake and translocation of CNTs in plants and their defense mechanisms against environmental stresses are discussed. Finally, the major shortcomings, threats, and challenges of CNTs are assessed to provide a broad and clear view of the potential and future directions for CNT-based agriculture applications to achieve the goal of sustainability.
Moderation and optimization of the photosynthetic function of higher plants by nanomaterials is under intensive investigation, but remain still far from practical utilization. We have previously demonstrated that foliar spraying of Pluronic P85-grafted single-walled carbon nanotubes (P85-SWCNT) affects the functionality and structural organization of the photosynthetic thylakoid membranes in pea plants. In the present work, we further study in more details the structural changes in the photosynthetic machinery induced by P85-SWCNT treatment. Evidences are provided that P85-SWCNT induces thylakoid membrane remodeling, namely—partial membrane unstacking, thermal stabilization of the major light-harvesting complex of photosystem II and its migration toward the stroma lamellae. The observed effects are most pronounced for the highest used concentration of 300 mg/L P85-SWCNT. Our results reveal that P85-SWCNT in concentrations below 300 mg/L is an interesting object for further investigation of the potential application of nanomaterials in plant science, e.g., as nanocarriers of beneficial substances reaching the photosynthetic apparatus.
The most prevalent microbe-caused issues that reduce agricultural output globally are viral and bacterial infections. It is currently quite challenging to identify pathogens due to the current living situation. Biosensors have become the standard for monitoring microbial and viral macromolecules. Disease diagnosis is improved by following the nanoparticles released by infections. Since the sensors' data includes different learning patterns, Machine Learning (ML) methods are used to analyze and interpret it. This research paper aimed to study whether Near-infrared (nIR) and Red, Green, and Blue (RGB) imaging might be used to define and detect Plant Disease (PD) using Convolutional Neural Network (CNN)-based Feature Extraction (FE) and Feature Classification (FC). A home-built Single-Walled Carbon NanoTube (SWCNTs) implemented with a Deoxyribonucleic Acid (DNA) aptamer that binds to a Hemi (HeApt + DNA + SWCNT) sensing device was used to analyze near-infrared (nIR) and RGB images of tea plant leaf samples. Three labels are extracted from the nIR + RGB using a Wasserstein Distance (WD)-based Feature Extraction Model (FEM), and then all those labels are loaded into the proposed CNN model to ensure precise classification. The proposed Wasserstein Distance-to-Convolutional Neural Network (WD2CNN) model was compared to different CNN architectures on the same dataset, achieving the highest accuracy of 98.72%. It is also the most computationally efficient, with the shortest average time per epoch. The model demonstrates high performance and efficiency in classifying biosensor images, which could aid in the early detection and prevention of Crop Diseases (CD).
The physiological process of ripening occurs rapidly when fruits and vegetables become mature, and beyond a specific stage after the harvest, they to undergo rapid deterioration in quality. Melatonin, a nontoxic biological molecule with significant antioxidant capacity, plays several roles, including delaying senescence, alleviating chilling injury, enhancing resistance to diseases, and tolerance to stress conditions during postharvest preservation of fruits and vegetables. Interestingly, the application of exogenous melatonin to prolong the shelf life of fruits and vegetables augment the endogenous molecule, thereby promoting these functions. There is crosstalk among different physiological and biochemical processes involved in melatonin action, which remain largely elusive. This chapter provides insights into those mechanisms and discusses several case studies demonstrating the promising effects of melatonin treatment on the postharvest preservation of fruits and vegetables.KeywordsMelatoninPostharvest biologyFruits and vegetablesCrosstalk, melatonin augmentation
Atropine is a well-known tropane alkaloid commonly employed in medicine class called anticholinergics. This study intends to address biochemical and molecular responses of Datura inoxia calluses to fortifying culture medium with carboxylic acid-functionalized multi-walled carbon nanotubes (COOH-MWCNTs). The application of MWCNTs influenced callogenesis performance and biomass in a dose-dependent manner. The MWCNT at 5 mgL-1 resulted in the highest biomass of calluses by 57%. While, MWCNTs at high concentrations were accompanied by cytotoxicity. On the other hand, MWCNTs at concentrations above 100 mgL-1 exhibited cytotoxicity, decreased callogenesis performance, and reduced Atropine biosynthesis. The MWCNTs increased the activity of phenylalanine ammonia-lyase (PAL) and catalase enzymes. The concentrations of proline and soluble phenols displayed upward trends in response to using MWCNTs. According to the HPLC assessment, enriching culture medium with MWCNTs at 5 mgL-1 elicited Atropine production in calluses by 64%. The quantitative PCR assessment referred to the upregulation in the transcription of the PAL gene. The expression of ornithine decarboxylase (ODC) and putrescine N-methyltransferase 1 (PMT) genes were also upregulated in calluses cultured in a medium supplemented with MWCNTs. Methylation Sensitive Amplification Polymorphism (MSAP) technique indicated that employing MWCNTs altered the DNA methylation profile, reflecting epigenetic modification. Overall, engineering plant cells with MWCNTs as a nano-elicitor can be suggested for large-scale synthesis of industrially-valuable secondary metabolites.
The use of NPs is expanding across a wide range of industries.
Human exposure to NPs, intentionally or accidently, is unavoidable due to their extensive use in several fields. NPs are
constantly exposed to people, and it is crucial to understand
the possible acute and long-term detrimental impacts they may
have. NMs can pass biological barriers and reach cells, tissues,
and organs. Inhalation or ingestion of NMs may allow them to
enter the bloodstream. The nanomaterials may then be carried throughout the body and make their way into the organs and tissues, such as the heart, kidney, liver, spleen, nervous system, and
bone marrow and induce toxicological effects. Therefore, all NMs
must undergo toxicological screening before being used practically. To safeguard both humans and the environment, toxicological studies of NMs are essential. To fill up the knowledge gap and
take advantage of the various possible uses for NPs, the relevant
harmful effects of NPs must be evaluated using globally approved
bias-free in vivo toxicological models.
The materials used for pollution remediation must not
become another pollutant themselves once utilized. For this
reason, using biodegradable materials is a particularly intriguing
avenue of research and development. Using biodegradable materials would not only increase consumer confidence and acceptance of a particular technology but could also provide an
environmentally friendly and safer alternative for the remediation of pollutants. Also, new technologies that can use targetspecific capture of contaminants are very appealing for safe
and effective environmental nanoremediation. There is a need
for nanotechnological studies combined with the chemical and
physical surface modifications of NMs to create tailored materials
that can overcome many of the problems of contamination
cleanup. Target-specific capture, toxicity, recyclability, easy synthesis, noncost-effectiveness, biodegradability, and the possibility
of recovery after use (regeneration) are some of the most important things to consider while synthesizing new nanomaterials for
environmental remediation. Methods should be developed in the
future to avoid agglomeration, improve monodispersity, and
boost stability. While beyond this, there needs to be a heightened
awareness regarding the risks and repercussions of environmental NMs. In addition, efforts must be made to produce new
materials using methodologies that are less detrimental to the
environment that has somewhat of an influence on the natural
world. Furthermore, certain rules and standards need to be
developed to regulate the use of NMs and minimize the negative
effects that they have on public health as well as the aquatic
environment.
Application of carbonaceous nanomaterials (CNMs) to the soil-plant system can affect plant physiology, with positive results ranging from enhanced seed germination and root system development to improved stress tolerance. The...
Carbon nanotubes (CNTs) are one of the most important nanomaterials, with applications in several areas. The exponential increase in the production and use of CNTs, however, increases the likelihood of their release into the environment and potential impacts on environmental systems. We evaluated the cytogenotoxic potential of carboxylated multi-walled carbon nanotubes (MWCNT-COOH) as well as its influence in the methylation patterns of Lactuca sativa meristematic cells. Root elongation was observed at concentrations of 1.0; 10.0; 50.0 and 100.0 μg/mL, and decreased seed germination at the highest concentration evaluated (100.0 μg/mL). Cytogenetic analysis revealed that MWCNT-COOH induced increases in the chromosomal aberration index and micronucleus frequency. Accumulations of cells in the sub G1 phase were also observed at low concentrations (0.1 μg / mL), which may be related to increased programmed cell death. Cytosine methylation profile analysis revealed cytosine hypermethylation at MWCNT-COOH concentrations of 1.0 and 10.0 μg / mL and cytosine hypomethylation at MWCNT-COOH concentrations of 50.0 and 100.0 μg / mL as compared to controls. We conclude that, in addition to cytogenotoxic effects, MWCNT-COOH alters cytosine methylation profiles and promotes root elongation.
Gibberellins (GAs) are a class of phytohormones, important for plant growth, and very difficult to distinguish because of their similarity in chemical structures. Herein, we develop the first nanosensors for GAs by designing and engineering polymer-wrapped single-walled carbon nanotubes (SWNTs) with unique corona phases that selectively bind to bioactive GAs, GA3 and GA4, triggering near-infrared (NIR) fluorescence intensity changes. Using a new coupled Raman/NIR fluorimeter that enables self-referencing of nanosensor NIR fluorescence with its Raman G-band, we demonstrated detection of cellular GA in Arabidopsis, lettuce, and basil roots. The nanosensors reported increased endogenous GA levels in transgenic Arabidopsis mutants that overexpress GA and in emerging lateral roots. Our approach allows rapid spatiotemporal detection of GA across species. The reversible sensor captured the decreasing GA levels in salt-treated lettuce roots, which correlated remarkably with fresh weight changes. This work demonstrates the potential for nanosensors to solve longstanding problems in plant biotechnology.
Carbon nanotubes (CNTs) regulate growth in many plants. Carbohydrates provide energy and carbon skeleton for cell growth. However, how CNTs influence plant carbohydrate metabolism remains largely unknown. For a comprehensive understanding the response of carbohydrate metabolism and accumulation in leaves of crabapple (Malus hupehensis Rehd) to single-walled carbon nanotubes (SWCNTs), the expression of key enzymes and genes involved in apple sugar metabolism was investigated. In this report, TEM showed that SWCNTs particles were absorbed in apple leaf. Foliar application of 10 and 20 mg/L SWCNTs promoted chlorophyll content, net photosynthetic rate, stomatal conductance and transpiration rate. SWCNTs up-regulate the activity of aldose-6-phosphate reductase (A6PR), accompanied by increased concentration of photosynthetic assimilate‒sorbitol. However, the activities of sucrose phosphate synthase (SPS) and the accumulation of sucrose did not change significantly in SWCNTs-sprayed apple leaves compared with the control. In addition, the activities of photoassimilate degradation enzyme (sorbitol dehydrogenase, SDH; sucrose synthase, SUSY; neutral invertase, NINV) and hexose degradation enzyme (fructokinase, FRK; hexokinase, HK) were higher in SWCNTs-treated apple leaves than that in the control leaves. Quantitative real-time polymerase chain reaction (qRT‒PCR) results indicated that the expression of genes associated with sugar metabolism changed significantly after SWCNTs application. Taken together, we propose that spraying apple leaves with 10 and 20 mg/L SWCNTs can improve photosynthetic activity and accelerate carbohydrate metabolism in apple leaves. Our results provide insight into understanding the biological effects of CNTs in plants and are valuable for continued use of SWCNTs in agri-nanotechnology.
Salt and drought stress are major environmental issues world-widely. These stresses can result in failures of seed
germination, limiting agricultural production. New approaches are needed to increase crop production, ensuring
food safety, quality, and agriculture sustainability. Nanopriming (priming seeds with nanomaterials) is an
emerging seed technology improving crop production under the drastic climate change associated with stress
factors. The present review not only provided an overview of nanopriming achieved salt and drought tolerance
but also tried to discuss the behind mechanisms. We argued that the physico-chemical properties of the nanomaterials
are key factors affecting their negative or positive effects on seed germination in terms of seed
nanopriming. Furthermore, we highlighted the possible critical role of seed coat anatomy in effective nanopriming,
in terms of saving costs and reducing biosafety issues. This review aims to help researchers to better
understand and follow this fast-developing, cost-effective, and environmentally friendly research area.
Carbon nanotubes have displayed great potential in enhancing phytoremediation of PAHs polluted soils. However, the response of plants to the coexistence of carbon nanotubes and PAHs and the associated influencing mechanisms remain largely unknown. Here, the effect of carbon nanotubes on alfalfa growth and pyrene uptake under exposure to pyrene was evaluated through sand culture experiment and gas chromatography time-of-flight mass spectrometer (GC-TOF-MS) based metabolomics. Results showed that pyrene at 10 mg kg⁻¹ obviously reduced the shoot fresh weight of alfalfa by 18.3 %. Multiwall carbon nanotubes (MWCNTs) at 25 and 50 mg kg⁻¹ significantly enhanced the shoot fresh weight in a dose-dependent manner, nearly by 80 % at 50 mg kg⁻¹. Pyrene was mainly accumulated in alfalfa roots, in which the concentration was 35 times as much as that in shoots. MWCNTs greatly enhanced the accumulation of pyrene in alfalfa roots, almost by two times at 50 mg kg⁻¹, while decreased pyrene concentration in shoots, from 0.11 mg kg⁻¹ to 0.044 mg kg⁻¹ at MWCNTs concentration of 50 mg kg⁻¹. Metabolomics data revealed that pyrene at 10 mg kg⁻¹ trigged significant metabolic changes in alfalfa root exudates, downregulating 27 metabolites. MWCNTs generated an increase in the contents of some downregulated metabolites caused by pyrene stress, which were restored to the original level or even higher, mainly including organic acids and amino acids. MWNCTs significantly enriched some metabolic pathways positively correlated with shoot growth and pyrene accumulation in shoots under exposure to pyrene, including TCA cycle, glyoxylate and dicarboxylate metabolism, cysteine and methione metabolism as well as alanine, aspartate and glutamate metabolism. This work highlights the regulation effect of MWCNTs on the metabolism of root exudates, which are helpful for alfalfa to alleviate the stress from pyrene contamination.
A critical approach against copper(Cu) toxicity is the use of carbon nanomaterials(CNM). However, the effect of CNMs on Cu toxicity-exposed chloroplasts is not clear. The photosynthetic, genetic and biochemical effects of multi-walled carbon nanotube(50-100-250mg L-1 CNT) were investigated under Cu stress(50-100µMCuSO4) in Zea mays chloroplasts. Fv/Fm and Fv/Fo were suppressed under stress. Stress altered antioxidant system and the expression of psaA, psaB, psbA and psbD. The chloroplastic activities of superoxide dismutase(SOD), ascorbate peroxidase(APX), glutathione S-transferase(GST) and glutathione peroxidase(GPX) increased under CNT+stress, and hydrogen peroxide(H2O2) and lipid peroxidation decreased. CNTs promoted to the maintenance of redox state by regulating enzyme/non-enzyme activity/contents involved in the AsA-GSH cycle. Furthermore, CNTs inverted the negative effects of Cu by upregulating the transcriptions of photosystems-related genes. However, the high CNT concentration had adverse effects on the antioxidant capacity. CNT has great potential to confer tolerance by reducing Cu-induced damage and protecting the biochemical reactions of photosynthesis.