Surface chemistry of carbon nanotubes impacts the growth and expression of water channel protein in tomato plants

Single-Cell Transcriptome Reveals Aquaporin-Mediated Carbon Nanosol-Induced Growth Promotion of Plants

Carbon nanosol (CNS) is a novel carbon nanomaterial with the potential for enhancing plant growth, yet the underlying mechanism remains unclear. Application of 10 mg L-1 CNS significantly promotes plant growth, increasing fresh mass by 59.51%. Track of fluorescent labeling CNS reveals that it is rapidly absorbed by roots and entered the vascular bundle and cortex within 2 h. A single-cell transcriptomic atlas of tobacco roots response to CNS treatment is generated, which comprises 7,897 cells representing 13 distinct cell types. CNS is found to affect gene expression in a cell type-specific manner, suggesting the heterogeneity of plant response to CNS. Further pseudo-time trajectory analysis reveals that most cell types undergo cell fate transitions toward a more mature state under CNS treatment. In addition, aquaporin proteins NIPs and TIPs are found to be activated and significantly upregulated in epidermal, cortical, and endodermal cells. Further genetic and physiological findings reveal that growth enhance effect of CNS for tip1;1 and tip2;1 mutants is significantly weakened compared to the wild type, indicating that aquaporins play an important role in CNS-mediated plant growth promotion. Overall, these results provide new insights into the mechanism by which CNS promotes plant growth at the single-cell level.

Different concentrations of carbon nanotubes promote or inhibit organogenesis of Arabidopsis explants by regulating endogenous hormone homeostasis

MAIN CONCLUSION

Carbon nanotubes concentration modulates endogenous hormone balance, influencing callogenesis and organogenesis efficiency, with potential for optimizing plant transformation programs. A unique feature of plant somatic cells is their remarkable ability to regenerate new organs and even an entire plant in vitro. In this work, we investigated how an important group of environmental factors, carbon nanotubes (CNTs) (both single-walled nanotubes as SWCNTs and multi-walled nanotubes as MWCNTs), affect the regenerative capacity of plants and the underlying molecular mechanisms. Our data show that both the induction of pluripotent callus from Arabidopsis root explants and the frequency of de novo shoot regeneration were influenced by the concentration, but not the type of CNTs. Raman analyses show that CNTs can be transported and accumulate in the callus tissue and in the newly formed seedlings. The contrasting effects of CNTs at 0.1 mg L-1 and 50 mg L-1 were reflected not only in the concentrations of endogenous auxin and trans-zeatin (tZT), but also in the changes in the expression levels of positive cell cycle regulators and transcriptional regulators that control callus pluripotency and the establishment of shoot apical meristem (SAM). Since most existing plant transformation strategies involve the conversion of dedifferentiated calli into regenerated plantlets and are very time consuming and inefficient, this work suggests that CNTs could be used as an additive to optimize plant micropropagation and genetic engineering systems by modulating hormone balance and stimulating the intrinsic totipotency of plants, thus overcoming organogenic recalcitrance.

Carbon-based nanocarriers for plant growth promotion: fuelling when needed

Climate change (i.e., rising temperature and precipitation) due to global warming is affecting soil fertility, thereby significantly causing a decrease in agriculture production worldwide. At the same time, increasing demands for food supplies with the growing global population puts extra pressure to improve agricultural production. Indeed, chemical fertilizers and pesticides are a great help in fuelling agro-production, but their excess use could deteriorate the environment and human health. Nevertheless, nanomaterials, especially carbon-based nanostructured materials (CB-NMs), have revolutionized the agricultural sector in various ways including the on-demand supply of essential nutrients, biomolecules, and growth factors to plants. Carbon nanofibers (CNFs) are one such example that can be tuned to carry essential nutrients (i.e., Fe, Cu, Zn, and Mo) and deliver to plants when and what is in need. As a result, it not only improves the crop yield but also maintains the nutritional quality (protein, carbohydrate, and mineral contents) of plant products. This review discusses the most innovative development in CB-NM-based carriers (CNFs, carbon nanotubes (CNTs), and graphene as well as its derivatives) for plant growth applications including the approaches being used for their lab-scale synthesis. In addition, their application as the carrier of micronutrients and biomolecules and the successful delivery (and the underlying mechanism) of genes, nucleic acids, microbes, and their components in plants are discussed.

Carbon Nanomaterials in Seed Priming: Current Possibilities

The prevailing agricultural system has become deeply ingrained and insufficient due to outdated practices inherited from the Green Revolution, necessitating innovative approaches for sustainable agricultural development. Nanomaterials possess the potential to significantly improve the efficient utilization of resources while simultaneously encouraging sustainability. Among these, carbonaceous nanomaterials have found diverse applications in agriculture, exhibiting remarkable capabilities in this domain. Notably, using biowaste to produce these materials makes them both cost-effective and environmentally friendly for seed priming. Seed priming is a technique that can potentially enhance germination rates and stress tolerance by effectively regulating gene pathways and metabolism. This review provides a comprehensive summary of recent progress in the field, highlighting the challenges and opportunities of applying carbonaceous materials in seed priming to advance sustainable agriculture practices. The existing reviews provide a general overview of using carbonaceous materials (graphene and derivatives) in agriculture. Yet, they often lack a comprehensive examination of their specific application in seed-related contexts. In this review, we aim to offer a detailed analysis of the application of carbonaceous materials in seed priming and elucidate their influence on germination. Furthermore, the review shows that crop response to carbonaceous nanomaterials is linked to material concentration and crop species.

Carbon dot unravels accumulation of triterpenoid in Evolvulus alsinoides hairy roots culture by stimulating growth, redox reactions and ANN machine learning model prediction of metabolic stress response

Evolvulus alsinoides, a therapeutically valuable shrub can provide consistent supply of secondary metabolites (SM) with pharmaceutical significance. Nonetheless, because of its short life cycle, fresh plant material for research and medicinal diagnostics is severely scarce throughout the year. The effects of exogenous carbon quantum dot (CD) application on metabolic profiles, machine learning (ML) prediction of metabolic stress response, and SM yields in hairy root cultures of E. alsinoides were investigated and quantified. The range of the particle size distribution of the CDs was between 3 and 7 nm. The CDs EPR signal and spin trapping experiments demonstrated the formation of O2-•spin-adducts at (g = 2.0023). Carbon dot treatment increased the levels of hydrogen peroxide and malondialdehyde concentrations as well as increased antioxidant enzyme activity. CD treatments (6 μg mL-1) significantly enhanced the accumulation of squalene and stigmasterol (7 and 5-fold respectively). The multilayer perceptron (MLP) algorithm demonstrated remarkable prediction accuracy (MSE value = 1.99E-03 and R2 = 0.99939) in both the training and testing sets for modelling. Based on the prediction, the maximum oxidative stress index and enzymatic activities were highest in the medium supplemented with 10 μg mL-1 CDs. The outcome of this study indicated that, for the first time, using CD could serve as a novel elicitor for the production of valuable SM. MLP may also be used as a forward-thinking tool to optimize and predict SM with high pharmaceutical significance. This study would be a touchstone for understanding the use of ML and luminescent nanomaterials in the production and commercialization of important SM.

Nanopriming boost seed vigor: Deeper insights into the effect mechanism

Nanopriming, an advanced seed priming technology, is highly praised for its environmental friendliness, safety, and effectiveness in promoting sustainable agriculture. Studies have shown that nanopriming can enhance seed germination by stimulating the expression of aquaporins and increasing amylase production. By applying an appropriate concentration of nanoparticles, seeds can generate reactive oxygen species (ROS), enhance their antioxidant capacity, improve their response to oxidative stress, and enhance their tolerance to both biotic and abiotic stresses. This positive impact extends beyond the seed germination and seedling growth stages, persisting throughout the entire life cycle. This review offers a comprehensive overview of recent research progress in seed priming using various nanoparticles, while also addressing current challenges and future opportunities for sustainable agriculture.

Phytogenic nanoparticles: synthesis, characterization, and their roles in physiology and biochemistry of plants

Researchers are swarming to nanotechnology because of its potentially game-changing applications in medicine, pharmaceuticals, and agriculture. This fast-growing, cutting-edge technology is trying different approaches for synthesizing nanoparticles of specific sizes and shapes. Nanoparticles (NPs) have been successfully synthesized using physical and chemical processes; there is an urgent demand to establish environmentally acceptable and sustainable ways for their synthesis. The green approach of nanoparticle synthesis has emerged as a simple, economical, sustainable, and eco-friendly method. In particular, phytoassisted plant extract synthesis is easy, reliable, and expeditious. Diverse phytochemicals present in the extract of various plant organs such as root, leaf, and flower are used as a source of reducing as well as stabilizing agents during production. Green synthesis is based on principles like prevention/minimization of waste, reduction of derivatives/pollution, and the use of safer (or non-toxic) solvent/auxiliaries as well as renewable feedstock. Being free of harsh operating conditions (high temperature and pressure), hazardous chemicals and the addition of external stabilizing or capping agents makes the nanoparticles produced using green synthesis methods particularly desirable. Different metallic nanomaterials are produced using phytoassisted synthesis methods, such as silver, zinc, gold, copper, titanium, magnesium, and silicon. Due to significant differences in physical and chemical properties between nanoparticles and their micro/macro counterparts, their characterization becomes essential. Various microscopic and spectroscopic techniques have been employed for conformational details of nanoparticles, like shape, size, dispersity, homogeneity, surface structure, and inter-particle interactions. UV-visible spectroscopy is used to examine the optical properties of NPs in solution. XRD analysis confirms the purity and phase of NPs and provides information about crystal size and symmetry. AFM, SEM, and TEM are employed for analyzing the morphological structure and particle size of NPs. The nature and kind of functional groups or bioactive compounds that might account for the reduction and stabilization of NPs are detected by FTIR analysis. The elemental composition of synthesized NPs is determined using EDS analysis. Nanoparticles synthesized by green methods have broad applications and serve as antibacterial and antifungal agents. Various metal and metal oxide NPs such as Silver (Ag), copper (Cu), gold (Au), silicon dioxide (SiO2), zinc oxide (ZnO), titanium dioxide (TiO2), copper oxide (CuO), etc. have been proven to have a positive effect on plant growth and development. They play a potentially important role in the germination of seeds, plant growth, flowering, photosynthesis, and plant yield. The present review highlights the pathways of phytosynthesis of nanoparticles, various techniques used for their characterization, and their possible roles in the physiology of plants.

Favorable physiological and morphological effects of molybdenum nanoparticles on tobacco (Nicotiana tabacum L.): root irrigation is superior to foliar spraying

Introduction

Nano fertilizers can provide efficient solutions to the increasing problem of nutrient deficiency caused by low availability. However, the most important prerequisite is to fully understand whether nanomaterials induce phytotoxicity in plants under a variety of different conditions. The mechanisms underlying interactions between molybdenum nanoparticles (Mo NPs) and plants with respect to their uptake and biological effects on crops are still not fully understood.

Methods

In this study, the impacts of Mo NPs over a range of concentrations (0, 25, and 100 μg/mL) on tobacco (Nicotiana tabacum L.) seedling growth were comparatively evaluated under foliar applications and root irrigation.

Results

The results indicated that more significant active biological effects were observed with root irrigation application of Mo NPs than with foliar spraying. The agronomic attributes, water content and sugar content of Mo NPs-exposed seedlings were positively affected, and morphologically, Mo NPs induced root cell lignification and more vascular bundles and vessels in tobacco tissues, especially when applied by means of root irrigation. Moreover, the photosynthetic rate was improved by 131.4% for root exposure to 100 μg/mL Mo NPs, mainly due to the increased chlorophyll content and stomatal conductance. A significant concentration-dependent increase in malonaldehyde (MDA) and defensive enzyme activity for the Mo NPs-treated tobacco seedlings were detected compared to the controls. Significantly improved absorption of Mo by exposed tobacco seedlings was confirmed with inductively coupled plasma mass spectrometry (ICP-MS) in tobacco tissues, regardless of application method. However, the accumulation of Mo in roots increased by 13.94 times, when roots were exposed to 100 mg/L Mo NPs, higher than that under treatment with foliar spray. Additionally, Mo NPs activated the expression of several genes related to photosynthesis and aquaporin processes.

Discussion

The present investigations offer a better understanding of Mo NPs-plant interactions in terrestrial ecosystems and provide a new strategy for the application of Mo NPs as nano fertilizers in crop production.

Multifaceted Role of Nanomaterials in Modulating In Vitro Seed Germination, Plant Morphogenesis, Metabolism and Genetic Engineering

The agricultural practices of breeding, farm management and cultivation have improved production, to a great extent, in order to meet the food demands of a growing population. However, the newer challenges of climate change, global warming, and nutritional quality improvement will have to be addressed under a new scenario. Plant biotechnology has emerged as a reliable tool for enhancing crop yields by protecting plants against insect pests and metabolic engineering through the addition of new genes and, to some extent, nutritional quality improvement. Plant tissue culture techniques have provided ways for the accelerated clonal multiplication of selected varieties with the enhanced production of value-added plant products to increase modern agriculture. The in vitro propagation method has appeared as a pre-eminent approach for the escalated production of healthy plants in relatively shorter durations, also circumventing seasonal effects. However, there are various kinds of factors that directly or indirectly affect the efficiency of in vitro regeneration like the concentration and combination of growth regulators, variety/genotype of the mother plant, explant type, age of seedlings and other nutritional factors, and elicitors. Nanotechnology as one of the latest and most advanced approaches in the material sciences, and can be considered to be very promising for the improvement of crop production. Nanomaterials have various kinds of properties because of their small size, such as an enhanced contact surface area, increased reactivity, stability, chemical composition, etc., which can be employed in plant sciences to alter the potential and performance of plants to improve tissue culture practices. Implementing nanomaterials with in vitro production procedures has been demonstrated to increase the shoot multiplication potential, stress adaptation and yield of plant-based products. However, nanotoxicity and biosafety issues are limitations, but there is evidence that implies the promotion and further exploration of nanoparticles in agriculture production. The incorporation of properly designed nanoparticles with tissue culture programs in a controlled manner can be assumed as a new pathway for sustainable agriculture development. The present review enlists different studies in which treatment with various nanoparticles influenced the growth and biochemical responses of seed germination, as well as the in vitro morphogenesis of many crop species. In addition, many studies suggest that nanoparticles can be useful as elicitors for elevating levels of important secondary metabolites in in vitro cultures. Recent advancements in this field also depict the suitability of nanoparticles as a promising carrier for gene transfer, which show better efficiency than traditional Agrobacterium-mediated delivery. This review comprehensively highlights different in vitro studies that will aid in identifying research gaps and provide future directions for unexplored areas of research in important crop species.

Fungi-mediated synthesis of nanoparticles: characterization process and agricultural applications

In the field of nanotechnology, the use of biologically active products from fungi for the reduction and synthesis of nanoparticles as an alternative to toxic chemicals has received extensive attention, due to their production of large quantities of proteins, high yields, easy handling, and the low toxicity of the residues. Fungi have become valuable tools for the manufacture of nanoparticles in comparison with other biological systems because of their enhanced growth control and diversity of metabolites, including enzymes, proteins, peptides, polysaccharides, and other macro-molecules. The ability to use different species of fungi and to perform the synthesis under different conditions enables the production of nanoparticles with different physicochemical characteristics. Fungal nanotechnology has been used to develop and offer products and services in the agricultural, medicinal, and industrial sectors. Agriculturally, it has found applications in plant disease management, crop improvement, biosensing, and the production of environmentally friendly, non-toxic pesticides and fertilizers to enhance agricultural production in general. The subject of this review is the application of fungi in the synthesis of inorganic nanoparticles, characterization, and possible applications of fungal nanoparticles in the diverse agricultural sector. The literature shows potential uses of fungi in biogenic synthesis, enabling the production of nanoparticles with different physiognomies. © 2023 Society of Chemical Industry.

Use of titanium dioxide doped multi-wall carbon nanotubes as promoter for the growth, biochemical indices of Sesamum indicum L. under heat stress conditions

The behavior of multi-walled carbon nanotubes (MWCNTs) and titanium dioxide nanoparticles (TiO2 NPs) as plant growth enhancers was still unclear; however, in this study, the effects of MWCNTs, TiO2NPs, 5%TiO2@MWCNTs, 10%TiO2@MWCNTs and 15%TiO2@MWCNTs on physical and biochemical contents in Sesamum indicum L. under heat stress conditions were studied. The content of malondialdehyde (MDA) and hydrogen peroxide (H2O2) concentrations were reduced by the spraying MWCNTs and TiO2 NPs on plants. The hydrogen peroxide (H2O2) content was reduced by 49.02% in plants treated with 15%TiO2@MWCNTs while 42.14% reduction was found in plants treated with 10%TiO2@MWCNTs. The proportion of oil and the peroxidase enzyme activity in plants treated with 15%TiO2@MWCNTs were increased by 48.99%, for the oil content, and 2.39 times for POD activity respected to the stressed plants. The proportion of unsaturated fatty acids increased in plants treated with 15%TiO2@MWCNTs, 10%TiO2@MWCNTs and TiO2 NPs by 2.7, 2.52, and 2.09 times, respectively, greater than the control of the Shandweel-3 variety. Finally, plants treated with 15%TiO2@MWCNTs showed increases in seed yield and weight 1000-seeds by 4.42 and 1.67 times, respectively. These findings suggest that TiO2@MWCNTs more effective than separated MWCNTs and TiO2 NPs in improve plant growth. In addition, the cultivar Shandweel-3 showed an improvement in growth indicators more than the Giza-32 cultivar.

Some Physiological Effects of Nanofertilizers on Wheat-Aphid Interactions

The increasing use of nanofertilizers in modern agriculture and their impact on crop yield and pest management require further research. In this study, the effects of nano-Fe, -Zn, and -Cu (which are synthesized based on nanochelating technology), and urea (N) fertilizers on the antioxidant activities of wheat plants (cv. Chamran), and the wheat green aphid Schizaphis graminum (Rondani) are investigated. The authors observed the highest levels of phenolics in non-infested nano-Zn-treated plants (26% higher compared with control). The highest H₂O₂ levels are in the infested and non-infested nano-Zn-treated and infested nano-Fe-treated plants (in infested nano-Zn and nano-Fe treated plants, 18% and non-infested nano-Zn-treated plants, 28% higher compared with control). The highest peroxidase (POX) activity is observed in the infested and non-infested N-treated and non-infested water-treated plants (almost 14%, 37%, and 46% higher than control, respectively). The lowest activity is in the infested plants' nano-Zn and -Fe treatments (almost 7 and 5 folds lower compared to the control, respectively). The highest and lowest catalase (CAT) activity are in the infested N-treated plants (almost 42% higher than control) and water-treated plants, respectively. The infested nano-Zn, -Fe, -Cu and Hoagland-treated plants showed the highest superoxide dismutase (SOD) activity. Regarding the antioxidant enzyme activities of S. graminum, the highest POX activity is in the nano-Cu treatment (more than two folds higher compared with control); the highest CAT and SOD activities are in the nano-Cu and -Zn treatments. It can be concluded that the application of nanofertilizers caused increasing effects on the wheat plant's antioxidant system and its resistance to S. graminum.

Foliar application of Phenylalanine functionalized multi-walled carbon nanotube improved the content of volatile compounds of basil grown in greenhouse

Carbon nanotubes are among the elicitors that have different effects on plants. Basil as a useful and valuable plant has significant medicinal properties; The aim of this research is to study the effect of different concentrations of functionalized multi-walled carbon nanotubes with phenylalanine and non-functionalized in concentrations of (0, 50, 100, 150 and 200 mg.l^-1) and activated carbon on total phenol and flavonoid content, antioxidant capacity, the content of H₂O₂, reactive oxygen species detection, antioxidant enzyme activity, and the concentration of volatile compounds of basil in the greenhouse culture, in an experiment in the form of a completely randomized design with three replications, and in the faculty of sciences of Urmia university's laboratory. The highest content of total phenol, flavonoid, anthocyanin, antioxidant capacity and hydrogen peroxide content were observed in the 200 mg.l^-1 functionalized carbon nanotube. The highest percentage of alpha-Copaene, trans-alpha-Bergamotene, alpha-Guaiene, Bicyclogermacrene, 1,10-di-epi-Cubenol and alpha-Eudesmol compounds at 150 mg.l^-1 of functionalized carbon nanotube and the highest percentage of compounds 1,8-cineole and eugenol was observed at 100 mg.l^-1 of functionalized carbon nanotube. The compounds of linalool, camphor and anethole also showed their highest amount in treatments of 200, 150 and 50 mg.l^-1 of carbon nanotube, respectively. In general, the observations of this research indicated that the use of functionalized carbon nanotubes as a stimulant has increased the antioxidant capacity of basil and on the other hand, it has led to an improving in the content of secondary metabolites.

Effects of Multi-Walled Carbon Nanotubes and Nano-Silica on Root Development, Leaf Photosynthesis, Active Oxygen and Nitrogen Metabolism in Maize

Carbon nanotubes (MWCNTs) and nano-silica (nano-SiO₂) are widely used in the field of life science because of their special physical and chemical properties. In this study, the effects of different concentrations of MWCNTs (0 mg·L^-1, 200 mg·L^-1, 400 mg·L^-1, 800 mg·L^-1 and 1200 mg·L^-1) and nano-SiO₂ (0 mg·L^-1, 150 mg·L^-1, 800 mg·L^-1, 1500 mg·L^-1 and 2500 mg·L^-1) on maize seedling growth and relative mechanisms were explored. The main results are as follows: MWCNTs and nano-SiO₂ can promote the growth of maize seedlings, and promote plant height, root length, the dry and fresh weight of seedlings, root-shoot ratio and so on. The ability to accumulate dry matter increased, the relative water content of leaves increased, the electrical conductivity of leaves decreased, the stability of cell membranes improved and the water metabolism ability of maize seedlings increased. The treatment of MWCNTs with 800 mg·L^-1 and nano-SiO₂ with 1500 mg·L^-1 had the best effect on seedling growth. MWCNTs and nano-SiO₂ can promote the development of root morphology, increase root length, root surface area, average diameter, root volume and total root tip number and improve root activity, so as to improve the absorption capacity of roots to water and nutrition. After MWCNT and nano-SiO₂ treatment, compared with the control, the contents of O₂·^- and H₂O₂ decreased, and the damage of reactive oxygen free radicals to cells decreased. MWCNTs and nano-SiO₂ can promote the clearance of reactive oxygen species and maintain the complete structure of cells, so as to slow down plant aging. The promoting effect of MWCNTs treated with 800 mg·L^-1 and nano-SiO₂ treated with 1500 mg·L^-1 had the best effect. After treatment with MWCNTs and nano-SiO₂, the activities of key photosynthesis enzymes PEPC, Rubisco, NADP-ME, NADP-MDH and PPDK of maize seedlings increased, which promoted the opening of stomata, improved the fixation efficiency of CO₂, improved the photosynthetic process of maize plants and promoted plant growth. The promoting effect was the best when the concentration of MWCNTs was 800 mg·L^-1 and the concentration of nano-SiO₂ was 1500 mg·L^-1. MWCNTs and nano-SiO₂ can increase the activities of the enzymes GS, GOGAT, GAD and GDH related to nitrogen metabolism in maize leaves and roots, and can increase the content of pyruvate, so as to promote the synthesis of carbohydrates and the utilization of nitrogen and promote plant growth.

Exogenous application of carbon nanoparticles alleviates drought stress by regulating water status, chlorophyll fluorescence, osmoprotectants, and antioxidant enzyme activity in Capsicum annumn L

Drought is one of the most important abiotic stresses that has a huge negative effect on crop yield. Carbon nanoparticles (CNPs) have received greater attention for their impact on the plants under abiotic stress conditions. However, it is urgently required to apply CNPs to the chili pepper (Capsicum annuum L. cv. Kaskada), which has not yet been studied. The goal of this study was to find out how CNPs affect the growth of chili pepper plants, chlorophyll pigments, proline content, and the activity of antioxidant enzymes when the plants are stressed by drought. Therefore, we synthesized and functionalized CNPs of oil fly ash by one-pot ball milling fabrication. X-ray photoelectron spectroscopy (XPS) was used to identify oxidative moieties on the CNPs surface after exposure to nitric and acetic acids. In the present study, functionalized CNPs were sprayed onto the leaves of 20-day-old plants at various concentrations (6 and 12 mg L^-1) to determine their effects. We demonstrate that drought stress considerably reduces the plant height, fresh weight (FW), and dry weight (DW). Nevertheless, the exogenous application of functionalized CNPs caused an increase in relative water content (RWC), chlorophyll stability index (CSI), and chlorophyll fluorescence (Fv/Fm) under drought stress. Exogenous functionalized CNPs dramatically increased proline content under drought by reducing abscisic acid (ABA) content in the leaves. When subjected to drought stress, functionalized CNPs boosted antioxidant activities such as superoxide dismutase (SOD) and catalase (CAT) activity. Overall, the positive effects of CNPs on chili pepper seedlings open up new possibilities for developing innovative agricultural techniques, especially when plants are grown in drought conditions.

Physiological Response, Oxidative Stress Assessment and Aquaporin Genes Expression of Cherry Tomato (Solanum lycopersicum L.) Exposed to Hyper-Harmonized Fullerene Water Complex

The rapid production and numerous applications of nanomaterials warrant the necessity and importance of examining nanoparticles in terms to their environmental and biological effects and implications. In this study, the effects of a water-soluble hyper-harmonized hydroxyl-modified fullerene (3HFWC) on cherry tomato seed germination, seedlings growth, physiological response and fruiting was evaluated. Changes in the photosynthetic pigments content, oxidative stress assessment, and aquaporin genes expression in cherry tomato plants were studied after during short- and long-term continuous exposure to 3HFWC nanosubstance (200 mg/L). Increased levels of photosynthetic pigments in leaves, lycopene in fruits, decreased levels of hydrogen peroxide content, activation of cellular antioxidant enzymes such as superoxide dismutase, catalase and peroxidase and increased aquaporin gene expression (PIP1;3, PIP1;5 and PIP2;4) were observed in 3HFWC nanosubstance-exposed plants in comparison to control, untreated cherry tomato plants. The 3HFWC nanosubstance showed positive effects on cherry tomato seed germination, plantlet growth and lycopene content in fruits and may be considered as a promising nanofertilizer.

Mitigation of the salinity stress in rapeseed (Brassica napus L.) productivity by exogenous applications of bio-selenium nanoparticles during the early seedling stage

In recent years, much attention has been directed toward using nanoparticles (NPs) as one of the most effective strategies to improve plant growth, especially under salt stress conditions. Further research has been conducted to develop NPs using various chemical ways; accordingly, knowledge about the beneficial effect of bioSeNPs in rapeseed is obscure. Selenium (Se) is a vital micronutrient with a series of physiological and antioxidative properties. Seed priming is emerging as a low-cost, efficient, and environment-friendly seed treatment in nanotechnology. The current study was carried out to examine the promising effects of nanopriming via bioSeNPs on the expression level of aquaporin genes, seed microstructure, seed germination, growth traits, physiochemical attributes, and minerals uptake of two rapeseed cultivars under salinity stress conditions. Our investigation monitored the positive effects of bioSeNPs on the expression level of aquaporin genes (BnPIP1-1 and BnPIP2-1) and water uptake during the seed imbibition (4 and 8 h of priming), which indicated higher imbibition potential and germination promotion with bioSeNPs application (most effective at 150 μmol/L). The total performance index was significantly enhanced with nano-treatments in rapeseed seedlings. Collectively, nano-application improved seed microstructure, seed germination, and photosynthetic efficiency directly correlated with higher seedlings biomass, especially with a higher concentration of bioSeNPs. The enhancement in α-amylase and free amino acid contents in nanoprimed seeds resulted in rapid seed germination. Moreover, bioSeNPs increased the osmotic adjustment and enhanced the efficiency of the plant's defense system by improving the activity of enzymatic and non-enzymatic antioxidants, thus enhancing ROS scavenging under salt stress. The obtained results may indicate the strengthening of seed vigor, improving seedling growth and physiochemical attributes via bioSeNPs. Our findings displayed that bioSeNPs modulated the Na⁺ and K⁺ uptake, which improved the rapeseed growth and showed a close relationship with the low contents of toxic Na⁺ ion; thus, it prevented oxidative damage due to salt stress. This comprehensive data can add more knowledge to understand the mechanisms behind plant-bioSeNPs interaction and provide physiological evidence for the beneficial roles of nanopriming using bioSeNPs on rapeseed germination and seedling development under salinity stress conditions. Such studies can be used to develop simple prepackaged nano primer products, which can be used before sowing to boost seed germination and crop productivity under stress conditions.

Multi-walled carbon nanotubes wrapped with polyvinylpyrrolidone can control the leaf yellowing of Alstroemeria cut flowers

The rapid yellowing of the leaves on cut flowers with leafy stems severely limits their vase life and commercial value. In this study, the effect of a composite of multi-walled carbon nanotubes (MWCNTs) and polyvinyl pyrrolidone (PVP) on the longevity of cut Alstroemeria flowers (Alstroemeria hybrida) was investigated to obtain a solution to this problem. A range of MWCNTs/PVP composite concentrations (0, 3, 6, and 9 mg L-1) was applied in a vase solution (for 24 h) as pulse treatments. Our findings indicate that the composite of MWCNTs and PVP exhibits excellent dispersibility in a vase solution. The results demonstrate that a 3 mg L-1 MWCNTs/PVP concentration was the most effective, extending the vase life of cut Alstroemeria flowers by up to 27 days. Pulsing with MWCNTs/PVP delayed the onset of floret abscission and leaf yellowing by 5 and 18 days, respectively. Additionally, when MWCNTs/PVP solution was applied to cut stems, water uptake remained consistently greater than that of the control. Additionally, MWCNTs/PVP increased the total chlorophyll content, soluble protein content, and POX enzyme activity of leaves while decreasing the malondialdehyde (MDA) content. The results indicate that this composite exhibited antimicrobial activity against gram-positive and -negative bacteria, particularly at a concentration of 3 mg L-1. This study demonstrated that adding MWCNTs/PVP to a vase solution of Alstroemeria cut flowers increased their longevity with minimal leaf yellowing symptoms compared to untreated cut stems. As a result, this nanocomposite can be used safely and effectively in vase solutions and in combination with other preservatives.

Engineering plants with carbon nanotubes: a sustainable agriculture approach

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.

Interactive effects of metals and carbon nanotubes in a microcosm agrosystem

Agricultural soils are exposed to multiple contaminants through the use of agrochemicals or sewage sludge, introducing metals, nanomaterials and others. Among nanomaterials, carbon nanotubes (CNTs) are known for their large surface area and adsorption capabilities, possibly modifying other element behavior. However, to date, very little is known about the impacts of such interactions in agrosystems. In this study, we aimed at understanding the transfer and toxicity of contaminants (Cd, Pb, Zn and CNTs) in microcosms including native soil bacteria, earthworms and lettuce. After a 6 week exposure, no effect of the addition of CNTs to metal contaminated soils was detected on bacterial concentration or earthworm growth. However, in lettuce, an interactive effect between CNTs and metals was highlighted: in the soil containing the highest metal concentrations the addition of 0.1 mg kg^-1 CNTs led to a biomass loss (-22%) and a flavonoid concentration increase (+27%). In parallel, the addition of CNTs led to differential impacts on elemental uptake in lettuce leaves possibly related to the soil organic matter content. For earthworms, the addition of 10 mg kg^-1 CNTs resulted in an increased body elemental transfer in the soil with the higher organic matter content (Pb: + 34% and Zn: + 25%).

Nano-priming as emerging seed priming technology for sustainable agriculture-recent developments and future perspectives

Nano-priming is an innovative seed priming technology that helps to improve seed germination, seed growth, and yield by providing resistance to various stresses in plants. Nano-priming is a considerably more effective method compared to all other seed priming methods. The salient features of nanoparticles (NPs) in seed priming are to develop electron exchange and enhanced surface reaction capabilities associated with various components of plant cells and tissues. Nano-priming induces the formation of nanopores in shoot and helps in the uptake of water absorption, activates reactive oxygen species (ROS)/antioxidant mechanisms in seeds, and forms hydroxyl radicals to loosen the walls of the cells and acts as an inducer for rapid hydrolysis of starch. It also induces the expression of aquaporin genes that are involved in the intake of water and also mediates H2O2, or ROS, dispersed over biological membranes. Nano-priming induces starch degradation via the stimulation of amylase, which results in the stimulation of seed germination. Nano-priming induces a mild ROS that acts as a primary signaling cue for various signaling cascade events that participate in secondary metabolite production and stress tolerance. This review provides details on the possible mechanisms by which nano-priming induces breaking seed dormancy, promotion of seed germination, and their impact on primary and secondary metabolite production. In addition, the use of nano-based fertilizer and pesticides as effective materials in nano-priming and plant growth development were also discussed, considering their recent status and future perspectives.

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

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

Impacts of typical engineering nanomaterials on the response of rhizobacteria communities and rice (Oryza sativa L.) growths in waterlogged antimony-contaminated soils

The combined eco-risks of Sb (widely presented in soils, especially nearing mining areas) and the engineering nanomaterials (ENMs) (applied in agriculture and soil remediation) still remain uncovered. The current study investigated the impacts of single and combined exposure of CuO, CeO₂ nanoparticles (NPs) and multi-walled carbon nanotube (MWCNTs) with Sb on rice growths and rhizosphere bacterial communities. The results showed that co-exposure of CuO NPs (0.075 wt%) with Sb (III) posed the most adverse impacts on root biomass and branches (up to 66.59% and 70.00% compared to other treatments, respectively). Treatments containing MWCNTs showed insignificant dose-dependent effects, while CeO₂ NPs combined with Sb (III) showed significant synergistic stimulating effects on the fresh weights of root and shoot, by 68.30% and 73.48% (p < 0.05) compared to single Sb exposure, respectively. The rice planting increased the percentage of non-specifically sorbed Sb in soils by 1.50-14.49 than the no-planting stage. Analysis on microbial communities revealed that co-exposure of CuO NPs with Sb (III) induced the greatest adverse impacts on rhizobacteria abundances and community structures at both phylum and genus levels. Therein, significant decrease of Bacteroidetes, Acidobacteria and increase of Firmicutes abundance at the phylum level were observed. This study provided information about the risks of different ENMs released to Sb-contaminated soils under flooded condition on both crops and bacterial communities.

Nano-enabled improvements of growth and colonization rate in wheat inoculated with arbuscular mycorrhizal fungi

Arbuscular mycorrhizal fungi display desired potential to boost crop productivity and drought acclimation. Yet, whether nanoparticles can be incorporated into arbuscular mycorrhizal fungi for better improvement and its relevant morphologic and anatomical evidences are little documented. Pot culture experiment on wheat (Triticum aestivum L.) was conducted under drought stress (30% FWC) as well as well watered conditions (80% FWC) that involved priming of wheat seeds with iron nanoparticles at different concentrations (5mg L^-1, 10 mg L^-1 and 15 mg L^-1) with and without the inoculation of Glomus intraradices. The effects of treatments were observed on morphological and physiological parameters across jointing, anthesis and maturity stage. Root colonization and nanoparticle uptake trend by seeds and roots was also recorded. We observed strikingly high enhancement in biomass up to 109% under drought and 71% under well-watered conditions, and grain yield increased to 163% under drought and 60% under well-watered conditions. Iron nanoparticles at 10 mg L^-1 when combined with Glomus intraradices resulted in maximum wheat growth and yield, which mechanically resulted from higher rhizosphere colonization level, water use efficiency and photosynthetic rate under drought stress (P < 0.01). Across growth stages, optical micrograph observations affirmed higher root infection rate when combined with nanoparticles. Transmission electron microscopy indicated the penetration of nanoparticles into the seeds and translocation across roots whereas energy dispersive X-ray analyses further confirmed the presence of Fe in these organs. Iron nanoparticles significantly enhanced the growth-promoting and drought-tolerant effects of Glomus intraradices on wheat.

Evaluating the metabolic functional profiles of the microbial community and alfalfa (Medicago sativa) traits affected by the presence of carbon nanotubes and antimony in drained and waterlogged sediments

Antimony (Sb) is the ubiquitous re-emerging contaminant greatly accumulated in sediments which has been revealed risky to ecological environment. However, the impacts of Sb (III/V) on microbes and plants in sediments, under different water management with presence of engineering materials are poorly understood. This study conducted sequential incubation of sediments (flooding, draining and planting) with presence of multiwall carbon nanotubes (MWCNTs) and Sb to explore the influence on microbial functional diversity, Sb accumulation and alfalfa traits. Results showed that water management and planting led to greater impacts of sediment enzyme activities and microbial community metabolic function and bioavailable Sb fractions (defined as sum of acid-soluble fraction and reducible fraction, F1 + F2). Available fractions of Sb (V) showed higher correlation to microbial metabolism (r = 0.933) than that of Sb (III) (r = -0.480) in planting stage. MWCNTs with increasing concentrations (0.011%, w/w) positively correlated to microbial community metabolic function in planting stage whereas resulted in decreasing of Sb (III/V) concentrations in alfalfa, although 0.01% MWCNT led to increase of Sb (V) and decrease of Sb (V) by 50.97% and 32.68% respectively. This study provided information for investigating combined ecological impacts of heavy metal and engineering materials under different water managing sediments.

Use of Carbon Nanoparticles to Improve Soil Fertility, Crop Growth and Nutrient Uptake by Corn (Zea mays L.)

The use of carbon nanoparticles (CNPs) as a fertilizer synergist to enhance crop growth has attracted increasing interest. However, current understanding about plant growth and soil response to CNPs is limited. In the present study, we investigated the effects of CNPs at different application rates on soil properties, the plant growth and nutrient use efficiency (NUE) of corn (Zea mays L.) in two agricultural soils (Spodosol and Alfisol). The results showed that CNPs affected corn growth in a dose-dependent manner, augmenting and retarding growth at low and at high concentrations, respectively. The amendment at the optimal rate of 200 mg CNPs kg⁻¹ significantly enhanced corn growth as indicated by improved plant height, biomass yield, nutrient uptake and nutrient use efficiency, which could be explained by the higher availability of phosphorus and nitrogen in the amended soils. The application of CNPs largely stimulated soil urease activity irrespectively of soil types. However, the responses of dehydrogenase and phosphatase to CNPs were dose dependent; their activity significantly increased with the increasing application rates of CNPs up to 200 mg kg⁻¹ but declined at higher rates (>400 mg kg⁻¹). These findings have important implications in the field application of CNPs for enhancing nutrient use efficiency and crop production in tropical/subtropical regions.

Priming with Nanoscale Materials for Boosting Abiotic Stress Tolerance in Crop Plants

Seed priming is a cost-effective, practical, environmental, and farmer-friendly method to improve seed germination that can potentially increase the growth and yield of plants. The priming process enhances various physiological and biochemical mechanisms of defense and empowers the seeds or seedlings to overcome different environmental stresses. However, under critical circumstances, plants are hindered from absorbing specific chemical priming reagents owing to their larger size, molecular structure, or lack of carriers. Therefore, nanoscale materials having exceptional physiochemical properties and a large surface/volume ratio are expected to be better absorbed by the seeds/seedlings as priming agents in comparison to bulk chemicals and can trigger enhanced molecular interactions at the cellular level. Further, the flexibility in altering the surface chemical properties of the nanomaterials can facilitate better interaction with the seeds/seedlings while inhibiting the wastage of priming agents. In this review, we have systematically discussed the potentiality of various nanostructured materials as priming agents in alleviating the adverse effects of various abiotic stresses, viz., drought, salinity, high temperature, cold temperature, and heavy metals, by studying the growth parameters and physiological and biochemical response of various crop plants subjected to these stress conditions. Also, we have highlighted the molecular mechanism and activation of genes involved in enabling abiotic stress tolerance in plants after being primed with nanostructured materials.

Role of nanoparticles in crop improvement and abiotic stress management

Nanoparticles (NPs) possess specific physical and chemical features and they are capable enough to cross cellular barriers and show their effect on living organisms. Their capability to cross cellular barriers have been noticed for their application not only in medicine, electronics, chemical and physical sciences, but also in agriculture. In agriculture, nanotechnology can help to improve the growth and crop productivity by the use of various nanoscale products such as nanofertilizers, nanoherbicides, nanofungicides, nanopesticides etc. An optimized concentration of NPs can be administered by incubation of seeds, roots, pollen, isolated cells and protoplast, foliar spraying, irrigation with NPs, direct injection, hydroponic treatment and delivery by biolistics. Once NPs come in contact with plant cells, they are uptaken by plasmodesmatal or endocytosed pathways and translocated via apoplastic and / symplastic routes. Once beneficial NPs reach different parts of plants, they boost photosynthetic rate, biomass measure, chlorophyll content, sugar level, buildup of osmolytes and antioxidants. NPs also improve nitrogen metabolism, enhance chlorophyll as well as protein content and upregulate the expression of abiotic- and biotic stress-related genes. Herein, we review the state of art of different modes of application, uptake, transport and prospective beneficial role of NPs in stress management and crop improvement.

New insight into the mechanism of graphene oxide-enhanced phytotoxicity of arsenic species

Graphene oxide (GO) has exhibited significant potential to improve crop cultivation and yield. The application of GO in agriculture will inevitably result in interactions with conventional contaminants, causing potential changes to environmental behavior and toxicity of conventional contaminants. This study explored the joint phytotoxicity of GO and arsenic species (arsenite [As (III)], arsenate [As (V)]) to monocot (Triticum aestivum L.) and dicot (Solamun lycopersicum) plant species. Under the environmentally relevant concentrations, GO (1 mg/L) significantly increased the phytotoxicity of As (III) and As (V) (1 mg/L), with effects being both As- and plant species-specific. One mechanism of enhanced arsenic phytotoxicity could be GO-induced up-regulation of the aquaporin and phosphate transporter related genes expression, which would lead to the increased accumulation of As (III) and As (V) in plants. In addition, co-exposure with GO resulted in more severe oxidative stress than single As exposure, which could subsequently induce damage in root plasma membranes and compromise key arsenic detoxification pathways such as complexation with glutathione and efflux. Co-exposure to GO and As also led to more significant reduction in macro- and micronutrient content. The provided data highlight the high-impact of nanomaterials on the environmental risk of As in agricultural systems.

Effects of graphene oxide on tomato growth in different stages

The nano-carbon graphene has unique structural and physicochemical properties, which are conducive to various biomedical applications. We assessed the effect of graphene oxide (GO) on tomato plants at the seedling and mature stages in terms of morphological and biochemical indices. GO treatment significantly improved the shoot/stem growth of tomato in a dose-dependent manner by increasing the cortical cells number, cross-sectional area, diameter and vascular-column area. In addition, GO also promoted the morphological development of the root system and increased biomass accumulation. The surface area of root tips and hairs of tomato plants treated with 50 mg/L and 100 mg/L GO were significantly greater compared to the untreated control. At the molecular level, GO induced the expression of root development-related genes (SlExt1 and LeCTR1) and inhibited the auxin-responsive gene (SlIAA3). However, 50 mg/L and 100 mg/L GO significantly increased the root auxin content, which in turn increased the number of fruits and hastened fruit ripening compared to the control plants. Taken together, GO can improve the tomato growth when used at the appropriate concentration, and is a promising nano-carbon material for agricultural use.

Effects of metal nanoparticle-mediated treatment on seed quality parameters of different crops

The increasing population of the world requires novel techniques to feed everyone, which can replace or work along with traditional methods to increase production of agricultural crops. In recent times, nanotechnology is considered as a promising and emerging approach to be incorporated in agriculture to improve productivity of different crops by the administration of nanoparticles through seed treatment, foliar spray on plants, nano-fertilizers for balanced crop nutrition, nano-herbicides for effective weed control, nanoinsecticides for plant protection, early detection of plant diseases and nutrient deficiencies using diagnostics kits, and nano-pheromones for effective monitoring of pests. Further, distinct nanoparticles with unique physicochemical and biological properties are used in agriculture to increase the percentage of seed germination, which is the initial step to increase the crop yield. In the context of agricultural crops, nanoparticles have both positive effects on seed quality parameters, such as germination percentage, seedling length, seedling dry weight and vigor indices, as well as negative impacts of causing toxicity toward the environment. Thus, the aim of this review article is to provide a comprehensive overview on the effects of super-dispersive metal powders, such as zinc, silver, and titanium nanoparticles on the seed quality parameters of different crops. In addition, the drawback of conventional seed growth enhancers, impact of metal nanoparticles toward seeds, and mechanism of nanoparticles to increase seed germination were also discussed.

Nanotechnology Potential in Seed Priming for Sustainable Agriculture

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

Impacts of surface chemistry of functional carbon nanodots on the plant growth

Functional carbon nanodots (FCNs) with multiple chemical groups have great impact on the growth regulation of plants. To understand the role of the chemical groups, FCNs were reduced from the raw material by pyrolysis method and hydrolysis method. The chemical structure of these materials were characterized by using TGA, TEM, FT-IR, XPS, Raman and elementary analysis. The raw and reduced FCNs were used as plants growth regulators in culture medium of Arabidopsis thaliana. Our results indicate there is a strong correlation between the physiological responses of plants and the surface chemistries (especially carboxyl group and ester group) of the nanomaterials. The quantum-sized FCNs with multiple carboxyl groups and ester groups show better aqueous dispersity and can induce various positive physiological responses in Arabidopsis thaliana seedlings compared with the FCNs decorated without carboxyl and ester as well as aggregated FCNs. The raw FCNs present higher promotion capacity in plants biomass and roots length, and the quantum-sized FCNs are easier to be absorbed by plants and generate more positive effects on plants.

A Plant Bioreactor for the Synthesis of Carbon Nanotube Bionic Nanocomposites

Bionic composites are an emerging class of materials produced exploiting living organisms as reactors to include synthetic functional materials in their native and highly performing structures. In this work, single wall carboxylated carbon nanotubes (SWCNT-COOH) were incorporated within the roots of living plants of Arabidopsis thaliana. This biogenic synthetic route produced a bionic composite material made of root components and SWCNT-COOH. The synthesis was possible exploiting the transport processes existing in the plant roots. Scanning electrochemical microscopy (SECM) measurements showed that SWCNT-COOH entered the vascular bundles of A. thaliana roots localizing within xylem vessels. SWCNT-COOH preserved their electrical properties when embedded inside the root matrix, both at a microscopic level and a macroscopic level, and did not significantly affect the mechanical properties of A. thaliana roots.

Phytochemical, antioxidant, enzyme activity and antifungal properties of Satureja khuzistanica in vitro and in vivo explants stimulated by some chemical elicitors

Context: Satureja khuzistanica Jamzad. (Lamiaceae), is known for its antifungal and antioxidant compounds, especially rosmarinic acid (RA).Objective: The study examines the effect of elicitors on RA production and phytochemical properties of S. khuzistanica.Materials and methods: In vitro plants were treated with methyl jasmonate (MeJA) and multi-walled carbon nanotubes (MWCNTs). In vivo plants were treated with MWCNTs and salicylic acid (SA). RA was measured by HPLC. Catalase (CAT), guaiacol peroxidase (POD) and ascorbate peroxidase (APX) were quantified. DPPH and β-carotene were assayed in in vivo extracts. The antifungal effects of extracts were evaluated against Fusarium solani K (FsK).Results: The highest RA contents of in vitro plants were 50 mg/L MeJA (140.99 mg/g DW) and 250 mg/L MWCNTs (140.49 mg/g DW). The highest in vivo were 24 h MWCNTs (7.13 mg/g DW) and 72 h SA (9.12 mg/g DW). The maximum POD and APX activities were at 100 mg/L MeJA (5 and 4 mg protein, respectively). CAT had the highest activities at 50 mg/L MeJA (2 mg protein). DPPH and β-carotene showed 50% and 80% inhibition, respectively. The FsK aggregation was the lowest for in vitro extract in number of conidia [1.82 × 1010], fresh weight (6.51 g) and dry weight (0.21 g) that proved RA inhibitory effects. The callus reduces FsK growth diameter to 2.75 on the 5th day.Discussion and conclusions: Application of MeJA, SA, and MWCNTSs could increase RA in S. khuzistanica and highlighted potential characteristics in pharmaceutical and antifungal effects.

1H Nuclear Magnetic Resonance and Liquid Chromatography Coupled with Mass Spectrometry-Based Metabolomics Reveal Enhancement of Growth-Promoting Metabolites in Onion Seedlings Treated with Green-Synthesized Nanomaterials

Seed priming is a promising approach to improve germination, emergence, and seedling growth by triggering pre-germinative metabolism and enhancing seedling vigor. Recently, nanopriming gained importance in seed improvement as a result of the small size and unique physicochemical characteristics of nanomaterials. In the present study, silver and gold nanoparticles were synthesized using onion extracts as the reducing agent. Similarly, the agro-food industrial byproducts citrus seed oil and curcumin-removed turmeric oleoresin were used for the preparation of nanoemulsions. For seed priming, these green-synthesized nanomaterials were incubated with seeds of two onion (Allium cepa L.) cultivars (Legend and 50147) for 72 h, and then the plants were grown in a greenhouse for 3 weeks. Seed priming with these nanomaterials increased seed germination and seedling emergence. One-dimensional ¹H nuclear magnetic resonance and liquid chromatography coupled with mass spectrometry metabolomics studies showed that different nanopriming treatments distinctly altered the metabolome of onion seedlings. Seed priming treatments significantly inhibited plant hormones and growth regulators, such as abscisic acid and cis-(+)-12-oxo-phytodienoic acid, and enhanced germination stimulators, such as γ-aminobutyric acid and zeatin, in onion seeds and seedlings. Therefore, these priming treatments have positive impact on improving seed performance and plant growth.

Seed Biofortification by Engineered Nanomaterials: A Pathway To Alleviate Malnutrition?

Micronutrient deficiencies in global food chains are a significant cause of ill health around the world, particularly in developing countries. Agriculture is the primary source of nutrients required for sound health, and as the population has continued to grow, the agricultural sector has come under pressure to improve crop production, in terms of both quantity and quality, to meet the global demands for food security. The use of engineered nanomaterial (ENM) has emerged as a promising technology to sustainably improve the efficiency of current agricultural practices as well as overall crop productivity. One promising approach that has begun to receive attention is to use ENM as seed treatments to biofortify agricultural crop production and quality. This review highlights the current state of the science for this approach as well as critical knowledge gaps and research needs that must be overcome to optimize the sustainable application of nano-enabled seed fortification approaches.

Reclaimed wastewater as a viable water source for agricultural irrigation: A review of food crop growth inhibition and promotion in the context of environmental change

The geographical and temporal distribution of precipitation has and is continuing to change with changing climate. Shifting precipitation will likely require adaptations to irrigation strategies, and because 35% of rainfed and 60% of irrigated agriculture is within 20 km of a wastewater treatment plant, we expect that the use of treated wastewater (e.g., reclaimed wastewater) for irrigation will increase. Treated wastewater contains various organic and inorganic substances that may have beneficial (e.g., nitrate) or deleterious (e.g., salt) effects on plants, which may cause a change in global food productivity should a large change to treated wastewater irrigation occur. We reviewed literature focused on food crop growth inhibition or promotion resulting from exposure to xenobiotics, engineered nanoparticles, nitrogen, and phosphorus, metals, and salts. Xenobiotics and engineered nanoparticles, in nearly all instances, were detrimental to crop growth, but only at concentrations much greater than would be currently expected in treated wastewater. However, future changes in wastewater flow and use of these compounds and particles may result in phytotoxicity, particularly for xenobiotics, as some are present in wastewater at concentrations within approximately an order of magnitude of concentrations which caused growth inhibition. The availability of nutrients present in treated wastewater provided the greatest overall benefit, but may be surpassed by the detrimental impact of salt in scenarios where either high concentrations of salt are directly deleterious to plant development (rare) or in scenarios where soils are poorly managed, resulting in soil salt accumulation.

Nano-enabled improvements of growth and nutritional quality in food plants driven by rhizosphere processes

With the rising global population growth and limitation of traditional agricultural technology, global crop production could not provide enough nutrients to assure adequate intake for all people. Nano-fertilizers and nano-pesticides have 20-30% higher efficacy than conventional products, which offer an effective solution to the above-mentioned problem. Rhizosphere is where plant roots, soil, and soil biota interact, and is the portal of nutrients transporting from soil into plants. The rhizosphere processes could modify the bioavailability of all nutrients and nanomaterials (NMs) before entering the food plants. However, to date, the overall rhizosphere processes regulating the behaviors and bioavailability of NMs to enhance the nutritional quality are still uncertain. In this review, a meta-analysis is conducted to quantitatively assess NMs-mediated changes in nutritional quality from food plants. Furthermore, the current knowledge and related mechanisms of the behavior and bioavailability of NMs driven by rhizosphere processes, e.g., root secretions, microbial and earthworm activities, are summarized. A series of rhizosphere processes can influence how NMs enter plants and change the biological responses, including signal transduction and nutrient absorption and transport. Moreover, future perspectives are presented to maximize the potentials of NMs applications for the enhancement of food crop production and global food security.

Effect of graphene quantum dot size on plant growth

We found a straightforward dependence of plant growth on the sizes of graphene quantum dots. Enormous GQDs, such as graphene with dimensions of micrometers, neither promoted nor inhibited the growth. In contrast, synthesized GQDs with dimensions of about 10 nm best promoted the plant growth. Moreover GQDs synthesized using an "intelligent" chemistry robot yielded even better growth results than did GQDs synthesized conventionally by humans. In addition, a theoretical model was derived for the mechanism of the promotion of plant growth by GQDs.

Multi-walled carbon nanotubes stimulate growth, redox reactions and biosynthesis of antioxidant metabolites in Thymus daenensis celak. in vitro

This research was aimed at determining the effects of multi-walled carbon nanotubes (MWCNTs) on seed germination, seedling growth parameters and secondary metabolite (SM) production of Thymus daenensis in vitro. Seeds were aseptically cultured in Murashige and Skoog medium (MS) with various concentrations of MWCNTs (0, 125, 250, 500, 1000 and 2000 μg ml^-1). Seed germination and morphological changes in seedlings were measured. The measurements were aimed at quantifying the total phenolic contents (TPC) and flavonoids (TFC), antioxidant activities and the activity of polyphenol oxidase (PPO), l-phenylalanine ammonia-lyase (PAL), dehydrogenase (DHA) and peroxidase enzyme (POD) of the seedling extract. Seedling biomass and seedling height grew significantly as the MWCNTs level increased. The biomass and height peaked at 250 μg ml^-1 (0.41 ± 0.01 gr FW, 5.99 ± 0.55 cm) and then rapidly decreased to 0.040 ± 0.1 gr FW and 1.42 ± 0.24 cm in response to 1000 μg ml^-1, 30 days after the treatment. Additionally, SM and the analyses of enzyme activity revealed that the highest amounts of TPC (6.70 ± 0.06 mg GAE g^-1 DW), TFC (8.19 ± 0.01 mg QUE g^-1 DW), antioxidant activities (73.88 ± 0.47%) and maximum PAL activity (1.25 ± 0.08 mM cm g^-1 FW) were detected in plants grown on MS media fortified with 250 μg ml^-1 MWCNTs. The results reveal that MWCNTs in low doses (250 μg ml^-1) can encourage the production of biomass, elicit more SM from seedlings and enhance the biosynthesis of antioxidants. TEM images showed that MWCNTs could cross the plant cell wall and enter the cellular cytoplasm.

Current trends in nano-technological interventions on plant growth and development: a review

Nanomaterials, recently have found burgeoning attention in the field of agriculture, owing to the positive correlation between nanoparticle (NP) application and the enhanced nutritional status of the applied plants. A wide range of NPs, namely carbon-based NPs, titanium dioxide NPs, silica NPs etc. has been found to influence plants in a positive way by increasing their nutrient uptake ratio, nutrient usage efficiency, among others. All these attributes have paved the way for possible improvement in plant growth, development, vigour etc. through the use of these NPs, mainly as nanofertiliser. In view of all these, it can also be concluded that in the global scenario of increased demand of food production and supply in the coming years, nanotechnology promises to play a critical role. In this review, an attempt has been made to consolidate all the positive trends with respect to application of NPs on plants, along with their probable mechanism of action, which may provide a comprehensive insight for researchers working in this field.

Comparative Study on the Fungicidal Activity of Metallic MgO Nanoparticles and Macroscale MgO Against Soilborne Fungal Phytopathogens

Engineered nanoparticles have provided a basis for innovative agricultural applications, specifically in plant disease management. In this interdisciplinary study, by conducting comparison studies using macroscale magnesium oxide (mMgO), we evaluated the fungicidal activity of MgO nanoparticles (nMgO) against soilborne Phytophthora nicotianae and Thielaviopsis basicola for the first time under laboratory and greenhouse conditions. In vitro studies revealed that nMgO could inhibit fungal growth and spore germination and impede sporangium development more efficiently than could macroscale equivalents. Indispensably, direct contact interactions between nanoparticles and fungal cells or nanoparticle adsorption thereof were found, subsequently provoking cell morphological changes by scanning electron microscopy/energy-dispersive spectrometry (SEM/EDS) and transmission electron microscopy (TEM). In addition, the disturbance of the zeta potential and accumulation of various modes of oxidative stress in nMgO-exposed fungal cells accounted for the underlying antifungal mechanism. In the greenhouse, approximately 36.58 and 42.35% decreases in tobacco black shank and black root rot disease, respectively, could testify to the efficiency by which 500 μg/ml of nMgO suppressed fungal invasion through root irrigation (the final control efficiency reached 50.20 and 62.10%, respectively) when compared with that of untreated controls or mMgO. This study will extend our understanding of nanoparticles potentially being adopted as an effective strategy for preventing diversified fungal infections in agricultural fields.

Enhanced bioaccumulation efficiency and tolerance for Cd (Ⅱ) in Arabidopsis thaliana by amphoteric nitrogen-doped carbon dots

Amphoteric nitrogen-doped carbon dots (N-CDs) that prepared environmentally friendly have rich functional groups, such as carboxyl, amino, hydroxyl, carbonyl, etc. Through electrostatic attraction and complexation between the chemical groups and metal ions, N-CDs present excellent adsorption capacity for Cd²⁺ in heavy polluted water with the saturated adsorption weight of 559  mg g^-1. The investigation of interaction between N-CDs, Cd²⁺ and Arabidopsis thaliana reveals that N-CDs (from 4  mg kg^-1 to 8  mg kg^-1) can dramatically enhance Cd bioaccumulation of plants by 58.3% of unit biomass and 260% of individual seedling when the plants were cultivated for 10 days under Cd stress (from 10 mg kg^-1 to 50 mg kg^-1). Simultaneously, N-CDs significantly alleviate the toxicity caused by high Cd stress on Arabidopsis thaliana seedlings growth. N-CDs induce higher germination rate (maximum: 2.5-fold), higher biomass (maximum: 3.7-fold), better root development (maximum: 1.4-fold), higher photosynthetic efficiency and higher antioxidant capacity in plants under Cd stress. When the Cd and N-CDs concentration are respective 20 mg kg-1 and 4 mg kg-1, the enzyme activities of the catalase and peroxidase increased to 2.73-fold and 1.45-fold, respectively. This research prove the potential application of amphoteric N-CDs in phytoremediation because N-CDs greatly mitigate the growth retardation of plant caused by Cd²⁺ even with the extremely increased Cd²⁺ concentration in vivo.

Carbon nanoparticles enhance potassium uptake via upregulating potassium channel expression and imitating biological ion channels in BY-2 cells

BACKGROUND

Carbon nanoparticles (CNPs) have been reported to boost plant growth, while the mechanism that CNPs enhanced potassium uptake for plant growth has not been reported so far.

RESULTS

In this study, the function that CNPs promoted potassium uptake in BY-2 cells was established and the potassium accumulated in cells had a significant correlation with the fresh biomass of BY-2 cells. The K+ accumulation in cells increased with the increasing concentration of CNPs. The K+ influx reached high level after treatment with CNPs and was significantly higher than that of the control group and the negative group treated with K+ channels blocker, tetraethylammonium chloride (TEA+). The K+ accumulation was not reduced in the presence of CNPs inhibitors. In the presence of potassium channel blocker TEA+ or CNPs inhibitors, the NKT1 gene expression was changed compared with the control group. The CNPs were found to preferentially transport K+ than other cations determined by rectification of ion current assay (RIC) in a conical nanocapillary.

CONCLUSIONS

These results indicated that CNPs upregulated potassium gene expression to enhance K+ accumulation in BY-2 cells. Moreover, it was speculated that the CNPs simulated protein of ion channels via bulk of carboxyl for K+ permeating. These findings will provide support for improving plant growth by carbon nanoparticles.

Property-Activity Relationship of Black Phosphorus at the Nano-Bio Interface: From Molecules to Organisms

As a novel member of the two-dimensional nanomaterial family, mono- or few-layer black phosphorus (BP) with direct bandgap and high charge carrier mobility is promising in many applications such as microelectronic devices, photoelectronic devices, energy technologies, and catalysis agents. Due to its benign elemental composition (phosphorus), large surface area, electronic/photonic performances, and chemical/biological activities, BP has also demonstrated a great potential in biomedical applications including biosensing, photothermal/photodynamic therapies, controlled drug releases, and antibacterial uses. The nature of the BP-bio interface is comprised of dynamic contacts between nanomaterials (NMs) and biological systems, where BP and the biological system interact. The physicochemical interactions at the nano-bio interface play a critical role in the biological effects of NMs. In this review, we discuss the interface in the context of BP as a nanomaterial and its unique physicochemical properties that may affect its biological effects. Herein, we comprehensively reviewed the recent studies on the interactions between BP and biomolecules, cells, and animals and summarized various cellular responses, inflammatory/immunological effects, as well as other biological outcomes of BP depending on its own physical properties, exposure routes, and biodistribution. In addition, we also discussed the environmental behaviors and potential risks on environmental organisms of BP. Based on accumulating knowledge on the BP-bio interfaces, this review also summarizes various safer-by-design strategies to change the physicochemical properties including chemical stability and nano-bio interactions, which are critical in tuning the biological behaviors of BP. The better understanding of the biological activity of BP at BP-bio interfaces and corresponding methods to overcome the challenges would promote its future exploration in terms of bringing this new nanomaterial to practical applications.