Coping with the Challenges of Abiotic Stress in Plants: New Dimensions in the Field Application of Nanoparticles

Can Boron and Cobalt Nanoparticles Be Beneficial Effectors to Prevent Flooding-Induced Damage in Durum and Bread Wheat at Germination and Tillering Stage?

In this study, we investigated the possible effects of cobalt and boron nanoparticles as an inducer of the first stages of development (germination) of hard and soft wheat when simulating flooding as one of the limiting environmental factors. We also investigated the remote effect of treating wheat grains with nanoparticles when flooding was applied already at the tillering stage. To identify the effects of nanoparticles, we used morphometric, biochemical and phenotypic parameters of seedlings and plants of two wheat species differing in origin and the response of these parameters to flooding. Positive effects were found at the germination stage, increasing quantitative indicators under stress. The sensitivity of wheat species to flooding was different, which corresponds to historical and climatic aspects of cultivation. Sensitivity to stress effects associated with loss of germination, decreased growth and photosynthesis was shown for both species. Treatment with cobalt and boron nanoparticles enhanced adaptation to stress and improved photosynthetic parameters, but the encouraging results under stressful conditions were ambiguous and in the case of soft wheat could lead to deterioration of some parameters. Thus, the use of boron and cobalt nanoparticles has potential for reducing productivity under stress, but requires a detailed assessment of the cultivation protocol depending on the genotype.

Nanomaterials impact in phytohormone signaling networks of plants - A critical review

Nanotechnology offers a transformative approach to augment plant growth and crop productivity under abiotic and biotic stress conditions. Nanomaterials interact with key phytohormones, triggering the synthesis of stress-associated metabolites, activating antioxidant defense mechanisms, and modulating gene expression networks that regulate diverse physiological, biochemical, and molecular processes within plant systems. This review critically examines the impact of nanoparticles on both conventional and genetically modified crops, focusing on their role in nutrient delivery systems and the modulation of plant cellular machinery. Nanoparticle-induced reactive oxygen species (ROS) generation plays a central role in altering secondary metabolite biosynthesis, highlighting their function as potent elicitors and stimulants in plant systems. The review underscores the significant contribution of nanoparticles in enhancing stress resilience through the modulation of phytohormonal signaling pathways, offering novel insights into their potential for improving crop health and productivity under environmental stressors.

Selenium-Containing Nanoformulations Capable of Alleviating Abiotic Stress in Plants

Climate changes cause various types of abiotic stress in plants, thus affecting plant growth and causing decline in yield. An urgent need exists to develop an environmentally friendly attitude based on principles of sustainable agriculture. Nanomaterials may improve plant growth and enhance crop productivity by handling the conditions considered stressful for plants in a sustainable and ecofriendly manner. Selenium (Se) has been put into the category of beneficial elements in plants. Se-enriched crops present a successful choice of dietary resource for Se-supplemented food and feed owing to their high bioavailability and accessibility. Researchers from distinct areas, including both nanoscience and plant science, should encourage emerging innovations that are linked with abiotic stress in crop production. The implementation of Se nanoparticles (SeNPs) is considered one of the predominating mechanisms by plants to ameliorate stressful conditions. Increasing evidence of earlier research revealed that SeNPs could enhance plant growth and development, nutrient bioavailability, soil fertility, and stress response while maintaining environmental safety. Meanwhile, some earlier studies reported that SeNPs might have a multilateral influence on plants dependent on diverse Se nanomaterial traits, doses, and plant species. More efforts are required to enhance the knowledge of how SeNPs impact crops exposed to different abiotic detrimental factors. In light of contemporary research challenges linked to SeNPs and the prolonged application of Se nanomaterials to plants, the aim of this review is elucidating the principal fruitful areas of SeNP exploration, comparisons with bulk Se, insights into mechanisms of abiotic stress alleviation in plants, existing research uncertainties, and practical challenges for SeNP applications under varying environments.

Nanomaterials-plants-microbes interaction: plant growth promotion and stress mitigation

Soil salinization, extreme climate conditions, and phytopathogens are abiotic and biotic stressors that remarkably reduce agricultural productivity. Recently, nanomaterials have gained attention as effective agents for agricultural applications to mitigate such stresses. This review aims to critically appraise the available literature on interactions involving nanomaterials, plants, and microorganisms. This review explores the role of nanomaterials in enhancing plant growth and mitigating biotic and abiotic stresses. These materials can be synthesized by microbes, plants, and algae, and they can be applied as fertilizers and stress amelioration agents. Nanomaterials facilitate nutrient uptake, improve water retention, and enhance the efficiency of active ingredient delivery. Nanomaterials strengthen plant antioxidant systems, regulate photosynthesis, and stabilize hormonal pathways. Concurrently, their antimicrobial and protective properties provide resilience against biotic stressors, including pathogens and pests, by promoting plant immune responses and optimizing microbial-plant symbiosis. The synergistic interactions of nanomaterials with beneficial microorganisms optimize plant growth under stress conditions. These materials also serve as carriers of nutrients, growth regulators, and pesticides, thus acting like "smart fertilizers. While nanotechnology offers great promise, addressing potential environmental and ecotoxicological risks associated with their use is necessary. This review outlines pathways for leveraging nanotechnology to achieve resilient, sustainable, and climate-smart agricultural systems by integrating molecular insights and practical applications.

Nano Silicon Modulates Chemical Composition and Antioxidant Capacities of Ajowan (Trachyspermum ammi) Under Water Deficit Condition

Ajowan (Trachyspermum ammi) is an important spice in the food industry, as a well as a medicinal plant with remarkable antioxidant properties. In this study, its essential oil content, chemical composition, flavonoid content, phenolic content, and antioxidant capacity were evaluated under three irrigation regimes (50, 70, and 90% field capacity) and different amounts of nano silicon (0, 1.5, and 3 mM) in ten populations of ajowan. Based on the GC-MS analysis, thymol, carvacrol, p-cymene, and γ-terpinene were determined as the main components of the oil. The thymol content ranged from 34.16% in the Ardabil population (irrigation at 50% and nano silicon at 1.5 mM) to 65.71% in the Khorbir population (without nano silicon and irrigation at 50%). The highest phenolic content was in Khormo with irrigation at 90% and without nano silicon (172.3 mg TAE/g DW), while the lowest was found in Hamedan (irrigation at 50% and without nano silicon (7.2 mg TAE/g DW)). Irrigation at 50% and no nano silicon treatment led to an increase in total flavonoids in Ardabil (46.786 mg QUE/g DW). The antioxidant activity of ajowan was evaluated using the DPPH assay. Accordingly, the highest antioxidant capacity was observed in Khormo (irrigation at 90% without nano silicon; 4126 µg/mL). Moreover, the highest thymol content was observed in the Khorbir population with irrigation at 50% and without nano silicon treatment. Furthermore, correlation and principal component analysis (PCA) provide new insights into the production of ajowan from their substrates under nano silicon treatment and water deficit conditions. Finally, the results revealed information on how to improve the desired essential oil profile and antioxidant capacity of extracts for industrial producers.

Biogenic nanoparticles and its application in crop protection against abiotic stress: A new dimension in agri-nanotechnology

The food demand to support the growing population worldwide is expected to increase up to 60 % by 2050. But, various abiotic stress including heat, drought, salinity, and heavy metal stress are becoming more prevalent due to global warming and seriously affecting the crop productivity. Nanotechnology has a great potential to solve this issue, as various nanoparticles (NPs) with their unique physical and chemical characteristics, have shown promising ability to enhance the stress tolerance and subsequently, improving the plant growth and development. Although NPs can be synthesized either via physically or chemically or biologically, application of biogenic NPs in agriculture are gaining strong attention due to their economic, environmental friendly, and sustainable benefits. The implementations of biogenic NPs have been reported to be enhancing both the quantitative and qualitative properties of crop production significantly by mitigating abiotic stress. Hence, this review paper critically discussed the application of biogenic NPs, synthesized using various biological methods i.e. bacteria, fungi, algae, and plant-based, in enhancing the abiotic stress resilience and crop production. Adverse effects of the major abiotic stresses on crops have also been highlighted in the paper. The paper also focused on the mechanistic insights of plant-NPs interactions, uptake, translocation and NPs-induced biochemical and molecular changes in plants to help mitigating the abiotic stress. The potential challenges and environmental implications of extensive use of biogenic NPs in agriculture compared to the chemogenic NPs has also been critically assessed. Future research direction is provided to delve into the potential of biogenic NPs as promising tools for mitigating abiotic stress, and improving plant growth and development for a sustainable agriculture via nanotechnology.

Exogenously Applied Triacontanol Mitigates Cadmium Toxicity in Vigna radiata L. by Optimizing Growth, Nutritional Orchestration, and Metal Accumulation

Cadmium (Cd) is one of the foremost phytotoxic elements. Its proportion in agricultural soil is increasing critically due to anthropogenic activities. Cd stress is a major crop production threat affecting food security globally. Triacontanol (TRIA) is a phytohormone that promotes growth, development, and metabolic processes in plants. The current study explicates the mitigation of Cd toxicity in Vigna radiata L. (mung bean) seedlings through the application of TRIA by a seed priming technique under Cd stress. The role of TRIA in improving metabolic processes to promote Vigna radiata (mung bean, green gram) vegetative growth and performance under both stressed and unstressed conditions was examined during this study. To accomplish this, three doses of TRIA (10, 20, and 30 µmol L-1) were used to pretreat V. radiata seeds before they were allowed to grow for 40 days in soil contaminated with 20 mg kg-1 Cd. Cd stress lowered seed germination, morphological growth, and biomass in V. radiata plants. The maximum root and shoot lengths, fresh and dry weights of roots, and shoot and seed germination rates were recorded for TRIA2 compared with those of TRIA1 and TRIA3 under Cd stress. In Cd-stressed V. radiata plants, TRIA2 increased the content of chlorophyll a (2.1-fold) and b (3.1-fold), carotenoid (4.3-fold), total chlorophyll (3.1-fold), and gas exchange attributes, such as the photosynthetic rate (2.9-fold), stomatal conductance (6.0-fold), and transpiration rate (3.5-fold), compared with those in plants treated with only Cd. TRIA seed priming increased nutrient uptake (K1+, Na1+, Mg2+, and Zn2+), total phenolic content, total soluble protein content, and DPPH (2,2-diphenyl-1-picrylhydrazyl) activity. Additionally, TRIA2 significantly reduced the quantity of Cd in the plants (3.0-fold) and increased the metal tolerance index (6.6-fold) in plants contrasted with those in the Cd-treated plants. However, TRIA2 promoted plant growth and biomass production by lowering Cd-induced stress through modifying the plant antioxidant machinery and reducing oxidative stress. The improved yield characteristics of V. radiata seedlings treated with TRIA suggest that exogenous TRIA may be used to increase plant tolerance to Cd stress.

Selenium mitigated cadmium-induced ovarian retardation in female Procambarus clarkii by regulating vitellogenin synthesis and transfer in the hepatopancreas

Cadmium (Cd) is prevalent in aquatic ecosystems and accumulates in various tissues of aquatic organisms, leading to severe biological toxicity. Selenium (Se) is recognized for mitigating heavy metal toxicity, though its protective effects against Cd in aquatic crustaceans remain underexplored. This study, therefore, assessed the effects of dietary Cd (15 mg/kg) exposure and Se (6 mg/kg) supplementation on the hepatopancreas and ovaries of female crayfish to uncover the mechanisms of Cd toxicity and the protective role of Se. The results showed that Cd accumulation in the hepatopancreas caused a reduced hepatopancreas index (HPI), decreased protein content, histopathological damage, and oxidative stress, while Se supplementation reduced Cd levels, mitigated damage, and restored tissue integrity and antioxidant defenses. Transcriptomic analysis further revealed significant alterations in gene expression related to detoxification, lipid metabolism, and energy production in response to Cd exposure, which were partially or fully restored by Se supplementation. Additionally, Se alleviated Cd-induced inhibition of ovarian development, as evidenced by improved ovary index, enhanced oocyte development, and normalization of essential trace element levels. Mechanistically, Se restored the Cd-disrupted vitellogenin (Vtg) synthesis in the hepatopancreas via regulating the mRNA expression of hsp70 and genes related to the molt-inhibiting hormone (MIH) (mih, rxr, and ecr). Overall, these findings indicate that Se supplementation mitigated Cd-induced hepatopancreatic dysfunction, restored Vtg synthesis, and consequently counteracted the inhibition of ovarian development in adult female crayfish.

Can nanotechnology and genomics innovations trigger agricultural revolution and sustainable development?

At the dawn of new millennium, policy makers and researchers focused on sustainable agricultural growth, aiming for food security and enhanced food quality. Several emerging scientific innovations hold the promise to meet the future challenges. Nanotechnology presents a promising avenue to tackle the diverse challenges in agriculture. By leveraging nanomaterials, including nano fertilizers, pesticides, and sensors, it provides targeted delivery methods, enhancing efficacy in both crop production and protection. This integration of nanotechnology with agriculture introduces innovations like disease diagnostics, improved nutrient uptake in plants, and advanced delivery systems for agrochemicals. These precision-based approaches not only optimize resource utilization but also reduce environmental impact, aligning well with sustainability objectives. Concurrently, genetic innovations, including genome editing and advanced breeding techniques, enable the development of crops with improved yield, resilience, and nutritional content. The emergence of precision gene-editing technologies, exemplified by CRISPR/Cas9, can transform the realm of genetic modification and enabled precise manipulation of plant genomes while avoiding the incorporation of external DNAs. Integration of nanotechnology and genetic innovations in agriculture presents a transformative approach. Leveraging nanoparticles for targeted genetic modifications, nanosensors for early plant health monitoring, and precision nanomaterials for controlled delivery of inputs offers a sustainable pathway towards enhanced crop productivity, resource efficiency, and food safety throughout the agricultural lifecycle. This comprehensive review outlines the pivotal role of nanotechnology in precision agriculture, emphasizing soil health improvement, stress resilience against biotic and abiotic factors, environmental sustainability, and genetic engineering.

Enhanced antioxidant phytochemicals and catalase activity of celery by-products by a combined strategy of selenium and PGPB under restricted N supply

Introduction

The reduction of N supplied combined with the use of biostimulants can be an efficient strategy that allows sustainable agriculture to achieve better economic, nutritional and environmental goals without reducing production. Moreover, the industrial processing of celery generates large amounts of waste. Therefore the purpose of this study was improve crop management strategies to reduce nitrate pollution while turning crop waste into value-added products for others sectors.

Methods

Consequently, in this work twelve treatments were examined: three N nitrogen content in the nutrient solution (100% control, 60%, and 30%) combined with the inoculation of the roots with Azotobacter salinestris, and foliar application selenium solution (8 μM, Na2SeO4). The celery parts from plants grown under limited N dose showed a higher antioxidant activity and TPC (total phenolic compounds) content.

Results and discussion

The antioxidant activity increased 28% in leaves and 41% in by-products and TPC improved 27% in leaves and 191% in by-products respect to the control. Besides, a significant reduction of β-carotene content (56%, 11% and 43% in petioles, leaves and by-products respect to the control, respectively) was obtained in plants fed with restricted dose of N. The catalase activity was not affected by N dose. The inoculation of the plants with Azotobacter, together with a reduced N dose, achieved a greater accumulation of all the parameters studied. This accumulation was maximum when Se was applied to the leaves compared with the control and depending on the celery part: TPC (121-450%); antioxidant activity (60-68%), of catalase activity (59% - 158%), and of pigments content (50-90%). These findings can boost the valorization of celery by-products as excellent source of bioactive compounds.

Surface modified ZnO NPs by betaine and proline build up tomato plants against drought stress and increase fruit nutritional quality

Drought stress is a serious challenge for global food production. Nanofertilizers and nanocomposites cope with such environmental stresses and also increase nutritional contents of fruits. An in vitro experiment was designed to use Zinc Oxide Nanoparticles (ZnO NPs) primed with Proline and Betaine (ZnOP and ZnOBt NPs) at 50 and 100 mg/kg soil against drought stress in Tomato (Solanum lycopersicum) plants. Plant morphological, biochemical, and fruit nutritional quality were accessed. Maximum plant height was observed under the treatment of ZnOP50 (1.09 m) and ZnO 100 (1.06 m). ZnOP and ZnOBt also improved the chlorophyll content up to 86% and 87.16%, respectively. Application of ZnOP NPs also demonstrated maximum tomato yield (204 g tomato/plant) followed by ZnO NPs and ZnOBt NPs. Nanocomposites decreased phenolics and flavonoids contents in drought stressed plants demonstrating the mitigation of oxidative stress. Nanofertilizer also increased the concentration of phenolics and flavonoids in fruits that increased the nutritional contents. Furthermore a significant accumulation of betaine, proline, and lycopene in fruits on nanocomposite treatment made it nutritional and healthy. Lycopene content increased up to 2.01% and 1.23% in presence of ZnOP50 and ZnOP100, respectively. These outcomes validate that drought stress in plant can be reduced by accumulation of different phytochemicals and quenching oxidative stress. The study deems that nano zinc carrying osmoregulators can greatly reduce the negative effects of drought stress and increase nutritional quality of tomato fruits.

Green iron oxide nanoparticles and magnetic nanobiochar: enhancing tomato performance, phytochemicals, and root-knot nematode resistance

BACKGROUND

Green nanoparticles are considered to be an effective strategy for improving phytochemicals and raising productivity in soil infected by root-knot nematodes. This work aims to understand the characteristics of certain nanomaterials, including non-iron (nFe), green non-iron (GnFe), and green magnetic nanobiochar (GMnB), and the effect of adding them at 3 and 6 mg kg- 1 on phytochemicals and tomato (Solanum lycopersicum) plant growth in soils infected by root-knot nematodes.

RESULTS

Spectroscopic characterization of nanomaterials showed that nFe, GnFe, and GMnB contained functional groups (e.g., Fe-O, S-H, C-H, OH, and C = C) and possessed a large surface area. Application of GMB at 6 mg kg- 1 was the most efficient treatment for increasing the phytochemicals of the tomato plant, with a rise of 123.2% in total phenolic, 194.7% in total flavonoids, 89.7% in total carbohydrate, 185.2% in total free amino acids, and 165.1% in total tannin compared to the untreated soil. Tomato plant growth and attributes increased with increasing levels of soil nano-amendment in this investigation. The addition of GnFe3 and GnFe6 increased the reduction of root galls of root-knot nematodes by 22.44% and 17.76% compared with nFe3 and nFe6, respectively. The inclusion of the examined soil nano-amendments increased phytochemicals and reduced the total number of root-knot nematodes on tomato plants at varying rates, which played a significant role in enhancing tomato growth.

CONCLUSIONS

In conclusion, treating tomato plants with GnFe or GMnB can be used as a promising green nanomaterial to eliminate root-knot nematodes and increase tomato yield in sandy clay loam soil.

Biofortification and Valorization of Celery byproducts Using Selenium and PGPB under Reduced Nitrogen Regimes

Due to climate change and exacerbated population growth, the search for new sustainable strategies that allow for greater food productivity and that provide greater nutritional quality has become imperative. One strategy for addressing this problem is the combined use of fertilization with a reduced dose of nitrogen and biostimulants. Celery processing produces a large amount of waste with its concomitant pollution. Therefore, it is necessary to address the valorization of its byproducts. Our results revealed reductions in the biomass, Na, P, Mn, B, sugars, and proteins in the byproducts and increased lipid peroxidation, Fe (all celery parts), and K (byproducts) when the N supplied was reduced. Plants inoculated with Azotobacter salinestris obtained a greater biomass, a higher accumulation of K (byproducts), a build-up of sugars and proteins, reduced concentrations of P, Cu, Mn, B, Fe (petioles), and Zn (byproducts), and reduced lipid peroxidation. The application of Se at 8 μM reinforced the beneficial effect obtained after inoculation with Azotobacter salinestris. In accordance with our results, edible celery parts are recommended as an essential ingredient in the daily diet. Furthermore, the valorization of celery byproducts with health-promoting purposes should be considered.

Unveiling Innovative Approaches to Mitigate Metals/Metalloids Toxicity for Sustainable Agriculture

Due to anthropogenic activities, environmental pollution of heavy metals/metalloids (HMs) has increased and received growing attention in recent decades. Plants growing in HM-contaminated soils have slower growth and development, resulting in lower agricultural yield. Exposure to HMs leads to the generation of free radicals (oxidative stress), which alters plant morpho-physiological and biochemical pathways at the cellular and tissue levels. Plants have evolved complex defense mechanisms to avoid or tolerate the toxic effects of HMs, including HMs absorption and accumulation in cell organelles, immobilization by forming complexes with organic chelates, extraction via numerous transporters, ion channels, signaling cascades, and transcription elements, among others. Nonetheless, these internal defensive mechanisms are insufficient to overcome HMs toxicity. Therefore, unveiling HMs adaptation and tolerance mechanisms is necessary for sustainable agriculture. Recent breakthroughs in cutting-edge approaches such as phytohormone and gasotransmitters application, nanotechnology, omics, and genetic engineering tools have identified molecular regulators linked to HMs tolerance, which may be applied to generate HMs-tolerant future plants. This review summarizes numerous systems that plants have adapted to resist HMs toxicity, such as physiological, biochemical, and molecular responses. Diverse adaptation strategies have also been comprehensively presented to advance plant resilience to HMs toxicity that could enable sustainable agricultural production.

Exploring the nano-wonders: unveiling the role of Nanoparticles in enhancing salinity and drought tolerance in plants

Plants experience diverse abiotic stresses, encompassing low or high temperature, drought, water logging and salinity. The challenge of maintaining worldwide crop cultivation and food sustenance becomes particularly serious due to drought and salinity stress. Sustainable agriculture has significant promise with the use of nano-biotechnology. Nanoparticles (NPs) have evolved into remarkable assets to improve agricultural productivity under the robust climate alteration and increasing drought and salinity stress severity. Drought and salinity stress adversely impact plant development, and physiological and metabolic pathways, leading to disturbances in cell membranes, antioxidant activities, photosynthetic system, and nutrient uptake. NPs protect the membrane and photosynthetic apparatus, enhance photosynthetic efficiency, optimize hormone and phenolic levels, boost nutrient intake and antioxidant activities, and regulate gene expression, thereby strengthening plant's resilience to drought and salinity stress. In this paper, we explored the classification of NPs and their biological effects, nanoparticle absorption, plant toxicity, the relationship between NPs and genetic engineering, their molecular pathways, impact of NPs in salinity and drought stress tolerance because the effects of NPs vary with size, shape, structure, and concentration. We emphasized several areas of research that need to be addressed in future investigations. This comprehensive review will be a valuable resource for upcoming researchers who wish to embrace nanotechnology as an environmentally friendly approach for enhancing drought and salinity tolerance.

Seed Priming with Zinc Oxide Nanoparticles to Enhance Crop Tolerance to Environmental Stresses

Drastic climate changes over the years have triggered environmental challenges for wild plants and crops due to fluctuating weather patterns worldwide. This has caused different types of stressors, responsible for a decrease in plant life and biological productivity, with consequent food shortages, especially in areas under threat of desertification. Nanotechnology-based approaches have great potential in mitigating environmental stressors, thus fostering a sustainable agriculture. Zinc oxide nanoparticles (ZnO NPs) have demonstrated to be biostimulants as well as remedies to both environmental and biotic stresses. Their administration in the early sowing stages, i.e., seed priming, proved to be effective in improving germination rate, seedling and plant growth and in ameliorating the indicators of plants' well-being. Seed nano-priming acts through several mechanisms such as enhanced nutrients uptake, improved antioxidant properties, ROS accumulation and lipid peroxidation. The target for seed priming by ZnO NPs is mostly crops of large consumption or staple food, in order to meet the increased needs of a growing population and the net drop of global crop frequency, due to climate changes and soil contaminations. The current review focuses on the most recent low-cost, low-sized ZnO NPs employed for seed nano-priming, to alleviate abiotic and biotic stresses, mitigate the negative effects of improper storage and biostimulate plants' growth and well-being. Taking into account that there is large variability among ZnO NPs and that their chemico-physical properties may play a role in determining the efficacy of nano-priming, for all examined cases, it is reported whether the ZnO NPs are commercial or lab prepared. In the latter cases, the preparation conditions are described, along with structural and morphological characterizations. Under these premises, future perspectives and challenges are discussed in relation to structural properties and the possibility of ZnO NPs engineering.

Ascorbic acid and selenium nanoparticles synergistically interplay in chromium stress mitigation in rice seedlings by regulating oxidative stress indicators and antioxidant defense mechanism

Ascorbic acid (AsA) and selenium nanoparticles (SeNPs) were versatile plant growth regulators, playing multiple roles in promoting plant growth under heavy metal stresses. This study aimed to evaluate the beneficial role of individual and combined effects of AsA and SeNPs on morpho-physio-biochemical traits of rice with or without chromium (Cr) amendment. The results indicated that Cr negatively affected plant biomass, gas exchange parameters, total soluble sugar, proline, relative water contents, and antioxidant-related gene expression via increasing reactive oxygen species (MDA, H2O2, O2•-) formation, resulting in plant growth reduction. The application of AsA and SeNPs, individually or in combination, decreased the uptake and translocation of Cr in rice seedlings, increased seedlings with tolerance to Cr toxicity, and significantly improved the rice seedling growth. Most notably, AsA + SeNP treatment strengthened the antioxidative defense system through ROS quenching and Cr detoxification. The results collectively suggested that the application of AsA and SeNPs alone or in combination had the potential to alleviate Cr toxicity in rice and possibly other crop species.

Silicon dioxide nanoparticles suppress copper toxicity in Mentha arvensis L. by adjusting ROS homeostasis and antioxidant defense system and improving essential oil production

Copper (Cu) is an essential micronutrient for plants; however, the excessive accumulation of Cu due to various anthropogenic activities generates progressive pollution of agricultural land and that causes a major constraint for crop production. Excess Cu (80 mg kg-1) in the soil diminished growth and biomass, photosynthetic efficiency and essential oil (EO) content in Mentha arvensis L., while amplifying the antioxidant enzyme's function and reactive oxygen species (ROS) production. Therefore, there is a pressing need to explore effective approaches to overcome Cu toxicity in M. arvensis plants. Thus, the present study unveils the potential of foliar supplementation of two distinct forms of silicon dioxide nanoparticles (SiO2 NPs) i.e., Aerosil 200F and Aerosil 300 to confer Cu stress tolerance attributes to M. arvensis. The experiment demonstrated that applied forms of SiO2 NPs (120 mg L-1), enhanced plants' growth and augmented the photosynthetic efficiency along with the activities of CA (carbonic anhydrase) and NR (nitrate reductase), however, the effects were more accentuated by Aerosil 200F application. Supplementation of SiO2 NPs also exhibited a beneficial effect on the antioxidant machinery of Cu-disturbed plants by raising the level of proline and total phenol as well as the activities of superoxide dismutase (SOD), catalase (CAT), peroxidase (POX), ascorbate peroxidase (APX) and glutathione reductase (GR), thereby lowering ROS and electrolytic leakage (EL). Interestingly, SiO2 NPs supplementation upscaled EO production in Cu-stressed plants with more pronounced effects received in the case of Aerosil 200F over Aerosil 300. We concluded that the nano form (Aerosil 200F) of SiO2 proved to be the best in improving the Cu-stress tolerance in plants.

Nanotechnology for endorsing abiotic stresses: a review on the role of nanoparticles and nanocompositions

Environmental stresses, including the salt and heavy metals contaminated sites, signify a threat to sustainable crop production. The existence of these stresses has increased in recent years due to human-induced climate change. In view of this, several remediation strategies including nanotechnology have been studied to find more effective approaches for sustaining the environment. Nanoparticles, due to unique physiochemical properties; i.e. high mobility, reactivity, high surface area, and particle morphology, have shown a promising solution to promote sustainable agriculture. Crop plants easily take up nanoparticles, which can penetrate into the cells to play essential roles in growth and metabolic events. In addition, different iron- and carbon-based nanocompositions enhance the removal of metals from the contaminated sites and water; these nanoparticles activate the functional groups that potentially target specific molecules of the metal pollutants to obtain efficient remediation. This review article emphasises the recent advancement in the application of nanotechnology for the remediation of contaminated soils with metal pollutants and mitigating different abiotic stresses. Different implementation barriers are also discussed. Furthermore, we reported the opportunities and research directions to promote sustainable development based on the application of nanotechnology.

Nanoparticles regulate redox metabolism in plants during abiotic stress within hormetic boundaries

Abiotic stress management remains under scrutiny because of the unpredictable nature of climate, which undergoes abrupt alterations. Population pressure, loss of cultivable lands, environmental pollution and other anthropogenic disturbances add to the problem and grossly hinder ongoing management strategies. This has driven increasing effort to find better performing, eco-friendly and reliable alternatives that can contribute to sustainable agricultural practices to manage abiotic stress. Nanotechnology and its implementation in agriculture have emerged as a promising option to cater to the problem of abiotic stress. Induction of reactive oxygen species (ROS) is an inevitable phenomenon linked to stress. Nanoparticles (NPs) perform dual actions in regulating ROS biology. The bidirectional roles of NPs in modulating ROS generation and/or ROS detoxification is tightly coupled within the hormetic boundaries. Nonetheless, how these NPs control the ROS metabolism within hormetic limits demands extensive investigation. This review focuses on the details of ROS metabolism under normal versus stressed conditions. It shall elaborate on the types, modes and process of uptake and translocation of NPs. The molecular dissection of the role of NPs in controlling transcriptomic expressions and modulating molecular crosstalks with other growth regulators, ions, reactive nitrogen species and other signalling molecules shall also be detailed. Throughout, this review aims to summarise the potential roles and regulation of NPs and consider how they can be used for green synthesis within a sustainable agricultural industry.

Changes in morphological traits, anatomical and molecular alterations caused by gamma-rays and zinc oxide nanoparticles in spinach (Spinacia oleracea L.) plant

Spinach seeds were irradiated with gamma-rays after that soaked in zinc oxide nanoparticles (ZnO-NPs) at 0.0, 50, 100 and 200 ppm for twenty-four hours at room temperature. Vegetative plant growth, photosynthetic pigments, and proline contents were investigated. Also, anatomical studies and the polymorphism by the SCoT technique were conducted. The present results revealed that the germination percentage was at the maximum values for the treatment of 100 ppm ZnO-NPs (92%), followed by 100 ppm ZnO-NPs + 60 Gy (90%). The application of ZnO-NPs resulted in an enhancement in the plant length. The maximum of chlorophylls and carotenoids content was recorded in the treatment, 100 ppm ZnO-NPs + 60 Gy. Meanwhile, the irradiation dose level (60 Gy) with all ZnO-NPs treatments increased proline content and reached its maximum increase to 1.069 mg/g FW for the treatment 60 Gy combined with 200 ppm ZnO-NPs. Also, the anatomical studies declared that there were variations between the treatments; un-irradiated and irradiated combined with ZnO-NPs plants which reveal that the leave epidermal tissue increased with 200 ppm ZnO-NPs in both the upper and lower epidermis. While irradiated plants with 60 Gy combined with 100 ppm ZnO-NPs gave more thickness of upper epidermis. As well as SCoT molecular marker technique effectively induced molecular alterations between the treatments. Where, SCoT primers targeted many new and missing amplicons that are expected to be associated with the lowly and highly expressed genes with 18.2 and 81.8%, respectively. Also, showed that the soaking in ZnO-NPs was helped for reducing molecular alteration rate, both spontaneous and induced by gamma irradiation. This nominates ZnO-NPs as potential nano-protective agents that can reduce irradiation-induced genetic damage.

Multifactorial role of nanoparticles in alleviating environmental stresses for sustainable crop production and protection

In the era of dire environmental fluctuations, plants undergo several stressors during their life span, which severely impact their development and overall growth in negative aspects. Abiotic stress factors, especially moisture stress i.e shortage (drought) or excess (flooding), salinity, temperature divergence (i.e. heat and cold stress), heavy metal toxicity, etc. create osmotic and ionic imbalance inside the plant cells, which ultimately lead to devastating crop yield, sometimes crop failure. Apart from the array of abiotic stresses, various biotic stress caused by pathogens, insects, and nematodes also affect production. Therefore, to combat these major challenges in order to increase production, several novel strategies have been adapted, among which the use of nanoparticles (NPs) i.e. nanotechnology is becoming an emerging tool in various facets of the current agriculture system, nowadays. This present review will elaborately depict the deployment and mechanisms of different NPs to withstand these biotic and abiotic stresses, along with a brief overview and indication of the future research works to be oriented based on the steps provided for future research in advance NPs application through the sustainable way.

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

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

Alleviation of chromium stress in plants using metal and metal oxide nanoparticles

Chromium (Cr), one of the hazardous pollutants, exists predominantly as Cr(VI) and Cr(III) in the environment. Cr(VI) is more toxic than Cr(III) due to its high mobility and solubility. Elevated levels of Cr in agricultural soil due to various anthropogenic activities cause Cr accumulation in plants, resulting in a significant reduction in plant yield and quality due to Cr-induced physiological, biochemical and molecular alterations. It can infiltrate the food chain through crop plants and cause harmful effects in humans via biomagnification. Cr(VI) is linked to cancer in humans. Therefore, mitigation strategies are required to remediate Cr-polluted soils and limit its accumulation in plants for safe food production. Recent research on metal and metal oxide nanoparticles (NPs) has shown that they can effectively reduce Cr accumulation and phytotoxicity. The effects of these NPs are influenced by their type and dose, exposure method, plant species and experimental settings. In this review, we present an up-to-date compilation and comprehensive analysis of the existing literature regarding the process of uptake and distribution of Cr and impact and potential mechanisms of metal and metal oxide nanoparticles led mitigation of Cr-induced stress in plants. We have also discussed recent developments, existing research gaps and future research directions in the field of Cr stress mitigation by NPs in plants. Overall, this review can provide valuable insights in reducing Cr accumulation and toxicity using metal and metal oxide nanoparticles, thereby promoting safe and sustainable cultivation of food and phytostabilization of Cr-polluted soil.

Advanced bioremediation by an amalgamation of nanotechnology and modern artificial intelligence for efficient restoration of crude petroleum oil-contaminated sites: a prospective study

Crude petroleum oil spillage is becoming a global concern for environmental pollution and poses a severe threat to flora and fauna. Bioremediation is considered a clean, eco-friendly, and cost-effective process to achieve success among the several technologies adopted to mitigate fossil fuel pollution. However, due to the hydrophobic and recalcitrant nature of the oily components, they are not readily bioavailable to the biological components for the remediation process. In the last decade, nanoparticle-based restoration of oil-contaminated, owing to several attractive properties, has gained significant momentum. Thus, intertwining nano- and bioremediation can lead to a suitable technology termed 'nanobioremediation' expected to nullify bioremediation's drawbacks. Furthermore, artificial intelligence (AI), an advanced and sophisticated technique that utilizes digital brains or software to perform different tasks, may radically transfer the bioremediation process to develop an efficient, faster, robust, and more accurate method for rehabilitating oil-contaminated systems. The present review outlines the critical issues associated with the conventional bioremediation process. It analyses the significance of the nanobioremediation process in combination with AI to overcome such drawbacks of a traditional approach for efficiently remedying crude petroleum oil-contaminated sites.

Nanoengineered particles for sustainable crop production: potentials and challenges

Nanoengineered nanoparticles have a significant impact on the morphological, physiology, biochemical, cytogenetic, and reproductive yields of agricultural crops. Metal and metal oxide nanoparticles like Ag, Au, Cu, Zn, Ti, Mg, Mn, Fe, Mo, etc. and ZnO, TiO2, CuO, SiO2, MgO, MnO, Fe2O3 or Fe3O4, etc. that found entry into agricultural land, alter the morphological, biochemical and physiological system of crop plants. And the impacts on these parameters vary based on the type of crop and nanoparticles, doses of nanoparticles and its exposure situation or duration, etc. These nanoparticles have application in agriculture as nanofertilizers, nanopesticides, nanoremediator, nanobiosensor, nanoformulation, phytostress-mediator, etc. The challenges of engineered metal and metal oxide nanoparticles pertaining to soil pollution, phytotoxicity, and safety issue for food chains (human and animal safety) need to be understood in detail. This review provides a general overview of the applications of nanoparticles, their potentials and challenges in agriculture for sustainable crop production.

Silicon nanoparticles: Synthesis, uptake and their role in mitigation of biotic stress

In the current scenario of global warming and climate change, plants face many biotic stresses, which restrain growth, development and productivity. Nanotechnology is gaining precedence over other means to deal with biotic and abiotic constraints for sustainable agriculture. One of nature's most beneficial metalloids, silicon (Si) shows ameliorative effect against environmental challenges. Silicon/Silica nanoparticles (Si/SiO₂NPs) have gained special attention due to their significant chemical and optoelectronic capabilities. Its mesoporous nature, easy availability and least biological toxicity has made it very attractive to researchers. Si/SiO₂NPs can be synthesised by chemical, physical and biological methods and supplied to plants by foliar, soil, or seed priming. Upon uptake and translocation, Si/SiO₂NPs reach their destined cells and cause optimum growth, development and tolerance against environmental stresses as well as pest attack and pathogen infection. Using Si/SiO₂NPs as a supplement can be an eco-friendly and cost-effective option for sustainable agriculture as they facilitate the delivery of nutrients, assist plants to mitigate biotic stress and enhances plant resistance. This review aims to present an overview of the methods of formulation of Si/SiO₂NPs, their application, uptake, translocation and emphasize the role of Si/SiO₂NPs in boosting growth and development of plants as well as their conventional advantage as fertilizers with special consideration on their mitigating effects towards biotic stress.

Responses of two strawberry cultivars to NaCl-induced salt stress under the influence of ZnO nanoparticles

Salinity stress is one of the most serious impacts of climate changes on agriculture production, especially in salt sensitive crop plants, like strawberry. Currently, the utilization of nanomolecules in agriculture is thought to be a useful strategy to compact abiotic and biotic stresses. This study aimed to investigate the effect of zinc oxide nanoparticles (ZnO-NPs) on the in vitro growth, ions uptake, biochemical and anatomical responses of two strawberry cvs (Camarosa and Sweet Charlie) under NaCl-induced salt stress. A 2x3x3 factorial experiment was conducted, with three levels of ZnO-NPs (0, 15 and 30 mg 1-^l) and three levels of NaCl-induced salt stress (0, 35 and 70 mM). The results showed that increased levels of NaCl in the medium had led to decrease in shoot fresh weight and proliferative potential. The cv Camarosa was found to be relatively more tolerant to salt stress. Additionally, salt stress leads to an accumulation of toxic ions (Na + and Cl^-), as well as a decrease in K + uptake. However, application of ZnO-NPs at a concentration of 15 mg 1-^l was found to alleviate these effects by increasing or stabilizing growth traits, decreasing the accumulation of toxic ions and the Na+/K + ratio, and increasing K + uptake. Additionally, this treatment led to elevated levels of catalase (CAT), peroxidase (POD) and proline content. The positive impacts of ZnO-NPs application were reflected on the leaf anatomical features, being better adapted to salt stress. The study highlighted the efficiency of utilizing tissue culture technique in screening of strawberry cultivars for salinity tolerance under the influence of NPs.

Efficacy of ZnO nanoparticles in Zn fortification and partitioning of wheat and rice grains under salt stress

Zinc (Zn) deficiency is a major health concern in developing countries due to dependency on cereal based diet. Cereals are inherently low in Zn and inevitable use of stressed land has further elevated the problem. The aim of current research was to improve wheat and rice grains grain Zn concentration grown in saline soils through zinc oxide nanoparticles (ZnO-NPs) due to their perspective high availability. The ZnO-NPs were prepared by co-precipitation method and characterized through X-ray diffraction (XRD) and Scanning Electron Microscope (SEM). Two separate pot experiments for wheat and rice were conducted to check the relative effectiveness of ZnO-NPs compared to other bulk Zn sources i.e., zinc sulphate heptahydrate (ZnSO₄·7H₂O) and ZnO. Results showed that salt stress negatively impacted the tested parameters. There was a significant (p ≤ 0.05) improvement in growth, salt tolerance, plant Zn uptake and grain Zn concentrations by Zn application through Zn sources. The ZnO-NPs showed maximum improvement in crops parameters as compared to other sources due to their higher uptake and translocation in plants under both normal and stressed soil conditions. Thus, ZnO nanoparticles proved to be more effective for grain Zn fortification in both tested wheat and rice crops under normal and saline conditions.

Nanoparticles assisted regulation of oxidative stress and antioxidant enzyme system in plants under salt stress: A review

The global biomass production from agricultural farmlands is facing severe constraints from abiotic stresses like soil salinization. Salinity-mediated stress triggered the overproduction of reactive oxygen species (ROS) that may result in oxidative burst in cell organelles and cause cell death in plants. ROS production is regulated by the redox homeostasis that helps in the readjustment of the cellular redox and energy state in plants. All these cellular redox related functions may play a decisive role in adaptation and acclimation to salinity stress in plants. The use of nanotechnology like nanoparticles (NPs) in plant physiology has become the new area of interest as they have potential to trigger the various enzymatic and non-enzymatic antioxidant capabilities of plants under varying salinity levels. Moreover, NPs application under salinity is also being favored due to their unique characteristics compared to traditional phytohormones, amino acids, nutrients, and organic osmolytes. Therefore, this article emphasized the core response of plants to acclimate the challenges of salt stress through auxiliary functions of ROS, antioxidant defense system and redox homeostasis. Furthermore, the role of different types of NPs mediated changes in biochemical, proteomic, and genetic expressions of plants under salt stress have been discussed. This article also discussed the potential limitations of NPs adoption in crop production especially under environmental stresses.

Zinc oxide nanoparticles as potential hallmarks for enhancing drought stress tolerance in wheat seedlings

Drought is one of the major abiotic stresses which negatively affects plant growth and development. The current study evaluated the effects of drought on the growth, physiology, and biochemical attributes of wheat seedlings; and examined the role of foliar application of ZnO nanoparticles in alleviating drought-induced effects. Two wheat cultivars i.e., Anaj-2017 and FSD-2018 were grown in soil-filled pots and were subjected to 100% field capacity (FC) (well watered) and 50% of FC (drought stress). Whilst different treatments of ZnO nanoparticles spray included no spray, water spray, and 50, 100, and 150 ppm ZnO. Results demonstrated that drought caused a significant reduction in seedling fresh and dry weights, photosynthetic pigmentation, and antioxidant activities compared with a well-watered treatment. Nevertheless, the application of 100 and 150 ppm of ZnO nanoparticles effectively ameliorated the negative effects of drought and enhanced the performance of both cultivars under drought. Data revealed a significant increase in fresh and dry weight of shoot and root with the application of ZnO nanoparticles. A substantial increase of 73.68% and 28.51% in chlorophyll "a" and 26.15% and 50.02% in chlorophyll "b" was recorded with the application of 100 ppm of ZnO nanoparticles in Anaj-2017 and FSD-2018, respectively over control (0 ppm). The application of these nanoparticles also triggered the antioxidant defense system and protected the crop from oxidative damage. Averaged across different stress treatments, application of 150 and 100 ppm of ZnO nanoparticles increased the peroxidase activity by 60% and 72% in FSD-2018, and 15% and 23% in Anaj-2017, respectively compared with no spray. FSD-2018 outperformed Anaj-2017 regarding its overall performance under ZnO treatments and drought conditions. In a nutshell, it can be concluded that ZnO nanoparticles ameliorated the negative impacts of drought by improving the growth, physiology, and antioxidant defense of both wheat cultivars.

Effect of zinc oxide nanoparticles synthesized from Carya illinoinensis leaf extract on growth and antioxidant properties of mustard (Brassica juncea)

BACKGROUND

The sustainability of crop production is impacted by climate change and land degradation, and the advanced application of nanotechnology is of paramount importance to overcome this challenge. The development of nanomaterials based on essential nutrients like zinc could serve as a basis for nanofertilizers and nanocomposite synthesis for broader agricultural applications and quality human nutrition. Therefore, this study aimed to synthesize zinc oxide nanoparticles (ZnO NPs) using pecan (Carya illinoinensis) leaf extract and investigate their effect on the growth, physiology, nutrient content, and antioxidant properties of mustard (Brassica juncea).

METHODS

The ZnO NPs were characterized by UV-Vis spectrophotometry, Dynamic Light Scattering (DLS), X-ray diffractometer (XRD), Scanning Electron Microscopy (SEM), and Fourier Transform Infra-Red Spectroscopy (FTIR). Mustard plants were subjected to different concentrations of ZnONPs (0, 20, 40, 60, 80, 100 and 200 mg L-1) during the vegetative growth stage.

RESULTS

The UV-Vis spectra of ZnO NPs revealed the absorption maxima at 362 nm and FTIR identified numerous functional groups that are responsible for capping and stabilizing ZnO NPs. DLS analysis presented monodispersed ZnO NPs of 84.5 nm size and highly negative zeta potential (-22.4 mV). Overall, the application of ZnO NPs enhanced the growth, chlorophyll content (by 53 %), relative water content (by 46 %), shoot biomass, membrane stability (by 54 %) and net photosynthesis significantly in a dose-dependent manner. In addition, the supplement of the ZnO NPs augmented K, Fe, Zn and flavonoid contents as well as overcome the effect of reactive oxygen species by increasing antioxidant capacity in mustard leaves up to 97 %.

CONCLUSIONS

In conclusion, ZnO NPs can be potentially used as a plant growth stimulant and as a novel soil amendment for enhancing crop yields. Besides, the biofortification of B. juncea plants with ZnO NPs helps to improve the nutritional quality of the crop and perhaps potentiates its pharmaceutical effects.

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

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

Salicylic acid functionalized zein for improving plant stress resistance and as a nanopesticide carrier with enhanced anti-photolysis ability

BACKGROUND

There is a serious global problem of salinization of arable land, causing large reduction in world food production. Use of plant hormones is an effective way to reduce damage caused to crops and salt stress.

RESULTS

In this study, PEI-EDA was modified with AM-zein and grafted with plant hormone SA (AM-zein-SA) and used as a nano-pesticide carrier to load emamectin benzoate (EB). The use of AM-zein-SA as a nano-pesticide carrier could reduce the damage caused by salt stress to crops. The structure of AM-zein-SA was characterized by FTIR, UV, fluorescence, Raman, and ¹H NMR spectroscopic techniques. AM-zein-SA could effectively improve the resistance of EB to ultraviolet radiations, resistance of cucumber to salt stress, and the absorption of EB by plants. The experimental results showed that AM-zein-SA could effectively improve the anti-UV property of EB by 0.88 fold. When treated with 120 mmol NaCl, the germination rate of cucumber seeds under salt stress increased by 0.93 fold in presence of 6.25 mg/L carrier concentration. The POD and SOD activities increased by 0.50 and 1.21 fold, whereas the content of MDA decreased by 0.23 fold. In conclusion, AM-zein-SA nano-pesticide carrier could be used to improve the salt resistance of crops and the adhesion of pesticides to leaves.

CONCLUSION

AM-zein-SA, without undergoing any changes in its insecticidal activity, could simultaneously improve the salt stress resistance and salt stress germination rate of cucumber, reduce growth inhibition due to stress under high-concentration salt, and had a good effect on crops. In addition, EB@AM-zein-SA obviously improved the upward transmission rate of EB, as compared with EB. In this study, SA was grafted onto zein-based nano-pesticide carrier, which provided a green strategy to control plant diseases, insects, and pests while reducing salt stress on crops in saline-alkali soil.

The Role of Nanoparticles in Response of Plants to Abiotic Stress at Physiological, Biochemical, and Molecular Levels

In recent years, the global agricultural system has been unfavorably impacted by adverse environmental changes. These changes in the climate, in turn, have altered the abiotic conditions of plants, affecting plant growth, physiology and production. Abiotic stress in plants is one of the main obstacles to global agricultural production and food security. Therefore, there is a need for the development of novel approaches to overcome these problems and achieve sustainability. Nanotechnology has emerged as one such novel approach to improve crop production, through the utilization of nanoscale products, such as nanofertilizer, nanofungicides, nanoherbicides and nanopesticides. Their ability to cross cellular barriers makes nanoparticles suitable for their application in agriculture. Since they are easily soluble, smaller, and effective for uptake by plants, nanoparticles are widely used as a modern agricultural tool. The implementation of nanoparticles has been found to be effective in improving the qualitative and quantitative aspects of crop production under various biotic and abiotic stress conditions. This review discusses various abiotic stresses to which plants are susceptible and highlights the importance of the application of nanoparticles in combating abiotic stress, in addition to the major physiological, biochemical and molecular-induced changes that can help plants tolerate stress conditions. It also addresses the potential environmental and health impacts as a result of the extensive use of nanoparticles.

Nanoparticles: The Plant Saviour under Abiotic Stresses

Climate change significantly affects plant growth and productivity by causing different biotic and abiotic stresses to plants. Among the different abiotic stresses, at the top of the list are salinity, drought, temperature extremes, heavy metals and nutrient imbalances, which contribute to large yield losses of crops in various parts of the world, thereby leading to food insecurity issues. In the quest to improve plants' abiotic stress tolerance, many promising techniques are being investigated. These include the use of nanoparticles, which have been shown to have a positive effect on plant performance under stress conditions. Nanoparticles can be used to deliver nutrients to plants, overcome plant diseases and pathogens, and sense and monitor trace elements that are present in soil by absorbing their signals. A better understanding of the mechanisms of nanoparticles that assist plants to cope with abiotic stresses will help towards the development of more long-term strategies against these stresses. However, the intensity of the challenge also warrants more immediate approaches to mitigate these stresses and enhance crop production in the short term. Therefore, this review provides an update of the responses (physiological, biochemical and molecular) of plants affected by nanoparticles under abiotic stress, and potentially effective strategies to enhance production. Taking into consideration all aspects, this review is intended to help researchers from different fields, such as plant science and nanoscience, to better understand possible innovative approaches to deal with abiotic stresses in agriculture.

Role of Nanoparticles in Enhancing Crop Tolerance to Abiotic Stress: A Comprehensive Review

Plants are subjected to a wide range of abiotic stresses, such as heat, cold, drought, salinity, flooding, and heavy metals. Generally, abiotic stresses have adverse impacts on plant growth and development which affects agricultural productivity, causing food security problems, and resulting in economic losses. To reduce the negative effects of environmental stress on crop plants, novel technologies, such as nanotechnology, have emerged. Implementing nanotechnology in modern agriculture can also help improve the efficiency of water usage, prevent plant diseases, ensure food security, reduce environmental pollution, and enhance sustainability. In this regard, nanoparticles (NPs) can help combat nutrient deficiencies, promote stress tolerance, and improve the yield and quality of crops. This can be achieved by stimulating the activity of certain enzymes, increasing the contents (e.g., chlorophyll) and efficiency of photosynthesis, and controlling plant pathogens. The use of nanoscale agrochemicals, including nanopesticides, nanoherbicides, and nanofertilizers, has recently acquired increasing interest as potential plant-enhancing technologies. This review acknowledges the positive impacts of NPs in sustainable agriculture, and highlights their adverse effects on the environment, health, and food chain. Here, the role and scope of NPs as a practical tool to enhance yield and mitigate the detrimental effects of abiotic stresses in crops are described. The future perspective of nanoparticles in agriculture has also been discussed.

Priming with gold nanoparticles leads to changes in the photosynthetic apparatus and improves the cold tolerance of wheat

Nanotechnologies provide a great platform for researching nanoparticles effects on living organisms including plants. This work shows the stimulating effect of seed priming with gold nanoparticles (AuNPs) on photosynthetic apparatus of Triticum aestivum seedlings. It was found using inductively coupled plasma-atomic emission and mass spectrometry that AuNPs (the average diameter of 15.3 nm, concentration of 20 μg ml^-1) penetrated into the seeds, but were not found in seedling leaves. Ultrastructural changes in chloroplasts were found using transmission electron microscopy in plants grown from treated seeds: increases in the size of plastids, starch grains, grana in chloroplasts, and the number of thylakoids in grana. The intensity of photosynthesis, the content of chlorophylls, and the portion of unsaturated fatty acids in the composition of total leaf lipids were increased in treated AuNPs plants. This study demonstrates that revealed changes determined the increased tolerance of wheat to low temperature. The adaptive significance of these changes, possible mechanisms of the AuNPs effects on plants and future perspectives of study are discussed. This is the first report showing nanopriming with AuNPs as a new method to study the mechanisms of stress tolerance.

Zinc Oxide Nanoparticles: Physiological and Biochemical Responses in Barley (Hordeum vulgare L.)

This work aimed to study the toxic implications of zinc oxide nanoparticles (ZnO NPs) on the physio-biochemical responses of spring barley (Hordeum sativum L.). The experiments were designed in a hydroponic system, and H. sativum was treated with two concentrations of ZnO NPs, namely 300 and 2000 mg/L. The findings demonstrated that ZnO NPs prevent the growth of H. sativum through the modulation of the degree of oxidative stress and the metabolism of antioxidant enzymes. The results showed increased malondialdehyde (MDA) by 1.17- and 1.69-fold, proline by 1.03- and 1.09-fold, and catalase (CAT) by 1.4- and 1.6-fold in shoots for ZnO NPs at 300 and 2000 mg/L, respectively. The activity of superoxide dismutase (SOD) increased by 2 and 3.3 times, ascorbate peroxidase (APOX) by 1.2 and 1.3 times, glutathione-s-transferase (GST) by 1.2 and 2.5 times, and glutathione reductase (GR) by 1.8 and 1.3 times in roots at 300 and 2000 mg/L, respectively. However, the level of δ-aminolevulinic acid (ALA) decreased by 1.4 and 1.3 times in roots and by 1.1 times in both treatments (nano-300 and nano-2000), respectively, indicating changes in the chlorophyll metabolic pathway. The outcomes can be utilized to create a plan of action for plants to withstand the stress brought on by the presence of NPs.

Silicon Nanoparticle-Induced Regulation of Carbohydrate Metabolism, Photosynthesis, and ROS Homeostasis in Solanum lycopersicum Subjected to Salinity Stress

Agricultural crops are facing major restraints with the rapid augmentation of global warming, salt being a major factor affecting productivity. Tomato (Solanum lycopersicum) plant has immense nutritional significance; however, it can be negatively influenced by salinity stress. Nanoparticles (NPs) have excellent properties, due to which these particles are used in agriculture to enhance various growth parameters even in the presence of abiotic stresses. The objective of this study was to investigate the effects of silicon NPs (Si-NPs) through root dipping and foliar spray on tomato in the presence/absence of salt stress. Plant root and leaf were used for the measurements of morphological, physiological, and biochemical parameters treated with Si-NPs under salt stress. At 45 days after sowing, the activity of antioxidant enzymes, photosynthesis, mineral concentration, chlorophyll index, and growth attributes of tomato plants were measured. The developmental processes of tomato plants were severely slowed down by salt stress upto 35.8% (shoot dry mass), 44.3% (root dry mass), 51% (shoot length), and 62% (root length), but this reduction was mitigated by the treatment of Si-NPs. Application of Si-NPs significantly increased the growth attributes (height and dry weight), mineral content [magnesium (Mg), potassium (K), copper (Cu), iron (Fe), manganese (Mn), zinc (Zn)], photosynthesis [net photosynthetic rate (P _N), stomatal conductance (gs), transpiration rate (E), internal CO₂ concentration (Ci)], and activity of antioxidative enzymes including superoxide dismutase and catalase in salt stress. Foliar application of Si-NPs in tomato plants appears to be more effective over root dipping and alleviates the salt stress by increasing the plant's antioxidant enzyme activity.

Mitigation of salinity stress in barley genotypes with variable salt tolerance by application of zinc oxide nanoparticles

Salinity has become a major environmental concern of agricultural lands, impairing crop production. The current study aimed to examine the role of zinc oxide nanoparticles (ZnO NPs) in reducing the oxidative stress induced by salinity and the overall improvement in phytochemical properties in barley. A total of nine different barley genotypes were first subjected to salt (NaCl) stress in hydroponic conditions to determine the tolerance among the genotypes. The genotype Annora was found as most sensitive, and the most tolerant genotype was Awaran 02 under salinity stress. In another study, the most sensitive (Annora) and tolerant (Awaran 02) barley genotypes were grown in pots under salinity stress (100 mM). At the same time, half of the pots were provided with the soil application of ZnO NPs (100 mg kg-1), and the other half pots were foliar sprayed with ZnO NPs (100 mg L-1). Salinity stress reduced barley growth in both genotypes compared to control plants. However, greater reduction in barley growth was found in Annora (sensitive genotype) than in Awaran 02 (tolerant genotype). The exogenous application of ZnO NPs ameliorated salt stress and improved barley biomass, photosynthesis, and antioxidant enzyme activities by reducing oxidative damage caused by salt stress. However, this positive effect by ZnO NPs was observed more in Awaran 02 than in Annora genotype. Furthermore, the foliar application of ZnO NPs was more effective than the soil application of ZnO NPs. Findings of the present study revealed that exogenous application of ZnO NPs could be a promising approach to alleviate salt stress in barley genotypes with different levels of salinity tolerance.

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.

Bio-Synthesized Nanoparticles in Developing Plant Abiotic Stress Resilience: A New Boon for Sustainable Approach

Agriculture crop development and production may be hampered in the modern era because of the increasing prevalence of ecological problems around the world. In the last few centuries, plant and agrarian scientific experts have shown significant progress in promoting efficient and eco-friendly approaches for the green synthesis of nanoparticles (NPs), which are noteworthy due to their unique physio-biochemical features as well as their possible role and applications. They are thought to be powerful sensing molecules that regulate a wide range of significant physiological and biochemical processes in plants, from germination to senescence, as well as unique strategies for coping with changing environmental circumstances. This review highlights current knowledge on the plant extract-mediated synthesis of NPs, as well as their significance in reprogramming plant traits and ameliorating abiotic stresses. Nano particles-mediated modulation of phytohormone content in response to abiotic stress is also displayed. Additionally, the applications and limitations of green synthesized NPs in various scientific regimes have also been highlighted.

Nanomaterials coupled with microRNAs for alleviating plant stress: a new opening towards sustainable agriculture

Plant growth and development is influenced by their continuous interaction with the environment. Their cellular machinery is geared to make rapid changes for adjusting the morphology and physiology to withstand the stressful changes in their surroundings. The present scenario of climate change has however intensified the occurrence and duration of stress and this is getting reflected in terms of yield loss. A number of breeding and molecular strategies are being adopted to enhance the performance of plants under abiotic stress conditions. In this context, the use of nanomaterials is gaining momentum. Nanotechnology is a versatile field and its application has been demonstrated in almost all the existing fields of science. In the agriculture sector, the use of nanoparticles is still limited, even though it has been found to increase germination and growth, enhance physiological and biochemical activities and impact gene expression. In this review, we have summarized the use and role of nanomaterial and small non-coding RNAs in crop improvement while highlighting the potential of nanomaterial assisted eco-friendly delivery of small non-coding RNAs as an innovative strategy for mitigating the effect of abiotic stress.

Titanium and Zinc Based Nanomaterials in Agriculture: A Promising Approach to Deal with (A)biotic Stresses?

Abiotic stresses, such as those induced by climatic factors or contaminants, and biotic stresses prompted by phytopathogens and pests inflict tremendous losses in agriculture and are major threats to worldwide food security. In addition, climate changes will exacerbate these factors as well as their negative impact on crops. Drought, salinity, heavy metals, pesticides, and drugs are major environmental problems that need deep attention, and effective and sustainable strategies to mitigate their effects on the environment need to be developed. Besides, sustainable solutions for agrocontrol must be developed as alternatives to conventional agrochemicals. In this sense, nanotechnology offers promising solutions to mitigate environmental stress effects on plants, increasing plant tolerance to the stressor, for the remediation of environmental contaminants, and to protect plants against pathogens. In this review, nano-sized TiO₂ (nTiO₂) and ZnO (nZnO) are scrutinized, and their potential to ameliorate drought, salinity, and xenobiotics effects in plants are emphasized, in addition to their antimicrobial potential for plant disease management. Understanding the level of stress alleviation in plants by these nanomaterials (NM) and relating them with the application conditions/methods is imperative to define the most sustainable and effective approaches to be adopted. Although broad-spectrum reviews exist, this article provides focused information on nTiO₂ and nZnO for improving our understanding of the ameliorative potential that these NM show, addressing the gaps in the literature.

Soil-based nano-graphene oxide and foliar selenium and nano-Fe influence physiological responses of 'Sultana' grape under salinity

Salinity is a worldwide stressor that influences the growth and productivity of plants. Some novel compounds like; graphene oxide and nutrients such as Se and Fe especially as nano form may improve plant responses to the environmental stress factors. The soil-based graphene oxide (0, 50, and 100 g kg⁻¹) and the foliar applications of Se and nano-Fe (control and 3 mg L⁻¹) were assayed on grapevine cv. Sultana under salinity (0, 50, and 100 mM NaCl). The top flavonoids, chlorophyll b, and plant dry weight belonged to graphene oxide and nano-Fe applications. CAT activity was improved in response to Se, nano-Fe, and graphene oxide (50 g kg⁻¹). The least Fe, K, Se, N, Mg, Mn, and Zn content was recorded for 100 mM NaCl. In contrast, the higher data for K, Se, Ca, Mg, Zn and Mn were acquired with graphene oxide × foliar treatments. In general, graphene oxide treatment (50 g kg⁻¹) × nano-Fe and Se foliar use ameliorated the adverse salinity effects with the improved biochemical and physiological responses of Sultana grape.

Nanobionics in Crop Production: An Emerging Approach to Modulate Plant Functionalities

The "Zero Hunger" goal is one of the key Sustainable Development Goals (SDGs) of the United Nations. Therefore, improvements in crop production have always been a prime objective to meet the demands of an ever-growing population. In the last decade, studies have acknowledged the role of photosynthesis augmentation and enhancing nutrient use efficiency (NUE) in improving crop production. Recently, the applications of nanobionics in crop production have given hope with their lucrative properties to interact with the biological system. Nanobionics have significantly been effective in modulating the photosynthesis capacity of plants. It is documented that nanobionics could assist plants by acting as an artificial photosynthetic system to improve photosynthetic capacity, electron transfer in the photosystems, and pigment content, and enhance the absorption of light across the UV-visible spectrum. Smart nanocarriers, such as nanobionics, are capable of delivering the active ingredient nanocarrier upon receiving external stimuli. This can markedly improve NUE, reduce wastage, and improve cost effectiveness. Thus, this review emphasizes the application of nanobionics for improving crop yield by the two above-mentioned approaches. Major concerns and future prospects associated with the use of nanobionics are also deliberated concisely.