Silicon dioxide nanoparticles enhance plant growth, photosynthetic performance, and antioxidants defence machinery through suppressing chromium uptake in Brassica napus L

Advances in silica nanoparticles for agricultural applications and biosynthesis

Nanotechnology has emerged as a revolutionary force in modern agriculture, opening new avenues for crop enhancement and sustainable farming practices. This review systematically evaluates the roles of silica nanoparticles (SiO2 NPs) in agricultural applications, with particular emphasis on their biosynthesis pathways and functional mechanisms. SiO2 NPs have demonstrated considerable potential to enhance crop resilience against both biotic (pathogens, pests) and abiotic (heavy metals, salinity, drought) stresses through phytohormonal regulation, defense gene activation, and metabolic modulation. As nanocarriers, these particles enhance pesticide and fertilizer delivery accuracy, reduce environmental contamination, and promote plant growth. Biosynthesis methods of SiO2 NPs range from conventional physical-chemical techniques to eco-friendly green approaches, including the utilization of biological cells/extracts, natural biomaterials, and peptide templates. Although green synthesis offers sustainability advantages, the agricultural adoption of SiO2 NPs faces critical challenges, such as insufficient understanding of their long-term environmental persistence and ecotoxicological impacts, high production costs related to green synthesis, and incomplete regulatory frameworks. Addressing these challenges is essential to enable their broader use in agriculture.

Enhancing water deficit tolerance in canola (Brassica napus L.) through the synergistic application of nano-silicon and sulfur

Water deficit stress is a critical constraint on global crop productivity, particularly in arid and semi-arid regions, where it severely compromises plant growth, yield, and nutritional quality. Sustainable strategies to enhance plant resilience under such conditions are urgently needed. Nano-silicon (Si-NPs) and sulfur (S) have emerged as promising amendments for mitigating abiotic stress, but their synergistic potential in alleviating water deficit stress in oilseed crops like canola (Brassica napus L.) remains underexplored. This study investigated the combined effects of Si-NPs (0, 100, 200, and 300 mg kg⁻1) and sulfur (0, 75, and 150 mg S kg⁻1) on the morphological, physiological, and nutritional responses of canola under three water deficit levels (0.8, 0.6, and 0.4 field capacity). Results demonstrated that water deficit stress significantly reduced photosynthetic efficiency, biomass accumulation, and yield components. However, Si-NPs and S application counteracted these adverse effects. Specifically, 100 mg Si-NPs kg⁻1 increased shoot and root weights by 19.3% and 22.9%, respectively, compared to the control. The most effective treatment-200 mg Si-NPs kg⁻1 combined with 75 mg S kg⁻1-enhanced chlorophyll (1.76 mg g⁻1 FW), carotenoids (0.51 mg g⁻1 FW), phosphorus uptake (0.85%), and silicon accumulation in shoots (4.3%), while reducing lipid peroxidation (malondialdehyde: 23.53 µg g⁻1 FW). These findings highlight the synergistic role of Si-NPs and S in improving drought resilience by enhancing photosynthetic capacity, nutrient homeostasis, and oxidative stress mitigation. This study provides actionable insights for integrating nano-enabled and sustainable nutrient management practices to bolster crop productivity in water-scarce agroecosystems. Future research should validate these results under field conditions and elucidate the molecular mechanisms driving these stress-adaptive responses.

Role of nanobionics to improve the photosynthetic productivity in plants and algae: an emerging approach

The domain of nanobionics has gained attention since its inception due to its potential applicability in plant, microalgal treatments, productivity enhancement. This review compares the intake and mobilization of nanoparticles (NPs) in plant and algal cell. In plants, NPs enter from root or other openings, and then carried by apoplastic or symplastic transport and accumulated in various parts, whereas in algae, NPs enter via endocytosis, passive transmission pathways, traverse the algal cell cytoplasm. This study demonstrated the mechanisms of metal-based NPs such as zinc (Zn), silver (Ag), iron (Fe), copper (Cu), titanium (Ti), and silica (Si) for seed priming or plant treatments to improve productivity. These metal NPs are used as nano-fertilizer for plant growths. It has also been observed that these NPs can reduce pathogenic infection and help to cope up with environmental stresses including heavy metals contamination such as arsenic (As), cadmium (Cd), chromium (Cr), and lead (Pb). Overall, the photosynthetic productivity increases through NPs as it increases ability to enhance light capture, improve electron transport, and optimize carbon fixation pathways and withstand stresses. These advancements not only elevate biomass production in plant improving agricultural output but also support the sustainable generation of biofuels and bioproducts from algae.

Feasibility of using silica (Na2SiO3 and SiO2NPs) to mitigate mercury in transgenic soybeans grown in contaminated soils and respective effects on nutrient homeostasis

This study aimed to investigate the potential of Silicon (SiO2NPs and Na2SiO3) to mitigate Hg absorption, accumulation, and toxicity in transgenic soybean plants. By analyzing Hg speciation, total Hg content, physiological characteristics, anatomical structures, and the homeostasis of macro (P, S, Ca, K, and Mg) and micro (Cu, Fe, Mn, Zn) nutrients, the impact of Si against Hg-induced stress was assessed. Plants were cultivated under six treatments: water, SiO2NPs, Na2SiO3, Na2SiO3 + HgCl2, SiO2NPs + HgCl2, and HgCl2. The addition of silicon to the soil, both in the form of nanoparticles and in its soluble form, did not negatively impact plant development. SiO2 NPs reduced Hg concentration in roots by 17% (RR) and 29% (INTACTA) and Na2SiO3 by 15% and 37%. In leaves, Hg reductions were 25% with SiO2NPs and 22% with Na2SiO3 for RR variety, while INTACTA showed decreases of 14% and 34%. Only Hg(II) species were found, indicating no Hg methylation in soil or plants. PCA revealed that Hg, alone or with Si, altered nutrient absorption. Morphological analyses showed that SiO2NPs and Na2SiO3 reduced Hg toxicity at the cellular level, highlighting their potential to mitigate heavy metal contamination in crops.

Nanopesticides for managing primary and secondary stored product pests: Current status and future directions

The preservation of agricultural commodities during storage is critical for ensuring food security and minimizing post-harvest losses. Both primary storage pests such as Callosobruchus maculatus, Callosobruchus chinensis, Sitophilus weevils, Rhyzopertha dominica, and Trogoderma granarium, and secondary storage pests like Tribolium castaneum cause significant damage to stored products, resulting in substantial economic losses. Traditional pest control methods, including chemical insecticides, face limitations due to environmental concerns and pest resistance. Consequently, nanoparticle-based insecticides are being extensively suggested as a promising alternative. This review analyzes the available literature on the efficacy of nanoparticles (NPs) against primary and some secondary storage pests. Green synthesis methods using plant extracts and other biological sources are highlighted for the production of environmentally friendly NPs. Studies demonstrate that NPs of alumina, carbon, silica, silver, copper, zinc oxide, nickel oxide, titanium dioxide, nano zeolite, as well as chitosan and polymers exhibit significant insecticidal activity against a variety of pests, in some cases surpassing mortality rates caused by traditional insecticides at recommended dosages. Structural, biochemical and molecular studies reveal that NPs induce oxidative stress, disrupt cellular homeostasis, and cause structural damage in pests. Histopathological evaluations indicate specific organ-related toxicity, emphasizing the need for comprehensive biosafety assessments. Additionally, the integration of NPs with conventional insecticides shows enhanced pest control efficiency, although challenges remain in standardizing synthesis methods and evaluating long-term environmental impacts. This review highlights the potential of NPs in sustainable pest management and underlines the importance of ongoing research to optimize specific formulations for specific groups of pests and ensure safety.

Evaluation of the molecular mechanism underlying proline metabolic and catabolic pathways and some morpho-physiological traits of tobacco (Nicotiana tabacum L.) plants under arsenic stress

BACKGROUND

In recent decades, arsenic (As) toxicity has emerged as a significant challenge in many countries. It not only reduces the growth and performance of plants, but also poses a threat to human health. The synthesis of compatible solutes, particularly proline, is a mechanism plants utilize to cope with stress. Investigating the metabolic pathways of proline would deepen our understanding for future molecular breeding or genetic engineering efforts. Therefore, the aim of this study was to explore the metabolic and catabolic pathways of proline, as well as the morpho-physiological traits of tobacco, under As stress.

RESULTS

The results revealed a significant decrease in morphological traits and photosynthetic efficiency, chlorophyll content, and total soluble protein content with increasing As concentration. The results also showed that proline content, total soluble carbohydrates, hydrogen peroxide, and malondialdehyde, as well as the activity of two antioxidant enzymes, superoxide dismutase and ascorbate peroxidase, increased with increasing As concentration. At 10 mg As Kg-1 soil, the expression of Δ1-pyrroline-carboxylate synthetase (P5CS) and P5C reductase (P5CR) genes was not different from the control, but their expression increased significantly at 20 and 40 mg As Kg-1 soil. At 10 mg As Kg-1 soil, the expression of proline dehydrogenase (PDH) and P5C dehydrogenase (P5CDH) genes decreased sharply compared to the control but remained unchanged at 20 and 40 mg As Kg-1 soil. At 10 and 20 mg As Kg-1 soil, expression of the ornithine δ-aminotransferase (OAT) gene was unchanged compared to the control, but at 40 mg As Kg-1 soil, it increased sharply.

CONCLUSION

The results showed that the accumulation of proline at the lowest (10 mg As Kg-1 soil) tested As concentration was due to a decrease in the expression of proline catabolic genes (PDH and P5CDH), while the genes involved in proline synthesis did not play a role. At 20 mg As Kg-1 soil, proline accumulation was caused by the increased expression of genes (P5CS and P5CR) involved in the glutamate pathway of proline synthesis. Additionally, at the highest concentration of arsenic (40 mg As Kg-1 soil), the OAT gene, which is active in the ornithine pathway, was also involved in proline synthesis, along with the P5CS and P5CR genes.

Iron oxide nanoparticles enhance alkaline stress resilience in bell pepper by modulating photosynthetic capacity, membrane integrity, carbohydrate metabolism, and cellular antioxidant defense

Bell pepper (Capsicum annuum L.) is a commercially important and nutritionally rich vegetable crop in the Solanaceae family. Alkaline stress (AS) can disrupt growth, metabolism, and, particularly, nutritional quality. This study aims to evaluate the role of iron oxide nanoparticles (FeNP) in mitigating AS and enhancing plant growth and metabolic functions by conducting experiments under controlled greenhouse conditions with four main treatments: AS (irrigating plants with alkaline salts mixture solution); FeNP (foliar application of Fe3O4 nanoparticles at 100 mg L-¹); AS + FeNP (integrated treatment of AS and FeNP); and CK (control). The results clearly demonstrated that the AS treatment negatively affects plant biomass, photosynthetic attributes, membrane integrity, carbohydrate metabolism, and the balance of the antioxidant system. Additionally, key phenolic and flavonoid compounds decreased under the AS, indicating a detrimental effect on the plant's secondary metabolites. In contrast, the application of FeNP under the AS not only improved growth and photosynthetic attributes but also enhanced membrane integrity and restored antioxidant balance. This restoration was driven by the accumulation of sugars (glucose, fructose, sucrose) and starch, along with key carbohydrate metabolism enzymes-sucrose phosphate synthase (SPS), sucrose synthase (SuSy), neutral invertase (NI), and vacuolar invertase (VI)-and their associated gene expression. The correlation analysis further revealed a tight regulation of carbohydrate metabolism at both enzymatic and transcript levels in all tissue types, except for SPS in the roots. Furthermore, the AS + FeNP treatment resulted in increased levels of key phenolics (dihydrocapsaicin, capsaicin, p-coumaric acid, sinapic acid, p-OH benzoic acid, p-OH benzaldehyde, and ferulic acid) and flavonoid compounds (dihydroquercetin, naringenin, kaempferol, dihydrokaempferol, and quercetin) compared to the AS treatment, thus suggesting that these secondary metabolites likely contribute to the stabilization of cellular structures and membranes, ultimately supporting improved physiological functions and resilience under stress. In conclusion, the application of FeNP demonstrate potential in enhancing the resilience of bell pepper plants against the AS by improving growth, carbohydrate metabolism, and the levels of secondary metabolites.

Antioxidant Responses in Chromium-Stressed Maize as Influenced by Foliar and Root Applications of Fulvic Acid

Maize (Zea mays L.) faces significant challenges to its growth and productivity from heavy metal stress, particularly Chromium (Cr) stress, which induces reactive oxygen species (ROS) generation and damages photosynthetic tissues. This study aimed to investigate the effects of fulvic acid (FA) application, via foliar spray or root irrigation, on mitigating chromium stress in maize by evaluating its impact on antioxidant activity and growth parameters. Two maize varieties, P3939 and 30Y87, were subjected to chromium stress (CrCl3·6H2O) at concentrations of 300 µM and 100 µM for a duration of 5 weeks. The experiment was conducted in a wire house under natural environmental conditions at the Seed Centre, Institute of Botany, University of the Punjab, Lahore, Pakistan. Physiological assessments included electrolyte leakage, chlorophyll pigment content, malondialdehyde (MDA) levels, and activities of antioxidant enzymes such as catalase (CAT), ascorbate peroxidase (APX), and guaiacol peroxidase (GPX) in maize leaves. Growth parameters were also monitored. The results revealed that chromium stress significantly reduced chlorophyll content and increased oxidative stress, as evidenced by elevated MDA levels and electrolyte leakage. However, FA application notably mitigated these effects: chlorophyll content improved by 15%, and MDA levels decreased significantly. Irrigation with FA was particularly effective, reducing MDA levels by 40% compared to the 300 µM chromium treatment. Furthermore, while chromium stress enhanced antioxidant enzyme activities, FA application further boosted total soluble protein levels and antioxidant enzyme activities under stress conditions. In conclusion, FA application demonstrates potential in improving maize tolerance to heavy metal stress by enhancing the antioxidant defense system and preserving photosynthetic pigments. These findings highlight FA's promise as a practical strategy for mitigating the negative impacts of chromium stress on maize, promoting sustainable agricultural practices in contaminated environments.

Fullerenol nanoparticles and AMF application for optimization of Brassica napus L. resilience to lead toxicity through physio-biochemical and antioxidative modulations

Crop plants are severely affected by heavy metals (HMs), leading to food scarcity and economical loss. Lead (Pb) is outsourced by use of lead-based fertilizers, batteries, mining, smelting and metal processing. It significantly reduces growth, development and yield of crops cultivated on contaminated sites. In this study, the ameliorative role of carbon based fullerenol nanoparticles (FNPs) in combination with Arbuscular Mycorrhizal Fungi (AMF) inoculation was examined in Brassica napus L. grown in Pb contaminated soil. A pot experiment in three-ways completely randomize fashion with three replicates was conducted. For Pb stress, a 200 µM PbCl2 solution was applied at a rate of 1 L per pot. FNPs were applied via foliar spray at a concentration of 3 mM. For AMF inoculation rhizospheric soil was collected from Sorghum bicolor fields and used in this experiment. Results of the study showed that Pb toxicity greatly reduced growth (shoot length; 15%, root length; 25%) of B. napus plants. It lowered photosynthesis (38%) and gas exchange related attributes. Pb contamination caused oxidative stress, evident from elevated level of malondialdehyde (62%), and reactive oxygen species (H2O2; 60%, OH-; 103% and O2•-; 23%). It also triggered the antioxidant defense system of B. napus. These plants also had high Pb metal ions in their root and shoot compared with control. Foliar application of FNPs along with AMF inoculation effectively mitigated oxidative stress caused by Pb via increasing antioxidant enzymes activities. Catalase, peroxidase, superoxide dismutase, ascorbate peroxidase, glutathione reductase, phenylalanine ammonia-lyase and polyphenol peroxidase activities were increased by 37, 19, 96, 200, 47, 117 and 47%, respectively. In conclusion, these treatments modulated photosynthetic machinery, antioxidant defense mechanism and nutrients uptake in B. napus plants to alleviate Pb stress. It is presumed that use of carbon-based nano particles in combination with AMF inoculation could effectively mitigate HMs stress in crop plants grown in contaminated soil.

Seed priming with Fe3O4-SiO2 nanocomposites simultaneously mitigate Cd and Cr stress in spinach (Spinacia oleracea L.): A way forward for sustainable environmental management

Seed priming with a composite of iron oxide (Fe3O4) and silicon dioxide (SiO2) nanoparticles (NPs) is an innovative technique to mitigate cadmium (Cd) and chromium (Cr) uptake in plants from rooting media. The current study explored the impact of seed priming with varying levels of Fe3O4 NPs, SiO2 NPs, and Fe3O4-SiO2 nanocomposites on Cd and Cr absorption and phytotoxicity, metal-induced oxidative stress mitigation, growth and biomass yield of spinach (Spinacia oleracea L.). The results showed that seed priming with the optimum level of 100 mg L-1 of Fe3O4-SiO2 nanocomposites significantly (p ≤ 0.05) increased root dry weight (144 %), shoot dry weight (243 %) and leaf area (34.4 %) compared to the control, primarily by safeguarding plant's photosynthetic machinery, oxidative stress and phytotoxicity of metals. Plants treated with this highest level of Fe3O4-SiO2 nanocomposites exhibited a substantial increase in photosynthetic and gas exchange indices of spinach plants and enhanced activities of superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX) antioxidant enzymes by 45 %, 48 %, and 60 %, respectively. Correspondingly, the relative gene expression levels of SOD, CAT, and APX also rose by 109 %, 181 %, and 137 %, respectively, compared to non-primed plants. This nanocomposite application also boosted the levels of phenolics (28 %), ascorbic acid (68 %), total sugars (129 %), flavonoids (39 %), and anthocyanin (29 %) in spinach leaves, while significantly reducing Cd (34.7 %, 53.4 %) and Cr (20.2 %, 28.8 %) contents in plant roots and shoots, respectively. These findings suggest that seed priming with Fe3O4-SiO2 nanocomposites effectively mitigated the toxic effects of Cd and Cr, enhancing the growth and biomass yield of spinach in Cd and Cr co-contaminated environments, offering a promising sustainable approach for producing metal-free crops.

Biochar and nanoscale silicon synergistically alleviate arsenic toxicity and enhance productivity in chili peppers (Capsicum annuum L.)

Arsenic (As) contamination in agricultural soils threatens crop productivity and food safety. In this study, we examined the efficacy of biochar (BC) and silicon nanoparticles (SiNPs) as environmentally sustainable soil amendments to alleviate As toxicity in chili (Capsicum annuum L.) plants. Our findings revealed that As stress severely inhibited the growth parameters of Capsicum annuum L., and subsequently reduced yield. However, the application of BC and SiNPs into the contaminated soil significantly reversed these negative effects, promoting plant length and biomass, particularly when applied together in a synergistic manner. Arsenic stress led to increased oxidative damage, as evidenced by a 29% increase in leaf malondialdehyde content as compared to the healthy plants. Nevertheless, the synergistic (BC + SiNPs) application effectively modulated antioxidant enzyme activity, resulting in a remarkable 55% and 66% enhancement in the superoxide dismutase and catalase levels, respectively, boosting chili's resistance against oxidative stress. Similarly, BC + SiNPs amendments improved photosynthesis by 52%, stomatal conductance by 39%, soluble sugars by 42%, and proteins by 30% as compared with those of control treatment. Additionally, the combined BC + SiNPs application significantly reduced root As content by 61% and straw As by 37% as compared with the control one. Transmission electron microscopy confirmed that the synergistic use of BC and SiNPs preserved chili leaf ultrastructure, shielding against As-induced damage. Overall, the supplementation of contaminated soil with BC and SiNPs was proved to be a sustainable strategy for mitigating As toxicity in chili peppers, enhancing plant growth, physiology, and yield, and thereby food safety.

Reclamation of co-pyrolyzed dredging sediment as soil cadmium and arsenic immobilization material: Immobilization efficiency, application safety, and underlying mechanisms

The safe management of toxic metal-polluted dredging sediment (DS) is imperative owing to its potential secondary hazards. Herein, the co-pyrolysis product (DS@BC) of polluted DS was creatively applied to immobilize soil Cd and As to achieve DS resource utilization, and the efficiency, safety, and mechanism were investigated. The results revealed that the DS@BC was more effective at reducing soil Cd bioavailability than the DS was (58.9-73.2% vs. 21.8-27.4%), except for the dilution effect, whereas the opposite phenomenon occurred for soil As (25.5-35.7% vs. 35.7-42.8%). The DS@BC immobilization efficiency was dose-dependent for both Cd and As. Soil labile Cd and As were transformed to more stable fractions after DS@BC immobilization. DS@BC immobilization inhibited the transfer of soil Cd and As to Brassica chinensis L. and did not cause excessive accumulation of other toxic metals in the plants. The appropriate addition of the DS@BC (8%) sufficiently alleviated the oxidative stress response of the plants and enhanced their growth. These findings indicate that the DS@BC was safe and effective for soil Cd and As immobilization. DS@BC immobilization decreased the diversity and richness of the rhizosphere soil bacterial community because of the dilution effect. The DS@BC immobilized soil Cd and As via direct adsorption, and indirect increasing soil pH, and regulating the abundance of specific beneficial bacteria (e.g., Bacillus). Therefore, the use of co-pyrolyzed DS as a soil Cd and As immobilization material is a promising resource utilization method for DS. Notably, to verify the long-term effects and safety of DS@BC immobilization, field trials should be conducted to explore the effectiveness and risk of harmful metal release from DS@BC immobilization under real-world conditions.

Nano-Fe3O4: Enhancing the tolerance of Elymus nutans to Cd stress through regulating programmed cell death

Cadmium (Cd) poses a significant threat to plant growth and the environment. Nano-Fe3O4 is effective in alleviating Cd stress in plants. Elymus nutans Griseb. is an important fodder crop on the Qinghai-Tibetan Plateau (QTP). However, the potential mechanism by which nano-Fe3O4 alleviates Cd stress in E. nutans is not well understood. E. nutans were subjected to single Cd, single nano-Fe3O4, and co-treatment with nano-Fe3O4 and Cd, and the effects on morphology, Cd uptake, antioxidant enzyme activity, reactive oxygen species (ROS) levels and programmed cell death (PCD) were studied to clarify the regulatory mechanism of nano-Fe3O4. The results showed that Cd stress significantly decreased the germination percentage and biomass of E. nutans. The photosynthetic pigment content decreased significantly under Cd stress. Cd stress also caused oxidative stress and lipid peroxidation, accumulation of excessive ROS, resulting in PCD, but the effect of nano-Fe3O4 was different. Seed germination, seedling growth, and physiological processes were analyzed to elucidate the regulatory role of nano-Fe3O4 nanoparticles in promoting photosynthesis, reducing Cd accumulation, scavenging ROS, and regulating PCD, to promote seed germination and seedling growth in E. nutans. This report provides a scientific basis for improving the tolerance of Elymus to Cd stress by using nano-Fe3O4.

Immunomodulating melatonin-decorated silica nanoparticles suppress bacterial wilt (Ralstonia solanacearum) in tomato (Solanum lycopersicum L.) through fine-tuning of oxidative signaling and rhizosphere bacterial community

BACKGROUND

Tomato (Solanum lycopersicum L.) production is severely threatened by bacterial wilt, caused by the phytopathogenic bacterium Ralstonia solanacearum. Recently, nano-enabled strategies have shown tremendous potential in crop disease management.

OBJECTIVES

This study investigates the efficacy of biogenic nanoformulations (BNFs), comprising biogenic silica nanoparticles (SiNPs) and melatonin (MT), in controlling bacterial wilt in tomato.

METHODS

SiNPs were synthesized using Zizania latifolia leaves extract. Further, MT containing BNFs were synthesized through the one-pot approach. Nanomaterials were characterized using standard characterization techniques. Greenhouse disease assays were conducted to assess the impact of SiNPs and BNFs on tomato plant immunity and resistance to bacterial wilt.

RESULTS

The SiNPs and BNFs exhibited a spherical morphology, with particle sizes ranging from 13.02 nm to 22.33 nm for the SiNPs and 17.63 nm to 21.79 nm for the BNFs, indicating a relatively uniform size distribution and consistent shape across both materials. Greenhouse experiments revealed that soil application of BNFs outperformed SiNPs, significantly enhancing plant immunity and reducing bacterial wilt incidence by 78.29% in tomato plants by maintaining oxidative stress homeostasis via increasing the activities of antioxidant enzymes such as superoxide dismutase (31.81%), peroxidase (32.9%), catalase (32.65%), and ascorbate peroxidase (47.37%) compared to untreated infected plants. Additionally, BNFs induced disease resistance by enhancing the production of salicylic acid and activating defense-related genes (e.g., SlPAL1, SlICS1, SlNPR1, SlEDS, SlPD4, and SlSARD1) involved in phytohormones signaling in infected tomato plants. High-throughput 16 S rRNA sequencing revealed that BNFs promoted growth of beneficial rhizosphere bacteria (Gemmatimonadaceae, Ramlibacter, Microscillaceae, Anaerolineaceae, Chloroplast and Phormidium) in both healthy and diseased plants, while suppressing R. solanacearum abundance in infected plants.

CONCLUSION

Overall, these findings suggest that BNFs offer a more promising and sustainable approach for managing bacterial wilt disease in tomato plants.

Cerium oxide nanoparticles promoted lateral root formation in Arabidopsis by modulating reactive oxygen species and Ca2+ level

Roots play an important role in plant growth, including providing essential mechanical support, water uptake, and nutrient absorption. Nanomaterials play a positive role in improving plant root development, but there is limited knowledge of how nanomaterials affect lateral root (LR) formation. Poly (acrylic) acid coated nanoceria (cerium oxide nanoparticles, PNC) are commonly used to improve plant stress tolerance due to their ability to scavenge reactive oxygen species (ROS). However, its impact on LR formation remains unclear. In this study, we investigated the effects of PNC on LR formation in Arabidopsis thaliana by monitoring ROS levels and Ca2+ distribution in roots. Our results demonstrate that PNC significantly promote LR formation, increasing LR numbers by 26.2%. Compared to controls, PNC-treated Arabidopsis seedlings exhibited reduced H2 O2 levels by 18.9% in primary roots (PRs) and 40.6% in LRs, as well as decreased O 2 · - levels by 47.7% in PRs and 88.5% in LRs. When compared with control plants, Ca2+ levels were reduced by 35.7% in PRs and 22.7% in LRs of PNC-treated plants. Overall, these results indicate that PNC could enhance LR development by modulating ROS and Ca2+ levels in roots.

Chromium uptake and its impact on antioxidant level, photosynthetic machinery, and related gene expression in Brassica napus cultivars

The development of heavy metals, particularly chromium (Cr)-tolerant crop cultivars, is hampered due to lack of understanding of the mechanisms behind Cr stress tolerance. In this study, two Brassica napus cultivars, ZS758 and ZD622, were compared for Cr stress resistance by using the chlorophyll a fluorescence technique and biochemical characteristics. In both cultivars, Cr stress dramatically decreased PSII and PSI efficiency, biomass accumulation, and antioxidant enzyme levels. Although, cultivar ZS758 showed reduction in oxidative stress by decreasing the production of reactive oxygen species (ROS) in terms of reduced H2O2 and MDA content and increased enzymatic activities of key antioxidants enzymes including SOD, APX, CAT, and POD activities that play a crucial role in the regulation of numerous transcriptional pathways involved in oxidative stress responses. Higher non-photochemical quenching (NPQ) and QY were found in tolerant ZS758 cultivar under Cr stress, indicating that tolerant cultivar had a greater capacity to preserve PSII activity under Cr stress by enhancing heat dissipation as a photo-protective component of NPQ. Lower PSI activity and electron transfer from PSII were confirmed by lower PSI efficiency and higher donor end limitation of PSI in both rapeseed cultivars. The Cr concentration was greater in the ZD622 as compared to ZS758, which affected the mineral nutrients profile and damaged the cellular ultrastructure and related gene expression levels. However, current study suggest that cultivar ZS758 is more resistant to Cr stress than ZD622 due to improved metabolism and structural integrity and Cr stress tolerance that is linked with the increased PSII activity, NPQ, and antioxidant potential; these physiological characteristics can be exploited to select cultivars for Cr stress tolerance.

Oryza glumaepatula and calcium oxide nanoparticles enhanced Cr stress tolerance by maintaining antioxidant defense, chlorophyll and gene expression levels in rice

Chromium (Cr), a potent heavy metal, threatens rice cultivation due to its escalating presence in soil from human activities. Wild rice contains useful genes for phytoremediation; however, it is difficult to use directly for metal mitigation. Here, a single segment substitution line (SSSL), SG001, was developed by crossing O. glumaepatula and Huajingxian74 (HJX) to evaluate the survival ability of plants against Cr. Further, we explored the potential effect of calcium oxide nanoparticles (CaO-NPs) (50 μM) to minimize the toxic effect of Cr (100 μM) in rice cultivars, SG001 and HJX. The findings of this study indicated that Cr toxicity led to increased oxidative stress. This was shown by higher levels of hydrogen peroxide (H2O2), which was increased by 104% in SG001 and 177% in HJX, and malondialdehyde (MDA) increased by 79% in SG001 and 135% in HJX. Furthermore, it also depicted that Cr toxicity considerably declined shoot and root length, shoot and root fresh weight by 30%, 27%, 25%, and 20% in SG001 and 44%, 51%, 42%, and 45% in HJX, respectively. This mitigation was evidenced by decreased Cr contents, increased calcium (Ca) levels in SG001, and the maintenance of chlorophyll, antioxidant defense, and gene expression levels. Moreover, there was a notable reduction in MDA and H2O2, while the defense mechanisms of key antioxidants, including ascorbate peroxidase, superoxide dismutase, glutathione, catalase, and peroxidase were upregulated, along with an increase in soluble protein contents in both rice cultivars after applying CaO-NPs. CaO-NPs effectively restored cellular and subcellular structural integrity and growth in both lines, which had been seriously disrupted by Cr toxicity. Overall, our findings suggest that SG001, in combination with CaO-NPs, could serve as an effective strategy to mitigate Cr toxicity in plants.

Molecular characterization and transcriptional response of Lactuca sativa seedlings to co-exposure to graphene nanoplatelets and titanium dioxide nanoparticles

The widespread use of nanomaterials in agriculture may introduce multiple engineered nanoparticles (ENPs) into the environment, posing a combined risk to crops. However, the precise molecular mechanisms explaining how plant tissues respond to mixtures of individual ENPs remain unclear, despite indications that their combined toxicity differs from the summed toxicity of the individual ENPs. Here, we used a variety of methods including physicochemical, biochemical, and transcriptional analyses to examine the combined effects of graphene nanoplatelets (GNPs) and titanium dioxide nanoparticles (TiO2 NPs) on hydroponically exposed lettuce (Lactuca sativa) seedlings. Results indicated that the presence of GNPs facilitated the accumulation of Ti as TiO2 NPs in the seedling roots. Combined exposure to GNPs and TiO2 NPs caused less severe oxidative damage in the roots compared to individual exposures. Yet, GNPs and TiO2 NPs alone and in combination did not cause oxidative damage in the shoots. RNA sequencing data showed that the mixture of GNPs and TiO2 NPs led to a higher number of differentially expressed genes (DEGs) in the seedlings compared to exposure to the individual ENPs. Moreover, the majority of the DEGs encoding superoxide dismutase displayed heightened expression levels in the seedlings exposed to the combination of GNPs and TiO2 NPs. The level of gene ontology (GO) enrichment in the seedlings exposed to the mixture of GNPs and TiO2 NPs was found to be greater than the level of GO enrichment observed after exposure to isolated GNPs or TiO2 NPs. Furthermore, the signaling pathways, specifically the "MAPK signaling pathway-plant" and "phenylpropanoid biosynthesis," exhibited a close association with oxidative stress. This study has provided valuable insights into the molecular mechanisms underlying plant resistance against multiple ENPs.

Nanoparticle-plant interactions: Physico-chemical characteristics, application strategies, and transmission electron microscopy-based ultrastructural insights, with a focus on stereological research

Ensuring global food security is pressing among challenges like population growth, climate change, soil degradation, and diminishing resources. Meeting the rising food demand while reducing agriculture's environmental impact requires innovative solutions. Nanotechnology, with its potential to revolutionize agriculture, offers novel approaches to these challenges. However, potential risks and regulatory aspects of nanoparticle (NP) utilization in agriculture must be considered to maximize their benefits for human health and the environment. Understanding NP-plant cell interactions is crucial for assessing risks of NP exposure and developing strategies to control NP uptake by treated plants. Insights into NP uptake mechanisms, distribution patterns, subcellular accumulation, and induced alterations in cellular architecture can be effectively drawn using transmission electron microscopy (TEM). TEM allows direct visualization of NPs within plant tissues/cells and their influence on organelles and subcellular structures at high resolution. Moreover, integrating TEM with stereological principles, which has not been previously utilized in NP-plant cell interaction assessments, provides a novel and quantitative framework to assess these interactions. Design-based stereology enhances TEM capability by enabling precise and unbiased quantification of three-dimensional structures from two-dimensional images. This combined approach offers comprehensive data on NP distribution, accumulation, and effects on cellular morphology, providing deeper insights into NP impact on plant physiology and health. This report highlights the efficient use of TEM, enhanced by stereology, in investigating diverse NP-plant tissue/cell interactions. This methodology facilitates detailed visualization of NPs and offers robust quantitative analysis, advancing our understanding of NP behavior in plant systems and their potential implications for agricultural sustainability.

Integrative approach to mitigate chromium toxicity in soil and enhance antioxidant activities in rice (Oryza sativa L.) using magnesium-iron nanocomposite and Staphylococcus aureus strains

Pollutants in soil, particularly chromium (Cr), pose high environmental and health risks due to their persistence, bioavailability, and potential for causing toxicity. Cr impairment in plants act as a deleterious environmental pollutant that enters the food chain and eventually disturbs human health. Current study demonstrated the potential of integrative foliar application of magnesium-iron (Mg + Fe) nanocomposite with Staphylococcus aureus strains to alleviate Cr toxicity in rice (Oryza sativa) crops by improving yield and defense system. Growth and yield traits such as shoot length (15%), root length (17%), shoot fresh weight (14%), shoot dry weight (9%), root fresh weight (23%), root dry weight (7%), number of tillers (33%), number of grains (10%) and spike length (13%) improved by combined application of Mg + Fe (20 mg L-1) nanocomposite and S. aureus strains with Cr (110 mg kg-1), compared to when applied alone. Mutual Mg + Fe and S. aureus strains application augmented the SPAD value (9%), total chlorophyll (11%), a (12%), b (17%), and carotenoids (32%), with Cr (110 mg kg-1), compared to alone. Malondialdehyde (13%), hydrogen peroxide (H2O2) (11%), and electrolyte leakage (7%) were significantly regulated in shoots with combined Mg + Fe and S. aureus strains application with Cr (110 mg kg-1) contrasted to alone. Peroxidase (20%), superoxide dismutase (17%), ascorbate peroxidase (18%), and catalase (20%) were increased in shoots with combined Mg + Fe and S. aureus strains application with Cr (110 mg kg-1) in comparison to alone. The combined application of Mg + Fe (20 mgL-1) nanocomposite and S. aureus strains with Cr (110 mg kg-1) enhanced the macro-micronutrients in shoots compared to alone. Cr accumulation in roots (21%), shoots (25%), and grains (47%) were significantly reduced under Cr (110 mg kg-1) with combined Mg + Fe and S. aureus strains application, compared to alone. Subsequently, applying combined Mg + Fe and S. aureus strains is a sustainable solution to boost crop production under Cr toxicity.

Silicon nanoparticles and indole butyric acid positively regulate the growth performance of Freesia refracta by ameliorating oxidative stress under chromium toxicity

Chromium (Cr) toxicity hampers ornamental crops' growth and post-harvest quality, especially in cut flower plants. Nano-enabled approaches have been developing with phenomenal potential towards improving floricultural crop production under heavy metal-stressed conditions. The current pot experiment aims to explore the ameliorative impact of silicon nanoparticles (Si-NPs; 10 mM) and indole butyric acid (IBA; 20 mM) against Cr stress (0.8 mM) in Freesia refracta. The results showed that Cr stress significantly reduced morphological traits, decreased roots-stems biomass, abridged chlorophyll (14.7%) and carotenoid contents (27.2%), limited gas exchange attributes (intercellular CO2 concentration (Ci) 24.8%, stomatal conductance (gs) 19.3% and photosynthetic rate (A) 28.8%), condensed proline (39.2%) and total protein (40%) contents and reduced vase life (15.3%) of freesia plants by increasing oxidative stress. Contrarily, antioxidant enzyme activities, MDA and H2O2 levels, and Cr concentrations in plant parts were remarkably enhanced in Cr-stressed plants than in the control. However, foliar supplementation of Si-NPs + IBA (combined form) to Cr-stressed plants increased defense mechanism and tolerance as revealed by improved vegetative and reproductive traits, increased biomass, photosynthetic pigments (chlorophyll 30.3%, carotenoid 57.2%) and gaseous exchange attributes (Ci 33.3%, gs 25.6%, A 31.1%), proline (54.5%), total protein (55.1%), and vase life (34.9%) of metal contaminated plants. Similarly, the improvement in the activities of peroxidase, catalase, and superoxide dismutase was recorded by 30.8%, 52.4%, and 60.8%, respectively, compared with Cr-stressed plants. Meanwhile, MDA (54.3%), H2O2 (32.7%) contents, and Cr levels in roots (43.3), in stems (44%), in leaves (52.8%), and in flowers (78.5%), were remarkably reduced due to combine application of Si-NPs + IBA as compared with Cr-stressed nontreated freesia plants. Thus, the hypothesis that the synergistic application of Si-NPs + IBA will be an effective approach in ameliorating Cr stress is authenticated from the results of this experiment. Furthermore, the study will be significant since it will demonstrate how Si-NPs and IBA can work synergistically to combat Cr toxicity, and even when added separately, they can improve growth characteristics both under stressed and un-stressed conditions.

Comparison of soil addition, foliar spraying, seed soaking, and seed dressing of selenium and silicon nanoparticles effects on cadmium reduction in wheat (Triticum turgidum L.)

Wheat cadmium (Cd) contamination is a critical food security issue worldwide, and selenium (Se) and silicon (Si) are widely reported to reduce Cd accumulation in cereal crops. However, few studies have compared the most effective pathway to reduce Cd accumulation in crops using Se nanoparticles (nano-Se), Si nanoparticles (nano-Si), and their mixtures. Here, we investigated the concentrations of Cd in wheat using four application modes: soil addition, foliar spraying, seed soaking, and seed dressing combined with three different materials. The concentration of Cd in wheat grains can be significantly reduced by 31.30-62.99% and 36.96-51.04% through four applications of nano-Se and soil application and seed soaking of nano-Si, respectively. However, all treatments involving mixtures of nano-Si and nano-Se did not show a reduction in Cd concentration. The applications of both nano-Se and nano-Si can enhance antioxidant enzyme systems and regulate Cd-related gene expression to safeguard wheat tissues from Cd stress. Downregulation of the influx transporter from soil to root (TaNramp5) and from root to shoot (TaLCT1), along with the upregulation of the efflux transporter from cytoplasm to vacuole (TaHMA3), contributed to the nano-Si/nano-Se dependent Cd transport and reduced Cd accumulation in wheat grains. Overall, the application of nano-Se instead of nano-Si, and soil addition rather than foliar spraying, seed soaking, and seed dressing, can be efficiently utilized to reduce grain Cd accumulation from Cd-contaminated soils.

Metal and metal oxide nanoparticles-induced reactive oxygen species: Phytotoxicity and detoxification mechanisms in plant cell

Nanotechnology is advancing rapidly in this century and the industrial use of nanoparticles for new applications in the modernization of different industries such as agriculture, electronic, food, energy, environment, healthcare and medicine is growing exponentially. Despite applications of several nanoparticles in different industries, they show harmful effects on biological systems, especially in plants. Various mechanisms for the toxic effects of nanoparticles have already been proposed; however, elevated levels of reactive oxygen species (ROS) molecules including radicals [(e.g., superoxide (O2•‒), peroxyl (HOO•), and hydroxyl (HO•) and non-radicals [(e.g., hydrogen peroxide (H2O2) and singlet oxygen (1O2) is more important. Excessive production/and accumulation of ROS in cells and subsequent induction of oxidative stress disrupts the normal functioning of physiological processes and cellular redox reactions. Some of the consequences of ROS overproduction include peroxidation of lipids, changes in protein structure, DNA strand breaks, mitochondrial damage, and cell death. Key enzymatic antioxidants with ROS scavenging ability comprised of superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), peroxidase (POD), and glutathione reductase (GR), and non-enzymatic antioxidant systems including alpha-tocopherol, flavonoids, phenolic compounds, carotenoids, ascorbate, and glutathione play vital role in detoxification and maintaining plant health by balancing redox reactions and reducing the level of ROS. This review provides compelling evidence that phytotoxicity of nanoparticles, is mainly caused by overproduction of ROS after exposure. In addition, the present review also summarizes the intrinsic detoxification mechanisms in plants in response to nanoparticles accumulation within plant cells.

Modulation of rhizosphere microbial community and metabolites by bio-functionalized nanoscale silicon oxide alleviates cadmium-induced phytotoxicity in bayberry plants

Cadmium (Cd) is an extremely toxic heavy metal that can originate from industrial activities and accumulate in agricultural soils. This study investigates the potential of biologically synthesized silicon oxide nanoparticles (Bio-SiNPs) in alleviating Cd toxicity in bayberry plants. Bio-SiNPs were synthesized using the bacterial strain Chryseobacterium sp. RTN3 and thoroughly characterized using advanced techniques. A pot experiment results demonstrated that Cd stress substantially reduced leaves biomass, photosynthesis efficiency, antioxidant enzyme activity, and induced oxidative damage in bayberry (Myrica rubra) plants. However, Bio-SiNPs application at 200 mg kg-1 significantly enhanced plant biomass, chlorophyll content (26.4 %), net photosynthetic rate (8.6 %), antioxidant enzyme levels, and mitigated reactive oxygen species production under Cd stress. Bio-SiNPs modulated key stress-related phytohormones by increasing salicylic acid (13.2 %) and abscisic acid (13.7 %) contents in plants. Bio-SiNPs augmented Si deposition on root surfaces, preserving normal ultrastructure in leaf cells. Additionally, 16S rRNA gene sequencing demonstrated that Bio-SiNPs treatment favorably reshaped structure and abundance of specific bacterial groups (Proteobacteria, Actinobacteriota, and Acidobacteriota) in the rhizosphere. Notably, Bio-SiNPs application significantly modulated the key metabolites (phenylacetaldehyde, glycitein, maslinic acid and methylmalonic acid) under both normal and Cd stress conditions. Overall, this study highlights that bio-nanoremediation using Bio-SiNPs enhances tolerance to Cd stress in bayberry plants by beneficially modulating biochemical, microbial, and metabolic attributes.

The role and transcriptomic mechanism of cell wall in the mutual antagonized effects between selenium nanoparticles and cadmium in wheat

Selenium nanoparticles (SeNPs) has been reported as a beneficial role in alleviating cadmium (Cd) toxicity in plant. However, underlying molecular mechanisms about SeNPs reducing Cd accumulation and alleviating Cd toxicity in wheat are not well understood. A hydroponic culture was performed to evaluate Cd and Se accumulation, cell wall components, oxidative stress and antioxidative system, and transcriptomic response of wheat seedlings after SeNPs addition under Cd stress. Results showed that SeNPs application notably reduced Cd concentration in root and in shoot by 56.9% and 37.3%, respectively. Additionally, SeNPs prompted Cd distribution in root cell wall by 54.7%, and increased lignin, pectin and hemicellulose contents by regulating cell wall biosynthesis and metabolism-related genes. Further, SeNPs alleviated oxidative stress caused by Cd in wheat through signal transduction pathways. We also observed that Cd addition reduced Se accumulation by downregulating the expression level of aquaporin 7. These results indicated that SeNPs alleviated Cd toxicity and reduced Cd accumulation in wheat, which were associated with the synergetic regulation of cell wall biosynthesis pathway, uptake transporters, and antioxidative system via signaling pathways.

Nanoparticles and root traits: mineral nutrition, stress tolerance and interaction with rhizosphere microbiota

MAIN CONCLUSION

This review article highlights a broader perspective of NPs and plant-root interaction by focusing on their beneficial and deleterious impacts on root system architecture (RSA). The root performs a vital function by securing itself in the soil, absorbing and transporting water and nutrients to facilitate plant growth and productivity. In dicots, the architecture of the root system (RSA) is markedly shaped by the development of the primary root and its branches, showcasing considerable adaptability in response to changes in the environment. For promoting agriculture and combating global food hunger, the use of nanoparticles (NPs) may be an exciting option, for which it is essential to understand the behaviour of plants under NPs exposure. The nature of NPs and their physicochemical characteristics play a significant role in the positive/negative response of roots and shoots. Root morphological features, such as root length, root mass and root development features, may regulated positively/negatively by different types of NPs. In addition, application of NPs may also enhance nutrient transport and soil fertility by the promotion of soil microorganisms including plant growth-promoting rhizobacteria (PGPRs) and also soil enzymes. Interestingly the interaction of nanomaterials (NMs) with rhizospheric bacteria can enhance plant development and soil health. However, some studies also suggested that the increased use of several types of engineered nanoparticles (ENPs) may disrupt the equilibrium of the soil-root interface and unsafe morphogenesis by causing the browning of roots and suppressing the growth of root and soil microbes. Thus, this review article has sought to compile a broader perspective of NPs and plant-root interaction by focusing on their beneficial or deleterious impacts on RSA.

Silicon Dioxide Nanoparticles-Based Amelioration of Cd Toxicity by Regulating Antioxidant Activity and Photosynthetic Parameters in a Line Developed from Wild Rice

An extremely hazardous heavy metal called cadmium (Cd) is frequently released into the soil, causing a considerable reduction in plant productivity and safety. In an effort to reduce the toxicity of Cd, silicon dioxide nanoparticles were chosen because of their capability to react with metallic substances and decrease their adsorption. This study examines the processes that underlie the stress caused by Cd and how SiO2NPs may be able to lessen it through modifying antioxidant defense, oxidative stress, and photosynthesis. A 100 μM concentration of Cd stress was applied to the hydroponically grown wild rice line, and 50 μM of silicon dioxide nanoparticles (SiO2NPs) was given. The study depicted that when 50 μM SiO2NPs was applied, there was a significant decrease in Cd uptake in both roots and shoots by 30.2% and 15.8% under 100 μM Cd stress, respectively. The results illustrated that Cd had a detrimental effect on carotenoid and chlorophyll levels and other growth-related traits. Additionally, it increased the levels of ROS in plants, which reduced the antioxidant capability by 18.8% (SOD), 39.2% (POD), 32.6% (CAT), and 25.01% (GR) in wild rice. Nevertheless, the addition of silicon dioxide nanoparticles reduced oxidative damage and the overall amount of Cd uptake, which lessened the toxicity caused by Cd. Reduced formation of reactive oxygen species (ROS), including MDA and H2O2, and an increased defense system of antioxidants in the plants provided evidence for this. Moreover, SiO2NPs enhanced the Cd resistance, upregulated the genes related to antioxidants and silicon, and reduced metal transporters' expression levels.

Comparative investigation on chemical and green synthesized titanium dioxide nanoparticles against chromium (VI) stress eliciting differential physiological, biochemical, and cellular attributes in Helianthus annuus L

Nanotechnology is a new scientific area that promotes unique concepts to comprehend the optimal mechanics of nanoparticles (NPs) in plants under heavy metal stress. The present investigation focuses on effects of synthetic and green synthesized titanium dioxide nanoparticles (TiO2 NPs and gTiO2 NPs) against Cr(VI). Green TiO2 NPs have been produced from plant leaf extract (Ricinus communis L.). Synthesis was confirmed employing an array of optical spectroscopic and electron microscopic techniques. Chromium strongly accelerated H2O2 and MDA productions by 227 % and 266 % at highest chromium concentration (60 mg/kg of soil), respectively, and also caused DNA damage, and decline in photosynthesis. Additionally, anomalies were observed in stomatal cells with gradual increment in chromium concentrations. Conversely, foliar applications of TiO2 NPs and gTiO2 NPs considerably mitigated chromium stress. Sunflower plants treated with modest amounts of green TiO2 NPs had significantly better growth index compared to chemically synthesized ones. Principal component analysis highlighted the variations among photosynthetic attributes, oxidative stress markers, and antioxidant defense systems. Notably, gTiO2 supplementation to the Cr(VI) strained plants minimized PC3 production which is a rare report so far. Conclusively, gTiO2 NPs have been identified to be promising nano-based nutrition resource for farming applications.

Plant-nano interactions: A new insight of nano-phytotoxicity

Whether nanoparticles (NPs) are boon or bane for society has been a centre of in-depth debate and key consideration in recent times. Exclusive physicochemical properties like small size, large surface area-to-volume ratio, robust catalytic activity, immense surface energy, magnetism and superior biocompatibility make NPs obligatory in many scientific, biomedical and industrial ventures. Nano-enabled products are newer entrants in the present era. To attenuate environmental stress and maximize crop yields, scientists are tempted to introduce NPs as augmented supplements in agriculture. The feasible approaches for NPs delivery are irrigation, foliar spraying or seed priming. Internalization of excessive NPs to plants endorses negative implications at higher trophic levels via biomagnification. The characteristics of NPs (dimensions, type, solubility, surface charge), applied concentration and duration of exposure are prime factors conferring nanotoxicity in plants. Several reports approved NPs persuaded toxicity can precisely mimic abiotic stress effects. The signature effects of nanotoxicity include poor root outgrowth, biomass reduction, oxidative stress evolution, lipid peroxidation, biomolecular damage, perturbed antioxidants, genotoxicity and nutrient imbalance in plants. NPs stress impels mitogen-activated protein kinase signaling cascade and urges stress responsive defence gene expression to counteract stress in plants. Exogenous supplementation of nitric oxide (NO), arbuscular mycorrhizal fungus (AMF), phytohormones, and melatonin (ME) is novel strategy to circumvent nanotoxicity. Briefly, this review appraises plants' physio-biochemical responses and adaptation scenarios to endure NPs stress. As NPs stress represents large-scale contaminants, advanced research is indispensable to avert indiscriminate NPs usage for synchronizing nano-security in multinational markets.

Silicon nanoparticles vs trace elements toxicity: Modus operandi and its omics bases

Phytotoxicity of trace elements (commonly misunderstood as 'heavy metals') includes impairment of functional groups of enzymes, photo-assembly, redox homeostasis, and nutrient status in higher plants. Silicon nanoparticles (SiNPs) can ameliorate trace element toxicity. We discuss SiNPs response against several essential (such as Cu, Ni, Mn, Mo, and Zn) and non-essential (including Cd, Pb, Hg, Al, Cr, Sb, Se, and As) trace elements. SiNPs hinder root uptake and transport of trace elements as the first line of defence. SiNPs charge plant antioxidant defence against trace elements-induced oxidative stress. The enrolment of SiNPs in gene expressions was also noticed on many occasions. These genes are associated with several anatomical and physiological phenomena, such as cell wall composition, photosynthesis, and metal uptake and transport. On this note, we dedicate the later sections of this review to support an enhanced understanding of SiNPs influence on the metabolomic, proteomic, and genomic profile of plants under trace elements toxicity.

Nano-enabled agrochemicals: mitigating heavy metal toxicity and enhancing crop adaptability for sustainable crop production

The primary factors that restrict agricultural productivity and jeopardize human and food safety are heavy metals (HMs), including arsenic, cadmium, lead, and aluminum, which adversely impact crop yields and quality. Plants, in their adaptability, proactively engage in a multitude of intricate processes to counteract the impacts of HM toxicity. These processes orchestrate profound transformations at biomolecular levels, showing the plant's ability to adapt and thrive in adversity. In the past few decades, HM stress tolerance in crops has been successfully addressed through a combination of traditional breeding techniques, cutting-edge genetic engineering methods, and the strategic implementation of marker-dependent breeding approaches. Given the remarkable progress achieved in this domain, it has become imperative to adopt integrated methods that mitigate potential risks and impacts arising from environmental contamination on yields, which is crucial as we endeavor to forge ahead with the establishment of enduring agricultural systems. In this manner, nanotechnology has emerged as a viable field in agricultural sciences. The potential applications are extensive, encompassing the regulation of environmental stressors like toxic metals, improving the efficiency of nutrient consumption and alleviating climate change effects. Integrating nanotechnology and nanomaterials in agrochemicals has successfully mitigated the drawbacks associated with traditional agrochemicals, including challenges like organic solvent pollution, susceptibility to photolysis, and restricted bioavailability. Numerous studies clearly show the immense potential of nanomaterials and nanofertilizers in tackling the acute crisis of HM toxicity in crop production. This review seeks to delve into using NPs as agrochemicals to effectively mitigate HM toxicity and enhance crop resilience, thereby fostering an environmentally friendly and economically viable approach toward sustainable agricultural advancement in the foreseeable future.

Effect of riboflavin on redox balance, osmolyte accumulation, methylglyoxal generation and nutrient acquisition in indian squash (Praecitrullus fistulosus L.) under chromium toxicity

The presence of high chromium (Cr) levels induces the buildup of reactive oxygen species (ROS), resulting in hindered plant development. Riboflavin (vitamin B2) is produced by plants, fungi, and microbes. It serves as a precursor to the coenzymes flavin adenine dinucleotide (FAD) and flavin mononucleotide (FMN), which play a crucial role in cellular metabolism. The objective of this work was to clarify the underlying mechanisms by which riboflavin alleviates Cr stress in Praecitrullus fistulosus L. Further, the role of riboflavin in growth, ions homeostasis, methylglyoxal detoxification, and antioxidant defense mechanism are not well documented in plants under Cr toxicity. We found greater biomass and minimal production of ROS in plants pretreated with riboflavin under Cr stress. Results manifested a clear abridge in growth, chlorophyll content, and nutrient uptake in Indian squash plants exposed to Cr stress. Findings displayed that Cr stress visibly enhanced oxidative injury reflected as higher malondialdehyde (MDA), hydrogen peroxide (H2O2), superoxide radical (O2•‒), methylglyoxal (MG) levels alongside vivid lipoxygenase activity. Riboflavin strengthened antioxidant system, enhanced osmolyte production and improved membrane integrity. Riboflavin diminished Cr accumulation in aerial parts that led to improved nutrient acquisition. Taken together, riboflavin abridged Cr phytotoxic effects by improving redox balance because plants treated with riboflavin had strong antioxidant system that carried out effective ROS detoxification. Riboflavin protected membrane integrity that, in turn, improved nutrient uptake in plants.