Combined effect of Bacillus fortis IAGS 223 and zinc oxide nanoparticles to alleviate cadmium phytotoxicity in Cucumis melo

Hormetic responses to cadmium exposure in wheat seedlings: insights into morphological, physiological, and biochemical adaptations

Cadmium is commonly recognized as toxic to plant growth, low-level Cd has promoting effects on growth performance, which is so-called hormesis. Although Cd toxicity in wheat has been widely investigated, knowledge of growth response to a broad range of Cd concentrations, especially extremely low concentrations, is still unknown. In this study, the morphological, physiological, and biochemical performance of wheat seedlings to a wide range of Cd concentrations (0-100 µΜ) were explored. Low Cd treatment (0.1-0.5 µM) improved wheat biomass and root development by enhancing the photosynthetic system and antioxidant system ability. Photosynthetic rate (Pn) was improved by 5.72% under lower Cd treatment (1 µΜ), but inhibited by 6.05-49.85% from 5 to 100 µΜ. Excessive Cd accumulation induced oxidative injury manifesting higher MDA content, resulting in lower photosynthetic efficiency, stunted growth, and reduction of biomass. Further, the contents of ascorbate, glutathione, non-protein thiols, and phytochelatins were improved under 5-100 µΜ Cd treatment. The ascorbate peroxidase activity in the leaf showed a hormetic dose-response characteristic. Correlation analysis and partial least squares (PLS) results indicated that antioxidant enzymes and metabolites were closely correlated with Cd tolerance and accumulation. The results of the element network, correlation analysis, and PLS showed a crucial role for exogenous Cd levels in K, Fe, Cu, and Mn uptake and accumulation. These results provided a deeper understanding of the hormetic effect of Cd in wheat, which would be beneficial for improving the quality of hazard and risk assessments.

The effect of cadmium on soil and plants, and the influence of Serendipita indica (Piriformospora indica) in mitigating cadmium stress

Due to environmental pollution, the risk of cadmium stress for crops is soaring, so researchers are exploring inexpensive solutions to enhance cultivated crops in contaminated soil. Using microorganisms to reduce cadmium risk has been one of the most effective strategies in recent decades. Serendipita indica (Piriformospora indica) is one of the best endophyte fungi that, in addition to reducing heavy metal stress for crops, can significantly reduce the threat of other abiotic stresses. As part of this research, cadmium in soil has been investigated, as well as its effects on plants' morphophysiological and biochemical characteristics. The present review has also attempted to identify the role of Serendipita indica in improving the growth and performance of crops, as well as its possible effect on reducing the risk of cadmium. The results showed that Serendipita indica enhance the growth and productivity of plants in contaminated environments by improving soil quality, reducing cadmium absorption, improving the activity of antioxidant enzymes and secondary metabolites, raising water and mineral absorption, and altering morphophysiological structures.

Alleviated cadmium toxicity in wheat (Triticum aestivum L.) by the coactive role of zinc oxide nanoparticles and plant growth promoting rhizobacteria on TaEIL1 gene expression, biochemical and physiological changes

Cadmium (Cd) contamination in agricultural soil is a major global concern among the multitude of human health and food security. Zinc oxide nanoparticles (ZnO-NPs) and plant growth promoting rhizobacteria (PGPR) have been known to combat heavy metal toxicity in crops. Herein, the study intended to explore the interactive effect of treatments mediated by inoculation of PGPR and foliar applied ZnO-NPs to alleviate Cd induced phytotoxicity in wheat plants which is rarely investigated. For this purpose, TaEIL1 expression, morpho-physiological, and biochemical traits of wheat were examined. Our results revealed that Cd reduced growth and biomass, disrupted plant physiological and biochemical traits, and further expression patterns of TaEIL1. The foliar application of ZnO-NPs improved growth attributes, photosynthetic pigments, and gas exchange parameters in a dose-additive manner, and this effect was further amplified with a combination of PGPR. The combined application of ZnO-NPs (100 mg L-1) with PGPR considerably increased the catalase (CAT; 52.4%), peroxidase (POD; 57.4%), superoxide dismutase (SOD; 60.1%), ascorbate peroxidase (APX; 47.4%), leading to decreased malondialdehyde (MDA; 47.4%), hydrogen peroxide (H2O2; 38.2%) and electrolyte leakage (EL; 47.3%) under high Cd (20 mg kg-1) stress. Furthermore, results revealed a significant reduction in roots (56.3%), shoots (49.4%), and grains (59.4%) Cd concentration after the Combined treatment of ZnO-NPs and PGPR as compared to the control. Relative expression of TaEIL1 (two homologues) was evaluated under control (Cd 0), Cd, ZnO-NPs, PGPR, and combined treatments. Expression profiling revealed a differential expression pattern of TaEIL1 under different treatments. The expression pattern of TaEIL1 genes was upregulated under Cd stress but downregulated under combined ZnO-NPs and PGPR, revealing its crucial role in Cd stress tolerance. Inferentially, ZnO-NPs and PGPR showed significant potential to alleviate Cd toxicity in wheat by modulating the antioxidant defense system and TaEIL1 expression. By inhibiting Cd uptake, and facilitating their detoxification, this innovative approach ensures food safety and security.

Copper oxide nanoparticles mitigate cadmium toxicity in rice seedlings through multiple physiological mechanisms

Heavy metal pollution poses a serious threat to crops growth and yield. Recently, nanoparticles (NPs) have emerged as a promising strategy to mitigate the negative effect of heavy metal on crop growth. This study investigated the beneficial effects of copper oxide nanoparticles (CuO NPs) on the morphological and physiological-biochemical traits of rice seedlings (Oryza sativa L.) under cadmium (Cd) stress. The results demonstrated that the application of CuO NPs increased the contents of nutrition elements in shoots and roots as well as photosynthetic pigments, consequently improving the growth of rice seedlings under Cd stress, especially at low level of Cd stress. Meanwhile, CuO NPs obviously decreased the Cd accumulation in the rice seedlings and immobilized Cd in less toxic chemical forms and subcellular compartments. Moreover, CuO NPs modulated the antioxidant system, ameliorating oxidative damage and membrane injury caused by Cd. Multivariate analysis established correlations between physio-biochemical parameters and further revealed the mitigation of Cd damage to rice seedlings by CuO NPs was associated with inhibition Cd accumulation, altering Cd chemical form and subcellular distribution, increasing the contents of mineral nutrients, photosynthetic pigments and secondary metabolites and antioxidant enzyme activities, and reducing oxidative damage. Overall, the present study indicated that CuO NPs could effectively reduce the Cd toxicity to rice seedlings, demonstrating their potential application in agricultural production.

An assessment of nanotechnology-based interventions for cleaning up toxic heavy metal/metalloid-contaminated agroecosystems: Potentials and issues

Heavy metals (HMs) are among the most dangerous environmental variables for a variety of life forms, including crops. Accumulation of HMs in consumables and their subsequent transmission to the food web are serious concerns for scientific communities and policy makers. The function of essential plant cellular macromolecules is substantially hampered by HMs, which eventually have a detrimental effect on agricultural yield. Among these HMs, three were considered, i.e., arsenic, cadmium, and chromium, in this review, from agro-ecosystem perspective. Compared with conventional plant growth regulators, the use of nanoparticles (NPs) is a relatively recent, successful, and promising method among the many methods employed to address or alleviate the toxicity of HMs. The ability of NPs to reduce HM mobility in soil, reduce HM availability, enhance the ability of the apoplastic barrier to prevent HM translocation inside the plant, strengthen the plant's antioxidant system by significantly enhancing the activities of many enzymatic and nonenzymatic antioxidants, and increase the generation of specialized metabolites together support the effectiveness of NPs as stress relievers. In this review article, to assess the efficacy of various NP types in ameliorating HM toxicity in plants, we adopted a 'fusion approach', in which a machine learning-based analysis was used to systematically highlight current research trends based on which an extensive literature survey is planned. A holistic assessment of HMs and NMs was subsequently carried out to highlight the future course of action(s).

Application of Zinc Oxide Nanoparticles to Mitigate Cadmium Toxicity: Mechanisms and Future Prospects

Cadmium (Cd), as the most prevalent heavy metal contaminant poses serious risks to plants, humans, and the environment. The ubiquity of this toxic metal is continuously increasing due to the rapid discharge of industrial and mining effluents and the excessive use of chemical fertilizers. Nanoparticles (NPs) have emerged as a novel strategy to alleviate Cd toxicity. Zinc oxide nanoparticles (ZnO-NPs) have become the most important NPs used to mitigate the toxicity of abiotic stresses and improve crop productivity. The plants quickly absorb Cd, which subsequently disrupts plant physiological and biochemical processes and increases the production of reactive oxygen species (ROS), which causes the oxidation of cellular structures and significant growth losses. Besides this, Cd toxicity also disrupts leaf osmotic pressure, nutrient uptake, membrane stability, chlorophyll synthesis, and enzyme activities, leading to a serious reduction in growth and biomass productivity. Though plants possess an excellent defense mechanism to counteract Cd toxicity, this is not enough to counter higher concentrations of Cd toxicity. Applying Zn-NPs has proven to have significant potential in mitigating the toxic effects of Cd. ZnO-NPs improve chlorophyll synthesis, photosynthetic efficiency, membrane stability, nutrient uptake, and gene expression, which can help to counter toxic effects of Cd stress. Additionally, ZnO-NPs also help to reduce Cd absorption and accumulation in plants, and the complex relationship between ZnO-NPs, osmolytes, hormones, and secondary metabolites plays an important role in Cd tolerance. Thus, this review concentrates on exploring the diverse mechanisms by which ZnO nanoparticles can alleviate Cd toxicity in plants. In the end, this review has identified various research gaps that need addressing to ensure the promising future of ZnO-NPs in mitigating Cd toxicity. The findings of this review contribute to gaining a deeper understanding of the role of ZnO-NPs in combating Cd toxicity to promote safer and sustainable crop production by remediating Cd-polluted soils. This also allows for the development of eco-friendly approaches to remediate Cd-polluted soils to improve soil fertility and environmental quality.

Decontamination of Chlorpyrifos Residue in Soil by Using Mentha piperita (Lamiales: Lamiaceae) for Phytoremediation and Two Bacterial Strains

This study utilizes Mentha piperita (MI) for the first time to investigate the uptake and translocation of chlorpyrifos (CPF; 10 µg g-1) from soil, introducing a new approach to improve the efficacy of this technique, which includes using biosurfactants (Bacillus subtilis and Pseudomonas aeruginosa) at 107 CFU/mL to degrade CPF under greenhouse conditions. Moreover, antioxidant enzymes, including superoxide dismutase (SOD) and peroxidase (Prx), and oxidative stress due to hydrogen peroxide (H2O2) and malondialdehyde (MDA) in MI roots and leaves were evaluated under CPF stress. Our results demonstrated that amending soil with MI and B. subtilis followed by P. aeruginosa significantly reduced CPF levels in the soil (p > 0.05) and enhanced CPF concentrations in MI roots and leaves after 1, 3, 7, 10, and 14 days of the experiment. Furthermore, CPF showed its longest half-life (t1/2) in soil contaminated solely with CPF, lasting 15.36 days. Conversely, its shortest half-life occurred in soil contaminated with CPF and treated with MI along with B. subtilis, lasting 4.65 days. Soil contaminated with CPF and treated with MI and P. aeruginosa showed a half-life of 7.98 days. The half-life (t1/2) of CPF-contaminated soil with MI alone was 11.41 days. A batch equilibrium technique showed that B. subtilis is better than P. aeruginosa for eliminating CPF from soil in In vitro experiments. Notably, CPF-polluted soil treated with coadministration of MI and the tested bacteria improved the activities of SOD and Prx and reduced H2O2 and MDA compared with CPF-polluted soil treated with MI alone. Our findings demonstrated that using B. subtilis and P. aeruginosa as biosurfactants to augment phytoremediation represents a commendable strategy for enhancing the remediation of CPF contamination in affected sites while reducing the existence of harmful pesticide remnants in crop plants.

Less is more: A new strategy combining nanomaterials and PGPB to promote plant growth and phytoremediation in contaminated soil

Novel combination strategies of nanomaterials (NMs) and plant growth-promoting bacteria (PGPB) may facilitate soil remediation and plant growth. However, the efficiency of the NM-PGPB combination and interactions among NMs, PGPB, and plants are still largely unknown. We used multiwalled carbon nanotubes (MWCNTs) and zero-valent iron (nZVI) combined with Bacillus sp. PGP5 to enhance the phytoremediation efficiency of Solanum nigrum on heavy metal (HM)-contaminated soil. The NM-PGPB combination showed the best promoting effect on plant growth, which also had synergistic effects on the bioaccumulation of HMs in S. nigrum. The MWCNT-PGP5 combination increased the Cd, Pb, and Zn removal efficiency of S. nigrum by 62.03%, 69.44%, and 61.31%, respectively. The underlining causes of improved plant growth and phytoremediation by NMs-PGPB combination were further elucidated. NM application promoted PGPB survival in soil. Compared with each single application, the combined application minimized disturbance to plant transcription levels and rhizosphere microbial community, resulting in the best performance on soil remediation and plant growth. The NM-PGPB-induced changes in the microbial community and root gene expression were necessary for plant growth promotion. This work reveals the "less is more" advantage of the NM-PGPB combination in soil remediation, providing a new strategy for soil management.

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.

Mechanism and synergistic effect of sulfadiazine (SDZ) and cadmium toxicity in spinach (Spinacia oleracea L.) and its alleviation through zinc fortification

Cadmium (Cd) and antibiotic's tendency to accumulate in edible plant parts and fertile land is a worldwide issue. The combined effect of antibiotics and heavy metals on crops was analyzed, but not mitigation of their toxicity. This study investigated the potential of zinc oxide nanoparticles (ZnO NPs) to alleviate the SDZ and Cd toxicity (alone/combined) to promote spinach growth. Results revealed that the ZnO 200 mg L-1 spray decreased the malondialdehyde (MDA) 14%, hydrogen peroxide (H2O2) 13%, and electrolyte leakage (EL) 7%, and increased the superoxide dismutase (SOD) 8%, peroxidase (POD) 25%, catalase (CAT) 39% and ascorbate peroxidase (APX) 12% in spinach leaves under combined SDZ+Cd (25 mg Kg-1 +50 mg Kg-1) stress compared to ZnO 100 mg L-1 spray. Likewise, ZnO NPs 200 mg L-1 spray enhanced the zinc (Zn) 97%, iron (Fe) 86%, magnesium (Mg) 35%, manganese (Mn) 8%, and potassium (K) 23% in shoots under combined SDZ+Cd (25 mg Kg-1 +50 mg Kg-1) stress compared to ZnO 100 mg L-1 spray. Further, ZnO 200 mg L-1 spray reduced Cd uptake in roots by 9% and shoots 15% under combined SDZ+Cd (25 mg Kg-1 +50 mg Kg-1) stress compared to ZnO 100 mg L-1. Overall, ZnO NPs alleviated the SDZ and Cd toxicity and enhanced spinach growth in all treatments.

ZnO nanoparticles mediated by Azadirachta indica as nano fertilizer: Improvement in physiological and biochemical indices of Zea mays grown in Cr-contaminated soil

The current investigation aimed at evaluating the impact of Azadirachta indica-mediated zinc oxide nanoparticles (Ai-ZnONPs) on the growth and biochemical characteristics of maize (sweet glutinous 3000) under exposure to 50 mg kg-1Ai-ZnONPs with Cr (VI) concentrations of 50 and 100 mg kg-1. The results indicate that plants exposed to Cr (VI) only experienced a decline in growth parameters. Conversely, the inclusion of Ai-ZnONPs caused a noteworthy increase in physiological traits. Specifically, shoot and root fresh weight increased by 28.02% and 16.51%, and 63.11% and 97.91%, respectively, when compared to Cr-50 and 100 treatments. Additionally, the SPAD chlorophyll of the shoot increased by 91.08% and 15.38% compared to Cr-50 and 100 treatments, respectively. Moreover, the antioxidant enzyme traits of plant shoot and root, such as superoxide dismutase (SOD 7.44% and 2.70%, and 4.45% and 3.53%), catalase (CAT 1.18% and 3.20%, and 5.03% and 5.78%), and peroxidase (POD 0.31% and 5.55%, and 4.72% and 3.61%), exhibited significant increases in Cr 50 and 100 treatments, respectively. The addition of Ai-ZnONPs to the soil also enhanced soil nutrient status and reduced Cr (VI) concentrations by 40.69% and 19.82% compared to Cr-50 and 100 treated soils. These findings suggest that Ai-ZnONPs can trigger the activation of biochemical pathways that enable biomass accumulation in meristematic cells. Further investigations are required to elucidate the mechanisms involved in growth promotion.

Efficacy of zinc-based nanoparticles in alleviating the abiotic stress in plants: current knowledge and future perspectives

Due to sessile, plants are unable to avoid unfavorable environmental conditions which leads to inducing serious negative effects on plant growth, crop yield, and food safety. Instead, various approaches were employed to mitigate the phytotoxicity of these emerging contaminants from the soil-plant system. However, recent studies based on the exogenous application of ZnO NPs approve of their important positive potential for alleviating abiotic stress-induced phytotoxicity leads to ensuring global food security. In this review, we have comprehensively discussed the promising role of ZnO NPs as alone or in synergistic interactions with other plant growth regulators (PGRs) in the mitigation of various abiotic stresses, i.e., heavy metals (HMs), drought, salinity, cold and high temperatures from different crops. ZnO NPs have stress-alleviating effects by regulating various functionalities by improving plant growth and development. ZnO NPs are reported to improve plant growth by stimulating diverse alterations at morphological, physiological, biochemical, and ultrastructural levels under abiotic stress factors. We have explained the recent advances and pointed out research gaps in studies conducted in earlier years with future recommendations. Thus, in this review, we have also addressed the opportunities and challenges together with aims to uplift future studies toward effective applications of ZnO NPs in stress management.

Contribution of Serendipita indica on growth improvement, antioxidative capacity of Dracocephalum kotschyi, and its resistance against cadmium stress

Cadmium pollution is a severe issue worldwide which causes an elevated concern in agriculture. The utilization of plant-microbial interactions offers a promising approach for the remediation of cadmium-polluted soils. To elucidate the mechanism of Serendipita indica-mediated cadmium stress tolerance, a potting experiment was conducted to study the impact of S. indica on Dracocephalum kotschyi plants grown under different cadmium concentrations (0, 5, 10, and 20 mg/kg). The effects of cadmium and S. indica on plant growth, antioxidant enzyme activities, and accumulation of cadmium were investigated. The results showed that cadmium stress significantly decreases biomass, photosynthetic pigments, and carbohydrate content concomitantly with increasing antioxidant activities, electrolyte leakage, and hydrogen peroxide, proline, and cadmium content. Inoculation with S. indica alleviated the adverse effect of cadmium stress by enhancing shoot and root dry weight, photosynthetic pigments, and carbohydrate, proline, and catalase activity. Unlike cadmium stress, the presence of fungus led to a reduction in electrolyte leakage and hydrogen peroxide content as well as the content of cadmium in D. kotschyi leaf which mitigates cadmium-induced oxidative stress. Our findings demonstrated S. indica inoculation alleviates the adverse effects of cadmium stress in D. kotschyi plants which could prolong their survival under stressful conditions. Due to the importance of D. kotschyi and the effect of biomass increase on the amount of its medicinal substances, exploiting S. indica not only promotes plant growth, but also may be used as a potential eco-friendly method for relieving the phytotoxicity of Cd and remediating Cd-contaminated soil.

Zinc and nano zinc mediated alleviation of heavy metals and metalloids in plants: an overview

Heavy metals and metalloids (HMs) contamination in the environment has heightened recently due to increasing global concern for food safety and human livability. Zinc (Zn2+ ) is an important nutrient required for the normal development of plants. It is an essential cofactor for the vital enzymes involved in various biological mechanisms of plants. Interestingly, Zn2+ has an additional role in the detoxification of HMs in plants due to its unique biochemical-mediating role in several soil and plant processes. During any exposure to high levels of HMs, the application of Zn2+ would confer greater plant resilience by decreasing oxidative stress, maintaining uptake of nutrients, photosynthesis productivity and optimising osmolytes concentration. Zn2+ also has an important role in ameliorating HMs toxicity by regulating metal uptake through the expression of certain metal transporter genes, targeted chelation and translocation from roots to shoots. This review examined the vital roles of Zn2+ and nano Zn in plants and described their involvement in alleviating HMs toxicity in plants. Moving forward, a broad understanding of uptake, transport, signalling and tolerance mechanisms of Zn2+ /zinc and its nanoparticles in alleviating HMs toxicity of plants will be the first step towards a wider incorporation of Zn2+ into agricultural practices.

Effect and mechanism of nano-materials on plant resistance to cadmium toxicity: A review

Cadmium (Cd), one of the most toxic heavy metals, has been extensively studied by environmental scientists because of its detrimental effects on plants, animals, and humans. Increased industrial activity has led to environmental contamination with Cd. Cadmium can enter the food chain and pose a potential human health risk. Therefore, reducing the accumulation of Cd in plant species and enhancing their detoxification abilities are crucial for remediating heavy metal pollution in contaminated areas. One innovative technique is nano-phytoremediation, which employs nanomaterials ranging from 1 to 100 nm in size to mitigate the accumulation and detrimental effects of Cd on plants. Although extensive research has been conducted on using nanomaterials to mitigate Cd toxicity in plants, it is important to note that the mechanism of action varies depending on factors such as plant species, level of Cd concentration, and type of nanomaterials employed. This review aimed to consolidate and organize existing data, providing a comprehensive overview of the effects and mechanisms of nanomaterials in enhancing plant resistance to Cd. In particular, its deep excavation the mechanisms of detoxification heavy metals of nanomaterials by plants, including regulating Cd uptake and distribution, enhancing antioxidant capacity, regulating gene expression, and regulating physiological metabolism. In addition, this study provides insights into future research directions in this field.

Deciphering the fertilizing and disease suppression potential of phytofabricated zinc oxide nanoparticles on Brassicajuncea

Every year 30-50% of crops suffer from fungal and bacterial diseases. Use of various chemically synthesized fungicides and bactericides make the soil environment more toxic and harmful to the plant health. Therefore, there is need to find non-toxic and cost effective alternative against plant pathogen. In recent years, nanotechnology has got attention because of its wide application in different areas of agriculture. Various nanoparticles have been used in agriculture for their fertilizing and antimicrobial potential. Among them zinc oxide nanoparticles (ZnO NPs) have gained the attention of agriculturists as zinc is an essential micronutrient for plants. Antifungal activity of Tb-ZnO NPs (Terminalia bellerica synthesized zinc oxide nanoparticles) against Alternaria brassicae causative agent of blight disease in Brassica juncea has been reported in our previous study. To use Tb-ZnO NPs as nanofungicides and simultaneously as nanofertilizers, the doses of Tb-ZnO NPs beneficial to the Brassica juncea crop is need to be known. Therefore, experiment has been designed to see the protective and curative potential of Tb-ZnO NPs in alluvial and calcareous soil. Biochemical constituents and stress enzymes analysis has shown significant potential of Tb-ZnO NPs at 200 ppm concentration in alleviating the stress caused by A. brassicae by modulating the photosynthetic, biochemical and enzymatic characteristics. Growth parameter analysis confirmed the role of Tb-ZnO NPs in increasing root and shoot length of B. juncea. Yield component such as seed number, seed weight and oil content of B. juncea crop also has been increased. There was one-fold increase in oil content of B. juncea as compared to control. Maximum percent disease control was found to be 70% in alluvial soil (protective method) grown plants. Therefore, present study supports the hypothesis of a relationship between nutrients and disease suppression.

Cichorium intybus L. is a potential Cd-accumulator for phytoremediation of agricultural soil with strong tolerance and detoxification to Cd

Identifying suitable plants for phytoremediation of Cd (cadmium) contaminated agricultural soil is critical. In this study, whether chicory (Cichorium intybus L.) qualified as an ideal accumulator for phytoremediation was investigated. The hydroponic and pot experiments showed that Cd concentration in chicory leaves exceeded 100 mg kg-1 (BCF >1, TF >1) with 40 mg kg-1 Cd in pot; No significant effects on chicory growth, leaf protein and physiological and biochemical aspects when treated with ≤ 20 μM or 40 mg kg-1 Cd, because chicory could relieve Cd toxicity by increasing activities of photoprotection mechanisms, the reactive oxygen species scavenging system and concentrations of functional groups in plant tissues. In field experiment, 16.2 and 26.6 t ha-1 of chicory leaves was harvested in winter and summer, respectively. The highest Cd concentration in leaves was close to 25.0 mg kg-1 (BCF >1, TF >1) from the acid soil with 0.980 mg kg-1 Cd. Over 320 g ha-1 Cd was extracted from soil by harvesting chicory leaves both in winter and summer, with 9.24% and 12.9% of theoretical phytoremediation efficiency. Therefore, chicory can be as an ideal Cd-accumulator for phytoremediation of slight-to-moderate Cd-contaminated agricultural soil in any season.

Halotolerant plant growth-promoting bacteria, Bacillus pumilus, modulates water status, chlorophyll fluorescence kinetics and antioxidant balance in salt and/or arsenic-exposed wheat

Seed priming is an effective and novel technique and the use of eco-friendly biological agents improves the physiological functioning in the vegetative stage of plants. This procedure ensures productivity and acquired stress resilience in plants against adverse conditions without contaminating the environment. Though the mechanisms of bio-priming-triggered alterations have been widely explained under induvial stress conditions, the interaction of combined stress conditions on the defense system and the functionality of photosynthetic apparatus in the vegetative stage after the inoculation to seeds has not been fully elucidated. After Bacillus pumilus inoculation to wheat seeds (Triticum aestivum), three-week-old plants were hydroponically exposed to the alone and combination of salt (100 mM NaCl) and 200 μM sodium arsenate (Na₂HAsO₄·7H₂O, As) for 72 h. Salinity and As pollutant resulted in a decline in growth, water content, gas exchange parameters, fluorescence kinetics and performance of photosystem II (PSII). On the other hand, the seed inoculation against stress provided the alleviation of relative growth rate (RGR), relative water content (RWC) and chlorophyll fluorescence. These negative impacts were reversed by B. pumilus inoculation. Since there was no effective antioxidant capacity, As and/or salinity caused induction of H₂O₂ accumulation and thiobarbituric acid reactive substances content (TBARS) in wheat leaves. The inoculated leaves had high activity of superoxide dismutase (SOD) under stress. B. pumilis decreased the NaCl-induced toxic H₂O₂ levels by increasing peroxidase (POX) and enzymes/non-enzymes related to ascorbate-glutathione (AsA-GSH) cycle. In the presence of As exposure, the inoculated plants exhibited an induction in CAT activity. On the other hand, for H₂O₂ scavenging, the improvement in the AsA-GSH cycle was observed in bacterium priming plants plus the combined stress treatment. Since B. pumilus inoculation reduced H₂O₂ levels against all stress treatments, lipid peroxidation subsequently decreased in wheat leaves. The findings obtained from our study explained that the seed inoculation with B. pumilus provided an activation in the defense system and protection in growth, water status, and gas exchange regulation in wheat leaves against the combination of salt and As.

Synergistic impact of nanomaterials and plant probiotics in agriculture: A tale of two-way strategy for long-term sustainability

Modern agriculture is primarily focused on the massive production of cereals and other food-based crops in a sustainable manner in order to fulfill the food demands of an ever-increasing global population. However, intensive agricultural practices, rampant use of agrochemicals, and other environmental factors result in soil fertility degradation, environmental pollution, disruption of soil biodiversity, pest resistance, and a decline in crop yields. Thus, experts are shifting their focus to other eco-friendly and safer methods of fertilization in order to ensure agricultural sustainability. Indeed, the importance of plant growth-promoting microorganisms, also determined as "plant probiotics (PPs)," has gained widespread recognition, and their usage as biofertilizers is being actively promoted as a means of mitigating the harmful effects of agrochemicals. As bio-elicitors, PPs promote plant growth and colonize soil or plant tissues when administered in soil, seeds, or plant surface and are used as an alternative means to avoid heavy use of agrochemicals. In the past few years, the use of nanotechnology has also brought a revolution in agriculture due to the application of various nanomaterials (NMs) or nano-based fertilizers to increase crop productivity. Given the beneficial properties of PPs and NMs, these two can be used in tandem to maximize benefits. However, the use of combinations of NMs and PPs, or their synergistic use, is in its infancy but has exhibited better crop-modulating effects in terms of improvement in crop productivity, mitigation of environmental stress (drought, salinity, etc.), restoration of soil fertility, and strengthening of the bioeconomy. In addition, a proper assessment of nanomaterials is necessary before their application, and a safer dose of NMs should be applicable without showing any toxic impact on the environment and soil microbial communities. The combo of NMs and PPs can also be encapsulated within a suitable carrier, and this method aids in the controlled and targeted delivery of entrapped components and also increases the shelf life of PPs. However, this review highlights the functional annotation of the combined impact of NMs and PPs on sustainable agricultural production in an eco-friendly manner.

Fulvic acid mitigates cadmium toxicity-induced damage in cucumber seedlings through the coordinated interaction of antioxidant enzymes, organic acid, and amino acid

Fulvic acid (FA) can significantly alleviate cadmium (Cd) stress, but the specific metabolic response of FA to Cd toxicity is still not clarified. In the present study, we used untargeted metabolomic [gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-mass spectrometry (LC-MS)] analysis to profile cucumber metabolism in response to Cd stress after spray application of FA. Our results showed that 331 differentially enriched metabolites (DEMs) were identified in leaf materials. These DEMs were enriched in 21 shared pathways in comparative groups of "Cd treatment vs. the control treatment" and "FA + Cd treatment vs. the Cd treatment." Specifically, treatment with FA significantly enhanced the organic acid content (citric acid, isocitric acid, 2-oxoglutaric acid, fumaric acid, and malic acid), which would contribute to provide sufficient substrates for the tricarboxylic acid (TCA) cycle and amino acid biosynthesis, thereby ensuring the normal production of energy and amino acid. At the same time, FA significantly increased the amino acid content (aspartate, citrulline, histidine, leucine, and phenylalanine). The accumulation of organic acid and amino acid can act as chelating agents for heavy metal ions and as scavengers of reactive oxygen species (ROS), thereby reducing intracellular oxidative damage. Furthermore, the application of FA improves antioxidant enzymes and accelerates ROS clearance. The improved contents of organic acid and amino acid, and the increased activity of antioxidant enzymes both played a central role in the reduction of malondialdehyde (MDA, 14.08%), hydrogen peroxide (H₂O₂, 61.70%) contents, and superoxide anion radical (O₂^-, 30.41%) production rate in plants under Cd stress. Taken together, the present study demonstrates the effects of FA on the antioxidant capacity and carbohydrate and amino acid metabolism of cucumber seedlings exposed to Cd stress, which provides comprehensive insights into the regulation of plants' response to Cd toxicity with FA was applied in cucumber.

Bionanotechnology in Agriculture: A One Health Approach

Healthy eating habits are one of the requirements for the health of society. In particular, in natura foods are increasingly encouraged, since they have a high concentration of nutrients. However, these foods are often grown in the presence of agrochemicals, such as fertilizers and pesticides. To increase crop productivity and achieve high vigor standards in less time, farmers make excessive use of agrochemicals that generate various economic, environmental, and clinical problems. In this way, bionanotechnology appears as an ally in developing technologies to improve planting conditions, ranging from the health of farmers and consumers to the production of new foods and functional foods. All these improvements are based on the better use of land use in synergy with the lowest generation of environmental impacts and the health of living beings, with a view to the study and production of technologies that take into account the concept of One Health in its processes and products. In this review article, we will address how caring for agriculture can directly influence the quality of the most desired foods in contemporary society, and how new alternatives based on nanotechnology can point to efficient and safe solutions for living beings on our planet.

Potassium silicate and zinc oxide nanoparticles modulate antioxidant system, membranous H+-ATPase and nitric oxide content in faba bean (Vicia faba) seedlings exposed to arsenic toxicity

Current research focused on the potential role of zinc oxide nanoparticles (ZnONPs) and potassium (K+ ) in mitigation of arsenic (As) toxicity in Vicia faba L. seedlings. Faba bean seedlings were grown for 30days in potted soil. As stress curtailed root and shoot length, chlorophyll (Chl) content and net photosynthetic rate in V. faba seedlings. However, ZnONPs and K+ curtailed As stress in faba bean seedling through enhanced activity of superoxide dismutase (SOD), ascorbate peroxidase (APX), catalase (CAT) and peroxidase (POD) enzyme. Furthermore, ZnONPs and K+ significantly enhanced cysteine (Cys) content and serine acetyletransferase (SAT) activity in faba bean seedling exposed to As-toxificated soil. Application of ZnONPs and K+ curtailed superoxide ionic content and hydrogen peroxide (H2 O2 ) accumulation in V. faba seedlings exposed to As-polluted soil. Nitric oxide (NO) content also increased in faba bean seedlings treated with ZnONPs and K+ in normal and As-polluted soil. As stress alleviation was credited to reduce As uptake in faba bean seedlings treated with synergistic application of ZnONPs and K+ . It is proposed that K+ interaction with nanoparticles can be exploited at molecular level to understand the mechanisms involved in abiotic stress tolerance.

Effect of soil texture and zinc oxide nanoparticles on growth and accumulation of cadmium by wheat: a life cycle study

Cadmium (Cd) is getting worldwide attention due to its continuous accumulation in agricultural soils which is due to anthropogenic activities and finally Cd enters in food chain mainly through edible plants. Cadmium free food production on contaminated soils is great challenge which requires some innovative measures for crop production on such soils. The current study evaluated the efficiency of zinc oxide nanoparticles (ZnONPs) (0, 150 and 300 mg/kg) on the growth of wheat in texturally different soils including clay loam (CL), sandy clay loam (SCL), and sandy loam (SL) which were contaminated with were contaminated with 25 mg/kg of Cd before crop growth. Results depicted that doses of ZnONPs and soil textures significantly affected the biological yields, Zn and Cd uptake in wheat plants. The application of 300 mg/kg ZnONPs caused maximum increase in dry weights of shoot (66.6%), roots (58.5%), husk (137.8%) and grains (137.8%) in CL soil. The AB-DTPA extractable Zn was increased while Cd was decreased with doses of NPs depending upon soil textures. The maximum decrease in AB-DTPA extractable Cd was recorded in 300 mg/kg of ZnONPs treatment which was 58.7% in CL, 33.2% in SCL and 12.1% in SL soil as compared to respective controls. Minimum Cd concentrations in roots, shoots, husk and grain were found in 300 mg/kg ZnONPs amended CL soil which was 58%, 76.7%, 58%, and 82.6%, respectively. The minimum bioaccumulation factor (0.14), translocation index (2.46) and health risk index (0.05) was found in CL soil with the highest dose of NPs. The results concluded that use of ZnONPs significantly decreased Cd concentration while increased Zn concentrations in plants depending upon doses of NPs and soil textures.

Ameliorating Drought Effects in Wheat Using an Exclusive or Co-Applied Rhizobacteria and ZnO Nanoparticles

Drought is a major abiotic factor and affects cereal-based staple food production and reliability in developing countries such as Pakistan. To ensure a sustainable and consistent food supply, holistic production plans involving the integration of several drought mitigation approaches are required. Using a randomized complete block design strategy, we examined the drought-ameliorating characteristics of plant growth-promoting rhizobacteria (PGPR) and nanoparticles (NPs) exclusively or as a combined application (T4) through three stages (D1, D2, and D3) of wheat growth (T1, control). Our field research revealed that Azospirillum brasilense alone (T2) and zinc oxide NPs (T3) improved wheat plant water relations, chlorophyll, proline, phenolics and grain quality, yield, and their allied traits over the stressed treatments. Specifically, the best outcome was observed in the combined treatment of PGPR and ZnO NPs (T4). Interestingly, the combined treatment delivered effective drought mitigation through enhanced levels of antioxidants (15% APX, 27% POD, 35% CAT, 38% PPO and 44% SOD) over controls at the grain-filling stage (GFS, D3 × T1). The 40% improvements were recorded under the combined treatment at GFS over their respective controls. Their combined usage (PGPR and ZnO NPs) was concluded as an effective strategy for building wheat resilience under drought, especially in arid and semi-arid localities.

Plant growth-promoting actinobacterial inoculant assisted phytoremediation increases cadmium uptake in Sorghum bicolor under drought and heat stresses

In this study, two proficient Cadmium (Cd) resistant and plant growth-promoting actinobacterial strains were isolated from metal-polluted soils and identified as Streptomyces sp. strain RA04 and Nocardiopsis sp. strain RA07. Multiple abiotic stress tolerances were found in these two actinobacterial strains, including Cd stress (CdS), drought stress (DS) and high-temperature stress (HTS). Both actinobacterial strains exhibited multifarious plant growth-promoting (PGP) traits such as phosphate solubilization, and production of indole-3-acetic acid, siderophores and 1-aminocyclopropane-1-carboxylate deaminase under CdS, DS and HTS conditions. The inoculation of strains RA04 and RA07 significantly increased Sorghum bicolor growth and photosynthetic pigments under CdS, DS, HTS, CdS + DS and CdS + HTS conditions as compared to their respective uninoculated plants. The actinobacterial inoculants reduced malondialdehyde concentration and enhanced antioxidant enzymes in plants cultivated under various abiotic stress conditions, indicating that actinobacterial inoculants reduced oxidative damage. Furthermore, strains RA04 and RA07 enhanced the accumulation of Cd in plant tissues and the translocation of Cd from root to shoot under CdS, CdS + DS and CdS + HTS treatments as compared to their respective uninoculated plants. These findings suggest that RA04 and RA07 strains could be effective bio-inoculants to accelerate phytoremediation of Cd polluted soil even in DS and HTS conditions.

Plant Growth-Promoting Rhizobacteria Eliminate the Effect of Drought Stress in Plants: A Review

Plants evolve diverse mechanisms to eliminate the drastic effect of biotic and abiotic stresses. Drought is the most hazardous abiotic stress causing huge losses to crop yield worldwide. Osmotic stress decreases relative water and chlorophyll content and increases the accumulation of osmolytes, epicuticular wax content, antioxidant enzymatic activities, reactive oxygen species, secondary metabolites, membrane lipid peroxidation, and abscisic acid. Plant growth-promoting rhizobacteria (PGPR) eliminate the effect of drought stress by altering root morphology, regulating the stress-responsive genes, producing phytohormones, osmolytes, siderophores, volatile organic compounds, and exopolysaccharides, and improving the 1-aminocyclopropane-1-carboxylate deaminase activities. The use of PGPR is an alternative approach to traditional breeding and biotechnology for enhancing crop productivity. Hence, that can promote drought tolerance in important agricultural crops and could be used to minimize crop losses under limited water conditions. This review deals with recent progress on the use of PGPR to eliminate the harmful effects of drought stress in traditional agriculture crops.

Combined Effect of Zinc Oxide Nanoparticles and Bacteria on Osmolytes and Antioxidative Parameters of Rice (Oryza sativa L.) Plant Grown in Heavy Metal-Contaminated Water

With the advancement in nanotechnology, the use of nanoparticles has been enhanced dramatically in biomedical, agriculture, and industrial processes. However, the combined effect of nanoparticles and bacteria on plant growth in heavy metal (Cd, Cr, Cu, and Pb)-contaminated wastewater is greatly limited. Therefore, the recent work was designed to determine the synergistic impact of green synthesized zinc oxide nanoparticles (ZnO-NPs) (5-10 mg/L) and Bacillus spp. (Bacillus cereus and Lysinibacillus macroides) on the physiological and biochemical activities of rice seedlings under heavy metal- (HM-) contaminated water. The results revealed that germination percentage (36%), root-shoot length (5.11 and 3.41 cm), fresh shoot-root weight (0.05 and 0.011 g), dry shoot-root weight (0.008 and 0.009 g), Chl a, Chl b, and carotenoid (5.4, 3.2 mg/g, and 4.3 μg/g), total soluble sugar (TSS) (26.44 mg/g), and total soluble protein (TSP) (21.99 mg/g) content considerably reduced in the plant tissues while combined impact of bacteria and ZnO NPs alleviates HM stress in contaminated water and improved seed germination (70%), root-shoot length (9.93 and 11.82 cm), fresh shoot-root weight (0.125 and 0.131 g), dry shoot-root weight (0.0532 and 0.042 g), Chl a, Chl b, and carotenoid (18.8, 13.9 mg/g, and 17.1 μg/g), TSS (57.651 mg/g), and TSP (47.990 mg/g) content. Lipid peroxidation induced by HM stress increased the amount of thiobarbituric acid reactive substances (TBRAS) (17.321 nM/mg) and hydrogen peroxide (H2O2) content (14.5 μM/g), stress markers such as glycine betaine (GB) (40.731 mg/g) and proline (Pro) (38.812 μmol/g) and antioxidant enzymes (SOD, POD, CAT, and APX) (180.87 U/mg, 450.677, 0.1066, and 0.631 μm/min/mg) under HM stress while the combined effect of ZnO NPs and bacteria reduced TBRAS (5.431 nM/mg), H2O2 content (2.25 μM/g), stress markers such as GB (24.731 mg/g) and Pro (18.811 μmol/g), and SOD, POD, CAT, and APX (187.53, 194.88, 0.061, and 0.271 μm/min/mg) contents. The present study suggested a potential role of combined impact of nanoparticles and bacteria in remediation of heavy metals from wastewater by improving plant growth.

Effects of water-soluble chitosan on Hylotelephium spectabile and soybean growth, as well as Cd uptake and phytoextraction efficiency in a co-planting cultivation system

Intercropping a Cd-accumulator with economically valuable crops is common in slightly or moderately Cd-polluted farmland soils. A field experiment was conducted to evaluate the effects of water-soluble chitosan (WSC) on the growth and Cd uptake of the Cd-accumulator Hylotelephium spectabile and soybean (Glycine max) during a co-cultivation in Cd-contaminated agricultural soil (WSC, 0 and 10 g·m-2). The results indicated that soybean yields were highest in response to the intercropping and WSC treatment. The results from the field trials generally showed that intercropping and WSC treatments significantly decreased Cd concentrations in inedible parts of soybean by 42.9-72.1% (except for stems), in the meantime, increased 95.8%-334.6% in shoot and root tissues of H. spectabile compared with the control (p < 0.05). The data revealed that Cd uptake was highest for H. spectabile during the intercropping and WSC treatment. The application of WSC in the intercropping system significantly increased the uptake of Cd by H. spectabile, but not by soybean. The findings of this study suggest that combining an intercropping system with a WSC treatment may be better for remediating Cd-contaminated soils than other methods involving the growth of a single hyperaccumulator.

Application of zinc oxide nanoparticles immobilizes the chromium uptake in rice plants by regulating the physiological, biochemical and cellular attributes

Zinc oxide nano particles (ZnO NPs) have been employed as a novel strategy to regulate plant tolerance and alleviate heavy metal stress, but our scanty knowledge regarding the systematic role of ZnO NPs to ameliorate chromium (Cr) stress especially in rice necessitates an in-depth investigation. An experiment was performed to evaluate the effect of different concentrations of ZnO NPs (e.g., 0, 25, 50, 100 mg/L) in ameliorating the Cr toxicity and accumulation in rice seedlings in hydroponic system. Our results demonstrated that Cr (100 µM) severely inhibited the rice seedling growth, whereas exogenous treatment of ZnO NPs significantly alleviated Cr toxicity stress and promoted the plant growth. Moreover, application of ZnO NPs significantly augmented the germination energy, germination percentage, germination index, and vigor index. In addition, biomass accumulation, antioxidants (SOD, CAT, POD), nutrient acquisition (Zn, Fe) was also improved in ZnO NPs-treated plants, while the lipid peroxidation (MDA, H₂O₂), electrolyte leakage as well as Cr uptake and in-planta accumulation was significantly decreased. The burgeoning effects were more apparent at ZnO NPs (100 mg/L) suggesting the optimum treatment to ameliorate Cr induced oxidative stress in rice plants. Furthermore, the treatment of ZnO NPs (100 mg/L) reduced the level of endogenous abscisic acid (ABA) and stimulated the growth regulator hormones such as brassinosteroids (BRs) possibly linked with enhanced phytochelatins (PCs) levels. The ultrastructure analysis at cellular level of rice revealed that the application of 100 mg/L ZnO NPs protected the chloroplast integrity and other cell organells via improvement in plant ionomics, antioxidant activities and down regulating Cr induced oxidative stress in rice plants. Conclusively, observations of the current study will be helpful in developing stratigies to decrease Cr contamination in food chain by employing ZnO NPs and to mitigate the drastic effects of Cr in plants for the sustainable crop growth.

Ameliorative effects of plant growth promoting bacteria, zinc oxide nanoparticles and oxalic acid on Luffa acutangula grown on arsenic enriched soil

Arsenic (As) contamination and bioaccumulation are a serious threat to agricultural plants. To address this issue, we checked the efficacy of As tolerant plant growth promoting bacteria (PGPB), zinc oxide nanoparticles (ZnO NPs) and oxalic acid (OA) in Luffa acutangula grown on As rich soil. The selected most As tolerant PGPB i.e Providencia vermicola exhibited plant growth promoting features i.e solubilzation of phosphate, potassium and siderophores production. Innovatively, we observed the synergistic effects of P. vermicola, ZnO NPs (10 ppm) and OA (100 ppm) in L. acutangula grown on As enriched soil (150 ppm). Our treatments both as alone and in combination alleviated As toxicity exhibited by better plant growth and metabolism. Results revealed significantly enhanced photosynthetic pigments, proline, relative water content, total sugars, proteins and indole acetic acid along with As amelioration in L. acutangula. Furthermore, upregulated plant resistance was manifested with marked reduction in the lipid peroxidation and electrolyte leakage and pronounced antagonism of As and zinc content in leaves under toxic conditions. These treatments also improved level of nutrients, abscisic acid and antioxidants to mitigate As toxicity. This marked improvement in plants' defense mechanism of treated plants under As stress is confirmed by less damaged leaves cell structures observed through the scanning electron micrographs. We also found substantial decrease in the As bioaccumulation in the L. acutangula shoots and roots by 40 and 58% respectively under the co-application of P. vermicola, ZnO NPs and OA in comparison with control. Moreover, the better activity of soil phosphatase and invertase was assessed under the effect of our application. These results cast a new light on the application of P. vermicola, ZnO NPs and OA in both separate and combined form as a feasible and ecofriendly tool to alleviate As stress in L. acutangula.

Foliar Application of Leaf Extracts of Glycyrrhiza uralensis Increases Growth and Nutritional Value of Chinese Flowering Cabbage Plants under Field Conditions

This study was conducted to explore the effects of ethanolic extracts of leaves of Glycyrrhiza uralensis on the growth and nutritional quality of Chinese flowering cabbage (Brassica rapa subsp. parachinensis) under field conditions. Preliminary greenhouse experiments were carried out with different concentrations of G. uralensis extracts to select the suitable dose for field studies. An extract concentration of 12.5 g/L was selected based on relative growth rate analysis and increase in photosynthetic pigment biosynthesis. Shoot length, shoot fresh weight and dry weight, number of leaves, and marketable value of Chinese flowering cabbage plants were significantly increased in the field trials with foliar application of G. uralensis leaves extracts at a concentration of 12.5 g/L. This biotic elicitor also enhanced the total phenolic and flavonoid contents, with optimal values increasing by 18.76% and 22.43%, respectively, compared with the control under field conditions. The total glucosinolate content was effectively increased (from 11.21 to 15.37 μmol·g−1 DW sinigrin equivalents), particularly 4-methoxyglucobrassicin (from 4.31 to 6.72 μmol·g−1 DW sinigrin equivalents) and glucoalyssin (from 0.14 to 0.19 μmol·g−1 DW sinigrin equivalents) compared with the control plants in field trials. Overall, foliar application of leaf extracts of G. uralensis can markedly increase the growth of Chinese flowering cabbage and enhance its medicinal and nutritional quality in the fields.

Improvement of Plant Responses by Nanobiofertilizer: A Step towards Sustainable Agriculture

Drastic changes in the climate and ecosystem due to natural or anthropogenic activities have severely affected crop production globally. This concern has raised the need to develop environmentally friendly and cost-effective strategies, particularly for keeping pace with the demands of the growing population. The use of nanobiofertilizers in agriculture opens a new chapter in the sustainable production of crops. The application of nanoparticles improves the growth and stress tolerance in plants. Inoculation of biofertilizers is another strategy explored in agriculture. The combination of nanoparticles and biofertilizers produces nanobiofertilizers, which are cost-effective and more potent and eco-friendly than nanoparticles or biofertilizers alone. Nanobiofertilizers consist of biofertilizers encapsulated in nanoparticles. Biofertilizers are the preparations of plant-based carriers having beneficial microbial cells, while nanoparticles are microscopic (1-100 nm) particles that possess numerous advantages. Silicon, zinc, copper, iron, and silver are the commonly used nanoparticles for the formulation of nanobiofertilizer. The green synthesis of these nanoparticles enhances their performance and characteristics. The use of nanobiofertilizers is more effective than other traditional strategies. They also perform their role better than the common salts previously used in agriculture to enhance the production of crops. Nanobiofertilizer gives better and more long-lasting results as compared to traditional chemical fertilizers. It improves the structure and function of soil and the morphological, physiological, biochemical, and yield attributes of plants. The formation and application of nanobiofertilizer is a practical step toward smart fertilizer that enhances growth and augments the yield of crops. The literature on the formulation and application of nanobiofertilizer at the field level is scarce. This product requires attention, as it can reduce the use of chemical fertilizer and make the soil and crops healthy. This review highlights the formulation and application of nanobiofertilizer on various plant species and explains how nanobiofertilizer improves the growth and development of plants. It covers the role and status of nanobiofertilizer in agriculture. The limitations of and future strategies for formulating effective nanobiofertilizer are mentioned.

Synergistic application of silver nanoparticles and indole acetic acid alleviate cadmium induced stress and improve growth of Daucus carota L

Cadmium (Cd) is one of the major hazardous elements that is very toxic to the health of both human and plants. The toxicity of Cd causes plants to suffer by disabling their overall physiological mechanisms. Therefore, present study was intended to investigate the synergistic role of AgNPs and IAA in improving the resilience against Cd toxicity and underlaying physiological and biochemical mechanisms in carrot (Daucus carota L.) plants. Also, the existence of genotypic variation for Cd tolerance in D. carota was also studied. The results revealed that Cd stress decreased plant growth attributes like root diameter, root length, root weight, shoot weight, shoot length, leaves fresh weight and leaves dry weight. Nonetheless, AgNPs and IAA mitigated Cd stress by detoxifying reactive oxygen species (ROS). Additionally, the application of AgNPs and IAA boosted plant growth through reducing the level of malondialdehyde (MDA). Enhancement in the activity of phenol synthesizing and oxidizing enzymes including peroxidase, polyphenol oxidase and phenylalanine ammonia-lyase was also observed by application of AgNPs and IAA. The increased activities of antioxidant enzymes including POX, PPO and PAL by the combined application of AgNPs and IAA advocate stress ameliorative role against Cd stress in plants. The enhanced Cd content was detected in the roots as compared to shoots of treated plants. Pre breed 22 was found as a Cd tolerant genotype.

Efficacy of citric acid chelate and Bacillus sp. in amelioration of cadmium and chromium toxicity in wheat

Heavy metals contamination in agricultural soil is a major issue having drastic effects on plants and human health. To solve this issue, we have formulated and tested a new approach of fusion of inorganic (citric acid chelate) and organic (Bacillus sp.) amelioration methods for heavy metals. The Bacillus sp. was heavy metal tolerant and showed plant growth-promoting characteristics including phosphate solubilization, siderophore production, hydrogen cyanide production, indole acetic acid production, and 1-Aminocyclopropane-1-carboxylate deaminase production. The analysis of data showed that plants receiving the combined application of citric acid (CA) chelate and Bacillus sp. mitigated heavy metal toxicity. They augmented the biomass production and amount of photosynthetic pigments in plant cells. They suppressed the negative effects of Cadmium (Cd) and Chromium (Cr) on plants' metabolic systems. A considerable increase was also observed in the activity of enzymatic and non-enzymatic antioxidants which reduced the damaging effects of reactive oxygen species and maintained internal structures of cells. The decrease in the content of Cr and Cd in wheat grains by the treatment of CA chelate and Bacillus sp. was 51%, and 27% respectively. The bioaccumulation of metals was also reduced to 49% (Cr) and 57% (Cd). This approach can be tested and applied in field conditions for soils with heavy metals contamination.

Therapeutic Applications of Curcumin in Diabetes: A Review and Perspective

Diabetes is a metabolic disease with multifactorial causes which requires lifelong drug therapy as well as lifestyle changes. There is now growing scientific evidence to support the effectiveness of the use of herbal supplements in the prevention and control of diabetes. Curcumin is one of the most studied bioactive components of traditional medicine, but its physicochemical characteristics are represented by low solubility, poor absorption, and low efficacy. Nanotechnology-based pharmaceutical formulations can help overcome the problems of reduced bioavailability of curcumin and increase its antidiabetic effects. The objectives of this review were to review the effects of nanocurcumin on DM and to search for databases such as PubMed/MEDLINE and ScienceDirect. The results showed that the antidiabetic activity of nanocurcumin is due to complex pharmacological mechanisms by reducing the characteristic hyperglycemia of DM. In light of these results, nanocurcumin may be considered as potential agent in the pharmacotherapeutic management of patients with diabetes.

The combined toxicity and mechanism of multi-walled carbon nanotubes and nano zinc oxide toward the cabbage

The natural environment is a complex system, and there is never only one kind of nanomaterial entering the environment. However, many studies only considered the plant toxicity of one kind of nanomaterial and do not consider the influence of two or more kinds of nanomaterials on plant toxicity. Multi-walled carbon nanotubes (MWCNTs) and zinc oxide nanoparticles (ZnO NPs) are two common and widely used nanomaterials in water environment, so these two kinds of nanomaterials were chosen to explore the effects of their combined toxicity on cabbage. This study investigated the toxicity of MWCNTs combined with ZnO NPs on cabbage by measuring the length of roots and stems, chlorophyll content, oxidative stress, antioxidant enzyme activity, metal element content, and root scanning electron microscopy. The toxicity of single MWCNTs toward cabbage was attributed to direct oxidative damage, while the toxicity of single ZnO NPs toward cabbage was due to the high level of zinc concentration. Moreover, ZnO NPs (10 mg/L) ameliorated MWCNTs toxicity toward cabbage by improving the activity of antioxidant enzymes. ZnO NPs (50 and 100 mg/L) because of the high content of zinc disrupted the balance of other metals in the plant and increased the toxicity of MWCNTs. In conclusion, the combined toxicity of different concentrations and types of nanomaterials should be considered for a more accurate assessment of environmental risks.

Recent Advancements and Development in Nano-Enabled Agriculture for Improving Abiotic Stress Tolerance in Plants

Abiotic stresses, such as heavy metals (HMs), drought, salinity and water logging, are the foremost limiting factors that adversely affect the plant growth and crop productivity worldwide. The plants respond to such stresses by activating a series of intricate mechanisms that subsequently alter the morpho-physiological and biochemical processes. Over the past few decades, abiotic stresses in plants have been managed through marker-assisted breeding, conventional breeding, and genetic engineering approaches. With technological advancement, efficient strategies are required to cope with the harmful effects of abiotic environmental constraints to develop sustainable agriculture systems of crop production. Recently, nanotechnology has emerged as an attractive area of study with potential applications in the agricultural science, including mitigating the impacts of climate change, increasing nutrient utilization efficiency and abiotic stress management. Nanoparticles (NPs), as nanofertilizers, have gained significant attention due to their high surface area to volume ratio, eco-friendly nature, low cost, unique physicochemical properties, and improved plant productivity. Several studies have revealed the potential role of NPs in abiotic stress management. This review aims to emphasize the role of NPs in managing abiotic stresses and growth promotion to develop a cost-effective and environment friendly strategy for the future agricultural sustainability.

Tandem application of endophytic fungus Serendipita indica and phosphorus synergistically recuperate arsenic induced stress in rice

In the context of eco-sustainable acquisition of food security, arsenic (As) acts as a deterring factor, which easily infiltrates our food chain via plant uptake. Therefore, devising climate-smart strategies becomes exigent for minimizing the imposed risks. Pertinently, Serendipita indica (S. indica) is well reputed for its post-symbiotic stress alleviatory and phyto-promotive potential. Management of phosphorus (P) is acclaimed for mitigating arsenic toxicity in plants by inhibiting the uptake of As molecules due to the competitive cationic exchange in the rhizosphere. The current study was designed to investigate the tandem effects of S. indica and P in combating As toxicity employing two rice genotypes, i.e., Guodao-6 (GD-6; As-sensitive genotype) and Zhongzhe You-1 (ZZY-1; As-tolerant genotype). After successful fungal colonization, alone and combined arsenic (10  μ M L^-1) and phosphorus (50  μ M L^-1) treatments were applied. Results displayed that the recuperating effects of combined S. indica and P treatment were indeed much profound than their alone treatments; however, most of the beneficial influences were harnessed by ZZY-1 in comparison with GD-6. Distinct genotypic differences were observed for antioxidant enzyme activities, which were induced slightly higher in S. indica-colonized ZZY-1 plants, with or without additional P, as compared to GD-6. Ultrastructure images of root and shoot exhibited ravages of As in the form of chloroplasts-, nuclei-and cell wall-damage with enlarged vacuole area, mellowed mostly by the combined treatment of S. indica and P in both genotypes. Gene expression of PHTs family transporters was regulated at different levels in almost all treatments across genotypes. Conclusively, the results of this study validated the promising role of S. indica and additional P in mitigating As stress, albeit corroborated that the extent of relevant benefit exploitation is highly genotype-dependent. Verily, unlocking the potential of nature-friendly solutions will mend the anthropogenic damage already been done to our environment.

Phenology forcing model to estimate phenology shifting ability of extreme environmental events

The current study considered the climate extreme index (CEI) values originated from extreme environmental events (EEEs) by following the National Oceanic and Atmospheric Administration (NOAA) guidelines. The EEEs were fractionated into six sub-categories (i.e., high temperature, low temperature, high precipitation, low precipitation, drought, and wind), and the combined impact of CEIs was utilized to develop an algorithm for the estimation of the phenology sensitivity index (P _Si ). Finally, the CEIs, and the P _Si were undergone the development of the phenology forcing (P^F ) model. The developed model showed a high sensitivity at the CEI value of as low as ≥1.0. Furthermore, the uncertainty index varied between 0.03 and 0.07, making a parabolic curvature at increasing CEIs (1.0-15.0). The current study precisely estimates the tendency of EEEs for phenology change. It will assist in policy-making and planning crop cultivation plans for achieving sustainable development goal 2 (SDG2) of the Food and Agriculture Organization (FAO).

Calcium Nanoparticles Impregnated With Benzenedicarboxylic Acid: A New Approach to Alleviate Combined Stress of DDT and Cadmium in Brassica alboglabra by Modulating Bioacummulation, Antioxidative Machinery and Osmoregulators

At present, the alleviation of stress caused by climate change and environmental contaminants is a crucial issue. Dichlorodiphenyltrichloroethane (DDT) is a persistent organic pollutant (POP) and an organochlorine, which causes significant health problems in humans. The stress caused by cadmium (Cd) and the toxicity of DDT have direct effects on the growth and yield of crop plants. Ultimately, the greater uptake and accumulation of DDT by edible plants affects human health by contaminating the food chain. The possible solution to this challenging situation is to limit the passive absorption of POPs into the plants. Calcium (Ca) is an essential life component mandatory for plant growth and survival. This study used impregnated Ca (Bd_Ca) of benzenedicarboxylic acid (Bd) to relieve abiotic stress in plants of Brassica alboglabra. Bd_Ca mitigated the deleterious effects of Cd and reduced DDT bioaccumulation. By increasing the removal efficacy (RE) up to 256.14%, Bd_Ca greatly decreased pollutant uptake (Cd 82.37% and DDT 93.64%) and supported photosynthetic machinery (86.22%) and antioxidant enzyme defenses (264.73%), in applied plants. Exogenously applied Bd also successfully improved the antioxidant system and the physiochemical parameters of plants. However, impregnation with Ca further enhanced plant tolerance to stress. This novel study revealed that the combined application of Ca and Bd could effectively relieve individual and combined Cd stress and DDT toxicity in B. alboglabra.

Revealing plant growth-promoting mechanisms of Bacillus strains in elevating rice growth and its interaction with salt stress

Soil salinity is a major environmental stress that has been negatively affecting the growth and productivity of rice. However, various salt-resistant plant growth-promoting rhizobacteria (PGPR) have been known to promote plant growth and alleviate the damaging effects of salt stress via mitigating physio-biochemical and molecular characteristics. This study was conducted to examine the salt stress potential of Bacillus strains identified from harsh environments of the Qinghai-Tibetan plateau region of China. The Bacillus strains NMTD17, GBSW22, and FZB42 were screened for their response under different salt stress conditions (1, 4, 7, 9, 11, 13, and 16%). The screening analysis revealed strains NMTD17, GBSW22, and FZB42 to be high-salt tolerant, moderate-salt tolerant, and salt-sensitive, respectively. The NMTD17 strain produced a strong biofilm, followed by GBSW22 and FZB42. The expression of salt stress-related genes in selected strains was also analyzed through qPCR in various salt concentrations. Further, the Bacillus strains were used in pot experiments to study their growth-promoting ability and antioxidant activities at various concentrations (0, 100, 150, and 200 mmol). The analysis of growth-promoting traits in rice exhibited that NMTD17 had a highly significant effect and GSBW22 had a moderately significant effect in comparison with FZB42. The highly resistant strain NMTD17 that stably promoted rice plant growth was further examined for its function in the composition of rhizobacterial communities. The inoculation of NMTD17 increased the relative abundance and richness of rhizobacterial species. These outcomes propose that NMTD17 possesses the potential of PGPR traits, antioxidants enzyme activities, and reshaping the rhizobacterial community that together mitigate the harmful effects of salinity in rice plants.

Physio-ultrastructural footprints and iTRAQ-based proteomic approach unravel the role of Piriformospora indica-colonization in counteracting cadmium toxicity in rice

Due to its immense capability to concentrate in rice grain and ultimately in food chain, cadmium (Cd) has become the cause of an elevated concern among agriculturists, scientists and the environmental activists. Symbiotic association of Piriformospora indica (P. indica) has been characterized as a potential aid in combating heavy metal stress in plants for sustainable crop production but our scant knowledge regarding ameliorative tendency of P. indica against Cd, specifically in rice, necessitates an in-depth investigation. This study aimed at elaborating the underlying mechanisms involved in P. indica-mediated tolerance against Cd stress in two rice genotypes, IR8 and ZX1H, varying in Cd accumulation pattern. Either colonized or un-inoculated with P. indica, seedlings of both genotypes were subjected to Cd stress. The results showed that P. indica colonization significantly supported plant biomass, photosynthetic attributes and chlorophyll contents in Cd stressed plants. P. indica colonization sustained chloroplast integrity and reduced Cd translocation (46% and 64%), significantly lowering malondialdehyde (MDA) content (11.3% and 50.4%) compared to uninoculated roots under Cd stress in IR8 and ZX1H, respectively. A genotypic difference was evident when a 2-fold enhancement in root peroxidase (POD) activity was recorded in P. indica colonized IR8 plants as compared to ZX1H. The root proteomic analysis was performed using isobaric tags for relative and absolute quantification (iTRAQ) and the results showed that P. indica alleviates Cd stress in rice via down-regulation of key glycolysis cycle enzymes in a bid to reduce energy consumption by the plants and possibly re-directing it to Cd defense response pathways; and up-regulation of glutamine synthetase, a key enzyme in the L-Arg-dependent pathway for nitric oxide (NO) production, which acts as a stress signaling molecule, thus conferring tolerance by reduction of NO-mediated modification of essential proteins in response to Cd stress. Conclusively, both the tested genotypes benefited from P. indica symbiosis at varying levels by an enhanced detoxification capacity and signaling efficiency in response to stress. Hence, a step forward towards the employment of an environmentally sound and self-renewing approach holding the hope for a healthy future.

Effect of Foliar Fertigation of Chitosan Nanoparticles on Cadmium Accumulation and Toxicity in Solanum lycopersicum

Simple Summary

The experiment conducted on Solanum lycopersicum provided an insight about Cd uptake, and the way a Solanum lycopersicum changes its physiological, biochemical and morphological responses when CTS-NPs are administered against Cd. As an effective important polymer, CTS-NPs enhanced the plant biomass, SPAD index, photosynthetic rate, and protein content in the Solanum lycopersicum plants grown in Cd stress, as a study herein. Addition of CTS-NPs reduced Cd accumulation by increasing the nutrient uptake. Furthermore, CTS-NPs treatment enhances tolerance to Cd stress through hampering ROS production accompanied by H₂O₂ activity, through reducing the peroxidation of lipids by minimizing MDA content, and through improving enzymatic (CAT, POX, SOD), non-enzymatic (GSH and AsA), and osmoprotectants (proline) antioxidant contents that are considered as a first line of defense to protect plants from stress.

Abstract

Cadmium (Cd) stress is increasing at a high pace and is polluting the agricultural land. As a result, it affects animals and the human population via entering into the food chain. The aim of this work is to evaluate the possibility of amelioration of Cd stress through chitosan nanoparticles (CTS-NPs). After 15 days of sowing (DAS), Solanum lycopersicum seedlings were transplanted into maintained pots (20 in number). Cadmium (0.8 mM) was providing in the soil as CdCl₂·2.5H₂O at the time of transplanting; however, CTS-NPs (100 µg/mL) were given through foliar spray at 25 DAS. Data procured from the present experiment suggests that Cd toxicity considerably reduces the plant morphology, chlorophyll fluorescence, in addition to photosynthetic efficiency, antioxidant enzyme activity and protein content. However, foliar application of CTS-NPs was effective in increasing the shoot dry weight (38%), net photosynthetic rate (45%) and SPAD index (40%), while a decrease in malondialdehyde (24%) and hydrogen peroxide (20%) was observed at the 30 DAS stage as compared to control plants. On behalf of the current results, it is demonstrated that foliar treatment of CTS-NPs might be an efficient approach to ameliorate the toxic effects of Cd.