Selenium nanoparticles stimulate growth, physiology, and gene expression to alleviate salt stress in Melissa officinalis

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.

Nanowonders in agriculture: Unveiling the potential of nanoparticles to boost crop resilience to salinity stress

Soil salinization significantly affects crop production by reducing crop quality and decreasing yields. Climate change can intensify salinity-related challenges, making the task of achieving global food security more complex. To address the problem of elevated salinity stress in crops, nanoparticles (NPs) have emerged as a promising solution. NPs, characterized by their small size and extensive surface area, exhibit remarkable functionality and reactivity. Various types of NPs, including metal and metal oxide NPs, carbon-based NPs, polymer-based NPs, and modified NPs, have displayed potential for mitigating salinity stress in plants. However, the effectiveness of NPs application in alleviating plant stress is dependent upon multiple factors, such as NPs size, exposure duration, plant species, particle composition, and prevailing environmental conditions. Moreover, alterations to NPs surfaces through functionalization and coating also play a role in influencing plant tolerance to salinity stress. NPs can influence cellular processes by impacting signal transduction and gene expression. They counteract reactive oxygen species (ROS), regulate the water balance, enhance photosynthesis and nutrient uptake and promote plant growth and yield. The objective of this review is to discuss the positive impacts of diverse NPs on alleviating salinity stress within plants. The intricate mechanisms through which NPs accomplish this mitigation are also discussed. Furthermore, this review addresses existing research gaps, recent breakthroughs, and prospective avenues for utilizing NPs to combat salinity stress.

Foliar-applied iron and zinc nanoparticles improved plant growth, phenolic compounds, essential oil yield, and rosmarinic acid production of lemon balm (Melissa officinalis L.)

Metallic nanoparticles (NPs) have been highlighted to improve plant growth and development in the recent years. Although positive effects of some NPs have been reported on medicinal plants, the knowledge for stimulations application of iron (Fe) and zinc (Zn) NPs is not available. Hence, the present work aimed to discover the effects of Fe NPs at 10, 20, and 30 mg L-1 and Zn NPs at 60 and 120 mg L-1 on growth, water content, photosynthesis pigments, phenolic content, essential oil (EO) quality, and rosmarinic acid (RA) production of lemon balm (Melissa officinalis L.). The results showed that Fe NPs at 20 and 30 mg L-1 and Zn NPs at 120 mg L-1 significantly improved biochemical attributes. Compared with control plants, the interaction of Fe NPs at 30 mg-1 and Zn NPs at 120 mg L-1 led to noticeable increases in shoot weight (72%), root weight (92%), chlorophyll (Chl) a (74%), Chl b (47%), RA (66%), proline (81%), glycine betaine (GB, 231%), protein (286%), relative water content (8%), EO yield (217%), total phenolic content (63%), and total flavonoid content (57%). Heat map analysis revealed that protein, GB, EO yield, shoot weight, root weight, and proline had the maximum changes upon Fe NPs. Totally, the present study recommended the stimulations application of Fe NPs at 20-30 mg L-1 and Zn NPs at 120 mg L-1 to reach the optimum growth and secondary metabolites of lemon balm.

Antioxidant activity, metabolic profiling, in-silico molecular docking and ADMET analysis of nano selenium treated sesame seed bioactive compounds as potential novel drug targets against cardiovascular disease related receptors

Sesame (Sesamum indicum) is abundant in a diverse range of lignans, including sesamin, and γ-tocopherol, constituting a cluster of bioactive phenolic compound used for food and medicinal purposes. Cardiovascular diseases remain a leading global health challenge, demanding vigilant prevention and innovative treatments. This study was carried out to evaluate the effect of plant mediated SeNPs on sesame metabolic profile and to screen and check the effect bioactive compounds against CVD via molecular drug docking technique. Three sesame germplasms TS-5, TH-6 and Till-18 were treated with varying concentrations (10, 20, 30, 40 and 50 ppm) of plant-mediated selenium nanoparticles (SeNPs). There were three groups of treatments group-1 got only seed pretreatments of SeNPs, Group-2 with only foliar applications of SeNPs and Group-3 with both seed pretreatments and foliar applications of SeNPs. It was found that plants treated with 40 ppm of SeNPS in group 3 exhibited the highest total phenolic and flavonoid content. Total phenolic content at T4 was highest for TS-5 (134%), TH-6 (132%), and Till-18 (112%). LCMS analysis revealed a total of 276 metabolites, with phenolics, flavonoids, and free fatty acids being most abundant. KEGG analysis indicated enrichment in free fatty acid and phenylalanine tryptophan pathways. ADMET analysis and virtual screening resulted in total of five metabolic compounds as a potential ligand against Hemoglobin beta subunit. Lowest binding energy was achieved by Delta-Tocopherol (-6.98) followed by Lactoflavin (-6.20) and Sesamin (-5.00). Lipinski rule of five revealed that all the compounds completely safe to be used as drug against CVD and specifically for HBB. It was concluded that bioactive compounds from sesame could be an alternative source of drug for CVD related problems and especially for HBB.

Alleviation potential of green-synthesized selenium nanoparticles for cadmium stress in Solanum lycopersicum L: modulation of secondary metabolites and physiochemical attributes

KEY MESSAGE

Selenium nanoparticles reduce cadmium absorption in tomato roots, mitigating heavy metal effects. SeNPs can efficiently help to enhance growth, yield, and biomolecule markers in cadmium-stressed tomato plants. In the present study, the effects of selenium nanoparticles (SeNPs) were investigated on the tomato plants grown in cadmium-contaminated soil. Nanoparticles were synthesized using water extract of Nigella sativa and were characterized for their size and shape. Two application methods (foliar spray and soil drench) with nanoparticle concentrations of 0, 100, and 300 mg/L were used to observe their effects on cadmium-stressed plants. Growth, yield, biochemical, and stress parameters were studied. Results showed that SeNPs positively affected plant growth, mitigating the negative effects of cadmium stress. Shoot length (SL), root length (RL), number of branches (NB), number of leaves per plant (NL), and leaf area (LA) were significantly reduced by cadmium stress but enhanced by 45, 51, 506, 208, and 82%, respectively, by soil drench treatment of SeNPs. Similarly, SeNPs increased the fruit yield (> 100%) and fruit weight (> 100%), and decreased the days to fruit initiation in tomato plants. Pigments were also positively affected by the SeNPs, particularly in foliar treatment. Lycopene content was also enhanced by the addition of NPs (75%). Furthermore, the addition of SeNPs improved the ascorbic acid, protein, phenolic, flavonoid, and proline contents of the tomato plants under cadmium stress, whereas stress enzymes also showed enhanced activities under cadmium stress. It is concluded from the present study that the addition of selenium nanoparticles enhanced the growth and yield of Cd-stressed plants by reducing the absorption of cadmium and increasing the stress management of plants.

Co-application of titanium nanoparticles and melatonin effectively lowered chromium toxicity in lemon balm (Melissa officinalis L.) through modifying biochemical characteristics

Chromium (Cr) toxicity can negatively affect plant growth and development, impacting agricultural productivity and posing risks to human health. Metallic nanoparticles (MNPs) such as titanium dioxide (TiO2) and natural growth regulators such as melatonin (MT) become a promising technology to manage heavy metal-contaminated soils and promote safe food production. The present work was conducted to find the effect of foliar application of TiO2 NPs (15 mg L-1) and MT (100 µM) on growth, biochemical attributes, and Cr accumulation in plant tissues of Melissa officinalis L. under Cr toxicity (50 and 100 mg Cr kg-1 soil). The results showed that Cr toxicity led to decreased plant performance, where 100 mg Cr kg-1 soil led to notable decreases in shoot weight (28%), root weight (27%), essential oil (EO) yield (34%), chlorophyll (Chl) a + b (33%), while increased malondialdehyde (MDA, 30%), superoxide dismutase (SOD) activity (51%), and catalase (CAT) activity (122%). The use of TiO2 NPs and MT, particularly their co-application, remarkably reduced Cr toxicity by enhancing plant weight, Chl content, and lowered MDA and antioxidant activity. Total phenolic content (TPC), total flavonoid content (TFC), EO percentage, and rosmarinic acid in plants treated with Cr at 50 mg Cr kg-1 soil and co-application of TiO2 NPs and MT were relatively higher than in other treatments. Under 100 mg Cr kg-1 soil, the synergic effect of TiO2 NPs and MT-enhanced rosmarinic acid content (22%) but lowered Cr accumulation in roots (51%) and shoots (72%). Heat map analysis showed that CAT, SOD, MDA, and EO yield had the maximum variability under Cr, TiO2 NPs, and MT. Exogenous TiO2 NPs and MT can be recommended to modulate Cr toxicity in lemon balm under soil Cr toxicity.

Nanoparticles synergy: Enhancing wheat (Triticum aestivum L.) cadmium tolerance with iron oxide and selenium

Nanotechnology is capturing great interest worldwide due to their stirring applications in various fields and also individual application of iron oxide nanoparticle (FeO - NPs) and selenium nanoparticles (Se - NPs) have been studied in many literatures. However, the combined application of FeO and Se - NPs is a novel approach and studied in only few studies. For this purpose, a pot experiment was conducted to examine various growth and biochemical parameters in wheat (Triticum aestivum L.) under the toxic concentration of cadmium (Cd) i.e., 50 mg kg-1 which were primed with combined application of two levels of FeO and Se - NPs i.e., 15 and 30 mg L-1 respectively. The results showed that the Cd toxicity in the soil showed a significantly (P < 0.05) declined in the growth, gas exchange attributes, sugars, AsA-GSH cycle, cellular fractionation, proline metabolism in T. aestivum. However, Cd toxicity significantly (P < 0.05) increased oxidative stress biomarkers, enzymatic and non-enzymatic antioxidants including their gene expression in T. aestivum. Although, the application of FeO and Se - NPs showed a significant (P < 0.05) increase in the plant growth and biomass, gas exchange characteristics, enzymatic and non-enzymatic compounds and their gene expression and also decreased the oxidative stress, and Cd uptake. In addition, individual or combined application of FeO and Se - NPs enhanced the cellular fractionation and decreases the proline metabolism and AsA - GSH cycle in T. aestivum. These results open new insights for sustainable agriculture practices and hold immense promise in addressing the pressing challenges of heavy metal contamination in agricultural soils.

Foliar-applied silicon and selenium nanoparticles modulated salinity stress through modifying yield, biochemical attribute, and fatty acid profile of Physalis alkekengi L

Soil salinity is a major environmental problem owing to its negative impact on agricultural productivity and sustainability. Nanoparticles (NPs) have recently been highlighted for their ability to alleviate salinity stress. The current study aimed to alleviate salt stress by using silicon (Si) and selenium (Se) NPs on the growth and physiological attributes of Physalis alkekengi L. Plants were irrigated with saline water at 50, 100, and 200 mM NaCl, and Si NPs (200 mg L-1) and Se NPs (50 mg L-1) were sprayed on leaves three times in a pot experiment in 2022. Leaf chlorophyll (Chl) content, antioxidant capacity, and fatty acid (FA) profile of fruits were measured to find the effects of NPs and salinity in the plants. Salinity at 50 mM did not significantly differ from the control, but at 100-200 mM, salt stress had a substantial impact on the majority of traits. Compared with non-saline conditions, 200 mM NaCl led to decreases in shoot weight (40%), fruit weight (30%), Chl a (30%), Chl b (39%), anthocyanin (31%), ascorbic acid (16%), total phenolic content (TPC, 11%) but increases in total soluble solids (TSS, 79%), titration acidity (TA, 17%), and TSS/TA (52%) in plants without spraying the NPs. However, Si and Se NPs modulated salinity stress by increasing shoot and fruit weight, Chl content, anthocyanin, and TPC, and with decreasing TSS and TSS/TA. Salinity elevated polyunsaturated fatty acids (PUFAs) and lowered monounsaturated fatty acids (MUFAs). According to multivariate analysis, 50 mM and control were found to be in the same cluster, whereas 100 and 200 mM were shown to be in different clusters. Foliar application of Si and Se NPs at 200 and 50 mg L-1, respectively, can be recommended for mitigating salt stress at 100-200 mM NaCl in P. alkekengi L. Plants. Farmers can use the findings to increase the ability of Si and Se NPs to protect plants against salt.

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

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

Seed nanopriming: How do nanomaterials improve seed tolerance to salinity and drought?

Salt and drought stress are major environmental issues world-widely. These stresses can result in failures of seed germination, limiting agricultural production. New approaches are needed to increase crop production, ensuring food safety, quality, and agriculture sustainability. Nanopriming (priming seeds with nanomaterials) is an emerging seed technology improving crop production under the drastic climate change associated with stress factors. The present review not only provided an overview of nanopriming achieved salt and drought tolerance but also tried to discuss the behind mechanisms. We argued that the physico-chemical properties of the nanomaterials are key factors affecting their negative or positive effects on seed germination in terms of seed nanopriming. Furthermore, we highlighted the possible critical role of seed coat anatomy in effective nanopriming, in terms of saving costs and reducing biosafety issues. This review aims to help researchers to better understand and follow this fast-developing, cost-effective, and environmentally friendly research area.

Effect of Phytosynthesized Selenium and Cerium Oxide Nanoparticles on Wheat (Triticum aestivum L.) against Stripe Rust Disease

In this study, selenium nanoparticles (SeNPs) and cerium oxide nanoparticles (CeONPs) were synthesized by using the extract of Melia azedarach leaves, and Acorus calamusas rhizomes, respectively, and investigated for the biological and sustainable control of yellow, or stripe rust, disease in wheat. The green synthesized NPs were characterized by UV-Visible spectroscopy, scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), and X-ray diffraction (XRD). The SeNPs and CeONPs, with different concentrations (i.e., 10, 20, 30, and 40 mg/L), were exogenously applied to wheat infected with Puccinia striformis. SeNPs and CeONPs, at a concentration of 30 mg/L, were found to be the most suitable concentrations, which reduced the disease severity and enhanced the morphological (plant height, root length, shoot length, leaf length, and ear length), physiological (chlorophyll and membrane stability index), biochemical (proline, phenolics and flavonoids) and antioxidant (SOD and POD) parameters. The antioxidant activity of SeNPs and CeONPs was also measured. For this purpose, different concentrations (50, 100, 150, 200 and 400 ppm) of both SeNPs and CeONPs were used. The concentration of 400 ppm most promoted the DPPH, ABTS and reducing power activity of both SeNPs and CeONPs. This study is considered the first biocompatible approach to evaluate the potential of green synthesized SeNPs and CeONPs to improve the health of yellow, or stripe rust, infected wheat plants and to provide an effective management strategy to inhibit the growth of Puccinia striformis.

Foliar-applied selenium nanoparticles alleviate cadmium stress through changes in physio-biochemical status and essential oil profile of coriander (Coriandrum sativum L.) leaves

Since large areas of agricultural soils around the world are contaminated by Cd, a cost-effective and practical method is needed for the safe production of edible plants. The effective role of many nanomaterials to improve plant yield by mitigating environmental pollutions is addressed; however, the impacts of selenium nanoparticles (Se-NPs) have not been well-known yet. The aim of this work was to investigate foliar application of Se-NPs on yield, water content, proline concentration, phenolic content, lipid peroxidation, and essential oil (EO) attributes of coriander (Coriandrum sativum L.) under Cd stress. The plants were exposed to Cd contamination (0, 4, and 8 mg L-1) and foliar application of Se-NPs (0, 20, 40, and 60 mg L-1). The results showed increased Cd accumulation in roots and shoots of coriander plants upon Cd stress; however, Se-NPs alleviated the uptake of Cd. Cd toxicity, particularly 8 mg L-1, decreased shoot and root weight, chlorophyll (Chl), and relative water content (RWC), while Se-NPs improved these attributes. The Cd concentration at 4 mg L-1 and Se-NPs at 40 or 60 mg L-1 increased phenolic and flavonoid contents as well as EO yield. Proline concentration and malondialdehyde (MDA) increased by enhancing Cd stress, but Se-NPs decreased MDA. The GC/MS analysis showed that the main EO constitutes were n-decanal (18.80-29.70%), 2E-dodecanal (14.23-19.87%), 2E-decanal (12.60-19.40%), and n-nonane (7.23-12.87%), representing different amounts under Cd pollution and Se-NPs. To sum up, Se-NPs at 40-60 mg L-1 are effective in alleviating Cd stress.

Green Synthesized Se Nanoparticle-mediated Alleviation of Salt Stress in Field Mustard TS-36 Variety

During this decade, selenium nanoparticles have been found to play a crucial role in helping plants endure several stress conditions, which thereby helps enhance the production of crops in such harsh environments. Globally, high salinity is considered a long-term stress in the crop fields which affects the growth and production of many crops, including mustard-one of the most important oil crops. Here, the activities of spherical-shaped selenium nanoparticles with an average particle size of 55.81nm, synthesized and functionalized by phytochemicals of fresh grape aqueous extract, were evaluated in the salinity stress (200mM NaCl) tolerance of mustard plants grown hydroponically in modified Hoagland's solution. These bioactive nanoparticles (30mg/L) have exhibited significant activity in alleviating the salt stress complications in mustard, enhancing the activities of antioxidant enzymes (SOD 41.20%, CAT 64.10%, APX 63.06%, and POX 70.43%), phenolic content (98.88%), flavonoid content (86.90%), and free radical scavenging activity (61.89%). The seed germination percentage, root and shoot length, fresh and dry weight per plant, water content percentage, chlorophyll content, carbohydrate content, and protein content were significantly improved by 39.66%, 75%, 60.64%, 41.2%, 22.11%, 1.02%, 81.92%, 24.65% and 79.14% respectively by the nano selenium application during NaCl stress compared to the control group growing under salt stress without nanoparticles. Gas chromatography-mass spectrometry chromatogram analysis inferred the interaction between the nano-selenium and mustard plants under salt stress. Besides, the in-silico analysis revealed the active molecular interactions between selenium and 20 different proteins of mustard, including glutathione peroxidase, an important antioxidant enzyme.

Foliar-applied magnesium nanoparticles modulate drought stress through changes in physio-biochemical attributes and essential oil profile of yarrow (Achillea millefolium L.)

Nanoparticles (NPs) are an emerging tool for mitigating environmental stresses. Although beneficial roles of NPs have been reported in some plants, there is little data on magnesium (Mg)-NPs in alleviating drought stress. Therefore, the field experiment was conducted to study changes in biochemical attributes and essential oil (EO) compositions of yarrow (Achillea millefolium L.) plants under drought stress and Mg-NPs in 2016 and 2017. Irrigation regimes were used in two levels as well-watered (irrigation intervals of 7 days) and drought stress (irrigation intervals of 14 days) conditions, and Mg-NPs were sprayed on leaves in four levels (0, 0.1, 0.3, and 0.5 g L-1). The results showed drought stress led to increased electrolyte leakage (EL), proline, carotenoid, anthocyanin, and total flavonoid content (TFC). However, flowers yield and EO yield were lower in plants exposed to drought stress as compared to well-watered conditions. The 0.3 and 0.5 g L-1 Mg-NPs were more effective in alleviating drought stress by enhancing these traits. Heat map results showed that EL and TSS represented the high variability upon different treatments. The GC and GC/MS results represented that α-pinene (8.60-12.20%), 1,8-cineol (9.03-14.02%), camphor (6.84-9.80%), α-bisabolol (8.54-18.81%), chamazulene (14.23-22.50%), and caryophyllene oxide (7.20-9.80%) were the min EO constitutes of yarrow plants. Totally, drought decreased monopertens but increased sesquiterpenes of EO. To sum up, foliar applied Mg-NPs in a range of 0.3-0.5 g L-1 can be recommended as effective tool to improve plant yield through changes in biochemical attributes of yarrow plants.