Aluminum (Al) toxicity is a major constraint for crop production in acid soils. Therefore, looking for sustainable solutions to increase plant tolerance to Al toxicity is needed. Although several ...studies addressed the potential utilization of silica or silicon dioxide nanoparticles (SNPs) to ameliorate heavy metal phytotoxicity, the exact mechanisms underlying SNPs-induced stress tolerance are still unknown. The current study investigated how SNPs could mitigate Al toxicity in maize plants grown on acidic soil. The impact of Al alone or in combination with SNPs on Al accumulation and detoxification, plant growth, photosynthetic C assimilation and redox homeostasis has been investigated. Al accumulation in stressed-maize organs reduced their growth, decreased photosynthesis related parameters and increased production of reactive oxygen species, through induced NADPH oxidase and photorespiration activities, and cell damage. These effects were more pronounced in roots than in leaves. SNPs ameliorated Al toxicity at growth, physiological and oxidative damage levels. Co-application of SNPs significantly reduced the activities of the photorespiratory enzymes and NADPH oxidase. It stimulated the antioxidant defense systems at enzymatic (superoxide dismutase, catalase, ascorbate and glutathione peroxidases) and non-enzymatic (ascorbate, glutathione, polyphenols, flavonoids, tocopherols, and FRAP) levels. Moreover, SNPs increased organic acids accumulation and metal detoxification (i.e. glutathione-S-transferase activity) in roots, as a protective mechanism against Al toxicity. The SNPs induced-protective mechanisms was dependent on the applied Al concentration and acted in organ-specific manner. Overall, the current study suggests the promising application of SNPs as an innovative approach to mitigate Al phytotoxicity in acidic soils and provides a comprehensive view of the cellular and biochemical mechanisms underlying this mitigation capacity.
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•Aluminum (Al) reduced the growth and photosynthesis and induced oxidative stress in maize plants.•Nano-SiO2 (SNPs) did not affect Al accumulation but mitigated its phytotoxicity.•SNPs induced organic acid exudation by roots and metal detoxification activity.•SNPs reduced ROS production and improved ROS scavenging systems.•Maize responses to Al and SNPs were in a dose- and organ-specific manner.
In this study, a single step in situ sol-gel method was used to syntheses nanocomposite films using chitosan (CS) as the basis material, with the addition of silver oxide nanoparticles (Ag2O) at ...several weight percentages (5 %, 10 %, and 15 % Ag2O/CS). The structural characteristics of Ag2O/CS films were investigated using a range of analytical techniques. The presence of the primary distinctive peaks of chitosan was verified using FTIR spectra analysis. However, a minor displacement was observed in these peaks due to the chemical interaction occurring with silver oxide molecules. XRD analysis demonstrated a significant increase in the crystallinity of chitosan when it interacted with metal oxide nanoparticles. Furthermore, it is believed that the interaction between silver oxide and the active binding sites of chitosan is responsible for the evenly dispersed clusters shown in the micrographs of the chitosan surface, as well as the random aggregations within the pores. EDS technique successfully identified the presence of distinctive silver signals within the nanocomposite material, indicating the successful absorption of silver into the surface of the polymer. The developed Ag2O/CS nanocomposite showed promising antibacterial activity against Gram-negative (Escherichia coli and Pseudomonas aeruginosa) and Gram-positive bacteria (Bacillus subtilis, Enterococcus faecalis and Staphylococcus aureus). Also, Ag2O/CS nanocomposite exhibited marked antifungal activity against Candida albicans, Aspergillus flavus, A. fumigatus, A. niger, and Penicillium chrysogenum. The antioxidant activity of the developed nanocomposite films was studied by ABTS radical scavenging. The highest antioxidant and antibacterial properties were achieved by including 15 % silver oxide into the chitosan. Therefore, our finding indicate that chitosan‑silver oxide nanocomposites exhibits significant potential as a viable material for application in several sectors of the food packaging industry.
Symbiotic plant-microorganisms interaction is a promising approach to avoid the environmental hazards of synthetic fertilizers and pesticides. Among these, arbuscular mycorrhizal fungi (AMF) are ...known to improve the growth and quality of many plant species; however the detailed metabolic mechanisms behind such beneficial effects are far from complete. Further, elevated levels of atmospheric CO2 (eCO2) could affect such AMF-plant association. Herein, we have investigated the individual and synchronous impact of AMF and eCO2 (620 ppm) on nutrient uptake, growth, photosynthesis, respiration, and levels of primary and secondary metabolites in oregano (Oreganum vulgare), an economically important herbal plant. Enhanced AMF colonization rate and a better mycelial growth were observed in roots of oregano grown under eCO2. Both AMF and eCO2 treatments significantly enhanced the growth and photosynthesis of oregano plants, however much improvements were observed by their synchronous application. eCO2 further increased the AMF-induced dark respiration and accumulation of macro and microelements. Hierarchical clustering analysis of individual primary and secondary metabolites revealed a metabolite-dependent response toward AMF and eCO2. The synchronous application of AMF and eCO2 resulted in promoted accumulation of the majority of the detected sugars, organic acids, amino acids, unsaturated fatty acids, phenolic acids and flavonoids, as compared with the sole treatments. Moreover, AMF and eCO2 acted synergistically in improving the antioxidant capacity and anti-lipid peroxidation activity of oregano. Therefore, this study suggests that AMF treatment induces a global metabolic change in oregano, the effect that is strengthened under eCO2.
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•AMF colonization and hyphal growth are improved under the eCO2 climate.•The impact of AMF on levels of most mineral nutrients is more obvious under eCO2.•AMF and eCO2 act synergistically to enhance the growth and photosynthesis of oregano.•AMF-induced global metabolic change is strengthened by eCO2.•Oregano metabolites respond differently to AMF and eCO2 treatments.
•eCO2 treatment supports the hypocholesterolaemic potential of fenugreek seeds.•eCO2-treated seeds are more potent in inhibiting cholesterol micellar solubility.•Inhibitory action of fenugreek seeds ...against pancreatic lipase is promoted by eCO2.•eCO2 induces the accumulation of phenolics, flavonoids, saponins and alkaloids.
A high level of serum cholesterol is a major cause of atherosclerosis. Fenugreek is a well-known hypocholesterolaemic agent with amazing phytochemical composition. Due to its impact on plant metabolism, CO2 enrichment was tested as a strategy to support functional values in fenugreek seeds. Phytochemical composition and biological activities of three fenugreek cultivars (G2, G6 and G30) grown under ambient (aCO2, 400 μmol mol−1) and elevated CO2 (eCO2, 620 μmol mol−1) were assessed. Applying eCO2 improved physical parameters of fenugreek seeds, and enhanced their biological activities. A significant increase in hypocholesterolaemic potential, as indicated by inhibition of cholesterol micellar solubility and pancreatic lipase activity, was recorded. In addition, antioxidant, anti-lipid peroxidation and antibacterial activities were improved. These enhanced biological activities were accompanied by improved seed chemical composition at the primary and secondary metabolic levels. Therefore, eCO2 treatment represents an efficient strategy to increase the hypocholesterolaemic, antioxidant and antibacterial activities of fenugreek seeds.
Drought represents a major constraint for agricultural productivity and food security worldwide. Plant growth promoting actinobacteria have attracted the attention as a promising approach to enhance ...plant growth and yield under stressful conditions. In this regard, bioprospecting in arid and semi-arid environments could reveal uncommon bacteria with improved biological activities. In the present study, the ability of actinobacteria isolated from a semi-arid environment (Saudi Arabia) to mitigate the negative impact of drought on growth and physiology of maize, a drought-sensitive crop, has been investigated. Among the different actinobacterial isolates screened for secondary metabolites production and biological activities, isolate Ac5 showed high ability of flavonoid, phytohormones and siderophores production. Moreover, Ac5 improved the growth and photosynthesis and induced a global metabolic change in the bacterized plants under water-deficit conditions. Interestingly, Ac5 treatment significantly mitigated the detrimental effects of drought stress on maize. Reduced H2O2 accumulation and lipid peroxidation accompanied with higher levels of molecular antioxidants (total ascorbate, glutathione, tocopherols, phenolic acids and flavonoids) were observed in the bacterized plants. From the osmoregulation point of view, drought-stressed bacterized maize accumulated higher levels of compatible solutes, such as sucrose, total soluble sugars, proline, arginine and glycine betaine, as compared with the non-bacterized plants. Therefore, this study highlights the comprehensive impact of actinobacteria on the global plant metabolism and suggests the potential utilization of actinobacteria isolated from semi-arid environments to mitigate the negative impact of drought on crop plants.
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•Biologically active actinobacteria were isolated from a semi-arid environment.•Actinobacteria improved the growth and photosynthesis of maize grown under drought.•Actinobacteria upregulated the osmoregulation and antioxidant defense metabolism.•Bacterized plants maintained proper redox homeostasis and showed lower cell damage.•Consequently, actinobacteria mitigated drought induced oxidative damage in maize.
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•HgO-NPs induced growth reduction and a severe oxidative damage in maize.•eCO2 reduced Hg uptake by maize roots and antagonized its phytotoxicity.•eCO2 enhanced photosynthesis and ...mitigated Hg-induced ROS production.•eCO2 induced ROS detoxification via more efficient antioxidant defense systems.
So far, the phytotoxic hazards of nano-sized mercuric oxide (HgO-NPs) are not investigated. Herein, the phytotoxicity of fully characterized HgO-NPs (100 mg/kg soil), prepared by coprecipitation method, on maize grown under ambient (aCO2, 410 ppm) and elevated CO2 (eCO2, 620 ppm) was investigated. Regardless of CO2 concentration, HgO-NPs treatment increased Hg levels in maize organs. HgO-NPs induced severe oxidative stress in aCO2 grown plants as indicated by reduced growth and photosynthesis and accumulation of reactive oxygen species (ROS), through photorespiration and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activities, and lipid and protein oxidation products. Although HgO-NPs increased molecular (polyphenols, flavonoids, tocopherols) and enzymatic (superoxide dismutase, catalase, peroxidase, ascorbate peroxidase, glutathione peroxidase) antioxidants in shoots of aCO2 plants, but this failed to fight the eruption of increased ROS. On contrary, eCO2 treatment mitigated the HgO-NPs impact by promoting photosynthesis and reducing the Hg-induced ROS production. Moreover, eCO2 promoted ROS detoxification via molecular antioxidants overproduction, enhanced superoxide dismutase, catalase and peroxidases activities, and modulation of reduced ascorbate/oxidized ascorbate and reduced glutathione/oxidized glutathione homeostasis. The combined HgO-NPs + eCO2 treatment also enhanced the glutathione-S-transferase activity. This study suggests that HgO-NPs cause severe phytotoxic hazards and this effect will be less detrimental under future CO2 climate.
Polymeric films made from chitosan (CS) doped with metal oxide (MO = cobalt (II) oxide and strontium oxide) nanoparticles at different concentrations (5, 10, 15, and 20% wt. MO/CS) were fabricated ...with the solution cast method. FTIR, SEM, and XRD spectra were used to study the structural features of those nanocomposite films. The FTIR spectra of chitosan showed the main characteristic peaks that are usually present, but they were shifted considerably by the chemical interaction with metal oxides. FTIR analysis of the hybrid chitosan-CoO nanocomposite exhibited notable peaks at 558 and 681 cm−1. Conversely, the FTIR analysis of the chitosan-SrO composite displayed peaks at 733.23 cm−1, 810.10 cm−1, and 856.39 cm−1, which can be attributed to the bending vibrations of Co-O and Sr-O bonds, respectively. In addition, the SEM graphs showed a noticeable morphological change on the surface of chitosan, which may be due to surface adsorption with metal oxide nanoparticles. The XRD pattern also revealed a clear change in the crystallinity of chitosan when it is in contact with metal oxide nanoparticles. The presence of characteristic signals for cobalt (Co) and strontium (Sr) are clearly shown in the EDX examinations, providing convincing evidence for their incorporation into the chitosan matrix. Moreover, the stability of the nanoparticle-chitosan coordinated bonding was verified from the accurate and broadly parametrized semi-empirical tight-binding quantum chemistry calculation. This leads to the determination of the structures’ chemical hardness as estimated from the frontier’s orbital calculations. We characterized the dielectric properties in terms of the real and imaginary dielectric permittivity as a function of frequency. Dielectric findings reveal the existence of extensive interactions of CoO and SrO, more pronounced for SrO, with the functional groups of CS through coordination bonding. This induces the charge transfer of the complexes between CoO and SrO and the CS chains and a decrease in the amount of the crystalline phase, as verified from the XRD patterns.
Arbuscular mycorrhizal fungi (AMF) and elevated CO2 (eCO2) have been effectively integrated to the agricultural procedures as an ecofriendly approach to support the production and quality of plants. ...However, less attention has been given to the synchronous application of AMF and eCO2 and how that could affect the global plant metabolism. This study was conducted to investigate the effects of AMF and eCO2, individually or in combination, on growth, photosynthesis, metabolism and the functional food value of Thymus vulgare. Results revealed that both AMF and eCO2 treatments improved the photosynthesis and biomass production, however much more positive impact was obtained by their synchronous application. Moreover, the levels of the majority of the detected sugars, organic acids, amino acids, unsaturated fatty acids, volatile compounds, phenolic acids and flavonoids were further improved as a result of the synergistic action of AMF and eCO2, as compared to the individual treatments. Overall, this study clearly shows that co-application of AMF and eCO2 induces a synergistic biofertilization impact and enhances the functional food value of T. vulgare by affecting its global metabolism.
Infestation by parasitic weeds is one of the most important environmental challenges threatening cropping systems worldwide. Among these, branched broomrape (
Orobanche ramosa
), a root holoparasitic ...weed, detrimentally affects many crops especially tomato (
Lycopersicon esculentum
) and causes severe crop losses. The positive role of silicon nanoparticles (SiNPs) in the growth and yield of plants grown under stressful conditions has been reported. However, no study has investigated the impact of SiNPs on plant-weed interaction. In this study, we conducted a green-house experiment to assess the physiological implications of SiNPs on tomato under the
Orobanche
challenge.
Orobanche
infection alone markedly inhibited tomato growth and photosynthesis (
P
< 0.0001) and induced oxidative damage
via
increased photorespiration (
P
< 0.0001) and NADPH oxidase activities (
P
< 0.01). Interestingly, SiNPs significantly reduced the infection severity by reducing both the number and biomass of
Orobanche
tubercles (13 and 31% decrease, respectively). Moreover, SiNPs dramatically ameliorated the physiological and biochemical disorders imposed by
Orobanche
in tomato. Consistently, SiNPs strengthened the cell wall of host roots by upregulating lignin biosynthesis that acts as a physical barrier against tubercle haustorial penetration. On the other hand, SiNPs caused a noticeable decrease in ROS production and improved both enzymatic and non-enzymatic detoxification systems, the thing that was more pronounced in roots than in shoots of infected tomato plants. Such organ-specific responses were confirmed by cluster analysis. Overall, this study suggests that tomato plants treated with SiNPs will be more tolerant to
Orobanche
infection through enhanced structural and metabolic responses.
An infographic diagram that summarizes the influence of SiNP-seed priming upon tomato plants under
Orobanche
infection conditions. GRW: growth, PHO: photosynthesis, NEAO: non-enzymatic antioxidants, ASE: antioxidant-scavenging enzymes.
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