Physiological Effects of Silver Nanoparticles and Silver Nitrate Toxicity in Triticum aestivum

Salinity stress mitigation in wheat through synergistic application of ascorbic acid, nanoparticles and Salvadora oleoides extract

Salinity stress adversely affects wheat growth and productivity, necessitating effective mitigation strategies. This study investigates the combined impact of ascorbic acid (AsA), silver nanoparticles (NPs), and Salvadora oleoides aqueous leaf extract (LE) on wheat tolerance to salinity stress. A randomized complete design (RCD) was employed with fourteen treatments: T1 (5 mM AsA), T2 (10 mM AsA), T3 (20 ppm AgNPs), T4 (40 ppm AgNPs), T5 (5% S. oleoides LE), T6 (10% S. oleoides LE), T7 (20 ppm AgNPs + 5 mM AsA), T8 (20 ppm AgNPs + 10 mM AsA), T9 (40 ppm AgNPs + 5 mM AsA), T10 (40 ppm AgNPs + 10 mM AsA), T11 (20 ppm AgNPs + 5% S. oleoides LE), T12 (20 ppm AgNPs + 10% S. oleoides LE), T13 (40 ppm AgNPs + 5% S. oleoides LE), and T14 (40 ppm AgNPs + 10% S. oleoides LE). Wheat plants were subjected to salinity stress (SS) and no-stress conditions (NoSS) for 50 days. Chlorophyll content, DPPH activity, total soluble proteins and sugars, antioxidant enzyme activities, lipid peroxidation, leaf ion concentrations, and nutrient uptake were analyzed. Under SS, T6 (10% LE) showed the lowest chlorophyll-a (90.04%) and b (57.84%). DPPH activity was highest in NoSS with T9 (40 ppm NPs + 5 mM AsA) at 14.40%, and lowest in SS with T6 (10% LE) at 6.67%. Total soluble proteins and sugars were highest in NoSS with T9 (40 ppm NPs + 5 mM AsA) and T6 (10% LE). In SS, SOD activity peaked with T6 (10% LE) at 8.39 U/mg protein, while CAT activity was highest with T9 (40 ppm NPs + 5 mM AsA) at 6.25 U/mg protein. Lipid peroxidation was highest in SS with T6 (10% LE) at 14.67 µM MDA/g fresh weight. Leaf Na and Cl concentrations were highest in SS with T9 (40 ppm NPs + 5 mM AsA), at 14.26% and 44.15%, respectively. The combined application of 40 NPs and 5 AsA (T9) proved most effective in enhancing chlorophyll content and DPPH activity under NoSS, while 10% LE (T6) showed significant improvements in SOD activity and lipid peroxidation mitigation under SS. Future research should explore optimizing treatment concentrations and combinations to further enhance wheat stress tolerance and evaluate long-term effects on crop yield and quality.

Machine Learning Analysis of the Impact of Silver Nitrate and Silver Nanoparticles on Wheat (Triticum aestivum L.): Callus Induction, Plant Regeneration, and DNA Methylation

The objective of this study was to comprehend the efficiency of wheat regeneration, callus induction, and DNA methylation through the application of mathematical frameworks and artificial intelligence (AI)-based models. This research aimed to explore the impact of treatments with AgNO3 and Ag-NPs on various parameters. The study specifically concentrated on analyzing RAPD profiles and modeling regeneration parameters. The treatments and molecular findings served as input variables in the modeling process. It included the use of AgNO3 and Ag-NPs at different concentrations (0, 2, 4, 6, and 8 mg L-1). The in vitro and epigenetic characteristics were analyzed using several machine learning (ML) methods, including support vector machine (SVM), random forest (RF), extreme gradient boosting (XGBoost), k-nearest neighbor classifier (KNN), and Gaussian processes classifier (GP) methods. This study's results revealed that the highest values for callus induction (CI%) and embryogenic callus induction (EC%) occurred at a concentration of 2 mg L-1 of Ag-NPs. Additionally, the regeneration efficiency (RE) parameter reached its peak at a concentration of 8 mg L-1 of AgNO3. Taking an epigenetic approach, AgNO3 at a concentration of 2 mg L-1 demonstrated the highest levels of genomic template stability (GTS), at 79.3%. There was a positive correlation seen between increased levels of AgNO3 and DNA hypermethylation. Conversely, elevated levels of Ag-NPs were associated with DNA hypomethylation. The models were used to estimate the relationships between the input elements, including treatments, concentration, GTS rates, and Msp I and Hpa II polymorphism, and the in vitro output parameters. The findings suggested that the XGBoost model exhibited superior performance scores for callus induction (CI), as evidenced by an R2 score of 51.5%, which explained the variances. Additionally, the RF model explained 71.9% of the total variance and showed superior efficacy in terms of EC%. Furthermore, the GP model, which provided the most robust statistics for RE, yielded an R2 value of 52.5%, signifying its ability to account for a substantial portion of the total variance present in the data. This study exemplifies the application of various machine learning models in the cultivation of mature wheat embryos under the influence of treatments and concentrations involving AgNO3 and Ag-NPs.

Silver Nanoparticle Effects on Antioxidant Response in Tobacco Are Modulated by Surface Coating

The antimicrobial properties of silver and enhanced reactivity when applied in a nanoparticle form (AgNPs) led to their growing utilization in industry and various consumer products, which raises concerns about their environmental impact. Since AgNPs are prone to transformation, surface coatings are added to enhance their stability. AgNP phytotoxicity has been mainly attributed to the excess generation of reactive oxygen species (ROS), leading to the induction of oxidative stress. Herein, in vitro-grown tobacco (Nicotiana tabacum) plants were exposed to AgNPs stabilized with either polyvinylpyrrolidone (PVP) or cetyltrimethylammonium bromide (CTAB) as well as to ionic silver (AgNO₃), applied in the same concentrations, either alone or in combination with cysteine, a strong silver ligand. The results show a higher accumulation of Ag in roots and leaves after exposure to AgNPs compared to AgNO₃. This was correlated with a predominantly higher impact of nanoparticle than ionic silver form on parameters of oxidative stress, although no severe damage to important biomolecules was observed. Nevertheless, all types of treatments caused mobilization of antioxidant machinery, especially in leaves, although surface coatings modulated the activation of its specific components. Most effects induced by AgNPs or AgNO₃ were alleviated with addition of cysteine.

Surface Coating-Modulated Phytotoxic Responses of Silver Nanoparticles in Plants and Freshwater Green Algae

Silver nanoparticles (AgNPs) have been implemented in a wide range of commercial products, resulting in their unregulated release into aquatic as well as terrestrial systems. This raises concerns over their impending environmental effects. Once released into the environment, they are prone to various transformation processes that modify their reactivity. In order to increase AgNP stability, different stabilizing coatings are applied during their synthesis. However, coating agents determine particle size and shape and influence their solubility, reactivity, and overall stability as well as their behavior and transformations in the biological medium. In this review, we attempt to give an overview on how the employment of different stabilizing coatings can modulate AgNP-induced phytotoxicity with respect to growth, physiology, and gene and protein expression in terrestrial and aquatic plants and freshwater algae.

Exposure of Brassica to Red Light Antagonizes Low Production of IAA in Leaf Through Root Signaling Under Stress Conditions

Plant leaf is highly sensitive to various growth promoting and restraining components. This sensitivity is normally caused by the alteration of different phyto-hormones (predominately by IAA), when the plants exposed to certain environmental conditions. We exposed the hydroponically grown Brassica campestris seedlings (7 days old) to red and green light in order to observe its effect on IAA secretion at leaf. The evaluated data showed that red light antagonized the low production of IAA in leaf by initiating the root signaling through flavonoids production and high redox activity. The study also explored the link between the differential phytohormonal response and biotic or abiotic stress elimination in leaf through root signaling under green or red light. The results exhibited that the biotic (P. syringae or F. alni) or abiotic stresses (100 mM AgNO₃ or 100 mM tert-butyl alcohol) inhibited flavonoids at the roots and resisted the restoration of IAA at the leaf. However, under green light where IAA was not inhibited, the stresses could not produce flavonoid at the root and further passing the signals to leaf. The results concluded that the growth and photosynthetic rates of the seedlings were improved under red light exposure through flavonoid inducing stresses.

Modulation of Organogenesis and Somatic Embryogenesis by Ethylene: An Overview

Ethylene is a plant hormone controlling physiological and developmental processes such as fruit maturation, hairy root formation, and leaf abscission. Its effect on regeneration systems, such as organogenesis and somatic embryogenesis (SE), has been studied, and progress in molecular biology techniques have contributed to unveiling the mechanisms behind its effects. The influence of ethylene on regeneration should not be overlooked. This compound affects regeneration differently, depending on the species, genotype, and explant. In some species, ethylene seems to revert recalcitrance in genotypes with low regeneration capacity. However, its effect is not additive, since in genotypes with high regeneration capacity this ability decreases in the presence of ethylene precursors, suggesting that regeneration is modulated by ethylene. Several lines of evidence have shown that the role of ethylene in regeneration is markedly connected to biotic and abiotic stresses as well as to hormonal-crosstalk, in particular with key regeneration hormones and growth regulators of the auxin and cytokinin families. Transcriptional factors of the ethylene response factor (ERF) family are regulated by ethylene and strongly connected to SE induction. Thus, an evident connection between ethylene, stress responses, and regeneration capacity is markedly established. In this review the effect of ethylene and the way it interacts with other players during organogenesis and somatic embryogenesis is discussed. Further studies on the regulation of ERF gene expression induced by ethylene during regeneration can contribute to new insights on the exact role of ethylene in these processes. A possible role in epigenetic modifications should be considered, since some ethylene signaling components are directly related to histone acetylation.

Brief overview of the application of silver nanoparticles to improve growth of crop plants

With the advancement in nanotechnology, nanoparticles are reported to have applications in various fields. Their positive role in the environment, especially in plant ecosystem, is extensively studied nowadays. Among the metal nanoparticles, the silver nanoparticles (AgNP) are receiving special attention because of their ability to increase the growth and yield in many crops. Although many studies are found containing toxic effects of AgNPs the perspective of the present review is to collect the information about their positive role in growth and yield enhancement of crops. During this brief overview, many important crop plants are found to have a positive response towards the application of AgNPs. The appropriate elucidation of physiological, biochemical and molecular mechanism of nanoparticles in plant leads to better plant growth and development. It is concluded from this review that cautious and sensible use of nanotechnology can warrant food security through boosting agricultural production.

The influence of cadmium and essential nanometals on the physiological And biochemical parameters of lettuce plants

Due to the aim the effect of pre-sowing treatment with a nonionic colloidal solution of the mix of copper, zinc, manganese and iron nanoparticles, cadmium ions and their combined action on the physiological and biochemical indices: the content of lipid peroxidation products and balance of photosynthetic pigments in green Lolo and red Lolo Ross varieties of Lactuca sativa L. was investigated. Spectrophotometric methods of investigating the content of peroxides, thiobarbiturate-active products (with use of the modified Kumar and Knowles method), as well as the content of the main photosynthetic pigments (chlorophyll a, b, a/b ratio, and the carotenoid content) with the Wintermans, de Mots calculations application were used. Due to the results, a decrease in the content of peroxides and growth of malonic dialdehyde was observed for most treatment variants of Lolo. The opposite tendency was observed for the Ross variety (the initial growth of these parameters under the nanoparticles influence decreased to the control during the fourteen-day exposure). The decrease of chlorophyll content was observed In the Lolo variety under the essential metal nanoparticles influence, in contrast to the action of cadmium.For the Ross variety, a significant reduction of both chlorophyll and carotenoid contents in all treatment types during exposure was calculated.The a/b-index for Lolo plants has significantly increased in variants of cadmium influence, for Ross plants the divergence of the influence of all treatment variants has been marked. As a result, the treatment with a mixture of essential nanometals showed additive stress-loading functions. It was observed in a growth of the level of lipid peroxidation products and the reduction of the photosynthetic pigment biomarkers in both varieties during the 0,1 mM cadmium exposure. The Lolo Ross variety showed a higher variability of results under different treatment, compared to the Lolo variety.