ZnO Nanoparticle-Mediated Seed Priming Induces Biochemical and Antioxidant Changes in Chickpea to Alleviate Fusarium Wilt

Nanopriming boost seed vigor: Deeper insights into the effect mechanism

Nanopriming, an advanced seed priming technology, is highly praised for its environmental friendliness, safety, and effectiveness in promoting sustainable agriculture. Studies have shown that nanopriming can enhance seed germination by stimulating the expression of aquaporins and increasing amylase production. By applying an appropriate concentration of nanoparticles, seeds can generate reactive oxygen species (ROS), enhance their antioxidant capacity, improve their response to oxidative stress, and enhance their tolerance to both biotic and abiotic stresses. This positive impact extends beyond the seed germination and seedling growth stages, persisting throughout the entire life cycle. This review offers a comprehensive overview of recent research progress in seed priming using various nanoparticles, while also addressing current challenges and future opportunities for sustainable agriculture.

Tetragonal crystalline MnO nanoparticles alleviate Pb stress in wheat by modulating antioxidant enzymes in leaves

Agriculture ecosystems are seriously threatened by lead (Pb) contamination, which impacts plant growth and productivity. In this study, green synthesized manganese oxide nanoparticles (MnO NPs) using citrus peel were used for priming of wheat seeds. For the synthesis of MnO nanoparticles, peel extract of Citrus paradisi and 1 mM solution of manganese acetate were stirred and calcinated at 500 °C. Successful synthesis of MnO NPs was determined using advanced techniques. In Fourier-transform infrared spectroscopy (FTIR), the presence of amines, alkanes, aldehydes, and alcohol molecules, on the surface of MnO NPs, confirmed their stability. X-ray diffraction analysis described their average size (22 nm), while scanning electron microscopy showed tetragonal crystalline shape and nano-flowers structure of MnO NPs. Sharp peaks of energy dispersive x-ray analysis described the presence of oxygen (28.81%) and manganese (71.19%) on MnO NPs. Priming of wheat seeds with synthesized MnO NPs significantly improved the growth attributes of wheat seedlings including the size of leaf, root length, size of shoots, chlorophyll and carotenoid contents, relative water content, decreased relative electrolyte leakage, high proline accumulation and decreased concentration of malondialdehyde. Application of MnO NPs also helped plants to accumulate antioxidant enzymes in their leaves. These results proved that the priming of MnO NPs can greatly reduce lead-induced stress in wheat seedlings and these NPs can also be used for the priming of other crops.

Harnessing biological synthesis: Zinc oxide nanoparticles for plant biotic stress management

Crop growth and yield are negatively impacted by increased biotic stress in the agricultural sector due to increasing global warming and changing climatic patterns. The host plant's machinery is exploited by biotic stress, which is caused by organisms like bacteria, fungi, viruses, insects, nematodes, and mites. This results in nutrient deprivation, increased reactive oxygen species and disturbances in physiological, morphological, and molecular processes. Although used widely, conventional disease management strategies like breeding, intercropping, and chemical fertilizers have drawbacks in terms of time commitment and environmental impact. An environmentally beneficial substitute is offered by the developing field of nanotechnology, where nanoparticles such as zinc oxide are gaining popularity due to their potential applications as antimicrobials and nano-fertilizers. This review delves into the biological synthesis of ZnO nanoparticles employing plants and microbes, function of ZnO nanoparticles in biotic stress mitigation, elucidating their effectiveness and toxicological implications in agricultural. This study supports a cautious approach, stressing the prudent application of ZnO nanoparticles to avoid possible toxicity, in line with the larger global agenda to end hunger, guarantee food security, and advance sustainable agriculture.

Nanoparticles as a Tool for Alleviating Plant Stress: Mechanisms, Implications, and Challenges

Plants, being sessile, are continuously exposed to varietal environmental stressors, which consequently induce various bio-physiological changes in plants that hinder their growth and development. Oxidative stress is one of the undesirable consequences in plants triggered due to imbalance in their antioxidant defense system. Biochemical studies suggest that nanoparticles are known to affect the antioxidant system, photosynthesis, and DNA expression in plants. In addition, they are known to boost the capacity of antioxidant systems, thereby contributing to the tolerance of plants to oxidative stress. This review study attempts to present the overview of the role of nanoparticles in plant growth and development, especially emphasizing their role as antioxidants. Furthermore, the review delves into the intricate connections between nanoparticles and plant signaling pathways, highlighting their influence on gene expression and stress-responsive mechanisms. Finally, the implications of nanoparticle-assisted antioxidant strategies in sustainable agriculture, considering their potential to enhance crop yield, stress tolerance, and overall plant resilience, are discussed.

Induction of tomato plant biochemical immune responses by the synthesized zinc oxide nanoparticles against wilt-induced Fusarium oxysporum

The current study used zinc oxide nanoparticles (ZnO-NPs) to protect the tomato plant against Fusarium wilt. Gamma rays were used to synthesize ZnO-NPs, and the designed ZnO-NPs were characterized using high-resolution transmission electron microscopy (HRTEM), scanning electron microscope (SEM), dynamic light scattering (DLS), energy-dispersive X-ray spectroscopy (EDX), and ultraviolet-visible (UV-Vis.) spectroscopy. We found that the 20 kGy dose is the most effective for ZnO-NPs synthesis, with the highest O.D. = 1.65 (diluted 3 times) at 400 nm. The scale of ZnO-NPs ranged from 10.45 to 75.25 nm with an average diameter of 40.20 nm. The results showed that the designed ZnO-NPs showed promising activity as a potent inducer of plant physiological immunity against Fusarium wilt disease. Likewise, ZnO-NPs significantly reduced the wilt disease symptoms incidence by 28.57% and high protection by 67.99% against F. oxysporum. Additionally, infected tomato plants treated with ZnO-NPs show improved shoot length (44.71%), root length (40.0%), number of leaves (60.0 %), chlorophyll a (36.93%), chlorophyll b (16.46%), and carotenoids (21.87%) versus infected plants. Notably, in the treatment of tomato seedlings, the beneficial effects of ZnO-NPs extended to increase not only in osmolyte contents but also total phenol contents in comparison with control plants. In conclusion, the designed ZnO-NPs can control Fusarium wilt disease and improve and develop biochemical compounds responsible for defense against fusarial infection.

Bacillus safensis filtrate-based ZnO nanoparticles control black heart rot disease of apricot fruits by maintaining its soluble sugars and carotenoids

Black heart rot is a serious disease of apricot and it has been reported to be caused by Alternaria solani, around the world. The present research was designed to control this disastrous disease using zinc oxide nanoparticles (b-ZnO NPs). These NPs were synthesized in the filtrate of a useful bacterium (Bacillus safensis) and applied to control black heart rot of apricot. After synthesis, the reduction of b-ZnO NPs was confirmed by UV-visible spectroscopy, at 330 nm. Fourier transform infrared (FTIR) spectra ensured the presence of multiple functional groups (alcohols, phenols, carboxylic acids, nitro compounds and amines) on the surface of b-ZnO NPs. X-Ray diffraction (XRD) analysis elucidated their average size (18 nm) while scanning electron microscopy (SEM) micrograph described the spherical shape of b-ZnO NPs. The synthesized b-ZnO NPs were applied in four different concentrations (0.25 mg/ml, 0.50 mg/ml, 0.75 mg/ml, 1.0 mg/ml) under both in vitro and in vivo conditions. These NPs were very efficient in inhibiting mycelial growth (85.1%) of A. solani at 0.75 mg/ml concentration of NPs, in vitro. Same concentration also performed best, in vivo, and significantly reduced disease incidence (by 67%) on self-inoculated apricot fruit. Apart from this, application of b-ZnO NPs helped apricot fruit to maintain its quality under fungal-stress conditions. The decay of apricot fruit was reduced and they maintained greater firmness and higher weight. Moreover, b-ZnO NPs treated fruits controlled black heart rot disease by maintaining higher contents of ascorbic acid, soluble sugars and carotenoids. These b-ZnO NPs were produced in powder form for their easy carriage to the farmers' fields.

Seed Priming with Zinc Oxide Nanoparticles to Enhance Crop Tolerance to Environmental Stresses

Drastic climate changes over the years have triggered environmental challenges for wild plants and crops due to fluctuating weather patterns worldwide. This has caused different types of stressors, responsible for a decrease in plant life and biological productivity, with consequent food shortages, especially in areas under threat of desertification. Nanotechnology-based approaches have great potential in mitigating environmental stressors, thus fostering a sustainable agriculture. Zinc oxide nanoparticles (ZnO NPs) have demonstrated to be biostimulants as well as remedies to both environmental and biotic stresses. Their administration in the early sowing stages, i.e., seed priming, proved to be effective in improving germination rate, seedling and plant growth and in ameliorating the indicators of plants' well-being. Seed nano-priming acts through several mechanisms such as enhanced nutrients uptake, improved antioxidant properties, ROS accumulation and lipid peroxidation. The target for seed priming by ZnO NPs is mostly crops of large consumption or staple food, in order to meet the increased needs of a growing population and the net drop of global crop frequency, due to climate changes and soil contaminations. The current review focuses on the most recent low-cost, low-sized ZnO NPs employed for seed nano-priming, to alleviate abiotic and biotic stresses, mitigate the negative effects of improper storage and biostimulate plants' growth and well-being. Taking into account that there is large variability among ZnO NPs and that their chemico-physical properties may play a role in determining the efficacy of nano-priming, for all examined cases, it is reported whether the ZnO NPs are commercial or lab prepared. In the latter cases, the preparation conditions are described, along with structural and morphological characterizations. Under these premises, future perspectives and challenges are discussed in relation to structural properties and the possibility of ZnO NPs engineering.

Concurrent application of bacterial-mediated and mycosynthesized ZnO nanofungicides to maintain high ascorbic acid and delay postharvest decay of apricot

Quality of apricot fruit is affected by different biotic stresses during growth, harvesting and storage. Due to fungal attack, huge losses of its quality and quantity are observed. The present research was designed for the diagnoses and management of postharvest rot disease of apricot. Infected apricot fruit were collected, and the causative agent was identified as A. tubingensis. To control this disease, both bacterial-mediated nanoparticles (b-ZnO NPs) and mycosynthesized nanoparticles (f-ZnO NPs) were used. Herein, biomass filtrates of one selected fungus (Trichoderma harzianum) and one bacterium (Bacillus safensis) were used to reduce zinc acetate into ZnO NPs. The physiochemical and morphological characters of both types of NPs were determined. UV-vis spectroscopy displayed absorption peaks of f-ZnO NPs and b-ZnO NPs at 310-380 nm, respectively, indicating successful reduction of Zinc acetate by the metabolites of both fungus and bacteria. Fourier transform infrared (FTIR) determined the presence of organic compounds like amines, aromatics, alkenes and alkyl halides, on both types of NPs, while X-ray diffraction (XRD) confirmed nano-size of f-ZnO NPs (30 nm) and b-ZnO NPs (35 nm). Scanning electron microscopy showed flower-crystalline shape for b-ZnO NPs and spherical-crystalline shape for f-ZnO NPs. Both NPs showed variable antifungal activities at four different concentrations (0.25, 0.50, 0.75 and 1.00 mg/ml). Diseases control and postharvest changes in apricot fruit were analyzed for 15 days. Among all treatments, 0.50 mg/ml concentration of f-ZnO NPs and 0.75 mg/ml concentration of b-ZnO NPs exhibited the strongest antifungal activity. Comparatively, f-ZnO NPs performed slightly better than b-ZnO NPs. Application of both NPs reduced fruit decay and weight, maintained higher ascorbic acid contents, sustained titratable acidity, and preserved firmness of diseased fruit. Our results suggest that microbial synthesized ZnO NPs can efficiently control fruit rot, extend shelf life, and preserve the quality of apricot.

Nano-sulfides of Fe and Mn Efficiently Augmented the Growth, Antioxidant Defense System, and Metal Assimilation in Rice Seedlings

Physiological and biochemical mechanisms behind nanoparticle (NP)-induced seed germination by nanopriming with metal sulfide NPs are lacunae in the field of agriculture. Sonochemically synthesized aqua-dispersed ferrous sulfide NPs (FeS-NPs) and manganese sulfide NPs (MnS-NPs) were examined as nanopriming agents for physiological, pathological, and antioxidative defense parameters of rice in the present study. Under pot house conditions, in vivo nanopriming of rice seeds with FeS NPs and MnS-NPs at a concentration of 35 μg/mL for 8 h significantly improved the physiological parameters, viz., germination percentage, seed germination index, mean germination time, dry weight, and vigor index, and decreased the phytopathological parameters of nanoprimed rice seeds, viz., mortality, seed rot, and seedling blight. Stimulation of superoxide dismutase (SOD ≥ 28.16%), ascorbate peroxidase (APX ≥ 52.38%), and catalase (CAT ≥ 28.57%) enzymes in FeS-NP- and MnS-NP-nanoprimed seeds as compared to control (hydroprimed seeds) enhanced the fitness of rice seedlings. The augmented levels of Fe and Mn content in the shoots and roots of NP-treated seedlings as compared to hydroprimed seedlings confirmed the incorporation nanometals in rice seedlings as nanonutrients for effective plant growth. Inclusively, FeS-NPs and MnS-NPs were shown to be effective nanopriming agents for promoting the germination of naturally fungal infested rice seeds.

Nanoparticles as a Promising Strategy to Mitigate Biotic Stress in Agriculture

Nanoparticles are recognized due to their particular physical and chemical properties, which are conferred due to their size, in the range of nanometers. Nanoparticles are recognized for their application in medicine, electronics, and the textile industry, among others, but also in agriculture. The application of nanoparticles as nanofertilizers and biostimulants can help improve growth and crop productivity, and it has therefore been mentioned as an essential tool to control the adverse effects of abiotic stress. However, nanoparticles have also been noted for their exceptional antimicrobial properties. Therefore, this work reviews the state of the art of different nanoparticles that have shown the capacity to control biotic stress in plants. In this regard, metal and metal oxide nanoparticles, polymeric nanoparticles, and others, such as silica nanoparticles, have been described. Moreover, uptake and translocation are covered. Finally, future remarks about the studies on nanoparticles and their beneficial role in biotic stress management are made.

Molecular Analysis of MgO Nanoparticle-Induced Immunity against Fusarium Wilt in Tomato

Fusarium wilt, caused by Fusarium oxysporum f. sp. lycopersici (FOL), is a devastating soilborne disease in tomatoes. Magnesium oxide nanoparticles (MgO NPs) induce strong immunity against Fusarium wilt in tomatoes. However, the mechanisms underlying this immunity remain poorly understood. Comparative transcriptome analysis and microscopy of tomato roots were performed to determine the mechanism of MgO NP-induced immunity against FOL. Eight transcriptomes were prepared from tomato roots treated under eight different conditions. Differentially expressed genes were compared among the transcriptomes. The Kyoto Encyclopedia of Genes and Genomes enrichment analysis revealed that in tomato roots pretreated with MgO NPs, Rcr3 encoding apoplastic protease and RbohD encoding NADPH oxidase were upregulated when challenge-inoculated with FOL. The gene encoding glycine-rich protein 4 (SlGRP4) was chosen for further analysis. SlGRP4 was rapidly transcribed in roots pretreated with MgO NPs and inoculated with FOL. Immunomicroscopy analysis showed that SlGRP4 accumulated in the cell walls of epidermal and vascular vessel cells of roots pretreated with MgO NPs, but upon FOL inoculation, SlGRP4 further accumulated in the cell walls of cortical tissues within 48 h. The results provide new insights into the probable mechanisms of MgO NP-induced tomato immunity against Fusarium wilt.