Antifungal Activity of Silver and Copper Nanoparticles on Two Plant Pathogens, Alternaria alternata and Botrytis cinerea

Mechanistic insight into the anti-alternaria activity of bimetallic zinc oxide and silver/zinc oxide nanoparticles

Alternaria alternata is an opportunistic phytopathogen that negatively impact the growth and production of a wide variety of host plants. In this study, we evaluated the antifungal potential of biogenic ZnO, and bimetallic silver and zinc oxide (Ag/ZnO) nanoparticles synthesized using seed extract of Abrus precatorious and characterized using different analytical tools. In vitro antifungal potentials of ZnO and Ag/ZnO nanoparticles were carried out using the food poison technique. Morphological and ultrastructure of the A. alternata treated with the nanoparticles were carried out using high resolution scanning and transmission electron microscopy (HRSEM and HRTEM). In addition, changes in polysaccharide production, chitin content and enzymatic (cellulase and lipase) activities of A. alternata were assayed. Double peak signifying a UVmax of 353.88 and 417.25 nm representing Ag and ZnO respectively was formed in the bimetallic nanoparticles. HRSEM and HRTEM results shows agglomerated nanoparticles with particle and crystallite size of 23.94 and 16.84 nm for ZnO nanoparticles, 35.12 and 28.99 nm for Ag/ZnO nanoparticles respectively. In vitro antifungal assay shows a significant concentration-dependent inhibition (p < 0.05) of A. alternata mycelia with highest percentage inhibition of 73.93 % (ZnO nanoparticles) and 68.26 % (Ag/ZnO nanoparticles) at 200 ppm. HRSEM and HRTEM micrographs of the treated A. alternata mycelia shows alteration of the cellular structure, clearance of the cytoplasmic organelles and localization of the nanoparticles within the cell. A. alternata treated with 200 ppm nanoparticles show a significant decrease (p < 0.05) in the polysaccharides and chitin contents, cellulase and lipase activities. The results suggests that ZnO and Ag/ZnO nanoparticles mode of action may be via alteration of the fungal cell wall through the inhibition of polysaccharides, chitin, cellulases and lipases synthesis. ZnO and Ag/ZnO nanoparticles may be a promising tool for the management and control of disease causing fungal phytopathogens.

Polyalthia longifolia-mediated green synthesis of zinc oxide nanoparticles: characterization, photocatalytic and antifungal activities

The biological synthesis of zinc oxide nanoparticles (ZnO NPs) from plant extracts has emerged as a novel method for producing NPs with great scalability and biocompatibility. The present study is focused on bio-fabricated zinc oxide nanomaterial characterization and investigation of its photocatalytic and antifungal activities. ZnO NPs were biosynthesized using the leaf extract of Polyalthia longifolia without using harmful reducing or capping chemicals, which demonstrated fungicidal activity against Fusarium oxysporum f. sp. ciceris. The results showed that the inhibition of the radial growth of F. oxysporum f. sp. ciceris was enhanced as the concentration increased from 100 ppm to 300 ppm. The effectiveness of the photocatalytic activity of biosynthesized ZnO NPs was analyzed using MB dye degradation in aqueous medium under ultraviolet (UV) radiation and natural sunlight. After four consecutive cycles, the photocatalytic degradation of MB was stable and was 84%, 83%, 83%, and 83%, respectively, during natural sunlight exposure. Under the UV sources, degradation reached 92%, 89%, 88%, and 87%, respectively, in 90 minutes. This study suggests that the ZnO NPs obtained from plant extract have outstanding photocatalytic and antifungal activities against F. oxysporum f. sp. ciceris and have the potential for application as a natural pest control agent to reduce pathogenesis.

Exploring the mechanism underlying the antifungal activity of chitosan-based ZnO, CuO, and SiO2 nanocomposites as nanopesticides against Fusarium solani and Alternaria solani

Chitosan-based nanocomposites (CS NCs) are gaining considerable attention as multifaceted antifungal agents. This study investigated the antifungal activity of NCs against two phytopathogenic strains: Fusarium solani (F. solani) and Alternaria solani (A. solani). Moreover, it sheds light on their underlying mechanisms of action. The NCs, CS-ZnO, CS-CuO, and CS-SiO2, were characterized using advanced methods. Dynamic and electrophoretic light scattering techniques revealed their size range (60-170 nm) and cationic nature, as indicated by the positive zeta potential values (from +16 to +22 mV). Transmission electron microscopy revealed the morphology of the NCs as agglomerates formed between the chitosan and oxide components. X-ray diffraction patterns confirmed crystalline structures with specific peaks indicating their constituents. Antifungal assessments using the agar diffusion technique demonstrated significant inhibitory effects of the NCs on both fungal strains (1.5 to 4-fold), surpassing the performance of the positive control, nystatin. Notably, the NCs exhibited superior antifungal potency, with CS-ZnO NCs being the most effective. A. solani was the most sensitive strain to the studied agents. Furthermore, the tested NCs induced oxidative stress in fungal cells, which elevated stress biomarker levels, such as superoxide dismutase (SOD) activity and protein carbonyl content (PCC), 2.5 and 6-fold for the most active CS-CuO in F. solani respectively. Additionally, they triggered membrane lipid peroxidation up to 3-fold higher compared to control, a process that potentially compromises membrane integrity. Laurdan fluorescence spectroscopy highlighted alterations in the molecular organization of fungal cell membranes induced by the NCs. CS-CuO NCs induced a membrane rigidifying effect, while CS-SiO2 and CS-ZnO could rigidify membranes in A. solani and fluidize them in F. solani. In summary, this study provides an in-depth understanding of the interactions of CS-based NCs with two fungal strains, showing their antifungal activity and offering insights into their mechanisms of action. These findings emphasize the potential of these NCs as effective and versatile antifungal agents.

Novel Zinc/Silver Ions-Loaded Alginate/Chitosan Microparticles Antifungal Activity against Botrytis cinerea

Addressing the growing need for environmentally friendly fungicides in agriculture, this study explored the potential of biopolymer microparticles loaded with metal ions as a novel approach to combat fungal pathogens. Novel alginate microspheres and chitosan/alginate microcapsules loaded with zinc or with zinc and silver ions were prepared and characterized (microparticle size, morphology, topography, encapsulation efficiency, loading capacity, and swelling behavior). Investigation of molecular interactions in microparticles using FTIR-ATR spectroscopy exhibited complex interactions between all constituents. Fitting to the simple Korsmeyer-Peppas empirical model revealed the rate-controlling mechanism of metal ions release from microparticles is Fickian diffusion. Lower values of the release constant k imply a slower release rate of Zn2+ or Ag+ ions from microcapsules compared to that of microspheres. The antimicrobial potential of the new formulations against the fungus Botrytis cinerea was evaluated. When subjected to tests against the fungus, microspheres exhibited superior antifungal activity especially those loaded with both zinc and silver ions, reducing fungal growth up to 98.9% and altering the hyphal structures. Due to the slower release of metal ions, the microcapsule formulations seem suitable for plant protection throughout the growing season. The results showed the potential of these novel microparticles as powerful fungicides in agriculture.

Post-harvest biocontrol of Fusarium infection in tomato fruits using bio-mediated selenium nanoparticles

The protection of post-harvest infection by Fusarium spp. is a major worldwide demand, especially using effective natural alternatives to chemical fungicides. In this respect, selenium nanoparticles (SeNPs) were biosynthesized using Fenugreek seeds aqueous extract. Bio-mediated SeNPs were characterized using XRD, FTIR, UV-Vis, TEM, and EDX. XRD confirmed the crystalline nature with six characteristic peaks corresponding to Se-nanocrystals. TEM showed spherical-shaped SeNPs with 34.02-63.61 nm diameter. FTIR verified the presence of different bio-functional groups, such as, N-H, O-H, C-N, and C-NH2 acting as stabilizing/reducing agents during the biosynthesis. Bio-mediated SeNPs exhibited excellent biocidal activity against F. oxysporum and F. moniliforme, with MIC of 0.25 and 1.7 mg/mL, respectively. Direct treatment of F. oxysporum with SeNPs led to significant deformation and lysis of the fungal hyphae within 18 h. The treatment of infected fruits with MIC of SeNPs reduced the infection signs by 100% and preserved the fresh-like appearance of treated fruits for 25 and 35 days when stored at 25 °C and 5 °C, respectively. Therefore, SeNPs is considered efficacious fungicidal against Fusarium spp. in-vitro and in-vivo. The treatment of tomato fruits with MIC of SeNPs positively affected its chemical properties, as well as decreased weight loss %, confirming the barrier effect of SeNPs, thus increasing fruits' shelf-life. Bio-mediated SeNPs appeared safe towards normal HSF and OEC cell lines with IC50> 300 μg/mL. Overall results recommend the usage of bio-mediated SeNPs as safe powerful bioagent against Fusarium infection, maintaining tomato quality, and providing protection from post-harvest invasion and/or destroying existing infections.

Metallic Nanoparticles: A Promising Arsenal against Antimicrobial Resistance-Unraveling Mechanisms and Enhancing Medication Efficacy

The misuse of antibiotics and antimycotics accelerates the emergence of antimicrobial resistance, prompting the need for novel strategies to combat this global issue. Metallic nanoparticles have emerged as effective tools for combating various resistant microbes. Numerous studies have highlighted their potential in addressing antibiotic-resistant fungi and bacterial strains. Understanding the mechanisms of action of these nanoparticles, including iron-oxide, gold, zinc oxide, and silver is a central focus of research within the life science community. Various hypotheses have been proposed regarding how nanoparticles exert their effects. Some suggest direct targeting of microbial cell membranes, while others emphasize the release of ions from nanoparticles. The most compelling proposed antimicrobial mechanism of nanoparticles involves oxidative damage caused by nanoparticles-generated reactive oxygen species. This review aims to consolidate knowledge, discuss the properties and mechanisms of action of metallic nanoparticles, and underscore their potential as alternatives to enhance the efficacy of existing medications against infections caused by antimicrobial-resistant pathogens.

In vitro and Quantitative and Structure Activity Relationship (QSAR) evaluation of the antifungal activity of terpenoid constituents of essential oils against Alternaria alternata and Fusarium oxysporum

INTRODUCTION

Fungal genera Alternaria and Fusarium include human and plant pathogenic species. Several antifungals have been used for their control, but excessive use has contributed to resistance development in pathogens. An alternative to searching for and developing new antifungal agents is using essential oils and their main components, which have biological activities of interest in medicine and food production.

OBJECTIVE

To evaluate in vitro and in silico the antifungal activities of terpenoids against Alternaria alternata and Fusarium oxysporum.

MATERIALS AND METHODS

The minimum inhibitory concentration and minimum fungicidal concentration values of 27 constituents of essential oils used against Alternaria alternata and Fusarium oxysporum were evaluated in vitro. In addition, using genetic algorithms, quantitative models of the structure-activity relationship were used to identify the structural and physicochemical properties related to antifungal activity.

RESULTS

The evaluated compounds proved to be effective antifungals. Thymol was the most active with a minimum inhibitory concentration of 91.6 ± 28.8 μg/ml for A. alternata and F. oxysporum. Quantitative structure-activity relationship models revealed the octanolwater cleavage ratio as the molecular property, and the phenols as the main functional group contributing to antifungal activity.

CONCLUSION

Terpenoids exhibit relevant antifungal activities that should be incorporated into the study of medicinal chemistry. Inclusion of in silico assays in the in vitro evaluation is a valuable tool in the search for and rational design of terpene derivatives as new potential antifungal agents.

Multifactorial role of nanoparticles in alleviating environmental stresses for sustainable crop production and protection

In the era of dire environmental fluctuations, plants undergo several stressors during their life span, which severely impact their development and overall growth in negative aspects. Abiotic stress factors, especially moisture stress i.e shortage (drought) or excess (flooding), salinity, temperature divergence (i.e. heat and cold stress), heavy metal toxicity, etc. create osmotic and ionic imbalance inside the plant cells, which ultimately lead to devastating crop yield, sometimes crop failure. Apart from the array of abiotic stresses, various biotic stress caused by pathogens, insects, and nematodes also affect production. Therefore, to combat these major challenges in order to increase production, several novel strategies have been adapted, among which the use of nanoparticles (NPs) i.e. nanotechnology is becoming an emerging tool in various facets of the current agriculture system, nowadays. This present review will elaborately depict the deployment and mechanisms of different NPs to withstand these biotic and abiotic stresses, along with a brief overview and indication of the future research works to be oriented based on the steps provided for future research in advance NPs application through the sustainable way.

Oliveira S, Pereira MDL, Wiart C, Wilairatana P, Eawsakul K, Rahmatullah M, Saravanabhavan SS, Nissapatorn V. Green synthesis of silver nanoparticles using Ocimum sanctum Linn. and its antibacterial activity against multidrug resistant Acinetobacter baumannii

The biosynthesis of nanoparticles using the green route is an effective strategy in nanotechnology that provides a cost-effective and environmentally friendly alternative to physical and chemical methods. This study aims to prepare an aqueous extract of Ocimum sanctum (O. sanctum)-based silver nanoparticles (AgNPs) through the green route and test their antibacterial activity. The biosynthesized silver nanoparticles were characterised by colour change, UV spectrometric analysis, FTIR, and particle shape and size morphology by SEM and TEM images. The nanoparticles are almost spherical to oval or rod-shaped with smooth surfaces and have a mean particle size in the range of 55 nm with a zeta potential of -2.7 mV. The antibacterial activities of AgNPs evaluated against clinically isolated multidrug-resistant Acinetobacter baumannii (A. baumannii) showed that the AgNPs from O. sanctum are effective in inhibiting A. baumannii growth with a zone of inhibition of 15 mm in the agar well diffusion method and MIC and MBC of 32 µg/mL and 64 µg/mL, respectively. The SEM images of A. baumannii treated with AgNPs revealed damage and rupture in bacterial cells. The time-killing assay by spectrophotometry revealed the time- and dose-dependent killing action of AgNPs against A. baumannii, and the assay at various concentrations and time intervals indicated a statistically significant result in comparison with the positive control colistin at 2 µg/mL (P < 0.05). The cytotoxicity test using the MTT assay protocol showed that prepared nanoparticles of O. sanctum are less toxic against human cell A549. This study opens up a ray of hope to explore the further research in this area and to improve the antimicrobial activities against multidrug resistant bacteria.

Using inorganic nanoparticles to fight fungal infections in the antimicrobial resistant era

Fungal infections pose a serious threat to human health and livelihoods. The number and variety of clinically approved antifungal drugs is very limited, and the emergence and rapid spread of resistance to these drugs means the impact of fungal infections will increase in the future unless alternatives are found. Despite the significance and major challenges associated with fungal infections, this topic receives significantly less attention than bacterial infections. A major challenge in the development of fungi-specific drugs is that both fungi and mammalian cells are eukaryotic and have significant overlap in their cellular machinery. This lack of fungi-specific drug targets makes human cells vulnerable to toxic side effects from many antifungal agents. Furthermore, antifungal drug resistance necessitates higher doses of the drugs, leading to significant human toxicity. There is an urgent need for new antifungal agents, specifically those that can limit the emergence of new resistant species. Non-drug nanomaterials have primarily been explored as antibacterial agents in recent years; however, they are also a promising source of new antifungal candidates. Thus, this article reviews current research on the use of inorganic nanoparticles as antifungal agents. We also highlight challenges facing antifungal nanoparticles and discuss possible future research opportunities in this field. STATEMENT OF SIGNIFICANCE: Fungal infections pose a growing threat to human health and livelihood. The rapid spread of resistance to current antifungal drugs has led to an urgent need to develop alternative antifungals. Nanoparticles have many properties that could make them useful antimycotic agents. To the authors' knowledge, there is no published review so far that has comprehensively summarized the current development status of antifungal inorganic nanomaterials, so we decided to fill this gap. In this review, we discussed the state-of-the-art research on antifungal inorganic nanoparticles including metal, metal oxide, transition-metal dichalcogenides, and inorganic non-metallic particle systems. Future directions for the design of inorganic nanoparticles with higher antifungal efficacy and lower toxicity are described as a guide for further development in this important area.

Nanotechnology for sustainable agro-food systems: The need and role of nanoparticles in protecting plants and improving crop productivity

The rapid population growth and environmental challenges in agriculture need innovative and sustainable solutions to meet the growing need for food worldwide. Recent nanotechnological advances found its broad applicability in agriculture's protection and post-harvesting. Engineered nanomaterials play a vital role in plant regulation, seed germination, and genetic manipulation. Their size, surface morphology, properties, and composition were designed for controlled release and enhanced properties in agriculture and the food industry. Nanoparticles can potentially be applied for the targeted and controlled delivery of fertilizers, pesticides, herbicides, plant growth regulators, etc. This help to eliminate the use of chemical-based pesticides and their water solubility, protect agrochemicals from breakdown and degradation, improve soil health, and naturally control crop pathogens, weeds, and insects, ultimately leading to enhanced crop growth and production capacity in the food industry. They can be effectively utilized for nano-encapsulation, seed germination, genetic manipulation, etc., for protecting plants and improving crop productivity, safe and improved food quality, and monitoring climate conditions. Nanoparticles played a crucial role in the uptake and translocation processes, genetically modifying the crops, high seed germination, and productivity. In this article, we have reviewed some important applications of nanoparticles for sustainable agro-food systems. The need and role of nanotechnology concerning challenges and problems faced by agriculture and the food industry are critically discussed, along with the limitations and future prospects of nanoparticles.

Mechanisms of Antifungal Properties of Metal Nanoparticles

The appearance of resistant species of fungi to the existent antimycotics is challenging for the scientific community. One emergent technology is the application of nanotechnology to develop novel antifungal agents. Metal nanoparticles (NPs) have shown promising results as an alternative to classical antimycotics. This review summarizes and discusses the antifungal mechanisms of metal NPs, including combinations with other antimycotics, covering the period from 2005 to 2022. These mechanisms include but are not limited to the generation of toxic oxygen species and their cellular target, the effect of the cell wall damage and the hyphae and spores, and the mechanisms of defense implied by the fungal cell. Lastly, a description of the impact of NPs on the transcriptomic and proteomic profiles is discussed.

Inhibition of Phytopathogenic and Beneficial Fungi Applying Silver Nanoparticles In Vitro

In the current research, our work measured the effect of silver nanoparticles (AgNP) synthesized from Larrea tridentata (Sessé and Moc. ex DC.) on the mycelial growth and morphological changes in mycelia from different phytopathogenic and beneficial fungi. The assessment was conducted in Petri dishes, with Potato-Dextrose-Agar (PDA) as the culture medium; the AgNP concentrations used were 0, 60, 90, and 120 ppm. Alternaria solani and Botrytis cinerea showed the maximum growth inhibition at 60 ppm (70.76% and 51.75%). Likewise, Macrophomina spp. required 120 ppm of AgNP to achieve 65.43%, while Fusarium oxisporum was less susceptible, reaching an inhibition of 39.04% at the same concentration. The effect of silver nanoparticles was inconspicuous in Pestalotia spp., Colletotrichum gloesporoides, Phytophthora cinnamomi, Beauveria bassiana, Metarhizium anisopliae, and Trichoderma viridae fungi. The changes observed in the morphology of the fungi treated with nanoparticles were loss of definition, turgidity, and constriction sites that cause aggregations of mycelium, dispersion of spores, and reduced mycelium growth. AgNP could be a sustainable alternative to managing diseases caused by Alternaria solani and Macrophomina spp.

Silver oxide nanostructures as a new trend to control strawberry charcoal rot induced by Macrophomina phaseolina

BACKGROUND

Silver oxide (Ag₂ O) nanostructures were fabricated and their ability to induce antifungal activity against Macrophomina phaseolina, which causes charcoal rot disease in strawberries, was evaluated under laboratory, greenhouse and field conditions. A real-time quantitative polymerase chain reaction was used to monitor expression of defense-related genes, which is essential to evaluate the potential of the manufactured nanoparticles to promote strawberry resistance against charcoal rot. The effect of Ag₂ O nanoparticles on growth characteristics in strawberry plants was also studied.

RESULTS

The results showed that Ag₂ O significantly inhibited M. phaseolina growth compared with untreated controls under in vitro conditions. Strawberry plants treated with Ag₂ O showed a significant decrease in the severity of charcoal rot disease in the greenhouse compared with untreated plants. Strawberry plants treated with Ag₂ O nanoparticles expressed defense gene (PR-1) involved in the salicylic acid signaling pathways at levels three to five times higher than in the control group. Ag₂ O nanoparticles significantly improved the growth and yield of the strawberry crop.

CONCLUSION

Use of Ag₂ O nanoparticles can be considered a new strategy to control M. phaseolina and this is the first report of this effect. © 2022 Society of Chemical Industry.

Gel-Forming Soil Conditioners of Combined Action: Laboratory Tests for Functionality and Stability

The research analyzes technological properties and stability of innovative gel-forming polymeric materials for complex soil conditioning. These materials combine improvements in the water retention, dispersity, hydraulic properties, anti-erosion and anti-pathogenic protection of the soil along with a high resistance to negative environmental factors (osmotic stress, compression in the pores, microbial biodegradation). Laboratory analysis was based on an original system of instrumental methods, new mathematical models, and the criteria and gradations of the quality of gels and their compositions with mineral soil substrates. The new materials have a technologically optimal degree of swelling (200−600 kg/kg in pure water and saline solutions with 1−3 g/L TDS), high values of surface energy (>130 kJ/kg), specific surface area (>600 m2/g), threshold of gel collapse (>80 mmol/L), half-life (>5 years), and a powerful fungicidal effect (EC50 biocides doses of 10−60 ppm). Due to these properties, the new gel-forming materials, in small doses of 0.1−0.3% increased the water retention and dispersity of sandy substrates to the level of loams, reduced the saturated hydraulic conductivity 20−140 times, suppressed the evaporation 2−4 times, and formed a windproof soil crust (strength up to 100 kPa). These new methodological developments and recommendations are useful for the complex laboratory testing of hydrogels in small (5−10 g) soil samples.

Ocimum basilicum-Mediated Synthesis of Silver Nanoparticles Induces Innate Immune Responses against Cucumber Mosaic Virus in Squash

Cucumber mosaic virus (CMV) causes a significant threat to crop output sustainability and human nutrition worldwide, since it is one of the most prevalent plant viruses infecting most kinds of plants. Nowadays, different types of nanomaterials are applied as a control agent against different phytopathogens. However, their effects against viral infections are still limited. In the current study, the antiviral activities of the biosynthesized silver nanoparticles (Ag-NPs) mediated by aqueous extract of Ocimum basilicum against cucumber mosaic virus in squash (Cucurbita pepo L.) were investigated. The prepared Ag-NPs were characterized using scanning electron microscopy (SEM), dynamic light scattering (DLS), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FTIR) and zeta potential distribution techniques. DLS, SEM, and TEM analyses showed that the Ag-NPs were spherical, with sizes ranging from 26.3 to 83 nm with an average particle size of about 32.6 nm. FTIR identified different functional groups responsible for the capping and stability of Ag-NPs. The zeta potential was reported as being -11.1 mV. Under greenhouse conditions, foliar sprays of Ag-NPs (100 µg/mL) promoted growth, delayed disease symptom development, and significantly reduced CMV accumulation levels of treated plants compared to non-treated plants. Treatment with Ag-NPs 24 h before or after CMV infection reduced CMV accumulation levels by 92% and 86%, respectively. There was also a significant increase in total soluble carbohydrates, free radical scavenging activity, antioxidant enzymes (PPO, SOD, and POX), as well as total phenolic and flavonoid content. Furthermore, systemic resistance was induced by significantly increasing the expression levels of pathogenesis-related genes (PR-1 and PR-5) and polyphenolic pathway genes (HCT and CHI). These findings suggest that Ag-NPs produced by O. basilicum could be used as an elicitor agent and as a control agent in the induction and management of plant viral infections.

The antifungal activity and mechanism of silver nanoparticles against four pathogens causing kiwifruit post-harvest rot

Post-harvest rot causes enormous economic loss to the global kiwifruit industry. Currently, there are no effective fungicides to combat the disease. It is unclear whether silver nanoparticles (AgNPs) are effective in controlling post-harvest rot and, if so, what the underlying antifungal mechanism is. Our results indicated that 75 ppm AgNPs effectively inhibited the mycelial growth and spore germination of four kiwifruit rot pathogens: Alternaria alternata, Pestalotiopsis microspora, Diaporthe actinidiae, and Botryosphaeria dothidea. Additionally, AgNPs increased the permeability of mycelium’s cell membrane, indicating the leakage of intracellular substance. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) observations revealed that AgNPs induced pathogen hypha shrinkage and distortion, as well as vacuolation in hypha cells, implying that AgNPs caused cellular and organelle structural degradation. The transcriptome sequencing of mycelium treated with AgNPs (24 h / 48 h) was performed on the Illumina Hiseq 4000 sequencing (RNA-Seq) platform. For the time points of 24 h and 48 h, AgNPs treatment resulted in 1,178 and 1,461 differentially expressed genes (DEGs) of A. alternata, 517 and 91 DEGs of P. microspora, 1,287 and 65 DEGs of D. actinidiae, 239 and 55 DEGs of B. dothidea, respectively. The DEGs were found to be involved in “catalytic activity,” “small molecule binding,” “metal ion binding,” “transporter activity,” “cellular component organization,” “protein metabolic process,” “carbohydrate metabolic process,” and “establishment of localization.” Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis also revealed that “carbohydrate metabolism,” “amino acid metabolism,” “energy metabolism,” and “xenobiotics biodegradation and metabolism” of “metabolism processes” were the most highly enriched pathways for these DEGs in four pathogens, with “cellular processes” being particularly enriched for B. dothidea. Furthermore, quantitative polymerase chain reactions (qPCRs) were used to validate the RNA-seq results. It was also confirmed that AgNPs could significantly reduce the symptoms of kiwifruit rot without leaving any Ag⁺ residue on the peel and flesh of kiwifruit. Our findings contributed to a better understanding of the antifungal effect and molecular mechanisms of AgNPs against pathogens causing kiwifruit post-harvest rot, as well as a new perspective on the application of this novel antifungal alternative to fruit disease control.

Biocontrol potential of mycogenic copper oxide nanoparticles against Alternaria brassicae

The biological synthesis of nanoparticles using fungal cultures is a promising and novel tool in nano-biotechnology. The potential culture of Trichoderma asperellum (T. asperellum) has been used to synthesize copper oxide nanoparticles (CuO NPs) in the current study. The necrotrophic infection in Brassica species is caused due to a foliar pathogen Alternaria brassicae (A. brassicae). Mycogenic copper oxide nanoparticles (M-CuO NPs) were characterized by spectroscopic and microscopic techniques such as UV–visible spectrophotometry (UV–vis), transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). The antifungal potential of CuO NPs was studied against A. brassicae. M-CuO NPs exhibited a surface plasmon resonance (SPR) at 303 nm, and XRD confirmed the crystalline phase of NPs. FTIR spectra confirmed the stretching of amide bonds, and the carbonyl bond indicated the presence of enzymes in T. asperellum filtrate. SEM and TEM confirmed the spherical shape of M-CuO NPs with an average size of 22 nm. Significant antifungal potential of M-CuO NPs was recorded, as it inhibited the growth of A. brassicae up to 92.9% and 80.3% in supplemented media with C-CuO NPs at 200 ppm dose. Mancozeb and propiconazole inhibited the radial growth up to 38.7% and 44.2%. SEM confirmed the morphological changes in hyphae and affected the sporulation pattern. TEM revealed hardly recognizable organelles, abnormal cytoplasmic distribution, and increased vacuolization, and light microscopy confirmed the conidia with reduced diameter and fewer septa after treatment with both types of NPs. Thus, M-CuO NPs served as a promising alternative to fungicides.

Application of nickel chitosan nanoconjugate as an antifungal agent for combating Fusarium rot of wheat

Agro-researchers are endlessly trying to derive a potential biomolecule having antifungal properties in order to replace the application of synthetic fungicides on agricultural fields. Rot disease often caused by Fusarium solani made severe loss of wheat crops every year. Chitosan and its metallic nano-derivatives hold a broad-spectrum antifungal property. Our interdisciplinary study deals with the application of nickel chitosan nanoconjugate (NiCNC) against Fusarium rot of wheat, in comparison with chitosan nanoparticles (CNPs) and commercial fungicide Mancozeb. CNPs and NiCNC were characterized on the basis of UV–Vis spectrophotometry, HR-TEM, FESEM, EDXS and FT-IR. Both CNPs and NiCNC were found effective against the fungal growth, of which NiCNC at 0.04 mg/mL showed complete termination of F. solani grown in suitable medium. Ultrastructural analysis of F. solani conidia treated with NiCNC revealed pronounced damages and disruption of the membrane surface. Fluorescence microscopic study revealed generation of oxidative stress in the fungal system upon NiCNC exposure. Moreover, NiCNC showed reduction in rot disease incidence by 83.33% of wheat seedlings which was further confirmed through the observation of anatomical sections of the stem. NiCNC application helps the seedling to overcome the adverse effect of pathogen, which was evaluated through stress indices attributes.

Engineered green nanoparticles interact with Nigrospora oryzae isolated from infected leaves of Arachis hypogaea

Oilseed crop diseases are a major concern around the world, particularly in India. The synthetic fungicides not only kill the pathogen, but they also harm the host plant and beneficial microbes and on continuous usage, they decrease the soil fertility. To overcome this problem, green nanotechnology has been a greater alternative with promising benefits. The green synthesized nanoparticles from the extract of various plant parts are an effective remedy for killing the pathogens without affecting the host plants and the environment. Hence, in our study silver nanoparticles were synthesized from Fennel seed (Foeniculum vulgare) extract. The synthesis of nanoparticles was confirmed using UV-vis, Fourier transform infrared, dynamic light scattering, zeta potential, and scanning electron microscopic analysis. The in vitro antifungal study was carried out and revealed that the nanoparticles had high efficacy against the isolated phytopathogen Nigrospora oryzae which causes tikka disease in Arachis hypogaea plants. Hence, F. vulgare seed nanoparticles can be used as an effective alternative to synthetic fungicides without causing any deleterious effect on soil microflora or the environment.

Comparative Effect of Commercially Available Nanoparticles on Soil Bacterial Community and “Botrytis fabae” Caused Brown Spot: In vitro and in vivo Experiment

This study revealed the possible effects of various levels of silver nanoparticle (AgNP) application on plant diseases and soil microbial diversity. It investigated the comparison between the application of AgNPs and two commercial nanoproducts (Zn and FeNPs) on the rhizobacterial population and Botrytis fabae. Two experiments were conducted. The first studied the influence of 13 AgNP concentration on soil bacterial diversity besides two other commercial nanoparticles, ZnNPs (2,000 ppm) and FeNPs (2,500 ppm), used for comparison and application on onion seedlings. The second experiment was designed to determine the antifungal activity of previous AgNP concentrations (150, 200, 250, 300, 400, and 500 ppm) against B. fabae, tested using commercial fungicide as control. The results obtained from both experiments revealed the positive impact of AgNPs on the microbial community, representing a decrease in both the soil microbial biomass and the growth of brown spot disease, affecting microbial community composition, including bacteria, fungi, and biological varieties. In contrast, the two commercial products displayed lower effects compared to AgNPs. This result clearly showed that the AgNPs strongly inhibited the plant pathogen B. fabae growth and development, decreasing the number of bacteria (cfu/ml) and reducing the rhizosphere. Using AgNPs as an antimicrobial agent in the agricultural domain is recommended.

Mung Bean (Vigna radiata) Treated with Magnesium Nanoparticles and Its Impact on Soilborne Fusarium solani and Fusarium oxysporum in Clay Soil

The nanotechnology revolution is developing daily all over the world. Soil-borne fungi cause a significant yield loss in mung beans. Our study was performed to identify the impact of different concentrations of MgO nanoparticles (MgONPs) and to assess the prevalence of Fusarium solani (F. solani) and Fusarium oxysporum (F. oxysporum) in mung bean plants under in vivo conditions and, subsequently, the remaining impacts on soil health. In vitro studies revealed that MgONPs could inhibit fungal growth. Mung bean plants treated with MgONPs showed a promotion in growth. The obtained MgONPs were applied to the roots of 14-day-old mung bean plants at a concentration of 100 µg/mL. The application of MgONPs at a concentration of 100 µg/mL caused an increase in mung bean seedlings. Compared to the control treated with water, plants exposed to MgONPs at 100 µg/mL showed improvements (p < 0.05) in shoot fresh weight (28.62%), shoot dry weight (85.18%), shoot length (45.83%), root fresh weight (38.88%), root dry weight (33.33%), root length (98.46%), and root nodule (70.75%). In the greenhouse, the severity of disease caused by F. solani decreased from approximately 44% to 25% and that by F. oxysporum from 39% to 11.4%, respectively. The results of this study confirm that the temporal growth of the soil microbial biomass was partially reduced or boosted following the nanoparticle drenching addition and/or plant infections at higher concentrations of 50 and 100 µg/mL while there was no significant decrease at the lowest concentration (25 µg/mL). The current research helps us to better understand how nanoparticles might be used to prevent a variety of fungal diseases in agricultural fields while avoiding the creation of environmental hazards to soil health.

Controllable synthesis and stabilization of Tamarix aphylla-mediated copper oxide nanoparticles for the management of Fusarium wilt on musk melon

Excessive use of pesticides and mineral fertilizers poses a serious threat to ecoenvironment sustainability and human health. Nano pesticides or Nano fungicides have attained great attention in the field of agriculture due to their unique characteristics, by improving crop growth with enhancing pathogenesis-related defense system. However, there is a need to develop a sustainable mechanism for the synthesis of fungicides which replace the chemical pesticides to avoid their hazardous impact. Here in, Tamarix aphylla mediated CuO-Nanoparticles (NPs) were synthesized, characterized and their activity was evaluated under in-vitro and in-vivo conditions. The structural and elemental analysis of NPs were carried out by using X-ray powder diffraction (XRD), Fourier transformed infrared spectroscopy (FTIR), UV-visible spectrophotometer, Scanning electron microscope (SEM) and Transmission electron microscope (TEM). In the greenhouse, at an optimum concentration of 50 mg/L reduced disease severity very effectively and enhanced plant growth. Application of NPs also assisted in the induction of systemic response of defense-related genes in melon. Under In vitro condition at 100 mg/L significantly reduced mycelial growth (84.5%) by directly acting on the pathogenic cell wall. Our work confirmed that dosedependent concentration of T. aphylla extract based biological CuO-NPs enhance plant growth and help to effectively resist against F. oxysporum infection.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-022-03189-0.

Innovative Approach for Controlling Black Rot of Persimmon Fruits by Means of Nanobiotechnology from Nanochitosan and Rosmarinic Acid-Mediated Selenium Nanoparticles

The protection of persimmon fruits (Diospyros kaki L.) from postharvest fungal infestation with Alternaria alternata (A. alternate; black rot) is a major agricultural and economic demand worldwide. Edible coatings (ECs) based on biopolymers and phytocompounds were proposed to maintain fruit quality, especially with nanomaterials’ applications. Chitosan nanoparticles (NCt), rosmarinic acid bio-mediated selenium nanoparticles (RA/SeNPs) and their composites were produced, characterized and evaluated as ECs for managing persimmon black rot. The constructed NCt, RA/SeNPs and NCt/RA/SeNPs composite had diminished particles’ size diameters. The ECs solution of 1% NCt and NCt/RA/SeNPs composite led to a significant reduction of A. alternata radial growth in vitro, with 77.4 and 97.2%, respectively. The most powerful ECs formula contained 10 mg/mL from NCt/RA/SeNPs composite, which significantly reduced fungal growth than imazalil fungicide. The coating of persimmon with nanoparticles-based ECs resulted in a significant reduction of black rot disease severity and incidence in artificially infected fruits; the treatment with 1% of NCt/RA/SeNPs could completely (100%) hinder disease incidence and severity in coated fruits, whereas imazalil reduced them by 88.6 and 73.4%, respectively. The firmness of fruits is greatly augmented after ECs treatments, particularly with formulated coatings with 1% NCt/RA/SeNPs composite, which maintain fruits firmness by 85.7%. The produced ECs in the current study, based on NCt/RA/SeNPs composite, are greatly recommended as innovatively constructed human-friendly matrix to suppress the postharvest destructive fungi (A. alternata) and maintain the shelf-life and quality of persimmon fruits.

Potential Applications of Engineered Nanoparticles in Plant Disease Management: A Critical Update

Plant diseases caused by pathogenic entities pose severe issues to global food security. Effective sensory applications and tools for the effective determination of plant diseases become crucial to the assurance of food supply and agricultural sustainability. Antibody-mediated molecular assays and nucleic acid are gold-standard approaches for plant disease diagnosis, but the evaluating methodologies are liable, complex, and laborious. With the rise in global food demand, escalating the food production in threats of diverse pathogen ranges, and climate change is a major challenge. Engineered nanoparticles (NPs) have been inserted into conventional laboratory sequence technologies or molecular assays that provide a remarkable increment in selectivity and sensitivity. In the present scenario, they are useful in plant disease management as well as in plant health monitoring. The use of NPs could sustainably mitigate numerous food security issues and or threats in disease management by decreasing the risk of chemical inputs and alleviating supra detection of pathogens. Overall, this review paper discusses the role of NPs in plant diseases management, available commercial products. Additionally, the future directions and their regulatory laws in the usage of the nano-diagnostic approach for plant health monitoring have been explained.

Fungal and oomycete pathogens and heavy metals: an inglorious couple in the environment

Heavy metal (HM) contamination of the environment is a major problem worldwide. The rate of global deposition of HMs in soil has dramatically increased over the past two centuries and there of facilitated their rapid accumulation also in living systems. Although the effects of HMs on plants, animals and humans have been extensively studied, yet little is known about their effects on the (patho)biology of the microorganisms belonging to a unique group of filamentous eukaryotic pathogens, i.e., fungi and oomycetes. Much of the literature concerning mainly model species has revealed that HM stress affects their hyphal growth, morphology, and sporulation. Toxicity at cellular level leads to disturbance of redox homeostasis manifested by the formation of nitro-oxidative intermediates and to the induction of antioxidant machinery. Despite such adverse effects, published data is indicative of the fact that fungal and oomycete pathogens have a relatively high tolerance to HMs in comparison to other groups of microbes such as bacteria. Likely, these pathogens may harbor a network of detoxification mechanisms that ensure their survival in a highly HM-polluted (micro)habitat. Such a network may include extracellular HMs immobilization, biosorption to cell wall, and/or their intracellular sequestration to proteins or other ligands. HMs may also induce a hormesis-like phenomenon allowing the pathogens to maintain or even increase fitness against chemical challenges. Different scenarios linking HMs stress and modification of the microorganisms pathogenicity are disscused in this review.

Antifungal Activities of Sulfur and Copper Nanoparticles against Cucumber Postharvest Diseases Caused by Botrytis cinerea and Sclerotinia sclerotiorum

Nanoparticles (NPs) have attracted great interest in various fields owing to their antimicrobial activity; however, the use of NPs as fungicides on plants has not been sufficiently investigated. In this study, the antifungal activities of sulfur nanoparticles (S-NPs) and copper nanoparticles (Cu-NPs) prepared by a green method were evaluated against Botrytis cinerea and Sclerotinia sclerotiorum. The formation of NPs was confirmed by transmission electron microscopy (TEM) and X-ray diffraction analysis (XRD). The antifungal activities of NPs (5–100 µg/mL), CuSO₄ (4000 µg/mL), and micro sulfur (MS) were compared to those of the recommended chemical fungicide Topsin-M 70 WP at a dose of 1000 µg/mL. They were evaluated in vitro and then in vivo at different temperatures (10 and 20 °C) on cucumber (Cucumis sativus) fruits. The total phenolic content (TPC) and total soluble solids (TSS) were determined to study the effects of various treatments on the shelf life of cucumber fruits, compared to untreated cucumber as a positive control. The diameters of S-NPs and Cu-NPs ranged from 10 to 50 nm, and 2 to 12 nm, respectively. The results revealed that S-NPs exhibited the highest antifungal activity, followed by Cu-NPs. However, CuSO₄ showed the lowest antifungal activity among all treatments. The antifungal activity of the prepared NPs increased with the increase in NP concentration, while the fungal growth was less at low temperature. The cytotoxicity of the prepared NPs was evaluated against the WI-38 and Vero cell lines in order to assess their applicability and sustainability. S-NPs caused less cytotoxicity than Cu-NPs.

Design, Characterization, and Antimicrobial Evaluation of Copper Nanoparticles Utilizing Tamarixinin a Ellagitannin from Galls of Tamarix aphylla

The application of plant extracts or plant-derived compounds in the green synthesis of metal nanoparticles (NPs) was researched. Determining the exact metabolite implicated in the formation of NPs would necessitate comprehensive investigations. Copper nanoparticles (CuNPs) are gaining a lot of attention because of their unique properties and effectiveness against a wide range of bacteria and fungi, as well as their potential for usage in catalytic, optical, electrical, and microelectronics applications. In the course of this study, we aimed to formulate CuNPs utilizing pure tamarixinin A (TA) ellagitannin isolated from Tamarix aphylla galls. The main particle size of the formed CuNPs was 44 ± 1.7 nm with zeta potential equal to −23.7 mV, which emphasize the stability of the CuNPs. The X-ray diffraction spectroscopy showed a typical centered cubic crystalline structure phase of copper. Scanning electron microscopy images were found to be relatively spherical and homogeneous in shape. The antimicrobial properties of TA, as well as its mediated CuNPs, have been evaluated through well diffusion assays against four bacterial, Bacillus subtilis NCTC 10400, Staphylococcus aureus ATCC 25923, Escherichia coli ATCC 25922, and Pseudomonas aeruginosa ATCC 27853, and two fungal, Candida albicans and Aspergillus flavus, strains. The distinctive antimicrobial activities were noted against the fungal strains and the Gram-negative bacterial strains P. aeruginosa ATCC 27853, and E. coli ATCC 25922. In conclusion, CuNPs mediated by TA can be applied for combating a wide range of bacterial and fungal species especially C. albicans, Asp. flavus, and P. aeruginosa in a variety of fields.

Trichoderma and Nanotechnology in Sustainable Agriculture: A Review

Due to their unique properties and functionalities, nanomaterials can be found in different activities as pharmaceutics, cosmetics, medicine, and agriculture, among others. Nowadays, formulations with nano compounds exist to reduce the application of conventional pesticides and fertilizers. Among the most used are nanoparticles (NPs) of copper, zinc, or silver, which are known because of their cytotoxicity, and their accumulation can change the dynamic of microbes present in the soil. In agriculture, Trichoderma is widely utilized as a safe biocontrol strategy and to promote plant yield, making it susceptible to be in contact with nanomaterials that can interfere with its viability as well as its biocontrol and plant growth promotion effects. It is well-known that strains of Trichoderma can tolerate and uptake heavy metals in their bulk form, but it is poorly understood whether the same occurs with nanomaterials. Interestingly, Trichoderma can synthesize NPs that exhibit antimicrobial activities against various organisms of interest, including plant pathogens. In this study, we summarize the main findings regarding Trichoderma and nanotechnology, including its use to synthesize NPs and the consequence that these compounds might have in this fungus and its associations. Moreover, based on these findings we discuss whether it is feasible to develop agrochemicals that combine NPs and Trichoderma strains to generate more sustainable products or not.

Metal Nanoparticles as Novel Antifungal Agents for Sustainable Agriculture: Current Advances and Future Directions

The use of metal nanoparticles is considered a good alternative to control phytopathogenic fungi in agriculture. To date, numerous metal nanoparticles (e.g., Ag, Cu, Se, Ni, Mg, and Fe) have been synthesized and used as potential antifungal agents. Therefore, this proposal presents a critical and detailed review of the use of these nanoparticles to control phytopathogenic fungi. Ag nanoparticles have been the most investigated nanoparticles due to their good antifungal activities, followed by Cu nanoparticles. It was also found that other metal nanoparticles have been investigated as antifungal agents, such as Se, Ni, Mg, Pd, and Fe, showing prominent results. Different synthesis methods have been used to produce these nanoparticles with different shapes and sizes, which have shown outstanding antifungal activities. This review shows the success of the use of metal nanoparticles to control phytopathogenic fungi in agriculture.

Antimicrobial silver nanoparticle-photodeposited fabrics for SARS-CoV-2 destruction

Surfaces containing antiviral nanoparticles could play a crucial role in minimizing the virus spread further, specifically for COVID-19. Here in, we have developed a facile and durable antiviral and antimicrobial fabric containing photodeposited silver nanoparticles. Scanning and transmission electron microscopy, UV-VIS spectroscopy, and XPS are used to characterize the silver nanoparticles deposited cloth. It is evident that Ag⁰/Ag⁺ redox couple is formed during fabrication, which acts as an active agent. Antiviral testing results show that silver nanoparticles deposited fabric exhibits 97% viral reduction specific to SARS-CoV-2. Besides its excellent antiviral property, the modified fabric also offers antimicrobial efficiency when tested with the airborne human pathogenic bacteria Escherichia coli and fungi Aspergillus Niger. The direct photodeposition provides Ag-O-C interaction leads to firmly grafted nanoparticles on fabric allow the modified fabric to sustain the laundry durability test. The straightforward strategy to prepare an efficient antimicrobial cloth can attract rapid large-scale industrial production.

Myco-Fabrication of Copper Nanoparticles and Its Effect on Crop Pathogenic Fungi

Phytopathogens are responsible for huge losses in the agriculture sector. Amongst them, fungal phytopathogen is quite difficult to control. Many chemicals are available in the market, claiming the high activity against them. However, the development of resistance by the fungal pathogen is the main concern to overcome their menace. Nanotechnology-based products can be a potential alternative to conventional fungicides. Amongst various nanoparticles, Copper nanoparticles (CuNPs) are appearing to be a promising antifungal candidate. It can be synthesized by various methods, but the myco-fabrication appears to be an environmental-friendly approach. Hence, the present study is an attempt to synthesize CuNPs using Aspergillus flavus. The myco-fabricated CuNPs were characterized by UV spectrophotometer, Fourier transform infrared spectroscopy (FTIR), Nanoparticles tracking and analysis system (NTA), Transmission Electron Microscopy (TEM), X-ray diffraction (XRD) and Zeta potential measurement. Myco-fabricated CuNPs showed maximum absorbance at 602 nm and particle size ranging 5-12 nm with the least average size of 8 nm with spherical shape and moderate stability. Myco-fabricated CuNPs tested against selected fungal crop pathogens viz. Aspergillus niger, Fusariumoxysporum, and Alternaria alternata reveal a significant effect. Besides these we have given the hypothetical mechanism depicting the antifungal action of myco-fabricated CuNPs.

Fungal-Metal Interactions: A Review of Toxicity and Homeostasis

Metal nanoparticles used as antifungals have increased the occurrence of fungal-metal interactions. However, there is a lack of knowledge about how these interactions cause genomic and physiological changes, which can produce fungal superbugs. Despite interest in these interactions, there is limited understanding of resistance mechanisms in most fungi studied until now. We highlight the current knowledge of fungal homeostasis of zinc, copper, iron, manganese, and silver to comprehensively examine associated mechanisms of resistance. Such mechanisms have been widely studied in Saccharomyces cerevisiae, but limited reports exist in filamentous fungi, though they are frequently the subject of nanoparticle biosynthesis and targets of antifungal metals. In most cases, microarray analyses uncovered resistance mechanisms as a response to metal exposure. In yeast, metal resistance is mainly due to the down-regulation of metal ion importers, utilization of metallothionein and metallothionein-like structures, and ion sequestration to the vacuole. In contrast, metal resistance in filamentous fungi heavily relies upon cellular ion export. However, there are instances of resistance that utilized vacuole sequestration, ion metallothionein, and chelator binding, deleting a metal ion importer, and ion storage in hyphal cell walls. In general, resistance to zinc, copper, iron, and manganese is extensively reported in yeast and partially known in filamentous fungi; and silver resistance lacks comprehensive understanding in both.

Changes in global Orchidaceae disease geographical research trends: recent incidences, distributions, treatment, and challenges

Many of the Orchidaceae species are threatened due to environmental changes and over exploitation for full fill global demands. The main objective of this article was critically analyzed the recent global distribution of Orchidaceae diversity, its disease patterns, microbial disease identification, detection, along with prevention and challenges. Critical analysis findings revealed that Orchidaceae growth and developments were affected indirectly or directly as a result of complex microbial ecological interactions. Studies have identified many species associated with orchids, some are pathogenic and cause symptoms such as soft rot, brown rot, brown spot, black rot, wilt, foliar, root rot, anthracnose, leaf spot. The review was provided the comprehensive data to evaluate the identification and detection of microbial disease, which is the most important challenge for sustainable cultivation of Orchidaceae diversity. Furthermore, this article is the foremost of disease triggering microbes, orchid relations, and assimilates various consequences that both promoted the considerate and facts of such disease multipart, and will permit the development of best operative disease management practices.

Chitosan/silica nanocomposite-based formulation alleviated gray mold through stimulation of the antioxidant system in table grapes

The main purpose of this study was to explore the ability of a novel silica/polysaccharide polymer-based formulation, namely, chitosan/silica nanocomposites (CSNs), to directly affect Botrytis cinerea in vitro and in inoculated berries, and indirectly to induce natural host resistance via enzymatic and nonenzymatic antioxidants against gray mold of table grapes. The results indicated a positive correlation in in vitro tests in terms of radial growth, spore germination and germ tube elongation, where those parameters were completely inhibited by CSN at 1%. SEM and TEM investigations showed that morphological and internal structural damage was observed in B. cinerea-hyphae/spores treated with CSN. Additionally, most of the treated spores were affected, and cellular vacuolization and cytoplasmic disorganization were observed. The results revealed that CSN reduced gray mold incidence and severity on inoculated berries directly and indirectly. In direct activity, CSN (1%) reduced mold incidence and severity by 100% compared to the control. In indirect activity, mold incidence and severity was reduced by 51% and 64%, respectively. CSN significantly increased superoxide dismutase, ascorbate peroxidase, peroxidase, total phenol and flavonoid at 48 h post-treatment by 1.2-, 1.6-, 1.3-, 1.3- and 1.6-fold, respectively, in grape-treated tissues. It could be concluded that CSN, as a promising alternative control method against gray mold of table grapes, can directly affect the pathogen and indirectly enhance the natural host resistance of the antioxidant system.

Nanoparticle-Based Sustainable Agriculture and Food Science: Recent Advances and Future Outlook

In the current scenario, it is an urgent requirement to satisfy the nutritional demands of the rapidly growing global population. Using conventional farming, nearly one third of crops get damaged, mainly due to pest infestation, microbial attacks, natural disasters, poor soil quality, and lesser nutrient availability. More innovative technologies are immediately required to overcome these issues. In this regard, nanotechnology has contributed to the agrotechnological revolution that has imminent potential to reform the resilient agricultural system while promising food security. Therefore, nanoparticles are becoming a new-age material to transform modern agricultural practices. The variety of nanoparticle-based formulations, including nano-sized pesticides, herbicides, fungicides, fertilizers, and sensors, have been widely investigated for plant health management and soil improvement. In-depth understanding of plant and nanomaterial interactions opens new avenues toward improving crop practices through increased properties such as disease resistance, crop yield, and nutrient utilization. In this review, we highlight the critical points to address current nanotechnology-based agricultural research that could benefit productivity and food security in future.

Cadmium Stress Reprograms ROS/RNS Homeostasis in Phytophthora infestans (Mont.) de Bary

Heavy metal pollution causes many soils to become a toxic environment not only for plants, but also microorganisms; however, little is known how heavy metal contaminated environment affects metabolism of phytopathogens and their capability of infecting host plants. In this study the oomycete Phytophthora infestans (Mont.) de Bary, the most harmful pathogen of potato, growing under moderate cadmium stress (Cd, 5 mg/L) showed nitro-oxidative imbalance associated with an enhanced antioxidant response. Cadmium notably elevated the level of nitric oxide, superoxide and peroxynitrite that stimulated nitrative modifications within the RNA and DNA pools in the phytopathogen structures. In contrast, the protein pool undergoing nitration was diminished confirming that protein tyrosine nitration is a flexible element of the oomycete adaptive strategy to heavy metal stress. Finally, to verify whether Cd is able to modify P. infestans pathogenicity, a disease index and molecular assessment of disease progress were analysed indicating that Cd stress enhanced aggressiveness of vr P. infestans towards various potato cultivars. Taken together, Cd not only affected hyphal growth rate and caused biochemical changes in P. infestans structures, but accelerated the pathogenicity as well. The nitro-oxidative homeostasis imbalance underlies the phytopathogen adaptive strategy and survival in the heavy metal contaminated environment.

Photocatalytic, antiproliferative and antimicrobial properties of copper nanoparticles synthesized using Manilkara zapota leaf extract: A photodynamic approach

Copper nanoparticles were synthesized using Manilkara zapota leaf extract. The synthesis of the nanoparticle was primarily visualized when the colour of the reaction mixture turned into reddish-brown. Biosynthesized nanoparticles were characterized by UV-vis, FT-IR, XRD, SEM and EDX. The UV spectra showed maximum absorption at 584 nm. FT-IR studies showed stretching frequency at 592.76 cm^-1, which is the fingerprint region for Cu-O bond. The crystallinity of the synthesized copper nanoparticles (Mz-Cu NPs) was revealed through XRD analysis. The synthesized Mz-Cu NPs were spherical with an average size of 18.9-42.5 nm and it was shown by SEM analysis. EDX analysis displayed that the nano sample contains 58 % of copper. The antimicrobial property of the synthesized nanoparticles was evaluated against fungal plant pathogens Rhizoctonia solani (MTCC 12232), Sclerotium oryzae (MTCC 12230) and bacterial species, namely Bacillus subtilis (ATCC 23857), Escherichia coli (ATCC 25922), Staphylococcus aureus (ATCC 25923), Vibrio harveyi (ATCC 35084), Vibrio parahaemolyticus (ATCC 33845). In in-vitro haemolytic assay, the particle showed 5.73, 3.34, 0.5 % hemolysis at 100, 50, 25 μg/mL concentration respectively. In the antiproliferative assay, the IC₅₀ values of MCF7 and Vero cells were found to be 53.89 and 883.69 μg/μl. The particle degraded Methyl violet, Malachite green and Coomassie brilliant blue by 92.2, 94.9 and 78.8 %, within 50, 40 and 60 min, respectively, through its photocatalytic activity.

Optimization of process parameters for the synthesis of silver nanoparticles from Piper betle leaf aqueous extract, and evaluation of their antiphytofungal activity

Biological methods offer eco-friendly and cost-effective alternatives for the synthesis of silver nanoparticles (AgNPs). The present study highlights a green process where AgNPs were synthesized and optimized by using silver nitrate (AgNO₃) and the aqueous extract of Piper betle (Pbet) leaf as the reducing and capping agent. The stable and optimized process for the synthesis of Pbet-AgNPs was exposure of reaction mixture into the sunlight for 40 min, pH 9.0, and 2 mM AgNO₃ using 1:4 diluted Pbet leaf aqueous extract. The optimized Pbet-AgNPs were characterized by UV-visible spectroscopy, high-resolution field emission scanning electron microscopy (FE-SEM), X-ray diffractometry (XRD), and Fourier-transform infrared spectroscopy (FTIR). The prepared Pbet-AgNPs were spherical in shape with size in the range of 6-14 nm. These nanoparticles were stable for 6 months in aqueous solution at room temperature under dark conditions. The biogenic synthesized Pbet-AgNPs are found to have significant antifungal activity against plant pathogenic fungi, Alternaria brassicae and Fusarium solani. Synthesized Pbet-AgNPs potentially reduced the fungal growth in a dose-dependent manner. Microscopic observation of treated mycelium showed that Pbet-AgNPs could disrupt the mycelium cell wall and induce cellular permeability. Protein leakage assay supports these findings. Overall, this study revealed the efficacy of green synthesized AgNPs to control the plant fungal pathogens. Pbet leaves are a rich source of phenolic biomolecule(s). It was hypothesized that these biomolecule(s) mediated metal reduction reactions. In this context, the present work investigates the phytobiomolecule(s) of the aqueous extract of Pbet leaves using high-resolution liquid chromatography-mass spectroscopy (HR-LCMS) method. The analysis revealed that eugenol, chavicol, and hydroxychavicol were present in the Pbet aqueous extract.

Green Synthesized ZnO Nanoparticles Mediated by Mentha Spicata Extract Induce Plant Systemic Resistance against Tobacco Mosaic Virus

Globally, plant viral infection is one of the most difficult challenges of food security, where considerable losses in crop production occur. Nanoparticles are an effective control agent against numerous plant pathogens. However, there is limited knowledge concerning their effects against viral infection. In the present study, the green synthesis of zinc oxide nanoparticles (ZnO NPs) using aqueous leaf extract of Mentha spicata was achieved. X-ray diffraction patterns confirmed the crystalline nature of the prepared ZnO NPs. Dynamic light scattering and scanning electron microscopy analyses revealed that the resultant ZnO NPs were spherical in shape with a particle size ranged from 11 to 88 nm. Fourier transmission infrared spectroscopy detected different functional groups, capping and stability agents, and showed Zn-O bond within wavenumber of 487 cm−1. Under greenhouse conditions, the antiviral activity of biological synthesized ZnO NPs (100 µg/mL) against Tobacco mosaic virus (TMV) was evaluated. The double foliar application of the prepared ZnO NPs, 24 h before and 24 h after TMV-inoculation, was the most effective treatment that showed a 90.21% reduction of viral accumulation level and disease severity. Additionally, the transcriptional levels of PAL, PR-1 (salicylic acid marker gene), CHS, and POD genes were induced and up-regulated in all ZnO NPs treated plants. Notably, the results exhibited that aqueous extract of Mentha spicata was an effective reducing agent for the green synthesis of ZnO NPs, which showed significant antiviral activity. Finally, the detected protective and curative activity of ZnO NPs against TMV can encourage us to recommend its application for plant viral disease management. To our knowledge, this is the first study describing the antiviral activity of the green synthesized ZnO NPs.