Mycosynthesis of ZnO Nanoparticles Using Trichoderma spp. Isolated from Rhizosphere Soils and Its Synergistic Antibacterial Effect against Xanthomonas oryzae pv. oryzae

A review on mycogenic metallic nanoparticles and their potential role as antioxidant, antibiofilm and quorum quenching agents

The emergence of antimicrobial resistance among biofilm forming pathogens aimed to search for the efficient and novel alternative strategies. Metallic nanoparticles have drawn a considerable attention because of their significant applications in various fields. Numerous methods are developed for the generation of these nanoparticles however, mycogenic (fungal-mediated) synthesis is attractive due to high yields, easier handling, eco-friendly and being energy efficient when compared with conventional physico-chemical methods. Moreover, mycogenic synthesis provides fungal derived biomolecules that coat the nanoparticles thus improving their stability. The process of mycogenic synthesis can be extracellular or intracellular depending on the fungal genera used and various factors such as temperature, pH, biomass concentration and cultivation time may influence the synthesis process. This review focuses on the synthesis of metallic nanoparticles by using fungal mycelium, mechanism of synthesis, factors affecting the mycosynthesis and also describes their potential applications as antioxidants and antibiofilm agents. Moreover, the utilization of mycogenic nanoparticles as quorum quenching agent in hampering the bacterial cell-cell communication (quorum sensing) has also been discussed.

Zinc oxide nanoparticles prepared through microbial mediated synthesis for therapeutic applications: a possible alternative for plants

Zinc oxide nanoparticles (ZnO-NPs) synthesized through biogenic methods have gained significant attention due to their unique properties and potential applications in various biological fields. Unlike chemical and physical approaches that may lead to environmental pollution, biogenic synthesis offers a greener alternative, minimizing hazardous environmental impacts. During biogenic synthesis, metabolites present in the biotic sources (like plants and microbes) serve as bio-reductants and bio-stabilizers. Among the biotic sources, microbes have emerged as a promising option for ZnO-NPs synthesis due to their numerous advantages, such as being environmentally friendly, non-toxic, biodegradable, and biocompatible. Various microbes like bacteria, actinomycetes, fungi, and yeast can be employed to synthesize ZnO-NPs. The synthesis can occur either intracellularly, within the microbial cells, or extracellularly, using proteins, enzymes, and other biomolecules secreted by the microbes. The main key advantage of biogenic synthesis is manipulating the reaction conditions to optimize the preferred shape and size of the ZnO-NPs. This control over the synthesis process allows tailoring the NPs for specific applications in various fields, including medicine, agriculture, environmental remediation, and more. Some potential applications include drug delivery systems, antibacterial agents, bioimaging, biosensors, and nano-fertilizers for improved crop growth. While the green synthesis of ZnO-NPs through microbes offers numerous benefits, it is essential to assess their toxicological effects, a critical aspect that requires thorough investigation to ensure their safe use in various applications. Overall, the presented review highlights the mechanism of biogenic synthesis of ZnO-NPs using microbes and their exploration of potential applications while emphasizing the importance of studying their toxicological effects to ensure a viable and environmentally friendly green strategy.

The Potential of Trichoderma-Mediated Nanotechnology Application in Sustainable Development Scopes

The environmental impact of industrial development has been well-documented. The use of physical and chemical methods in industrial development has negative consequences for the environment, raising concerns about the sustainability of this approach. There is a growing need for advanced technologies that are compatible with preserving the environment. The use of fungi products for nanoparticle (NP) synthesis is a promising approach that has the potential to meet this need. The genus Trichoderma is a non-pathogenic filamentous fungus with a high degree of genetic diversity. Different strains of this genus have a variety of important environmental, agricultural, and industrial applications. Species of Trichoderma can be used to synthesize metallic NPs using a biological method that is environmentally friendly, low cost, energy saving, and non-toxic. In this review, we provide an overview of the role of Trichoderma metabolism in the synthesis of metallic NPs. We discuss the different metabolic pathways involved in NP synthesis, as well as the role of metabolic metabolites in stabilizing NPs and promoting their synergistic effects. In addition, the future perspective of NPs synthesized by extracts of Trichoderma is discussed, as well as their potential applications in biomedicine, agriculture, and environmental health.

Entomopathogenic Fungi: An Eco-Friendly Synthesis of Sustainable Nanoparticles and Their Nanopesticide Properties

The agricultural industry could undergo significant changes due to the revolutionary potential of nanotechnology. Nanotechnology has a broad range of possible applications and advantages, including insect pest management using treatments based on nanoparticle insecticides. Conventional techniques, such as integrated pest management, are inadequate, and using chemical pesticides has negative consequences. As a result, nanotechnology would provide ecologically beneficial and effective alternatives for insect pest control. Considering the remarkable traits they exhibit, silver nanoparticles (AgNPs) are recognized as potential prospects in agriculture. Due to their efficiency and great biocompatibility, the utilization of biologically synthesized nanosilver in insect pest control has significantly increased nowadays. Silver nanoparticles have been produced using a wide range of microbes and plants, which is considered an environmentally friendly method. However, among all, entomopathogenic fungi (EPF) have the most potential to be used in the biosynthesis of silver nanoparticles with a variety of properties. Therefore, in this review, different ways to get rid of agricultural pests have been discussed, with a focus on the importance and growing popularity of biosynthesized nanosilver, especially silver nanoparticles made from fungi that kill insects. Finally, the review highlights the need for further studies so that the efficiency of bio-nanosilver could be tested for field application and the exact mode of action of silver nanoparticles against pests can be elucidated, which will eventually be a boon to the agricultural industry for putting a check on pest populations.

Native Trichoderma Induced the Defense-Related Enzymes and Genes in Rice against Xanthomonas oryzae pv. oryzae (Xoo)

The application of Trichoderma is a form of biological control that has been effective in combating Xanthomonas oryzae pv. oryzae, the causative agent of the devastating disease known as bacterial blight of rice. In this present study, four strains of Trichoderma, viz., T. paraviridescens (BDISOF67), T. erinaceum (BDISOF91), T. asperellum (BDISOF08), and T. asperellum (BDISOF09), were collected from the rice rhizosphere and used to test their potentiality in reducing bacterial blight. The expression patterns of several core defense-related enzymes and genes related to SA and JA pathways were studied to explore the mechanism of induced resistance by those Trichoderma strains. The results primarily indicated that all Trichoderma were significantly efficient in reducing the lesion length of the leaf over rice check variety (IR24) through enhancing the expression of core defense-related enzymes, such as PAL, PPO, CAT, and POD activities by 4.27, 1.77, 3.53, and 1.57-fold, respectively, over control. Moreover, the results of qRT-PCR exhibited an upregulation of genes OsPR1, OsPR10, OsWRKY45, OsWRKY62, OsWRKY71, OsHI-LOX, and OsACS2 after 24 h of inoculation with all tested Trichoderma strains. However, in the case of RT-PCR, no major changes in OsPR1 and OsPR10 expression were observed in plants treated with different Trichoderma strains during different courses of time. Collectively, Trichoderma induced resistance in rice against X. oryzae pv. oryzae by triggering these core defense-related enzymes and genes associated with SA and JA pathways.

Mycosynthesis of AgNPs: mechanisms of nanoparticle formation and antimicrobial activities

INTRODUCTION

The inactivation and eradication of multidrug-resistant bacteria, fungi, and viruses by conventional antibiotics and drugs have not been effective. The hindering of these pathogens in hospital-acquired infections caused by Gram-positive bacteria, particularly strains of S. aureus including community-acquired methicillin-resistant (CA-MRSA) and hospital-acquired MRSA (HA-MRSA), is more complicated, specifically in patients having immunodeficiency syndrome.

RESEARCH AREA

Bare and functionalized metal and metal oxide nanoparticles (NPs) specifically silver (Ag) NPs have shown significant antibacterial, antifungal, and antiviral activities. Biosynthesis of AgNPs by fungal species in media of cell-free filtrate and culture supernatant can provide new therapeutic properties compared to physical and chemical methods.

EXPERT OPINION

Various primary and secondary metabolites of fungi such as phytochelatin, trichodin, primin, altersolanol A, periconicin A, brefeldin A, graphislactone A, phomol, polysaccharides (chitin, glucans, and galactomannans), and enzymes can contribute to reducing Ag⁺ ions and stabilizing NPs in one-pot method. These natural compounds can augment antimicrobial activity by bypassing multidrug-resistance barriers in viruses, bacteria, and fungi. Controlling physicochemical properties and effective therapeutic concentration of fungal AgNPs can be the determinative parameters for the antimicrobial strength of AgNPs. Therefore, in this review, we have tried to address the antimicrobial mechanisms and physicochemical properties of fungal synthesized AgNPs.

Biological evaluation of extracellular mycosynthesized silver nanoparticles by Trichoderma asperellum

Mycosynthesis of silver nano-scale particles by fungi is an important aspect in nanotechnology due to its eco-friendly, safe, and cost-effective nature. It also provides protein-capped nanoparticles, which are very stable and have good dispersion. The Mycosynthesis of silver nano-scale particles (SNPs) by Trichoderma asperellum Filtrate (TAF) was evaluated. The characterizations of TAFSNPs were done by UV-visible spectroscopy, FTIR, SEM, and EDX. Biological evaluations such as antibacterial activity against some pathogens, in-vivo immuno-stimulatory, and antitumor potential and hematological parameters of SNPs of T. asperellum were investigated. Changes in color from yellow to brown indicate the formation of nanoparticles. TAFSNPs biosynthesis had a Surface Plasmon Resonance peak at 450 nm. The nanoparticles were spherical, with a size ranging from 0.7 to 10.0 nm. EDX analysis revealed a strong signal for the silver element. TAFSNPs had profound antagonistic activity against the test microorganism. B. subtilis, S. aureus, and Salmonella typhi were highly susceptible with inhibition zone of 24.3 mm, 21.8 mm, and 21.3 mm. TAFSNPs had significant immune-stimulation in the treated mice with an increase in IgA and IgM production, which ranged from 169 0.83d-269 0.56a mg/dl and 26 0.16d-69 0.27a mg/dl. TAFSNPs had CEA level reduction capability (3.62-4.05 ng/L). TAFSNPs had the highest amounts of PCV, Red blood cells, heamoglobin, and neutrophils (38%, 5.7 × 1012%, 14.09 g/dl, and 71%). Significant improvement was recorded on the lifespan of the TAFSNPs treated tumor-induced mice. Conclusively, TAFSNPs have good antimicrobial, immuno-stimulatory, and antitumor potential.

Biomolecules in modern and sustainable agriculture

This review presents scientific findings which indicate biomolecules are excellent candidates for the development of biopesticides. Efforts are being done to find routes to increase their concentrations in the cultivation media because this concentration facilitates applications, storage, and transportation. Some of these routes are co-fermentation and ultrasound-assisted fermentation. Ultrasonication increases metabolite production and growth rates by improvement of cell permeability and nutrient uptake rates through cell membranes. For example, 24% increase in the enzymatic activity of cellulases produced by Trichoderma reesei in solid-state fermentation was achieved with ultrasonication. Also, chitinase and β-1,3-glucanase productions were stimulated by ultrasound in Beauveria bassiana cultivation, presenting positive results. The common parameters evaluated in the production of biomolecules by ultrasound-assisted fermentation are the duty cycle, time of application, power, energetic density, and how long the sonication is maintained in the fermentation media. Many successful cases are reported and discussed, which include the final formulation of bioproducts for agricultural applications. In this trend, nanotechnology is a promising tool for the development of nanoformulations. Nanoemulsification, green synthesis, biosynthesis, or biogenic synthesis are technologies used to produce such nanoformulations, allowing the controlled release of control agents, as well as the delivery of biomolecules to specific targets.

Trichoderma-Mediated ZnO Nanoparticles and Their Antibiofilm and Antibacterial Activities

Antimicrobial resistance is a major global health concern and one of the gravest challenges to humanity today. Antibiotic resistance has been acquired by certain bacterial strains. As a result, new antibacterial drugs are urgently required to combat resistant microorganisms. Species of Trichoderma are known to produce a wide range of enzymes and secondary metabolites that can be exploited for the synthesis of nanoparticles. In the present study, Trichoderma asperellum was isolated from rhizosphere soil and used for the biosynthesis of ZnO NPs. To examine the antibacterial activity of ZnO NPs against human pathogens, Escherichia coli and Staphylococcus aureus were used. The obtained antibacterial results show that the biosynthesized ZnO NPs were efficient antibacterial agents against the pathogens E. coli and S. aureus, with an inhibition zone of 3-9 mm. The ZnO NPs were also effective in the prevention of S. aureus biofilm formation and adherence. The current work shows that the MIC dosages of ZnO NPs (25, 50, and 75 μg/mL) have effective antibacterial activity and antibiofilm action against S. aureus. As a result, ZnO NPs can be used as a part of combination therapy for drug-resistant S. aureus infections, where biofilm development is critical for disease progression.

Application and mechanisms of metal-based nanoparticles in the control of bacterial and fungal crop diseases

Nanotechnology is a young branch of the discipline generated by nanomaterials. Its development has greatly contributed to technological progress and product innovation in the field of agriculture. The antimicrobial properties of nanoparticles (NPs) can be used to develop nanopesticides for plant protection. Plant diseases caused by bacterial and fungal infestations are the main types of crop diseases. Once infected, they will seriously threaten crop growth, reduce yield and quality, and affect food safety, posing a health risk to humans. We reviewed the application of metal-based nanoparticles in inhibiting plant pathogenic bacteria and fungi, and discuss the antibacterial mechanisms of metal-based nanoparticles from two aspects: the direct interaction between nanoparticles and pathogens, and the indirect effects of inducing plant resilience to disease. © 2022 Society of Chemical Industry.

Trichoderma and its role in biological control of plant fungal and nematode disease

Trichoderma is mainly used to control soil-borne diseases as well as some leaf and panicle diseases of various plants. Trichoderma can not only prevent diseases but also promotes plant growth, improves nutrient utilization efficiency, enhances plant resistance, and improves agrochemical pollution environment. Trichoderma spp. also behaves as a safe, low-cost, effective, eco-friendly biocontrol agent for different crop species. In this study, we introduced the biological control mechanism of Trichoderma in plant fungal and nematode disease, including competition, antibiosis, antagonism, and mycoparasitism, as well as the mechanism of promoting plant growth and inducing plant systemic resistance between Trichoderma and plants, and expounded on the application and control effects of Trichoderma in the control of various plant fungal and nematode diseases. From an applicative point of view, establishing a diversified application technology for Trichoderma is an important development direction for its role in the sustainable development of agriculture.

Mycosynthesis of Metal-Containing Nanoparticles-Synthesis by Ascomycetes and Basidiomycetes and Their Application

Fungi contain species with a plethora of ways of adapting to life in nature. Consequently, they produce large amounts of diverse biomolecules that can be generated on a large scale and in an affordable manner. This makes fungi an attractive alternative for many biotechnological processes. Ascomycetes and basidiomycetes are the most commonly used fungi for synthesis of metal-containing nanoparticles (NPs). The advantages of NPs created by fungi include the use of non-toxic fungus-produced biochemicals, energy efficiency, ambient temperature, pressure conditions, and the ability to control and tune the crystallinity, shape, and size of the NPs. Furthermore, the presence of biomolecules might serve a dual function as agents in NP formation and also capping that can tailor the (bio)activity of subsequent NPs. This review summarizes and reviews the synthesis of different metal, metal oxide, metal sulfide, and other metal-based NPs mediated by reactive media derived from various species. The phyla ascomycetes and basidiomycetes are presented separately. Moreover, the practical application of NP mycosynthesis, particularly in the fields of biomedicine, catalysis, biosensing, mosquito control, and precision agriculture as nanofertilizers and nanopesticides, has been studied so far. Finally, an outlook is provided, and future recommendations are proposed with an emphasis on the areas where mycosynthesized NPs have greater potential than NPs synthesized using physicochemical approaches. A deeper investigation of the mechanisms of NP formation in fungi-based media is needed, as is a focus on the transfer of NP mycosynthesis from the laboratory to large-scale production and application.

Antibacterial activity of peptaibols from Trichoderma longibrachiatum SMF2 against gram-negative Xanthomonas oryzae pv. oryzae, the causal agent of bacterial leaf blight on rice

Bacterial leaf blight caused by Gram-negative pathogen Xanthomonas oryzae pv. oryzae (Xoo) is one of the most destructive bacterial diseases on rice. Due to the resistance, toxicity and environmental issues of chemical bactericides, new biological strategies are still in need. Although peptaibols produced by Trichoderma spp. can inhibit the growth of several Gram-positive bacteria and plant fungal pathogens, it still remains unclear whether peptaibols have anti-Xoo activity to control bacterial leaf blight on rice. In this study, we evaluated the antibacterial effects of Trichokonins A (TKA), peptaibols produced by Trichoderma longibrachiatum SMF2, against Xoo. The in vitro antibacterial activity analysis showed that the growth of Xoo was significantly inhibited by TKA, with a minimum inhibitory concentration of 54 μg/mL and that the three TKs in TKA all had remarkable anti-Xoo activity. Further inhibitory mechanism analyses revealed that TKA treatments resulted in the damage of Xoo cell morphology and the release of intracellular substances, such as proteins and nucleic acids, from Xoo cells, suggesting the damage of the permeability of Xoo cell membrane by TKA. Pathogenicity analyses showed that the lesion length on rice leaf was significantly reduced by 82.2% when treated with 27 μg/mL TKA. This study represents the first report of the antibacterial activity of peptaibols against a Gram-negative bacterium. Thus, TKA can be of a promising agent in controlling bacterial leaf blight on rice.

Antimicrobial activity of the biologically synthesized zinc oxide nanoparticles against important rice pathogens

Global rice production is seriously affected by many abiotic and biotic factors. Among the aggressive rice pathogens, Xanthomonas oryzae pv. oryzae (X. o. pv. oryzae), Bipolaris oryzae (B. oryzae) and Sphaerulina oryzina (S. oryzina) cause bacterial leaf blight, brown leaf spot and narrow brown leaf spot diseases, respectively. The objective of this study was to evaluate the efficacy of biogenic zinc oxide nanoparticles (ZnO NPs) as antimicrobial agent to control rice pathogens. This is the first report of antifungal activity evaluation of ZnO NPs against B. oryzae and S. oryzina. A pre-characterized bacterial strain Escherichia sp. SINT7 was bio-prospected for synthesis of green ZnO NPs. The NPs were confirmed by a characteristic peak measured at 360.96 nm through UV-Vis spectroscopy. Further, the NPs were characterized to elucidate the surface capping molecules, crystallite structure and morphology by various spectroscopic and imaging techniques, which confirmed the spherical shape of NPs with size ranging from 13.07 to 22.25 nm. In vitro studies against X. o. pv. oryzae pathogen depicted the substantial antibacterial activity (up to 25.7 mm inhibition zone at 20 μg/ml NPs concentration). Similarly, ZnO NPs reduced the mycelial growth of B. oryzae and S. oryzina up to 72.68 and 95.78%, respectively at 50 μg/ml concentration on potato dextrose agar plates, while the mycelial biomass reduction was found to be 64.66 and 68. 49% for B. oryzae and S. oryzina, respectively on potato dextrose broth media as compared to control without the addition of NPs. The green ZnO NPs also significantly reduced the fungal spore germination and a disintegration of fungal hyphae for both fungal strains was observed under the microscope as a result of NPs treatment. Hence, it was concluded that biologically synthesized ZnO NPs are potential antimicrobials and could be compared in greenhouse pathogenicity assays with commercial pesticides to control rice pathogens.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12298-022-01251-y.

Biosynthesis of zinc oxide nanoparticles via endophyte Trichoderma viride and evaluation of their antimicrobial and antioxidant properties

The biogenic method for synthesis of nanoparticles is preferred over the traditional strategies, on account of its ease, environmental friendliness, and cost-effectivity, wherein fungi endorse themselves to be the most appropriate precursor for the same. In recent times numerous metal nanoparticles have been reported to exhibit significant therapeutic activities, out of which Zinc Oxide nanoparticles (ZnO NPs) stand apart on account of their multidimensional nature. Thus, this study was carried out with an aim to biosynthesize ZnO NPs utilizing endophyte Trichoderma viride, isolated from the seeds of Momordica charantia. The physicochemical characterization of NPs was done via employing a combination of spectroscopic and microscopic techniques. The NPs were found to have a hexagonal shape and possessed an average particle size of around 63.3 nm. The antimicrobial activity of NPs was evaluated against multi-drug resistant organisms and it was observed to be an appreciable one whereas the antioxidant activity was deduced to be dose-dependent. Thus, these ZnO NPs can be considered as a probable active ingredient of any future therapeutic conceptualization after undertaking a thorough toxicological assessment.

Exploiting the antibacterial mechanism of phenazine substances from Lysobacter antibioticus 13-6 against Xanthomonas oryzae pv. oryzicola

Bacterial leaf streak caused by Xanthomonas oryzae pv. oryzicola (Xoc) is one of the most destructive diseases affecting rice production worldwide. In this study, we extracted and purified phenazine substances from the secondary metabolites of Lysobacter antibioticus 13-6. The bacteriostatic mechanism of phenazine substances against Xoc was investigated through physiological response and transcriptomic analysis. Results showed that phenazine substances affects the cell membrane permeability of Xoc, which causes cell swelling and deformation, blockage of flagellum synthesis, and imbalance of intracellular environment. The changes in intracellular environment affect the physiological and metabolic functions of Xoc, which reduces the formation of pathogenic factors and pathogenicity. Through transcriptomic analysis, we found that among differentially expressed genes, the expression of 595 genes was induced significantly (275 up-regulated and 320 down-regulated). In addition, we observed that phenazine substances affects three main functions of Xoc, i.e., transmembrane transporter activity, DNA-mediated transposition, and structural molecular activity. Phenazine substances also inhibits the potassium ion transport system that reduces Xoc resistance and induces the phosphate ion transport system to maintain the stability of the internal environment. Finally, we conclude that phenazine substances could retard cell growth and reduce the pathogenicity of Xoc by affecting cell structure and physiological metabolism. Altogether, our study highlights latest insights into the antibacterial mechanism of phenazine substances against Xoc and provides basic guidance to manage the incidence of bacterial leaf streak of rice.

Trichoderma: An Eco-Friendly Source of Nanomaterials for Sustainable Agroecosystems

Traditional nanoparticle (NP) synthesis methods are expensive and generate hazardous products. It is essential to limit the risk of toxicity in the environment from the chemicals as high temperature and pressure is employed in chemical and physical procedures. One of the green strategies used for sustainable manufacturing is microbial nanoparticle synthesis, which connects microbiology with nanotechnology. Employing biocontrol agents Trichoderma and Hypocrea (Teleomorphs), an ecofriendly and rapid technique of nanoparticle biosynthesis has been reported in several studies which may potentially overcome the constraints of the chemical and physical methods of nanoparticle biosynthesis. The emphasis of this review is on the mycosynthesis of several metal nanoparticles from Trichoderma species for use in agri-food applications. The fungal-cell or cell-extract-derived NPs (mycogenic NPs) can be applied as nanofertilizers, nanofungicides, plant growth stimulators, nano-coatings, and so on. Further, Trichoderma-mediated NPs have also been utilized in environmental remediation approaches such as pollutant removal and the detection of pollutants, including heavy metals contaminants. The plausible benefits and pitfalls associated with the development of useful products and approaches to trichogenic NPs are also discussed.

Titanium and Zinc Based Nanomaterials in Agriculture: A Promising Approach to Deal with (A)biotic Stresses?

Abiotic stresses, such as those induced by climatic factors or contaminants, and biotic stresses prompted by phytopathogens and pests inflict tremendous losses in agriculture and are major threats to worldwide food security. In addition, climate changes will exacerbate these factors as well as their negative impact on crops. Drought, salinity, heavy metals, pesticides, and drugs are major environmental problems that need deep attention, and effective and sustainable strategies to mitigate their effects on the environment need to be developed. Besides, sustainable solutions for agrocontrol must be developed as alternatives to conventional agrochemicals. In this sense, nanotechnology offers promising solutions to mitigate environmental stress effects on plants, increasing plant tolerance to the stressor, for the remediation of environmental contaminants, and to protect plants against pathogens. In this review, nano-sized TiO₂ (nTiO₂) and ZnO (nZnO) are scrutinized, and their potential to ameliorate drought, salinity, and xenobiotics effects in plants are emphasized, in addition to their antimicrobial potential for plant disease management. Understanding the level of stress alleviation in plants by these nanomaterials (NM) and relating them with the application conditions/methods is imperative to define the most sustainable and effective approaches to be adopted. Although broad-spectrum reviews exist, this article provides focused information on nTiO₂ and nZnO for improving our understanding of the ameliorative potential that these NM show, addressing the gaps in the literature.

QTL Analysis Revealed One Major Genetic Factor Inhibiting Lesion Elongation by Bacterial Blight (Xanthomonas oryzae pv. oryzae) from a japonica Cultivar Koshihikari in Rice

Xanthomonas oryzae pv. oryzae (Xoo) is a pathogen that has ravaged the rice industry as the causal agent of bacterial blight (BB) diseases in rice. Koshihikari (KO), an elite japonica cultivar, and ARC7013 (AR), an indica cultivar, are both susceptible to Xoo. Their phenotypic characteristics reveal that KO has shorter lesion length than that of AR. The F₂ population from KO × AR results in continuous distribution of lesion length by inoculation of an Xoo race (T7147). Consequently, quantitative trait loci (QTL) mapping of the F₂ population is conducted, covering 12 chromosomes with 107 simple sequence repeat (SSR) and insertion/deletion (InDel) genetic markers. Three QTLs are identified on chromosomes 2, 5, and 10. Of them, qXAR5 has the strongest resistance variance effect of 20.5%, whereas qXAR2 and qXAR10 have minor QTL effects on resistance variance, with 3.9% and 2.3%, respectively, for a total resistance variance of 26.7%. The QTLs we examine for this study differ from the loci of BB resistance genes from earlier studies. Our results can help to facilitate understanding of genetic and morphological fundamentals for use in rice breeding programs that are more durable against evolving Xoo pathogens and uncertain climatic temperature.

Comparison of the Antagonistic Potential of the Entomopathogenic Bacterium Serratia nematodiphila GCSR38 with other Effective Microorganisms for the Control of Rice Bacterial Leaf Blight

The efficacy of antagonistic microorganisms and secondary metabolites of entomopathogenic bacteria was evaluated in vitro and in vivo against Xanthomonas oryzae pv. oryzae (Xoo), a causal agent of rice bacterial leaf blight. The effect of the culture filtrates of the microorganisms was tested against Xoo, using the agar well diffusion assay. Trichoderma sp. UB05/3 was the most effective against Xoo. However, the results were not statistically different from those of the entomopathogenic bacterium Serratia nematodiphila GCSR38 with a 22.97 mm and 19.15 mm zone of inhibition, respectively. The effect of the secondary metabolite crude extracts of antagonistic microorganisms (2,000 µg/ml) on Xoo inhibition was tested by the paper disc diffusion method. Only S. nematodiphila GCSR38 was able to control Xoo, with an inhibition zone of 17.60 mm. Minimum inhibitory concentration (MIC) was determined using a 96-well microtiter plate. The MIC of secondary metabolites crude extracts of S. nematodiphila GCSR38 was 1,000 µg/ml and the minimum bactericidal concentration (MBC) was 1,000 µg/ml. The efficacy of the secondary metabolite crude extract of S. nematodiphila GCSR38 against Xoo was tested using the detached leaf technique; the secondary metabolite crude extracts controlled the disease, with 24.45% and 15.56% disease severity when used before and after inoculation with Xoo, respectively. Inoculation with Xoo alone resulted in a disease severity of 44.45%. The secondary metabolite crude extracts of S. nematodiphila GCSR38 can reduce disease severity of bacterial leaf blight in rice by 28.89%, whereas zinc thiazole causes a disease severity of 22.22% and Xoo alone causes a disease severity of 66.67%.

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.

Trichoderma harzianum-Mediated ZnO Nanoparticles: A Green Tool for Controlling Soil-Borne Pathogens in Cotton

ZnO-based nanomaterials have high antifungal effects, such as inhibition of growth and reproduction of some pathogenic fungi, such as Fusarium sp., Rhizoctonia solani and Macrophomina phaseolina. Therefore, we report the extracellular synthesis of ZnONPs using a potential fungal antagonist (Trichoderma harzianum). ZnONPs were then characterized for their size, shape, charge and composition by visual analysis, UV–visible spectrometry, X-ray diffraction (XRD), Zeta potential, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and energy-dispersive X-ray analysis (EDX). The TEM test confirmed that the size of the produced ZnONPs was 8–23 nm. The green synthesized ZnONPs were characterized by Fourier transform infrared spectroscopy (FTIR) studies to reveal the functional group attributed to the formation of ZnONPs. For the first time, trichogenic ZnONPs were shown to have fungicidal action against three soil–cotton pathogenic fungi in the laboratory and greenhouse. An antifungal examination was used to evaluate the bioactivity of the mycogenic ZnONPs in addition to two chemical fungicides (Moncut and Maxim XL) against three soil-borne pathogens, including Fusarium sp., Rhizoctonia solani and Macrophomina phaseolina. The findings of this study show a novel fungicidal activity in in vitro assay for complete inhibition of fungal growth of tested plant pathogenic fungi, as well as a considerable reduction in cotton seedling disease symptoms under greenhouse conditions. The formulation of a trichogenic ZnONPs form was found to increase its antifungal effect significantly. Finally, the utilization of biocontrol agents, such as T. harzianum, could be a safe strategy for the synthesis of a medium-scale of ZnONPs and employ it for fungal disease control in cotton.

Green synthesis, antimicrobial, antibiofilm and antitumor activities of superparamagnetic γ-Fe2O3 NPs and their molecular docking study with cell wall mannoproteins and peptidoglycan

Fatty acids-assisted superparamagnetic maghemite (γ-Fe₂O₃) NPs was biologically synthesized using extract of polyherbal drug Liv52 (L52E). The NPs were characterized by UV-vis spectroscopy, FT-IR, SEM, TEM, EDX, XRD and VSM. The major biological molecules present in L52E analysed by GC-MS were saturated fatty acids (palmitic acid 21.95%; stearic acid 13.99%; myristic acid 1.14%), monounsaturated fatty acid (oleic acid 18.43%), polyunsaturated fatty acid (linoleic acid 20.45%), and aromatic phenol (cardanol monoene 11.92%) that could imply in bio-fabrication and stabilization of γ-Fe₂O₃ NPs. The FT-IR spectra revealed involvement of carboxylic group of fatty acids, amide group of proteins and hydroxyl group of phenolic compounds that acts as reducing and capping agents. The synthesized NPs were used to investigate their antimicrobial, antibiofilm activity against P. aeruginosa, MRSA and C. albicans and anticancer activity on colon cancer cells (HCT-116) for biomedical applications. Further, molecular docking study was performed to explore the interaction of Fe₂O₃ NPs with major cell wall components i.e., peptidoglycan and mannoproteins. The docking studies revealed that Fe₂O₃ interacted efficiently with peptidoglycan and mannoproteins and Fe₂O₃ get accommodated into catalytic cleft of mannoprotein. Due to magnetic property, the biological activity of γ-Fe₂O₃ can be further enhanced by applying external magnetic field alone or in amalgamation with other therapeutics drugs.