Plant Pathogen Fusarium Oxysporum Research Articles

Evaluation of ALA-Capped Silver, Cooper, and Silver-Copper Nanoparticles for Controlling Fungal Plant Pathogens.

Phytopathogenic fungi significantly threaten global food security, causing substantial yield and quality losses. Sustainable solutions are urgently needed to combat these agricultural pathogens. This study explored the potential of silver (Ag), copper (Cu), and combined Ag/Cu nanoparticles capped with aminolevulinic acid (ALA) as antifungal agents. The nanoparticles (ALAAg, ALACu, and ALAAgCu) were synthesized via photoreduction and characterized using various techniques (UV-Vis, TEM, XRD, Zeta potential). Their antifungal activity against four key plant pathogens (Alternaria grandis, Colletotrichum truncatum, Corynespora cassiicola, and Fusarium oxysporum) was evaluated using poisoned food techniques. Notably, ALAAgCuNPs demonstrated superior antifungal activity compared to a conventional fungicide against two fungal strains. Even at lower concentrations, ALAAgCuNPs exhibited fungistatic effects comparable to those of the control. These promising results suggest the potential of ALAAgCu NPs as a broad-spectrum, potentially eco-friendly alternative for fungal control in plants and seeds. This approach is crucial for ensuring crop health, harvest quality, and food safety.

Antifungal activity of a methanolic extract of Glycyrrhiza uralensis Fisch. root against Fusarium oxysporum and Phytophthora capsici

In the present study, we investigated the antifungal activity of a methanolic extract of Glycyrrhiza uralensisFisch. root, which inhibited the growth of the plant pathogens Fusarium oxysporum and Phytophthora capsici. The EC50 values of the G. uralensis Fisch. extract three, six, and nine days after treatment were 113.4, 150.6, and 191.4 μg/ml for F. oxysporum and 84.7, 148.6, and 190.1 μg/ml for P. capsici, respectively, and the antifungal activity exhibited a dose-dependent response. The MIC value of G. uralensis Fisch. extract was found to be 100, 200, and 400 μg/ml at three, six, and nine days after treatment for F. oxysporum. In contrast, for P. capsici, the MIC value was 50, 100, and 100 μg/ml at three, six, and nine days after treatment. After three days of incubation with 400 μg/ml G. uralensis Fisch. extract, the hyphae of F. oxysporum exhibited abnormalities and atrophy, leading to mycelial collapse. In contrast, the hyphae of P. capsici displayed swelling with increased branching. These results furnish valuable insights into the antifungal metabolites present in G. uralensis Fisch. extract, contributing to the development of environmentally friendly products aimed at controlling the growth of pathogenic fungi.

Peribacillus frigoritolerans T7-IITJ, a potential biofertilizer, induces plant growth-promoting genes of Arabidopsis thaliana.

This study aimed to isolate plant growth and drought tolerance-promoting bacteria from the nutrient-poor rhizosphere soil of Thar desert plants and unravel their molecular mechanisms of plant growth promotion. Among our rhizobacterial isolates, Enterobacter cloacae C1P-IITJ, Kalamiella piersonii J4-IITJ, and Peribacillus frigoritolerans T7-IITJ, significantly enhanced root and shoot growth (4-5-fold) in Arabidopsis thaliana under PEG-induced drought stress. Whole genome sequencing and biochemical analyses of the non-pathogenic bacterium T7-IITJ revealed its plant growth-promoting traits, viz., solubilization of phosphate (40-73µg/ml), iron (24±0.58mm halo on chrome azurol S media), and nitrate (1.58±0.01µg/ml nitrite), along with production of exopolysaccharides (125±20µg/ml) and auxin-like compounds (42.6±0.05µg/ml). Transcriptome analysis of A. thaliana inoculated with T7-IITJ and exposure to drought revealed the induction of 445 plant genes (log2fold-change>1, FDR<0.05) for photosynthesis, auxin and jasmonate signalling, nutrient uptake, redox homeostasis, and secondary metabolite biosynthesis pathways related to beneficial bacteria-plant interaction, but repression of 503 genes (log2fold-change < -1) including many stress-responsive genes. T7-IITJ enhanced proline 2.5-fold, chlorophyll 2.5-2.8-fold, iron 2-fold, phosphate 1.6-fold, and nitrogen 4-fold, and reduced reactive oxygen species 2-4.7-fold in plant tissues under drought. T7-IITJ also improved the germination and seedling growth of Tephrosia purpurea, Triticum aestivum, and Setaria italica under drought and inhibited the growth of two plant pathogenic fungi, Fusarium oxysporum, and Rhizoctonia solani. P. frigoritolerans T7-IITJ is a potent biofertilizer that regulates plant genes to promote growth and drought tolerance.

Segmental duplications drive the evolution of accessory regions in a major crop pathogen.

Many pathogens evolved compartmentalized genomes with conserved core and variable accessory regions (ARs) that carry effector genes mediating virulence. The fungal plant pathogen Fusarium oxysporum has such ARs, often spanning entire chromosomes. The presence of specific ARs influences the host range, and horizontal transfer of ARs can modify the pathogenicity of the receiving strain. However, how these ARs evolve in strains that infect the same host remains largely unknown. We defined the pan-genome of 69 diverse F. oxysporum strains that cause Fusarium wilt of banana, a significant constraint to global banana production, and analyzed the diversity and evolution of the ARs. Accessory regions in F. oxysporum strains infecting the same banana cultivar are highly diverse, and we could not identify any shared genomic regions and in planta-induced effectors. We demonstrate that segmental duplications drive the evolution of ARs. Furthermore, we show that recent segmental duplications specifically in accessory chromosomes cause the expansion of ARs in F. oxysporum. Taken together, we conclude that extensive recent duplications drive the evolution of ARs in F. oxysporum, which contribute to the evolution of virulence.

Green Waste Compost Impacts Microbial Functions Related to Carbohydrate Use and Active Dispersal in Plant Pathogen-Infested Soil

The effects of compost on physical and chemical characteristics of soil are well-studied but impacts on soil microbiomes are poorly understood. This research tested effects of green waste compost on bacterial communities in soil infested with the plant pathogen Fusarium oxysporum. Compost was added to pathogen-infested soil and maintained in mesocosms in a greenhouse experiment and replicated growth chamber experiments. Bacteria and F. oxysporum abundance were quantified using quantitative PCR. Taxonomic and functional characteristics of bacterial communities were measured using shotgun metagenome sequencing. Compost significantly increased bacterial abundance 8 weeks after amendment in one experiment. Compost increased concentrations of chemical characteristics of soil, including phosphorus, potassium, organic matter, and pH. In all experiments, compost significantly reduced abundance of F. oxysporum and altered the taxonomic composition of soil bacterial communities. Sixteen bacterial genera were significantly increased from compost in every experiment, potentially playing a role in pathogen suppression. In all experiments, there was a consistent negative effect of compost on functions related to carbohydrate use and a positive effect on bacteria with flagella. Results from this work demonstrate that compost can reduce the abundance of soilborne plant pathogens and raise questions about the role of microbes in plant pathogen suppression.

A novel isatin Schiff based cerium complex: synthesis, characterization, antimicrobial activity and molecular docking studies

In this work, a novel isatin-Schiff base L2 had been synthesized through a simple reaction between isatin and 2-amino-5-methylthio-1,3,4-thiadiazole. The produced Schiff base L2 was then subjected to a hydrothermal reaction with cerium chloride to produce the cerium (III)-Schiff base complex C2. Several spectroscopic methods, including mass spectra, FT-IR, elemental analysis, UV–vis, 13C-NMR, 1H-NMR, Thermogravimetric Analysis, HR-TEM, and FE-SEM/EDX, were used to completely characterize the produced L2 and C2. A computer simulation was performed using the MOE software program to find out the probable biological resistance of studied compounds against the proteins in some types of bacteria or fungi. To investigate the interaction between the ligand and its complex, we conducted molecular docking simulations using the molecular operating environment (MOE). The docking simulation findings revealed that the complex displayed greater efficacy and demonstrated a stronger affinity for Avr2 effector protein from the fungal plant pathogen Fusarium oxysporum (code 5OD4) than the original ligand. The antibacterial activity of the ligand and its Ce3+ complex were applied in vitro tests against different microorganism. The study showed that the complex was found to be more effective than the ligand.

Determination of Antifungal Activity of Leaf Extracts from Hypericum ssp. Against Plant Pathogenic Fungi Fusarium oxysporum and Alternaria Alternata

In this study, the antifungal activity of ethanol extracts of three plant species of Hypericum perforatum, Hypericum scabrum and Hypericum origanifolium were evaluated for against two plant pathogenic fungal species of Fusarium oxysporum and Alternaria alternata.The antifungal activities of Hypericum ssp. extracts (3, 15, 45, 80, 120, 200, 240, 300 ppm) were tested against fungi. Ethanol 30% as control; Commercial fungicide (1 μg/mL) was used as a positive control. All Hypericum ssp. plant extracts were effective in different rates against the fungi depending on the doses. In addition, IC50 values of the three selected plant Hypericum ssp. leaf extract against pathogenic fungus F.oxysporum and A. alternata were determined with of probit analysis. In terms of the IC50 values, the antifungal activity of H. perforatum plant exract against F.oxysporum (122.525 μg/mL) &amp;gt; A.alternata (108.484 μg/mL). On the other hand, IC50 values of H. scabrum against A.alternata (126.390 μg/mL) &amp;gt; F.oxysporum (113.714 μg/mL). Moreover, the IC50 value of H. origanifolium against two pathogenic fungi was calculated as F.oxysporum (159.931 μg/mL) &amp;gt; A.alternata (55.759 μg/mL). Results showed that H.origanifolium has the best fungicidal activity, with IC50 value of 55.759 μg/mL against A.alternata and H.scabrum 113.717 μg/mL against F.oxysporum. However, the highest concentrations (300 ppm) caused completely inhibition in the both fungi mycelial growth followed by lower concentrations of plant extracts. A. alternata were the sensitive fungal species, while the F. oxysporum were a more resistant to the Hypericum ssp. extracts. Based on the antifungal activity tests, these plants extracts this may have effective as the new natural fungicide protecting crops against fungal diseases.

Transposon-based identification of genes involved in the rimocidin biosynthesis in Streptomyces rimosus M527.

The transposon mutagenesis strategy has been employed to generate random insertion mutants and analyze the correlation between genes and secondary metabolites in the genus Streptomyces. In this study, our primary objective was to identify an unknown gene involved in rimocidin biosynthesis and elucidate its role in rimocidin production in Streptomyces rimosus M527. To achieve this, we established a random mutant library of S. rimosus M527 using a Tn5 transposon-mediated random mutagenesis strategy. Among the 137 isolated mutants, M527-G10 and M527-W5 exhibited the most significant variations in antagonistic activity against the plant pathogenic fungus Fusarium oxysporum f. sp. cucumerinum. Specifically, M527-G10 displayed a 72.93% reduction, while M527-W5 showed a 49.8% increase in rimocidin production compared to the wild-type (WT) strain S. rimosus M527. Subsequently, we employed a plasmid rescue strategy to identify the insertion loci of the transposon in the genomes of mutants M527-G10 and M527-W5, revealing a response regulator transcription factor (rrt) and a hypothetical protein (hyp), respectively. The roles of rrt and hyp in rimocidin biosynthesis were determined through gene deletion, overexpression in the WT strain, and complemented expression in the transposon mutants. Notably, the gene-deletion mutants M527-ΔRRT and M527-ΔHYP exhibited similar behavior in rimocidin production compared to the corresponding transposon mutants M527-G10 and M527-W5, suggesting that transposon insertions in genes rrt and hyp led to alterations in rimocidin production. Furthermore, both gene deletion and overexpression of rrt and hyp had no discernible effects on cell growth. These results reveal that genes rrt and hyp have positive and negative impacts on rimocidin production in S. rimosus M527, respectively.

Evaluation of some bioactive compounds of &lt;i&gt;Azadirachta indica&lt;/i&gt; extracts and its application as safe fungicide against different plant pathogenic fungi

Extracts of leaves, seeds and twigs of Azadirachta indica was carried out using Soxhlet extraction technique. These extracts were  subjected to percent yield, in vitro phytochemical screening and antifungal activities (minimum fungicidal concentration (MFC), minimum  inhibitory concentration (MIC), zone of inhibition and spore germination assay) against plant pathogenic fungi Cladosporium fulvum,  Colletotrichum coccodes, Fusarium oxysporum and Rhizoctonia solani. The Soxhlet extractive solvents were methanol, ethanol,  chloroform, ethyl acetate and n–hexane. The maximum extractive yield were calculated in ethanol leaves (26±1.5%), methanol leaves  (22±01%), n–hexane seeds (32±0.8%) and ethanol seeds (24±01%), while twigs calculated minimum extractive yield. The phytochemicals  screening findings confirmed the occurrence of terpenoids, phenols, flavonoids, glycosides, alkaloids, tannins and saponins. The  antifungal activities observed that leaves and seeds extracts of neem might cause the inhibition of mycelium and spore germination of  tested fungi, though the antifungal activities rate of under study fungal strains diverse with dissimilar concentration and nature of  extracts. However the entire concentrations of extract and crude extract especially the methanol and ethanol extracts of neem seeds and  leaves reduce the plant pathogenic fungi growth at noteworthy rate. It was concluded from our results that neem leaves and seeds  extracts were effectual as antifungal agents against the entire under study fungal strains however the most sensitive fungi were  Rhizoctonia solani and Fusarium oxysporum. The findings acquired from this study revealed that chemical constituents from neem seeds  and leaves may be formulated as latent agrochemical fungicides. 

Assessing long-distance atmospheric transport of soilborne plant pathogens

Pathogenic fungi are a leading cause of crop disease and primarily spread through microscopic, durable spores adapted differentially for both persistence and dispersal via soil, animals, water, and/or the atmosphere. Computational Earth system models and air pollution models have been used to simulate atmospheric spore transport for aerial-dispersal-adapted (airborne) rust diseases, but the importance of atmospheric spore transport for soil-dispersal-adapted (soilborne) diseases remains unknown. While a few existing simulation studies have focused on intracontinental dispersion, transoceanic and intercontinental atmospheric transport of soilborne spores entrained in agricultural dust aerosols is understudied and may contribute to disease spread. This study adapts the Community Atmosphere Model, the atmospheric component of the Community Earth System Model, to simulate the global transport of the plant pathogenic soilborne fungus Fusarium oxysporum (F. oxy). Our sensitivity study assesses the model’s accuracy in long-distance aerosol transport and the impact of deposition rate on simulated long-distance spore transport in Summer 2020 during a major dust transport event from Northern Sub-Saharan Africa to the Caribbean and southeastern United States (U.S.). We find that decreasing wet and dry deposition rates by an order of magnitude improves representation of long-distance, trans-Atlantic dust transport. Simulations also suggest that a small number of spores can survive trans-Atlantic transport to be deposited in agricultural zones. This number is dependent on source spore parameterization, which we improved through a literature search to yield a global map of F. oxy spore distribution in source agricultural soils. Using this map and aerosol transport modeling, we show how potentially viable spore numbers in the atmosphere decrease with distance traveled and offer a novel danger index for modeled viable spore deposition in agricultural zones. Our work finds that intercontinental transport of viable spores to cropland is greatest between Eurasia, North Africa, and Sub-Saharan Africa, suggesting that future observational studies should concentrate on these regions.

Antifungal activity of Terminalia chebula extract against wilt fungi Fusariumoxysporum an important plant pathogen

Terminalia chebula, a deciduous plant, endogenous to India has medicinal value. Its fruits are known for its cure to many ailments in human beings. This study is to test the Biological activity of these compounds tested against plant pathogenic fungai Fusarium oxysporum which cause wilt in economically important crops. Wilt is a devastating disease whichdestroys the infected plant and cause economic loss to farmers. Panama disease in bananas is a type of wilt disease which is very prevalent in India. This fungai has broad host range from tomato, cotton etc. Outbreak reported in many parts of India. Standard culture of Fusarium oxysporum ITCC -6246, Fusarium oxysporum f. sp. ciceri ITCC 3636 and Fusarium oxysporum f. sp. Lycopersici MTCC 10270 were used to detect the potential chemical compound in dried fruitby macro-dilution.Each organic solvent (Water, Ethanol, Chloroform, Benzene) has different extraction capacity based on the polarity of chemical compound in plants. These chemical compounds extensively studied for their antioxidant property and preliminary screening of chemical compound constituents in all extract. Mycelium growth inhibition tested on solid medium and inhibition measured in mm diameter. Spores of Fusarium sp. present in soil for many months in dormant form. Under suitable climatic conditions this will germinate and cause infection in plants. Rate of spore germination inhibition in liquid medium measured and calculated for every solvent extract. Rate of inhibition was calculated and analysed statistically by t test. The efficient solvent extract determined for bulk extraction of biologically active compound from seeds.

Antifungal activity of Terminalia chebula extract against wilt fungi Fusarium oxysporum an important plant pathogen

Terminalia chebula, a deciduous plant, endogenous to India has medicinal value. Its fruits are known for its cure to many ailments in human beings. This study is to test the biological activity of these compounds tested against plant pathogenic fungi Fusarium oxysporum which cause wilt in economically important crops. Wilt is a devastating disease which destroys the infected plant and cause economic loss to farmers. Panama disease in bananas is a type of wilt disease which is very prevalent in India. This fungi has broad host range from tomato, cotton etc. Outbreak reported in many parts of India. Standard culture of Fusarium oxysporum ITCC -6246, Fusarium oxysporum f. sp. ciceri ITCC 3636 and Fusarium oxysporum f. sp. lycopersici MTCC 10270 were used to detect the potential chemical compound in dried fruit by macro-dilution. Each organic solvent (Water, Ethanol, Chloroform, Benzene) has different extraction capacity based on the polarity of chemical compound in plants. These chemical compounds extensively studied for their antioxidant property and preliminary screening of chemical compound constituents in all extract. Mycelium growth inhibition tested on solid medium and zone of inhibition measured in mm diameter. Spores of Fusarium sp. present in soil for many months in dormant form. Under suitable climatic conditions this will germinate and cause infection in plants. Rate of spore germination inhibition in liquid medium measured and calculated for every solvent extract. Rate of inhibition was calculated and analysed statistically by t test. The efficient solvent extract determined for bulk extraction of biologically active compound from seeds.

Antifungal activity of myco-synthesized bimetallic ZnO-CuO nanoparticles against fungal plant pathogen Fusarium oxysporum

Abstract Fusarium species are considered one of the most destructing plant pathogens. In the current study, bimetallic zinc oxide-copper oxide nanoparticles (ZnO-CuO NPs) were myco-synthesized using Aspergillus fumigatus for controlling Fusarium oxysporum growth. Aspergillus fumigatus was isolated from soil and identified morphologically and genetically. The myco-synthesized ZnO-CuO NPs were characterized using UV-Vis, DLS, HR-TEM, SEM, and XRD analyses. HR-TEM characterization method indicated that, the biosynthesized bimetallic ZnO-CuO NPs appeared as semi-spherical with the average diameter specified as 54.18 ± 1.9 nm. The DLS method described the characteristic particle size diffusion and was calculated as 85.52 nm, 90.85 nm, and 92.85 nm for ZnO NPs, CuO NPs, and ZnO-CuO NPs, respectively. Additionally, the SEM image of ZnO-CuO NPs displays basic NP surface character and the exterior impression was apparent. The biosynthesized ZnO-CuO NPs were separated naturally as spherical particles connected within the fungal filtrate, which displays as illuminated NPs fused and capped with the fungal filtrate. Antifungal activity of bimetallic ZnO-CuO NPs was evaluated against F. oxysporum. Results revealed that bimetallic ZnO-CuO NPs exhibited promising antifungal activity toward F. oxysporum where inhibition zone at 1000 µg/ml was 22.8 ± 0.76 mm, and MIC was 125 µg/ml. Moreover, growth inhibition percentages of F. oxysporum at different concentrations of bimetallic ZnO-CuO NPs 1000, 500, 250, and 125 µg/ml were 88.9, 65.5, 41.1, and 8.9% respectively, where the highest inhibition was 88.9% at concentration 1000 µg/ml, while the lowest inhibition was 8.9% at concentration 125 µg/ml. In TEM ultrastructure results, the treated F. oxysporum with ZnO-CuO NPs, a clear destruction was found in all cell contents and disintegration of the cell wall as well as destruction of the plasma membrane. Also, the nucleus appeared as small size and damaged shape and the chromatin materials distributed with several dark stained bodies in cytoplasm. In conclusion, bimetallic ZnO-CuO NPs were successfully myco-synthesized using A. fumigatus, where it had promising antifungal activity against F. oxysporum.

Biocontrol Efficiency of Rhizospheric Bacillus against the Plant Pathogen Fusarium oxysporum: A Promising Approach for Sustainable Agriculture

Among plant disease management strategies, biological control is a sustainable alternative to the use of chemicals for the control of vascular wilt caused by Fusarium oxysporum. Fusarium wilt is the most devastating disease affecting a wide variety of plants. Bacillus species are the most widely used biological control candidates for the control of these fungal diseases. This review describes the pathogenicity of F. oxysporum, its virulence mechanisms, and host plant–pathogen interactions. The control means deployed by Bacillus species inhibit or kill these phytopathogens. Bacillus spp. produce a wide range of secondary metabolites, including volatile and non-volatile organic compounds. Biocontrol potential is achieved through direct antimicrobial activity, the induction of the host plant’s immune response (Induced Systemic Resistance), and competition for nutrients and space. In addition, parameters governing the selection of effective biocontrol agents and their survival in plant microbial communities are discussed. The influence of the microbiota on the establishment and development of biocontrol agents can assess the potential of these treatments and facilitate the development of effective biopesticides during their field application.

Pantothenate Auxotrophy in a Naturally Occurring Biocontrol Yeast.

The genus Hanseniaspora is characterized by some of the smallest genomes among budding yeasts. These fungi are primarily found on plant surfaces and in fermented products and represent promising biocontrol agents against notorious fungal plant pathogens. In this work, we identify pantothenate auxotrophy of a Hanseniaspora meyeri isolate that shows strong antagonism against the plant pathogen Fusarium oxysporum. Furthermore, strong biocontrol activity in vitro required both pantothenate and biotin in the growth medium. We show that the H. meyeri isolate APC 12.1 can obtain the vitamin from plants and other fungi. The underlying reason for the auxotrophy is the lack of two key pantothenate biosynthesis genes, but six genes encoding putative pantothenate transporters are present in the genome. By constructing and using a Saccharomyces cerevisiae reporter strain, we identified one Hanseniaspora transporter that conferred pantothenate uptake activity to S. cerevisiae. Pantothenate auxotrophy is rare and has been described in only a few bacteria and in S. cerevisiae strains that were isolated from sake. Such auxotrophic strains may seem an unexpected and unlikely choice as potential biocontrol agents, but they may be particularly competitive in their ecological niche and their specific growth requirements are an inherent biocontainment strategy preventing uncontrolled growth in the environment. Auxotrophic strains, such as the H. meyeri isolate APC 12.1, may thus represent a promising strategy for developing biocontrol agents that will be easier to register than prototrophic strains, which are normally used for such applications. IMPORTANCE As a precursor of the essential coenzyme A (CoA), pantothenate is present in all organisms. Plants, bacteria, and fungi are known to synthesize this vitamin, while animals must obtain it through their diet. Pantothenate auxotrophy has not been described in naturally occurring, environmental fungi and is an unexpected property for an antagonistic yeast. Here, we report that yeasts from the genus Hanseniaspora lack key enzymes for pantothenate biosynthesis and identify a transporter responsible for the acquisition of pantothenate from the environment. Hanseniaspora isolates are strong antagonists of fungal plant pathogens. Their pantothenate auxotrophy is a natural biocontainment feature that could make such isolates interesting candidates for new biocontrol approaches and allow easier registration as plant protection agents than prototrophic strains.

Metatranscriptome-based strategy reveals the existence of novel mycoviruses in the plant pathogenic fungus Fusarium oxysporum f. sp. cubense.

Fusarium oxysporum f. sp. cubense (Foc) is a devastating plant pathogen that caused a great financial loss in the banana's source area. Metatranscriptomic analysis was used to determine the diversity of mycoviruses in 246 isolates of F. oxysporum f. sp. cubense. Partial or nearly complete genomes of 20 mycoviruses were obtained by BLASTp analysis of RNA sequences using the NCBI database. These 20 viruses were grouped into five distinct lineages, namely Botourmiaviridae, Endornaviridae, Mitoviridae, Mymonaviridae, Partitiviridae, and two non-classified mycoviruses lineages. To date, there is no report of the presence of mycoviruses in this pathogen. In this study, we demonstrate the presence of mycoviruses isolated from Foc. These findings enhance our overall knowledge of viral diversity and taxonomy in Foc. Further characterization of these mycoviruses is warranted, especially in terms of exploring these novel mycoviruses for innovative biocontrol of banana Fusarium wilt disease.

Isolation, Identification and Cultivation of Ganoderma spp. and Evaluation of Their Efficiency in Inhibiting Plant Pathogenic Fungi Fusarium oxysporum and Alternaria tenuissima

Fruit bodies of three Ganoderma isolates coded by Has.AA-6, Has.AA-7 and Has.AA-8 were collected from the trunks of Poplar, Sidr and Apricot trees, respectively, from some districts in Salah al-Din Governorate. It was phenotypically diagnosed to the genus level depending on the shapes, colors and sizes of the fruit bodies as well as the internal tissues and basidiospores. Molecular diagnoses to the species level was carried out depending on the percentage of identical 5.8S rRNA gene sequences with strains of fungi in the World Genetic Bank at the NCBI. Ganoderma isolates identified as G. applanatum Has.AA-6, G. lucidum Has.AA-7 and G. resinaceum Has.AA-8, and recorded in the World Genetic Bank at the NCBI under the accession number ON834523.1, ON834541.1 and ON834527.1, respectively. The results of cultivation of Ganoderma spp. showed a superiority of the biological efficiency of the corn cobs supplemented with wheat bran, which were 27.73, 31.27, 31.64 and 32.07%, compared to unsupplemented this medium, as the biological efficiency reached 26.18, 26.67, 27.21, 27.22, and 27.22% for G. lucidum, G. applanatum, G. resinaceum and G. resinaceum 1049 respectively. The role of the filtrate, mycelium biomass and fruit bodies of Ganoderma spp. against the pathogenic fungi F. oxysporum and A. tenuissima was studied, the results showed that the extracts of all Ganoderma spp. have a significant superiority in inhibiting the growth of both pathogenic fungi compared to the control treatment, the alcoholic extract of G. resinaceum fruit bodies recorded the highest inhibition of the F. oxysporum and A. tenuissima in which the colonies diameters reached 3.21 and 2.4cm, respectively, while G. lucidum gave the lowest colony diameter of F. oxysporum and A. tenuissima, which reached 2.61 and 2.25 cm, respectively, compared to with a diameter of 8.5 cm for colonies of both pathogenic fungi in the control.

Improvement of antagonism and fungicides tolerance in Trichoderma harzianum and T.viride local isolates by Ultra-Violet irradiation

Among 22 Iraqi Trichoderma harzianum  and T.viride isolates, T3,T5,D5,S1 and S6 related to T. harzianum  showed a higher antagonistic activity against the plant pathogenic fungi  Fusarium oxysporum and Rhizoctonia solani. These isolates were selected for improvement their biocontrol activity by usi&#x0D; ng uv-irradiation. The optimum exposure time to ultraviolet irradiation is 30 min, in which, the percentage of kill was 98-99% .After UV-irradiation treatment (Quartz lamps 30W at 240-280 nm, peak 254nm, distance from the source was 20 cm), antagonistic capability against R. solani and F. oxysporum was improved in mutants MT3,MT5,MS1 and MS6, in which antagonistic reaction score were 3.6,3.9,3.2 and 3.6 against F. oxysporum and 3.7,4,3.4 and 4 against R. solani compared to 3.2, 2.8, 2.6 and 2.8 against F. oxysporum and 2.7, 2.9,3.1 and 3 against R. solani in the wild types T3, T5, S1 and S6,respectively. The growth of T. harzianum isolates (estimated as colony diameter) was significantly increased in all T. harzianum mutants except MT3 and MD5 mutants, CMCase activity was increased from 13.2, 16.2, 10 and 15.8 U/ml / mg protein in the wild isolates T3, T5, S1 and S6 to 18.6, 20.3, 17.7 and 22.5 U/ml / mg protein in the mutants MT3, MT5, MS1 and MS6, respectively. Chitinase activity was also increased in these mutants to 88.4,132.3,86.1 and 136.7 U/ml / mg protein, compared to 82.7, 93.2, 74.5 and 103.2 U/ml / mg protein in their wild, respectively. As comparison between wild types and mutants, the maximum growth was 5.2 and 4.8 cm (as colonies diameters) by MT5 in present of 25% of the recommended field rate of Topsin and Benomyl, compared to 3.3 and 2.2 cm in the wild type T5, respectively, followed by MS6,in which, the maximum growth in this mutant was 4.8 and 4.2 cm in the same concentration of these two fungicides, compared to 3.4 and 2.5 cm in the wild type S6, respectively. According to these results, the mutants MT5 and MS6 developed from UV-irradiation treatment, showed as promising T. harzianum mutants through their antagonistic activity (at mycoparasitism level) , fast growth, higher  CMCase and chitinase activity and growth in 25% of the recommended field rate of Elsa , 25 and 50% of the recommended field rate of Diathen and Mizab and all concentrations of Topsin and Benomyl with complete inhibition of pathogenic fungi F. oxysporum and R. solani.

Antifungal Activity of Selenium Nanoparticles Obtained by Plant-Mediated Synthesis.

The continuous need to satisfy world food demand has led to the search for new alternatives to combat economic losses in agriculture caused by phytopathogenic fungi. These organisms cause plant diseases, reducing their productivity and decreasing fruit quality. Among the new tools being explored is nanotechnology. Nanoparticles with antimicrobial properties could be an excellent alternative to address this problem. In this work, selenium nanoparticles (SeNPs) were obtained using plant extracts of Amphipterygium glaucum leaves (SeNPs-AGL) and Calendula officinalis flowers (SeNPs-COF). Characterization of the SeNPs was performed and their ability as antifungal agents against two commercially relevant plant pathogenic fungi, Fusarium oxysporum and Colletotrichum gloeosporioides, was evaluated. Assays were performed with different concentrations of SeNPs (0, 0.25, 0.5, 1.0, and 1.7 mg/mL). It was observed that both SeNPs had antifungal activity against both plant pathogens at concentrations of 0.25 mg/mL and above. SeNPs-AGL demonstrated better antifungal activity and smaller size (around 8.0 nm) than SeNPs-COF (134.0 nm). FTIR analysis evidenced the existence of different functional groups that constitute both types of SeNPs. There are factors that have to be considered in the antimicrobial activity of SeNPs such as nanoparticle size and phytochemical composition of the plant extracts used, as these may affect their bioavailability.

Design, synthesis and antifungal activity of novel pyrazole amides derivates

With the help of active substructure splicing strategy, 36 novel pyridine ring pyrazolamide derivatives were designed and synthesized. The structures of those compounds were confirmed and characterized by 1H NMR, 13C NMR, FT-IR, and HRMS. The compound 2i was identified by X-ray crystal diffraction. The fungicidal effects of the pyrazolamide derivates against four plant pathogenic fungi, Colletotrichum gloeosporioides, Fusarium oxysporum, Sphaeropsis sapinea and Fusarium moniliforme, was determined by the mycelial growth rate. The results showed that the designed compounds had certain antifungal activity at the concentration of 200 mg/L. Compared with the positive control carbendazim, compounds 1e, 1g and 1h exhibited stronger antifungal activity on Sphaeropsis sapinea and Fusarium moniliforme. The antifungal activity of compound 1a-1s (R1 = H) was better than that of compound 2a-2p (R1 = CH3). Compounds 1d, 1e, 1g, 1h, 1i, 2g and 2i showed good antifungal activity, and the introduction of halogen groups (except F) on benzene ring may have an important effect on biological activity. Compound 1g had a good inhibitory effect on the growth of a variety of plant pathogenic fungi. Molecular docking revealed that the -CH3 group at R1 position would reduce the binding affinity between these compounds and receptor, which would reduce the antifungal activity of the compound. Compound 1g is promising to become the lead compound of pesticide in the future, which is worthy of further study.