Fungi Pythium Aphanidermatum Research Articles

The Efficiency of some Control Agents in Resisting the Okra Root Rot Disease Caused by the Fungus Pythium aphanidermatum

This study was conducted in the laboratory and plastic house belonging to the Department of plant protection – faculty of Agriculture - Anbar University to evaluate the efficiency of the biological control agent Trichoderma harzianum and the chemical inducing agents sodium bicarbonate NaHCO3 and melatonin C13H16N2O2 in inducing resistance in seeds and seedlings of okra to infection with the disease of seed rot and the fall of seedlings caused by the semi-pathogenic fungus Pythium aphanidermatum double transplantation of some isolates of the-biotic fungus T. harzianum that isolation T2 (centre of Organic Agriculture-Ministry of Agriculture-Iraq) achieved the highest ability in inhibiting the growth of pathogenic semi-fungus, reaching a degree of contrast of 1, while the result of measuring the effectiveness of volatile substances on the PDA medium of the same isolates showed that isolation T2 (center of Organic Agriculture-Ministry of Agriculture-Iraq) gave the highest percentage of inhibition against pathogenic semi-fungus P. aphanidermatum reached 36.4% and the test of the effectiveness of the inducing agents in protecting the seeds of okra, Petra on the medium of PDA showed the effectiveness of the inducing agents sodium bicarbonate and melatonin in protecting the seeds, as the germination rate reached 100% for both, while the bio-fungi isolates achieved isolation T2 (Organic Agriculture Center-Ministry of Agriculture-Iraq) the best germination rate reached 100% and the results of the plastic house experiment showed that the treatment with bio-fungi by soaking for 20 minutes gave high efficiency in the percentage of germination reached 83.33% and reduced the percentage and severity of infection to 23.67% and 18.33% respectively, as for the soaking treatment with melatonin 200 micromuller, the percentage of germination decreased to 63.67% or the percentage and severity The infection rate reached 43.33% and 37% sequentially, as for the spraying treatment with biological agent isolation T2 (Organic Agriculture Centre-Ministry of Agriculture-Iraq) after 15 days of germination reduced the percentage and severity of infection to 32.67% and 25% sequentially and the spraying treatment with melatonin after 15 days of germination achieved the percentage and severity of infection reached 49% and 39.33% sequentially, as for the spraying treatment with biological agent isolation T2 (Organic Agriculture Center-Ministry of Agriculture-Iraq) after 25 days of germination, it gave the highest efficiency in reducing the percentage and severity of infection 35.67% and 29.67% sequentially, while the percentage and severity of infection in the melatonin spraying treatment after 25 days of germination reached 51.33% and 43.67% sequentially compared to the comparison treatment Contaminated with semi-pathogenic fungus Pythium aphanidermatum .

Testing the Effect of Some Materials to Control Pythium Aphanidermatum Isolated from Cucumber

he main objective of this study was to identify the effectiveness of household materials that are used to sterilize vegetables from the fungus Pythium aphanidermatum (P. aphanidermatum). Samples were taken from the damaged cucumber in the local markets of Babil Governorate, Iraq. These samples were kept in sterile cool containers until they reached the Microbiology lab. of the Department of Community Health, Technical Institute of Babylon. The samples were cultured laboratory in the Sabouraud Dextrose Agar (SDA), then a microscopic examination was carried out to identify the fungus using the lacto phenol cotton blue dye. Use in this study most common household materials to sterilize vegetables before keeping them in the refrigerator or before eating are Potassium Permanganate (KMnO4), Sodium Hypochloride (NaOCl) and table salt (NaCl). Five concentrations were used for each sterile material, and five replicates of culture dishes were used for each concentration (A mixture of sterile material with the SDA) after which the fungus was cultured. By using the minimum inhibitory concentration assay, the radial growth inhibition assay and the microscopic fungal examination, the efficacy of sterilizers was identified. The final results showed the presence of antifungal efficacy for all sterilizers used, with different concentrations. This study concluded that these materials can be used by housewives to sterilize vegetables before keeping them in the refrigerator or eating them. How to Cite: Ibtisam Mohammed Hussein, Abbas Razzaq Abed, 2023. "Testing the Effect of Some Materials to Control Pythium Aphanidermatum Isolated from Cucumber." Journal of Agriculture and Crops, vol. 9, pp. 266-272.

Screening and Characterization of Plant Growth Promoting Endophytic Microbes of Tomato (Solanum lycopersicum L.) combats Pythium aphanidermatum

About 45 bacteria, 9 fungi, 3 yeast, and 1 actinobacterium were isolated from plant tissues of tomato and screened for their plant growthpromoting traits and antagonistic activity against damping-off fungus Pythium aphanidermatum. The bacterial isolate, Bacillus pumilus TEB10 exhibited pathogen inhibition of about 55 and 79%, while yeast isolate Candida tropicalis TEY1 showed 30 and 68% in the dual plate and inverted plate assay, respectively. In addition, the Bacillus pumilus TB10 showed siderophore, HCN, cellulase, and phosphate solubilization activities. Similarly, yeast isolate Candida tropicalis TEY1 exhibited catalase, phosphate, and zinc solubilization activities. The sterol biosynthesis pathway end product ergosterol was profiled in secondary metabolites of P. aphanidermatum, suggesting the potentiality of this pathogenesis.

Isolation and Molecular Identification Of Lactobacillus Bacteria and Evaluation of Their Efficacy In Inhibiting The Pathogenic Fungus Pythium aphanidermatum

Twenty-eight isolates of Lactobacillus were isolated from the rhizosphere of pea cultivated in the fields of five districts in Salah al-Din, which included: Tikrit, Al-Alam, Al-Sharqat, Samarra and Al-Baiji. The isolates identified according to molecular diagnosis using the analysis of the 16S rRNA sequences and were divided into five species: 7 Isolates of L. fermentum, 3 isolates of L. casei, 9 isolates of L. plantarum, 4 isolates of L. herbarum and 5 isolates of L. paralimentarius. Antagonism tests were conducted for these isolates against the pathogen Pythium aphanidermatum, the highest rate of inhibition was by isolates of bacteria L. paralimentarius 1981 reached 2.7 mm, followed by isolate L.plantarum 1982 with an inhibition rate of 2.5 mm. In the antagonism test using bacterial filtrate of L. paralimentarius 1981, the concentration of 30% was the highest in inhibiting the pathogenic fungus, as the fungus colony diameter reached 3.22 cm, followed by the concentration of 20 and 25%, as the colony diameter reached 4.47 and 3.68 cm, respectively. L. paralimentarius 1081 was recorded in the databases of the World Genetic Bank within the accession number MW149434.1. This is the first record of this bacteria in Iraq. L. paralimentarius 1081 showed the highest production of the antibacterial active substances including siderophores, total phenols and bacteriocin reached to 61.24%, 1.05 mg/ml and 18.02 mg/ml, respectively, as well as pH decreased to 4.5. The results also showed there are a strong correlation of pathogenic fungus inhibition with high concentrations of siderophores, total phenols, bacteriocin and low pH in the bacterial filtrate.

Molecular identification based on the sequence of internal transcribed spacer (ITS) of the ribosomal nuclear DNA (rDNA) of pathogenic fungus Pythium aphanidermatum (Edson) Fitzp. isolated from soil and its morphology

Molecular identification based on the sequence of internal transcribed spacer (ITS) of the ribosomal nuclear DNA (rDNA) of pathogenic fungus Pythium aphanidermatum (Edson) Fitzp. isolated from soil and its morphology

Novel cross linked guar gum-g-poly(acrylate) porous superabsorbent hydrogels: Characterization and swelling behaviour in different environments

A new series of eco-friendly cross linked guar gum-g-poly(acrylate) porous superabsorbent hydrogels was prepared by in situ grafting polymerization and cross-linking on to a natural guar gum employing N,N-methylene bis acrylamide as cross linker. Morphological and structural characterization of the prepared hydrogels (SPHs) done by Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and solid state C13 NMR spectroscopy confirmed formation of porous grafted and crosslinked hydrogel structure. Increase in cross linker concentration in the feed mass exhibited decrease in porosity and increase in density of the hydrogels. Swelling of an optimized hydrogel (SPH) in response to external stimuli namely, salt solutions, fertilizer solutions, temperature, and pH exhibited high swelling ratios in various environments. Swelling rate of the SPH was faster than the corresponding nonporous superabsorbent hydrogel. The prepared hydrogels can serve as excellent carriers of pesticides, fertilizers and agriculturally important microbes. Biocontrol formulations based on a representative SPH exhibited excellent shelf-life characteristics and bioefficacy against phytopathogenic fungus Pythium aphanidermatum.

Identification and characterization of microRNAs in turmeric (Curcuma longa L.) responsive to infection with the pathogenic fungus Pythium aphanidermatum

Soft rot fungus, Pythium aphanidermatum, is the most devastating pathogen posing a serious constraint to turmeric (Curcuma longa L.) production worldwide. MicroRNAs (miRNAs) are a class of small non-coding RNAs that act as important modulators of gene expression related to several stress responses. However, to the best of our knowledge, there is no report on miRNA expression profiling in turmeric and miRNA functions in response to P. aphanidermatum remains unclear. In the present study, we sequenced a small RNA library developed from P. aphanidermatum infected turmeric rhizomes and employed a de novo assembled turmeric genome for miRNA prediction and target characterization. In total, 28 miRNAs representing 25 conserved and three novel sequences responsive to P. aphanidermatum were identified. Stem-loop reverse transcription PCR validated the expression of representative miRNAs from different families. Further, we computationally predicted the miRNA targets, many of which were experimentally confirmed using ligation mediated 5′ rapid amplification of cDNA ends analysis. Quantitative RT-PCR analysis of 12 selected miRNAs revealed simultaneous reciprocal changes in the expression patterns of six miRNAs (miR159, miR160, miR164, miR393, miR482 and miRx2) and their target genes in the infected rhizomes, thus suggesting their critical involvement in the modulation of a compatible interaction between turmeric and P. aphanidermatum. Our results suggest that P. aphanidermatum may have developed a virulence mechanism by interfering with plant miRNAs like miR164, miR393, miR482 and miRx2 to reprogram the defense gene expression in turmeric and facilitate pathogenesis.

Synthesis, Characterization, and Antifungal Studies of Cr(III) Complex of Norfloxacin and Bipiridyl Ligand.

A novel slightly distorted octahedral complex of Cr(III) of norfloxacin (Nor) with the formula [CrIII(Nor)(Bipy)Cl2]Cl·2CH3OH has been synthesized hydrothermally in the presence of a N-containing heterocyclic compound 2,2′-bipyridyl (Bipy). The complex was characterized with FT-IR, elemental analysis, UV-visible spectroscopy, and X-ray crystallography. Spectral studies suggest that the Nor acts as a deprotonated bidentate ligand. Thermal studies were also carried out. The synthesised complex was screened against four fungi Pythium aphanidermatum (PA), Sclerotinia rolfsii (SR), Rhizoctonia solani (RS), and Rhizoctonia bataticola (RB).

Biochemical characterization and antifungal activity of an endo-1,3-beta-glucanase of Paenibacillus sp. isolated from garden soil.

A 44-kDa 1,3-beta-glucanase was purified from the culture medium of a Paenibacillus strain with a 28-fold increase in specific activity with 31% recovery. The purified enzyme preferentially catalyzes the hydrolysis of glucans with 1,3-beta-linkage and has an endolytic mode of action. The enzyme also showed binding activity to various insoluble polysaccharides including unhydrolyzable substrates such as xylan and cellulose. The antifungal activity of this Paenibacillus enzyme and a previously purified 1,3-beta-glucanase from Streptomyces sioyaensis were examined in this study. Both enzymes had the ability to damage the cell-wall structures of the growing mycelia of phytopathogenic fungi Pythium aphanidermatum and Rhizoctonic solani AG-4. Nonetheless, the Paenibacillus enzyme had a much stronger effect on inhibiting the growth of fungi tested.

Effect of Feeding Salicylic Acid on 2,3-Dihydroxybenzoic Acid Formation in Cultured Cells of Catharanthus roseus

Catharanthus roseus cell cultures produce a high amount of 2,3-dihydroxybenzoic acid (2,3-DHBA) and salicylic acid (SA) with a concomitant induction of isochorismate synthase (ICS, EC 5.4.99.6) after addition of a fungus Pythium aphanidermatum. To investigate whether 2,3-DHBA might be formed through an intermediacy of SA, the cells were fed with this compound. A significant increase of glycosidically bound 2,3-DHBA was obtained, although no effect on ICS was observed in the cells treated with SA. On the contrary, the addition of SA in combination with fungal elicitor led to a lower level of the total 2,3-DHBA found in the cells and the medium, but no influence on the induction of ICS activity. These results suggest SA is unlikely a direct precursor of 2,3-DHBA. However, it might have a regulatory role in the 2,3-DHBA biosynthetic pathway.

Controle químico de fungos associados a sementes de sorgo e proteção contra fungos do solo

Este trabalho teve como objetivo avaliar a eficiência de alguns fungicidas no controle de fungos associados a sementes de sorgo cultivar CMS 182R e na proteção delas contra fungos do solo. A microbiota das sementes de sorgo, composta por Fusarium moniliforme, Penicillium spp., Alternaria tenuis, Cladosporium spp. e Phoma sorghina, foi patogênica a essas sementes, e os fungos Pythium aphanidermatum e Sclerotium rolfsii, infectantes do solo de monocultivo de sorgo, também se mostraram patogênicos. Os fungicidas captan, thiram, captan + thiabendazole, thiram + thiabendazole, iprodione + thiram e tolylfluanid foram os mais eficientes no controle não só de toda a microbiota das sementes, como também na proteção das sementes contra Pythium aphanidermatum e Sclerotium rolfsii.

Chitinolytic and cellulolytic Pseudomonas sp. antagonistic to fungal pathogens enhances nodulation by Mesorhizobium sp. Cicer in chickpea

Pseudomonas strains isolated from the rhizosphere of chickpea (Cicer arietinum L.) and green gram (Vigna radiata L.) were screened for the production of chitinases and cellulases. Five Pseudomonas strains were found to produce appreciable amounts of both enzymes in culture-free supernatants and showed growth inhibition of the two fungi Pythium aphanidermatum (Oomycete) and Rhizoctonia solani (Basidiomycete) in plates on potato dextrose agar medium. The fungal growth inhibition was not correlated with cell wall-degrading enzyme activity, which suggested that other antifungal compounds produced by these rhizobacteria were also involved in antagonism. Coinoculation of the Pseudomonas strains with the Mesorhizobium sp. Cicer strain Ca 181 resulted in a significant increase in nodule biomass when grown under sterilized chillum jar conditions. The results suggest that hydrolytic enzymes produced by Pseudomonas sp. contribute to suppression of plant diseases by inhibiting growth of phytopathogenic fungi and also promote nodulation of legumes by rhizobia.

Elicitor-induced cell death and phytoalexin synthesis in Daucus carota L.

Suspension-cultured carrot cells and intact leaves respond to crude and purified protein elicitors from the non-host fungus Pythium aphanidermatum by activating the general phenylpropanoid pathway and incorporating de-novo-synthesized 4-hydroxybenzoic acid (4-HBA) into the cell wall. The cultured cells undergo a very rapid elicitor-induced cell death. Both reactions are directly correlated in their time course and their dose dependency. Cell death in elicitor-treated protoplasts resulted in early membrane damage and the digestion of DNA into oligonucleosomal fragments. The same pattern of DNA degradation could be induced in protoplasts by the G-protein activators Mas-7 or mastoparan. In cell cultures, both activators induced a rapid loss of viability without the activation of the general phenylpropanoid pathway. The elicitor-induced reactions, the loss of viability and the induction of 4-HBA biosynthesis were blocked by the calcium-channel blocker nifedipine. Neomycin and U73122, two inhibitors of phospholipase C, blocked the induction of 4-HBA biosynthesis but did not affect the loss in viability. The injection of the elicitor into the leaves of intact carrot plants confirmed the results obtained with cell cultures with regard to the induction of the hypersensitive response. The purification of the active compound revealed a 25-kDa protein which triggers both cell death and 4-HBA synthesis. The signalling pathways to both reactions could be independently blocked or induced.

A Microcalorimetric Technique for Rapid Assessment of Fungicide Activity

Screening for antifungal metabolites from microbial fermentation broths or extracted plant samples is used to identify compounds with potential novel modes of action. The isolation of fungicidal secondary metabolites from these samples relies on the use of a sensitive detection method that can be evaluated in a timely fashion. This paper describes the use of isothermal microcalorimetry to rapidly assess fungicide activity. An in vivo screening test can require from 1 to 4 weeks and milligram quantities of material. Many in vitro tests require only microgram quantities, with test durations of from 2 to 5 days. Microcalorimetry, with its ability to detect microwatt changes in metabolic heat, extends this range of sensitivity. By this method, fungicidal activities can be assessed in 4 to 8 hours with only nanogram quantities of material. Techniques for the use of isothermal microcalorimetry were developed for the filamentous fungi Pythium aphanidermatum and Pyricularia oryzae

Transient induction of tryptophan decarboxylase (TDC) and strictosidine synthase (SS) genes in cell suspension cultures of Catharanthus roseus

When cell suspension cultures of Catharanthus roseus are treated with autoclaved elicitor from the fungus Pythium aphanidermatum, they respond with the rapid transient induction of tryptophan decarboxylase (TDC) and strictosidine synthase (SS) enzyme activities, followed by the accumulation of indole alkaloids (Eilert et al., 1987). In this report, we demonstrate that expression of TDC and SS enzyme activities is preceeded by the transient appearance of mRNAs for both enzymes, suggesting transcriptional control of these events. The strong transient accumulation of both TDC and SS enzyme transcripts observed in elicitor-treated cell suspension cultures contrasts with the barely detectable level of TDC transcripts and the undetectable level of SS transcripts observed in developing seedlings.

Monoclonal antibodies to cell surface components of zoospores and cysts of the fungus Pythium aphanidermatum reveal species-specific antigens

A panel of monoclonal antibodies (MAbs) designated PA1 to PA8 has been raised against cell surface components of zoospores and cysts of the pathogenic fungus Pythium aphanidermatum. The antibodies were selected on the basis of binding assays using indirect immunofluorescence. Four binding patterns were observed: PA1 labeled the entire zoospore surface including both flagella, PA2 binding was restricted to the anterior flagellum, PA3–PA6 bound to the adhesive cell coat secreted by zoospores during encystment, and PA7 and PA8 labeled zoospores and the cyst cell wall. Electron microscopic immunogold labeling of zoospores showed that PA2 bound to the mastigonemes on the anterior flagellum. The MAbs were tested for binding to zoospores and cysts of several isolates of P. aphanidermatum, and to zoospores and cysts of several species of Pythium, Phystophthora, Aphanomyces, and Saprolegnia. The results showed that the antigens recognized by MAbs PA1–PA6 were restricted to P. aphanidermatum, whereas those recognized by PA7 and PA8 occurred on all species tested.