Hyphal Structures Research Articles

Bacillus vallismortis TU-Orga21 blocks rice blast through both direct effect and stimulation of plant defense.

Beneficial microorganisms are an important strategy for sustainable plant production processes such as stimulate root exudation, stress tolerance, and yield improvement. This study investigated various microorganisms isolated from the rhizosphere of Oryza sativa L. in order to inhibit Magnaporthe oryzae cause of rice blast, by direct and indirect mode of action. The results indicated that Bacillus vallismortis strain TU-Orga21 significantly reduced M. oryzae mycelium growth and deformed the hyphal structures. The effects of biosurfactant TU-Orga21 was studied against M. oryzae spore development. The dose of ≥5% v/v biosurfactant significantly inhibited the germ tubes and appressoria formation. The biosurfactants were evaluated as surfactin and iturin A by Matrix-assisted laser desorption ionization dual time-of-flight tandem mass spectrometry. Under greenhouse conditions, priming the biosurfactant three times before M. oryzae infection significantly accumulated endogenous salicylic acid, phenolic compounds, and hydrogen peroxide (H2O2) during the infection process of M. oryzae. The SR-FT-IR spectral changes from the mesophyll revealed higher integral area groups of lipids, pectins, and proteins amide I and amide II in the elicitation sample. Furthermore, scanning electron microscope revealed appressorium and hyphal enlargement in un-elicitation leaves whereas appressorium formation and hyphal invasion were not found in biosurfactant-elicitation at 24h post inoculation. The biosurfactant treatment significantly mitigated rice blast disease severity. Therefore, B. vallismortis can be a promising novel biocontrol agent which contains the preformed active metabolites for a rapid control of rice blast by a direct action against pathogen and by boosting plant immunity.

Post COVID-19: Risk Factors, Prevention, and Management of Black Fungus

Background: Mucormycosis is a genuine, however uncommon shrewd fungal contamination that spreads quickly, and subsequently brief analysis and treatment are important to stay away from the high pace of mortality and morbidity rates. Mucormycosis is brought about by the inward breath of its filamentous (hyphal structure) fungus, particularly in immunosuppressed patients. The pandemic of COVID -19 stays on an upsurge pattern. The second rush of this infection has prompted alarm in numerous nations, including India and a few pieces of the world experiencing the third wave. As there could be no appropriate treatment choices or cures accessible for this lethal contamination, steady consideration gears like oxygen chambers, ventilators and substantial utilization of steroids assume an imperative part in the management of COVID-19. Amidst this pandemic, the COVID-19 patients are procuring optional contaminations, for example, mucormycosis otherwise called black fungus infection. Objective: It is important to lead research on COVID-19 patients to even more likely to forestall and oversee pioneering contaminations to diminish their occurrence and bleakness. So, this paper is to foster preventive treatment plans and use corticosteroids sanely. Methods: Using search engines like Embase, PubMed, Google Scholar, etc., various research, review articles, and some book chapters, also various articles on websites and guidelines on the ICMR portal were accessed, after which we prepared this review article. In this review, we have included reported cases and case series of mucormycosis among patients with and without COVID-19 spanning the period of 1969 to 2021 and have described the clinical features and outcomes. Results: In gentle instances of COVID-19 (without hypoxemia) or when utilizing higher dosages of glucocorticoids, glucocorticoids ought to be kept away from ongoing investigations which have archived a disturbing number of COVID-19 patients with mucormycosis contamination. A large portion of these patients had diabetes which was controlled with the use of steroids. Conclusion: Thus, the current article underlines mucormycosis and its connected conditions, its component in typical and COVID-19 influenced people, affecting variables and difficulties to defeat this disease. Early distinguishing proof and further examination of its growth will altogether diminish the seriousness of the sickness and death rate in COVID-19- influenced patients.

Fungal drops: a novel approach for macro- and microscopic analyses of fungal mycelial growth.

This study presents an inexpensive approach for the macro- and microscopic observation of fungal mycelial growth. The 'fungal drops' method allows to investigate the development of a mycelial network in filamentous microorganisms at the colony and hyphal scales. A heterogeneous environment is created by depositing 15-20µl drops on a hydrophobic surface at a fixed distance. This system is akin to a two-dimensional (2D) soil-like structure in which aqueous-pockets are intermixed with air-filled pores. The fungus (spores or mycelia) is inoculated into one of the drops, from which hyphal growth and exploration take place. Hyphal structures are assessed at different scales using stereoscopic and microscopic imaging. The former allows to evaluate the local response of regions within the colony (modular behaviour), while the latter can be used for fractal dimension analyses to describe the hyphal network architecture. The method was tested with several species to underpin the transferability to multiple species. In addition, two sets of experiments were carried out to demonstrate its use in fungal biology. First, mycelial reorganization of Fusarium oxysporum was assessed as a response to patches containing different nutrient concentrations. Second, the effect of interactions with the soil bacterium Pseudomonas putida on habitat colonization by the same fungus was assessed. This method appeared as fast and accessible, allowed for a high level of replication, and complements more complex experimental platforms. Coupled with image analysis, the fungal drops method provides new insights into the study of fungal modularity both macroscopically and at a single-hypha level.

Rapid Cytological Diagnosis With Evaluation of Pre- and Post-Therapeutic Fungal Morphological Characteristics in Mucormycosis.

Mucormycosis necessitates rapid diagnosis and treatment. Microscopy and culture have been considered the gold standard for diagnosis but both take time of 3 - 5 days. KOH mount is another method for fungal identification that takes 1 - 2 h, but it has its own limitations. This study evaluated crush smear as a means of rapid cytological diagnosis. Biopsy tissue (pre-treatment) from clinically suspicious mucormycosis patients (n = 52) was received in normal saline and crush/imprint smears were prepared; the remaining tissue was processed as routine biopsy specimen. After the rapid initial cytological identification, the patients were managed according to the standard clinical protocol. Random post-therapeutic biopsy samples of some of these patients (n = 19) were also obtained and again evaluated cytologically. Crush smears showed sensitivity/specificity of 77.7%/75.0% with histopathology and 72.2%/62.5% with culture, respectively, while KOH mount had values of 71.4%/70.5% with histopathology and 79.3%/69.5% with culture, respectively. Degenerative fungal morphological characteristics and cellular inflammatory infiltrate (predominantly neutrophilic) in the vicinity of fungal hyphae were compared in pre- and post-treatment groups, and we found a statistically significant difference (P < 0.05) between them. Our preliminary results suggest that crush smear cytology is a simple, rapid, cost-effective and easily available method for diagnosing mucormycosis. Moreover, crush smears also demonstrated morphological alteration in hyphal structure and accompanying immune cell infiltration which may provide valuable insights into mechanism of therapy/host immune response against fungal pathogen.

Raman microscopy tracks maturity of melanin intermediates in Botrytis cinerea, a plant pathogen.

We use Raman microscopy to describe the structure and chemical composition of both conidiophore and hyphae of Botrytis cinerea, a common plant pathogen. To interpret experimental data, we use density functional theory (DFT) to compute Raman tensors specific to an important fungal glycopeptide, a segment of α-chitin, and several naphthalene-based precursors of increasing complexity, which we propose play a role in the melanin synthesis pathway. Using spectral interpretations based on quantum chemical validation, we review microscopy images reconstructed for specific Raman activities and describe differences in distributions of structural components, photo-protective secondary naphthalene-based pigments, and proteins in both spores and hyphal filaments. Comparison of our results with literature data on other fungi suggests an example of convergent evolution expressed at the level of secondary metabolites specific to plant pathogenic fungi. Our results indicate that pre-resonant Raman monitoring of melanin precursors may help assessment of local Botrytis population biology to aid agricultural production.

Cell Cycle Analysis of Candida albicans by Flow Cytometry.

The cell cycle is a vital process of cell division that is required to sustain life. Since faithful cell division is critical for the proper growth and development of an organism, the study of the cell cycle becomes a fundamental research objective. Saccharomyces cerevisiae has been an excellent unicellular system for unraveling the secrets of cell division, and the process of synchronization in budding yeast has been standardized. Cell synchronization is a crucial step of cell cycle analysis, where cells in a culture at different stages of the cell cycle are arrested to the same phase and, upon release, they progress synchronously. The cellular synchronization of S. cerevisiae is easily achieved by a pheromone or other chemicals like hydroxyurea treatment; however, such methodologies seem to be ineffective in synchronizing cells of multimorphic fungi such as Candida albicans. C. albicans is a human pathogen that can grow in yeast, pseudohyphal, and hyphal forms; these forms differ in morphology as well as cell cycle progression. More importantly, upon subjecting to DNA replication inhibitors for synchronization, C. albicans develops hyphal structures and grows asynchronously. Therefore, here we describe a simple and easy method to synchronize C. albicans cells in the G1 phase and the subsequent analysis of cell cycle progression by using flow cytometry.

Controlled-Release of Plant Volatiles: New Composite Materials of Porous Carbon-Citral and Their Fungicidal Activity against Exobasidium vexans

Citral (Eo) exhibits excellent fungicidal activities. However, it is difficult to maintain long-term fungicidal activity due to its strong volatility. Herein, a controlled-release strategy by using biomass-derived porous carbon (BC) was developed to overcome the drawback of Eo. New composite materials were prepared by loading Eo on tea stem porous carbon (BC@Eo), and their controlled-release fungicidal activity against Exobasidium vexans was assessed. BC with a large specific surface area of 1001.6 m2/g and mesoporous structure was fabricated through carbonization temperature of 700°C. The BC@Eo materials were characterized using Fourier-transform infrared spectroscopy and X-ray powder diffraction. The results suggested that chemical and physical interactions occurred in BC@Eo. The Eo release profile suggested a biphasic pattern with an initial fast release on days 1–14 and a subsequent controlled phase on days 14–30. The in vitro cumulative release percentage of Eo from BC@Eo was 51% during one month, and this result was significantly lower than that from free Eo (cumulative release percentage of Eo of 82% in one week). The antifungal activities of Eo and BC@Eo against E. vexans were determined using the inhibition zone method. The results indicated that Eo and BC@Eo formed large inhibition zones of 19.66 ± 0.79 and 21.92 ± 0.77 mm, respectively. The influence on the hyphal structure of E. vexans was observed by scanning electron microscopy on day 30. The hyphal structure of E. vexans treated with BC@Eo was more shrunken than that treated with Eo at 30 days, suggesting that BC@Eo prolongs the fungicidal activity against E. vexans. This study demonstrated that the encapsulation of Eo in BC for developing the BC@Eo materials could be a promising strategy to inhibit volatility and maintain the fungicidal activity of Eo and provide a potential alternative for the reuse of abundant tea biomass waste resources.

Management of Chili Root Rot Pathogen, Rhizoctonia solani, with Potential Rhizobacteria

Chili (Capsicum annuum L.) belongs to the solanaceae family. It is a major vegetable crop grown on a wide scale in Asia. Nearly 20% of Pakistan's total vegetable producing land is utilized for cultivating chili. Various plant pathogens including viruses, fungi, bacteria and nematodes are responsible for causing diseases in chili crop. Among fungal diseases, root rot is an important fungal disease which is caused by Rhizoctonia solani. In the present study, a survey of different localities of Multan district were conducted and plants with prominent root rot symptoms were collected and subjected to characterization. Moreover, the disease incidence and prevalence was calculated in surveyed localities. Highest disease incidence i.e. 20.77% was evident in samples collected from Tatay Pur and the lowest disease incidence (7.59%) was observed in samples of Suraj Miani. Morphological identification of root rot samples was carried out based on growth, shape, color, and hyphae structure and confirmed the association of R. solani. Koch’s postulates were confirmed after pathogenicity test which was accomplished by stem application method. About 10 rhizobacteria were isolated from rhizospheric soils of healthy plants and dual culture technique was used to manage the R. solani mycelial growth under in vitro conditions. Our results revealed that rhizobacteria 7 (RB7) exhibited the highest inhibition percentage 54.81% while the lowest inhibition percentage i.e. 40% was evident using rhizobacteria 4 (RB4) compared to control. This study helped us to provide the alternatives to the chemical fungicides that could be explored under field conditions against root rot disease as they are ecofriendly and has less impact to the human life.

Alpinia officinarum mediated copper oxide nanoparticles: synthesis and its antifungal activity against Colletotrichum gloeosporioides.

Green synthesis offers an environmentally friendly and cost-effective alternative for the synthesis of copper oxide nanoparticles (CuO NPs). In this study, the synthesis of CuO NPs was optimized by using copper sulfate (CuSO4) and the aqueous extract of Alpinia officinarum and its antifungal activity were investigated. The synthesized CuO NPs were characterized by UV-visible spectroscopy (UV-vis), X-ray diffraction (XRD), Fourier-transform infrared radiation spectroscopy (FT-IR), scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), dynamic light scattering (DLS), and transmission electron microscopy (TEM). The results showed that the optimized conditions for the synthesis of CuO NPs were 1:2 ratio of extract and CuSO4 solution, pH 7, and 30°C. The characteristic UV-vis peak of A. officinarum synthesized CuO NPs was at 264nm. The synthesized CuO NPs had high crystallinity and purity and were spherical in morphology with the mean size of 46.40nm. The synthesized CuO NPs reduced the fungal growth of Colletotrichum gloeosporioides in a dose-dependent manner. The minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) of the CuO NPs were 125μg·mL-1 and 500μg·mL-1, respectively. The antifungal activity of CuO NPs may be attributed to its ability to deform the structure of fungal hyphae, induce excessive reactive oxygen species accumulation and lipid peroxidation in fungi, disrupt the mycelium cell membrane, and result cellular leakage.

Szczepkamyces quercicola sp. nov. (Polyporales, Basidiomycota) evidenced by morphological characters and molecular phylogeny

Szczepkamyces, typified by Szczepkamyces campestris, was a monotypic genus. Based on distinct morphological characters and phylogeny inferred from the combined 2-locus dataset [ITS1-5.8S-ITS2 (ITS) + nuclear large subunit RNA (nLSU)], another species of the genus, Szczepkamyces quercicola sp. nov., is confirmed. It is characterized by annual, resupinate, yellowish basidiocarps with big pores, a dimitic hyphal structure, generative hyphae with clamp connections, indextrinoid skeletal hyphae, the absence of hyphal pegs, the presence of dendrohyphidia, cylindrical basidiospores measuring 15–17.5 × 5–6 µm, and growth on Quercus in boreal forests in east Himalayas. Morphologically S. quercicola resembles Megasporoporia sensu lato, but phylogenetically it is closely related to S. campestris. The differences between S. quercicola and its similar or related species are discussed.

Antifungal activity and genomic characterization of the biocontrol agent Bacillus velezensis CMRP 4489

The development of bio-based products has increased in recent years, and species of the Bacillus genus have been widely used for product development due to their elevated production of antimicrobial molecules and resistance to extreme environmental conditions through endospore formation. In this context, the antifungal potential of Bacillus velezensis CMRP 4489 was investigated using in silico predictions of secondary metabolites in its genome and in vitro tests against the following phytopathogenic fungi: Sclerotinia sclerotiorum, Macrophomina phaseolina, and Botrytis cinerea. The in-silico predictions indicated that CMRP 4489 possesses several Biosynthetic Gene Clusters (BGCs) capable of producing molecules with antifungal properties and other non-identified BGCs. The in vitro assay results evidenced strong antifungal activity, inhibiting more than 60% of the tested fungi, and the isolate’s molecules were stable under diverse physicochemical conditions. The in vitro assay evidenced significant antifungal activity, deformation of the hyphal structure in SS, biofilm formation capacity, and swarming motility. In the colonization assay, we observed attachment, colonization, and net-shaped biofilm formation, with the strain transitioning from the seeds to nearby structures. Therefore, CMRP 4489 showed to be a potential biocontrol agent against various diseases with agronomic importance and can be used under adverse environmental conditions.

Broad-spectrum resistance mechanism of serine protease Sp1 in Bacillus licheniformis W10 via dual comparative transcriptome analysis.

Antagonistic microorganisms are considered to be the most promising biological controls for plant disease. However, they are still not as popular as chemical pesticides due to complex environmental factors in the field. It is urgent to exploit their potential genetic characteristics and excellent properties to develop biopesticides with antimicrobial substances as the main components. Here, the serine protease Sp1 isolated from the Bacillus licheniformis W10 strain was confirmed to have a broad antifungal and antibacterial spectrum. Sp1 treatment significantly inhibited fungal vegetative growth and damaged the structure of hyphae, in accordance with that caused by W10 strain. Furthermore, Sp1 could activate the systemic resistance of peach twigs, fruits and tobacco. Dual comparative transcriptome analysis uncovered how Sp1 resisted the plant pathogenic fungus Phomopsis amygdali and the potential molecular resistance mechanisms of tobacco. In PSp1 vs. P. amygdali, RNA-seq identified 150 differentially expressed genes (DEGs) that were upregulated and 209 DEGs that were downregulated. Further analysis found that Sp1 might act on the energy supply and cell wall structure to inhibit the development of P. amygdali. In TSp1 vs. Xanthi tobacco, RNA-seq identified that 5937 DEGs were upregulated and 2929 DEGs were downregulated. DEGs were enriched in the metabolic biosynthesis pathways of secondary metabolites, plant hormone signal transduction, plant–pathogen interactions, and MAPK signaling pathway–plant and further found that the genes of salicylic acid (SA) and jasmonic acid (JA) signaling pathways were highly expressed and the contents of SA and JA increased significantly, suggesting that systemic resistance induced by Sp1 shares features of SAR and ISR. In addition, Sp1 might induce the plant defense responses of tobacco. This study provides insights into the broad-spectrum resistance molecular mechanism of Sp1, which could be used as a potential biocontrol product.

Bioinspired Hydrophilic and Oleophilic Absorption Media from Biotemplated Fungi

Fungi are an incredibly diverse biological kingdom with organisms that have a wide range of morphologies, properties, and structures. Previous research has investigated the use of filamentous fungi, which have naturally porous structures created by hyphal filaments, as a means of phytoremediation. This study uses these natural fungal structures to create bioinspired materials that capture both the structure and functional absorption properties of fungi. Three types of filamentous fungi with different hyphal structures (monomitic, dimitic, and trimitic) are used as organic templates to create inorganic media using two different biotemplating methods to create silica and hybrid samples. Characterization of these samples is completed using scanning electron microscope imaging, chemical characterization, nanoindentation, and hydrophilic and oleophilic absorption tests. Biotemplated samples have similar structures as their organic templates, but contained silica, which is not present in natural, dehydrated fungal samples. Fourier transform infrared analysis shows better cross‐linking in the hybrid samples, which also have higher mechanical resistance than the silica samples. Absorption testing demonstrates that silica samples are closest to mimicking the absorption properties of natural, dehydrated samples. Of the three hyphal structures, the monomitic samples show the greatest increase in mechanical properties and maintenance of absorption properties when biotemplated.

2,4-Diacetylphloroglucinol Modulates Candida albicans Virulence.

The dimorphic fungus Candida albicans is one of the most important opportunistic pathogens for humankind. The use of fungicides against Candida could be associated with sub-inhibitory effects, which are referred to as fungal stress responses and are undesirable for the host. In this work, we investigated the antifungal action of 2,4-diacetylphloroglucinol (2,4-DAPG) against Candida albicans ATCC 10231 with a focus on their biofilm-forming ability. We found that 2,4-DAPG was able to reduce the ability of Candida cells to form biofilms, but complete inhibition and eradication effects were not achieved. Furthermore, C. albicans cells in the adherent state were characterized by reduced susceptibility to 2,4-DAPG compared to planktonic cells. The investigation of the mechanisms that could explain the antibiofilm action of 2,4-DAPG revealed a reduction in the cell`s surface hydrophobicity and the inhibition of the yeast-to-hyphae transition. The inhibition of the Candida cells filamentation was accompanied by an increase in the expression of the NRG1 gene, which is a negative regulator of hyphal development. In addition, we microscopically visualized the treated biofilms and revealed numerous channels that were decorated with particles and localized on the hyphae. We assumed that these hyphal structures could be associated with the secretion of aspartyl proteases (Sap). The performed assessments revealed an increase in the activity of Sap, which was accompanied by an increase in the expression of the sap2 and sap4 genes. The antifungal action of 2,4-DAPG is known to be associated with affecting the permeability of cellular structures, which leads to H+ATPase malfunction and the disruption of mitochondrial respiration. The subsequent cytosol acidification and generation of ROS trigger the inhibition of Candida filamentation and activation of Sap production. The introduction of antioxidant Trolox simultaneously with 2,4-DAPG leads to a reduction in Sap production. Collectively, the obtained data indicate new aspects of the interaction of fungal cells with 2,4-DAPG, an antimicrobial metabolite of Pseudomonas spp.

Acrophialophora jodhpurensis: an endophytic plant growth promoting fungus with biocontrol effect against Alternaria alternata.

In this study, efficiency of the endophytic fungal isolate Msh5 was evaluated on promoting tomato plant growth and controlling Alternaria alternata, the causal agent of early blight in tomatoes. Morphological and molecular (ITS and tub2 sequences) analyses revealed that the fungal isolate, Msh5, was Acrophialophora jodhpurensis (Chaetomium jodhpurense Lodha). This beneficial fungus was capable of producing indole-3-acetic acid (IAA), urease, siderophore, extracellular enzymes, and solubilized phosphate. Under laboratory conditions, the Msh5 isolate of A. jodhpurensis inhibited A. alternata growth in dual culture, volatile and non-volatile metabolites assays. The supernatant of this endophytic fungus was capable of reducing spore germination and altering the hyphal structure of A. alternata and the spores produced germ tubes showed vacuolization and abnormal structure compared to the control. Also, the effect of A. jodhpurensis on plant growth parameters (such as shoot and root weight and length) and suppressing A. alternata was investigated in vivo via seed inoculation with spores of A. jodhpurensis using 1% sugar, 0.5% carboxymethyl cellulose (CMC) or 0.5% molasses solution as stickers. Colonization of tomato roots by the endophytic fungus resulted in significant increasing plant growth parameters and reduction in the progress of the diseases caused by A. alternata compared to the controls. Among the different coating materials used as stickers, sugar was found to be the most effective for enhancing plant growth parameters and decreasing the disease progress. Therefore, A. jodhpurensis isolate Msh5 can be suggested as a potential biofertilizer and biocontrol agent for protecting tomato plants against A. alternata.

CHICKEN FEATHER DEGRADATION BY KERATINOLYTIC ASPERGILLUS SPECIES ISOLATED FROM FEATHER WASTE DUMPING SOIL

Slaughterhouses and poultry processing units worldwide dispose of huge amount of chicken feathers that accumulate as solid waste in the environment and cause serious consequences. Keratinases are a group of enzymes, produced by microorganisms have the ability to degrade tough recalcitrant keratin that is abundantly present in chicken feathers. Soil sample was collected from a feather dumping site at Virudhunagar (9° 35' 13.9524'’ N Latitude and 77° 57' 5.1516'’ E Longitude), Tamil Nadu, India. Soil sample was serially diluted, inoculated on to feather meal agar plates and incubated at 37 °C for 7 days to isolate keratinolytic fungal strains. The isolated strains were screened for proteolytic activity on skim milk agar for 8 days and three better strains were identified based on morphology, mycelial growth, and structure of hyphae using lactophenol cotton blue staining and confirmed by ITS primer sequencing method as Aspergillus niger, Aspergillus terreus and Aspergillus flavus respectively. Different range of pH (7 to 11), temperature (25 to 45 °C), substrate (bovine serum albumin, feather, peptone and gelatin) and feather concentration (0.5g, 1g, 1.5g and 2g) were tested to find out the optimum conditions for the growth and keratin degradation of the chosen fungal strains. The temperature and feather concentration for the optimum growth of A. niger, A. terreus and A. flavus were 25 °C and 1.5g, 45 °C and 1g and 30 °C and 1.5g respectively. All three Aspergillus species exerted better growth at pH 9 and with bovine serum albumin as the substrate.

ISOLATION AND MOLECULAR IDENTIFICATION OF PHYTOPHTHORA INFESTANS (MONT.) DE BARY THE CAUSAL AGENTS OF POTATO LATE BLIGHT

Potato (Solanum tubersum L.) is an important crop in Iraq. Samples of potato plants infected with late blight were collected from potato fields in Nineveh Governorate, northern Iraq, during the autumn season of 2020. The causal agent being isolated and identified initially according to its morphological features utilizing hyphal and sporangial structures. According to cultural and morphological features, the pathogen was identified from the phenotypic diagnosis as Phytophthora infestans and the pathogen was confirmed by Koch's hypotheses. This was confirmed by the molecular identification test, methodology confirmed it. Molecular identification pathogen was performed via implementing transcribed internal spacer (ITS) conserved ribosomal region of DNA. All sequences as ITS proved homologous to isolates of P. infestans in database of GenBank at similarity % of 99. At Gen-Bank, Iraqi isolate was assigned as Accession No. : MZ675523.1. Up to our best knowledge, this is 1st molecular record of P. infestans on potato in Iraq.

Biofilm Formation and Structure in the Filamentous Fungus Fusarium graminearum, a Plant Pathogen.

ABSTRACTBiofilms are protective structures for pathogens of plants and animals, in which cells are shielded from host defense responses and antimicrobial treatments. Although biofilms are well studied in bacterial pathogens, their development and structure in filamentous fungi, as well as their role in pathogenicity, are poorly understood. We show that the economically important plant pathogen Fusarium graminearum, a filamentous fungus, forms biofilms in vitro, which adhere to polystyrene, a hydrophobic surface. The biofilms have complex hyphal structures surrounded by a polymeric matrix that consists primarily of polysaccharides and extracellular nucleic acids, and lack lipids. Pellicles are formed in liquid cultures, floating biofilm masses that are common in bacterial biofilms, and noted but undescribed in filamentous fungal biofilms. Commonly, F. graminearum grows as hyphal colonies; however, on media which lack electron acceptors, an altered morphology is formed with predominantly short, bulbous hyphae embedded in the matrix. Supplementation of the biofilm-inducing medium with an electron acceptor restores the filamentous hyphal morphology, demonstrating that the formation of bulbous hyphae is due, at least in part, to oxidative stress. Plant hosts infected with pathogens generally respond by producing reactive oxygen species, commonly produced as a defense response. Thus, the formation of biofilms strongly suggests a role in protecting cells from host responses during the course of plant disease.IMPORTANCE Fusarium graminearum is a filamentous fungal pathogen that causes Fusarium head blight (FHB) in cereal crops, leading to devastating crop losses. We have demonstrated the ability of this pathogen to form biofilms. Biofilms are likely to be important in the disease cycle of F. graminearum and other plant pathogens, protecting cells from plant defenses and environmental conditions. Towards this end, we have characterized the formation of biofilms in F. graminearum in vitro, which, together with ongoing characterization of their association with host plants, provides a basis for understanding the functionality of biofilms in the pathogen disease cycle.

Antifungal Potential of Bacillus velezensis CE 100 for the Control of Different Colletotrichum Species through Isolation of Active Dipeptide, Cyclo-(D-phenylalanyl-D-prolyl).

Colletotrichum species are important fungal pathogens causing anthracnose of tropical and subtropical fruit and vegetable crops. Dual culture assay indicated that Bacillus velezensis CE 100 was a strong antagonist against C. acutatum, C. coccodes, C. dematium, and C. gloeosporioides. The volatile organic compounds produced by B. velezensis CE 100 affected mycelial growth of Colletotrichum species tested in our study and caused twisted hyphal structures of all these fungal species. Chloroform crude compounds of B. velezensis CE 100 inhibited four Colletotrichum species in a concentration-dependent manner and induced severe damage in hyphal morphology of these fungal pathogens, including swelling, bulging, and multiple branching. Moreover, the active cyclic dipeptide, cyclo-(D-phenylalanyl-D-prolyl), was isolated from chloroform crude extract and identified by nuclear magnetic resonance (NMR) and mass spectrometry. The inhibitory effect of cyclo-(D-phenylalanyl-D-prolyl) on conidial germination of C. gloeosporioides occurred in a concentration-dependent manner. The conidial germination rate was completely inhibited by a concentration of 3 mg/mL of cyclo-(D-phenylalanyl-D-prolyl). Scanning electron micrographs revealed that the exposure to cyclic dipeptide resulted in seriously deformed hyphae and conidia with shriveled surfaces in dipeptide-treated C. gloeosporioides. Therefore, active dipeptide-producing B. velezensis CE 100 is a promising biocontrol agent for Colletotrichum species causing anthracnose.

Coat protein of partitiviruses isolated from mycorrhizal fungi functions as an RNA silencing suppressor in plants and fungi

Orchid seeds depend on colonization by orchid mycorrhizal (OM) fungi for their germination; therefore, the orchids and OM fungi have long maintained a close relationship (e.g., formation of the hyphal mass structure, peloton) during their evolution. In the present study, we isolated new partitiviruses from OM fungi; partitivirus were separately found in different subcultures from the same fungi. Partitiviruses have been believed to lack an RNA silencing suppressor (RSS), which is generally associated with viral pathogenicity, because most partitiviruses isolated so far are latent in both plants and fungi. However, we found that the coat protein (CP) of our partitiviruses indeed had RSS activity, which differed among the virus isolates from OM fungi; one CP showed RSS activity in both plants and fungi, while another CP showed no activity. The family Partitiviridae include viruses isolated from plants and fungi, and it has been suggested that these viruses may occasionally be transmitted between plant and fungal hosts. Given that there are several reports showing that viruses can adapt to nonhost using strong RSS, we here discussed the idea that partitiviruses may be better able to migrate between the orchid and fungus probably through the pelotons formed in the orchid cells, if host RNA silencing is suppressed by partitivirus RSS.