Fungal Plant Research Articles

Potential application of actinomycetes as natural fungicide

Fungal diseases in green leafy vegetables are commonly under-estimated. However, the application of agrochemical fungicide has raised multiple drawbacks such as the higher amount of chemical residues and intensified microbial community stress. There is an urgent need to establish a bio-control antifungal agent with minimal toxicity threat, which sourced from natural environment. This study aimed to isolate soil-borne fungi from soil underneath infected green leafy vegetables and identify the antifungal activities of actinomycete strains on the isolated fungi strain. Fungi were isolated from 3 soils collected underneath the infected green leafy vegetables. Actinomycete strains were screened for antifungal potential against selected fungi strains using agar plug assay. Forty-one fungal strains were isolated from the soil samples. Actinomycetes strain C.D6.5 exhibited the largest inhibition zone on five selected fungal strains, whereas actinomycetes strain C.KSJ 13.3 produced the broadest spectrum of antifungal activities. It can be concluded that actinomycetes strain have significant antagonistic activity against fungi and pure antifungal component can be extracted as an effective and environmental friendly bio-control agent on plant fungi.

MASS TRANSFER COEFFICIENT OF EXTRACTION TANNIN COMPOUNDS FROM PAPAYA LEAVES WITH 96% ETHANOL SOLVENT

Papaya leaves contain antibacterial compounds such as flavonoids, terpenoids, alkaloids, tannins, and saponins.. Tannins are compounds that are often used as antibacterial, antioxidant, pest control, plant fungi, tanners and as a corrosion inhibitor.In this study, the value of the mass transfer coefficient was determined. This study used two varied operating conditions, namely stirring rotational speed (100, 200, 300 rpm) and extraction time (30, 60, 90, 120, and 150 minutes). The extraction process is carried out using a stirred extractor at a temperature of 65 ° C.The value of the mass transfer coefficient obtained is 0.00004 second-1 (100 rpm), 0.00005 second-1 (200 rpm), and 0.00007 second-1 (300 rpm) for the best concentration obtained at 150 minutes with speed turn the stirrer 300 rpm

Diet of Grauer’s Gorillas (Gorilla beringei graueri) in a Low-Elevation Forest

Although the vast majority of critically endangered Grauer’s gorillas (Gorilla beringei graueri) inhabit low-elevation rain forests, current insights into this ape’s life history and ecology stem predominantly from 2 small populations ranging in highland habitats. Here, we provide an initial and non-exhaustive overview of food items of Grauer’s gorillas in the Nkuba Conservation Area (NCA), a lower-elevation (500–1,500 m) forest located between Kahuzi-Biega National Park and Maiko National Park in the Democratic Republic of the Congo. Community-based conservation efforts at the NCA aim to protect a population of unhabituated Grauer’s gorillas, which we have studied since 2014. Between 2014 and 2020, we simultaneously tracked 1–3 gorilla groups and recorded a total of 10,514 feeding signs on at least 100 plant species, ants, termites, and fungi. Vegetative plant parts (plant stems, leaves, pith, bark, and roots), especially of Marantaceae and Fabaceae, made up close to 90% of recorded feeding signs, with fruit accounting for most of the remainder and a small (<1%) number of feeding signs on invertebrates and fungi. We found that the most frequently recorded food items were consumed year-round, though fruit intake seems to peak in the September-December wet season, possibly reflecting patterns in fruit phenology. The diet of Grauer’s gorillas in the NCA differed from that of Grauer’s gorillas in highland habitat and instead showed similarities with Grauer’s gorillas at the lowland forest of Itebero and with western lowland gorillas (G. gorilla), which live under ecologically comparable conditions.

ANTAGONISTIC POTENTIAL OF SALT TOLERANT BACTERIA AND OPTIMIZATION OF THEIR CULTURE CONDITIONS FOR ENHANCEMENT OF THE ACTIVITY

The antagonistic potential of bacteria is being applied to biocontrol the infectious diseases caused by pathogenic fungi in plants that are one of the major threats to the growth and productivity of crop plants. In the present study, bacterial strains were isolated from soil samples collected from the rhizosphere of Sorghum (Sorghum bicolor) and Wheat (Triticum aestivum). Microscopic analysis revealed that all three bacterial isolates were Gram-positive, rod-shaped and spore-forming. The isolates Bacillus subtilis BP171 and Bacillus amyloliquefaciens BP124 demonstrated salt tolerance up to 12% while Bacillus subtilis BP67 tolerated up to 10% of NaCl. All the three strains were screened against seven test pathogenic fungi like Bipolaris sorokiniana, Fusarium oxysporum, Aspergillus sp., Penicillium sp., Rhizoctonia solani, Aspergillus niger, and Fusarium sp. for their antagonistic activity. BP124 was found to be the most potent in comparison to BP67 and BP171. Bacillus amyloliquefaciens BP124 demonstrated significantly highest (p&lt;.0001) inhibition percentage against Fusarium sp., (61%) and Fusarium oxysporum (60%). The optimization of various parameters like pH, temperature, inoculum size, agitation, carbon sources, and nitrogen sources was carried out to enhance the antagonistic potential of bacterial isolates. The results revealed that the bacterial isolates were able to demonstrate significantly highest (p&lt;.0001) antagonistic potential when inoculum size required for the growth was 1ml, agitation rate at 150 rpm, while the medium of pH at 7.0 and 30o C incubation temperature. Starch as carbon source and peptone as nitrogen source supported significantly highest (p&lt;.0001) antagonistic activity against all the fungal pathogens for all the bacterial isolates. Therefore, the study showed that appropriate and optimum fermentation conditions can be of great importance in enhancing the antagonistic potential of bacterial isolates.

Antifungal and Larvicidal Activities of Phlorotannins from Brown Seaweeds.

Phlorotannins are secondary metabolites produced by brown seaweeds with antiviral, antibacterial, antifungal, and larvicidal activities. Phlorotannins’ structures are formed by dibenzodioxin, ether and phenyl, ether, or phenyl linkages. The polymerization of phlorotannins is used to classify and characterize. The structural diversity of phlorotannins grows as polymerization increases. They have been characterized extensively with respect to chemical properties and functionality. However, review papers of the biological activities of phlorotannins have focused on their antibacterial and antiviral effects, and reviews of their broad antifungal and larvicidal effects are lacking. Accordingly, evidence for the effectiveness of phlorotannins as antifungal and larvicidal agents is discussed in this review. Online databases (ScienceDirect, PubMed, MEDLINE, and Web of Science) were used to identify relevant articles. In total, 11 articles were retrieved after duplicates were removed and exclusion criteria were applied. Phlorotannins from brown seaweeds show antifungal activity against dermal and plant fungi, and larvicidal activity against mosquitos and marine invertebrate larvae. However, further studies of the biological activity of phlorotannins against fungal and parasitic infections in aquaculture fish, livestock, and companion animals are needed for systematic analyses of their effectiveness. The research described in this review emphasizes the potential applications of phlorotannins as pharmaceutical, functional food, pesticide, and antifouling agents.

Nep1-like proteins as a target for plant pathogen control.

The lack of efficient methods to control the major diseases of crops most important to agriculture leads to huge economic losses and seriously threatens global food security. Many of the most important microbial plant pathogens, including bacteria, fungi, and oomycetes, secrete necrosis- and ethylene-inducing peptide 1 (Nep1)-like proteins (NLPs), which critically contribute to the virulence and spread of the disease. NLPs are cytotoxic to eudicot plants, as they disturb the plant plasma membrane by binding to specific plant membrane sphingolipid receptors. Their pivotal role in plant infection and broad taxonomic distribution makes NLPs a promising target for the development of novel phytopharmaceutical compounds. To identify compounds that bind to NLPs from the oomycetes Pythium aphanidermatum and Phytophthora parasitica, a library of 587 small molecules, most of which are commercially unavailable, was screened by surface plasmon resonance. Importantly, compounds that exhibited the highest affinity to NLPs were also found to inhibit NLP-mediated necrosis in tobacco leaves and Phytophthora infestans growth on potato leaves. Saturation transfer difference-nuclear magnetic resonance and molecular modelling of the most promising compound, anthranilic acid derivative, confirmed stable binding to the NLP protein, which resulted in decreased necrotic activity and reduced ion leakage from tobacco leaves. We, therefore, confirmed that NLPs are an appealing target for the development of novel phytopharmaceutical agents and strategies, which aim to directly interfere with the function of these major microbial virulence factors. The compounds identified in this study represent lead structures for further optimization and antimicrobial product development.

Exploring arbuscular mycorrhizal symbiosis in wetland plants with a focus on human impacts

Presence and functional roles of arbuscular mycorrhizal (AM) fungi in wetland environment have gained a global importance in recent past. Wetlands build a low-oxygen atmosphere, forming a completely different ecological environment for AM fungi, known more to occur in terrestrial environment. Nevertheless, as many 101 of AM fungi species, belonging to 19 genera and 9 families have been observed in the rhizosphere of wetland plants. In order to obtain oxygen, AM fungi expand the aeration system of wetland plants, store oxygen through their own vesicles, or change the structure of AM to survive. Human activities negatively affect the wetland environment, thus, reducing the population of AM fungi, while certain AM fungi species still improved the survival and development of wetland plants. AM fungi regulate different physiological activities of wetland plants in response to waterlogging stress, including an enhancement of antioxidant defense system, increased proline accumulation, improved plant growth and root morphology, responses of nutrients and aquaporins, and suppression in ethanol accumulation. The current review briefly summarized different species of wetland plants forming AM structures, the population of AM fungi inhabiting the rhizosphere of wetland plant, AM fungi-colonization of wetland plants, and the effect of AM fungi on physiological functions of wetland plants to neutralize the negative impact of waterlogging in addition to outlook of researchable issues. This review also highlighted human impacts on AM fungi of wetland plants and the impact of AM fungi on wetland environments and wetland plants.

Nanoparticles: Mechanism of biosynthesis using plant extracts, bacteria, fungi, and their applications

The synthesis of eco-friendly nanoparticles (NPs) is a crucial step in nanotechnology. In recent years, to avoid environmental contamination, many efforts have been made many efforts are made to develop green methods for this purpose. For this reason, natural resources including plant extract, fungi and bacteria have been used to synthesize NPs. Plant extract contains active compounds of terpenoids, alkaloids, phenols, tannins, and vitamins that act as capping and reducing agents. The size, shape and applications of NPs are determined by the source from which they are manufactured. While active compounds of bacteria and fungi are intracellular enzymes, sugar molecules, canonical membrane proteins, Nicotinamide Adenine Dinucleotide (NADH) and Nicotinamide Adenine Dinucleotide Phosphate (NADPH) dependent enzymes play a crucial part as reducing agents. The characterization of NPs can be done by Fourier-Transform Infrared Spectroscopy (FTIR), X-ray Crystallography (XRD), Energy-dispersive X-ray Spectroscopy (EDX), Scanning Electron Microscope (SEM), Transmission Electron microscopy (TEM) and UV–Visible spectroscopy. This review paper elaborates major natural resources with detailed mechanisms involved in NPs synthesis and their few applications in biomedical science, life science and electronics.

Soil Bacteria and Fungi Respond Differently to Organisms Covering on Leshan Giant Buddha Body

Soil microbial communities play a key role in the functioning of terrestrial ecosystems, in particular through their interaction with above-ground plants and weathering of rocks. In this study, the chemical properties and microbial diversity of soils covered by different organisms on Leshan Giant Buddha body were analyzed. The results showed that the concentration of soil total organic carbon (TOC), total nitrogen (TN) and total phosphorus (TP) increased significantly with the change of above-ground organisms from lichens to bryophytes and vascular plants. TOC, TN, TP, C:N, and C:P were significantly correlated with the composition of microbial community. Bacterial and fungal diversity responded differently to the change of organisms, and the diversity of bacterial communities changed significantly among different sites. The settlement of Embryogenic plants increased the α-diversity indices including Sobs, Shannon, Ace and Chao indices, which were highest in sites covered with Ferns. The relative abundances of Chloroflexi, Acidobacteria, Nitrospirae and Planctomycetes increased with the order of Bryophyte, Fern, Grass and Shrub, and Cyanobacteria was opposite, with the highest in samples covered with lichens. These results improve understanding of plant–fungi–bacteria interactions during the early stages of soil development, and provide a scientific basis for protection of Leshan Giant Buddha.

Biosurfactants from Trichoderma Filamentous Fungi-A Preliminary Study.

Biosurfactants represent a structurally diverse group of secondary metabolites produced by bacteria, yeasts, and filamentous fungi. Their character is often associated with numerous additional properties. The observation of Trichoderma fungi of various species used as a source of bioinhibitors against pathogenic plants fungi focuses attention to the often quite specific behavior of preparations in contact with, among others, plant leaves, dependent on strain. Thus, an evaluation of the selected strains belonging to the species: T. atroviride, T. citrinoviride, T. reesei and T. harzianum was conducted towards their capability of the extracellular secretion of surfactants, with a simultaneous attempt to pre-determine their chemical nature. Two mineral-organic media were used for this purpose, and the culture fluid was extensively tested using a variety of methods. A decrease in surface tension was observed in culture fluid of each tested strain, especially T. citrinoviride HL and C1. The results strongly depended on medium composition, of which Saunders 1 and MGP 1 were most beneficial. The secreted compounds were further analyzed to pre-determine their chemical nature using IR, GC, and NMR. In the case of most efficient biosurfactant producers, a lipopeptide structure of the surfactants was concluded.

Research of fungal diseases of herbaceous plants exposed from Aksu Ferroalloy Plant

Main problem: Technogenic "metamorphosis" of vegetation near such large industrial facilities as Pavlodar is considered to be the result of various active chemical and mechanical factors provoked by economic activities associated with the influence of emissions from industrial companies. The effect of anthropogenic impacts on vegetation in all regions of Kazakhstan varies and is largely dependent on the economic development of the territory, but in any case, the end result of this impact is the change in the vegetation, causing violations of with structure, reduced vodorazdelnaya flora and productivity of communities. This, in turn, can cause infection of herbaceous plants with pathogenic fungi, which then carry with them: a decrease in the intensity of plant growth, a deterioration in their decorative qualities, a decrease in the survival of the biological species. Purpose: to study the types of fungi-pathogens of phytopathogenic diseases and to determine the degree of modification of the plant component, which is under intense negative technogenic influence from the Aksu Ferroalloy Plant (AFР). Мethods: For the experimental study, species of plants such as: Artemisia dracunculus L; Artemesia vulgaris L; Atriplex fera L; Atriplex patula L; Artemisia annua L were selected for the content of fungi- pathogens of phytopathogenic diseases. Results and their significance: This experimental study was aimed at the presence of fungi-pathogens of herbaceous plants as a result of human impact, occurring near the industrial zone "AFР". The composition of fungi-pathogens of herbaceous plants collected in this industrial zone was considered and studied. According to the results of an experimental laboratory study, phytopathogenic fungi of herbaceous plants belonging to 1 ordo, 1 familia, and 4 species were found.

Facile green synthesis of ZnO nanoparticles using natural-based materials: Properties, mechanism, surface modification and application

An enormous amount of research had been dedicated to exploring the nanotechnology over the past decade. The fast-paced development of nanomaterial production has enhanced the application of zinc oxide (ZnO) in a wide variety fields. ZnO nanoparticles can be obtained mechanically or chemically for commercial use. However, the environmental issues raised by these techniques have been brought to the world’s attention. Nowadays, green synthesis of ZnO nanoparticles is of particular interest in the research field aiming to mitigate environmental problems. In this green approach, natural based materials such as plant extract, microbes, fungus and algae are used as bio-reductants and bio-stabilizers due to their enrichment in bioactive phytochemicals. Numerous studies have proven that the green synthesis is facile and feasible to produce ZnO nanopowder with advanced properties as compared to the chemically synthesized ZnO nanoparticles. In order to make the green synthesized ZnO nanoparticles more applicable in a wide range of uses, surface modification using metal and non-metal ions are applied to alter and improve the properties of ZnO nanoparticles. The findings available currently represent an excellent initial step towards the promising green approach in the synthesis of ZnO nanoparticles and additional work should be undertaken to exploit the application of green synthesis in the commercial platform.

Frenemies: Interactions between Rhizospheric Bacteria and Fungi from Metalliferous Soils

Is it possible to improve the efficiency of bioremediation technologies? The use of mixed cultures of bacteria and fungi inoculated at the rhizosphere level could promote the growth of the associated hyperaccumulating plant species and increase the absorption of metals in polluted soils, broadening new horizons on bioremediation purposes. This work investigates interactions between Ni-tolerant plant growth-promoting bacteria and fungi (BF) isolated from the rhizosphere of a hyperaccumulating plant. The aim is to select microbial consortia with synergistic activity to be used in integrated bioremediation protocols. Pseudomonas fluorescens (Pf), Streptomyces vinaceus (Sv) Penicillium ochrochloron (Po), and Trichoderma harzianum group (Th) were tested in mixes (Po-Sv, Po-Pf, Th-Pf, and Th-Sv). These strains were submitted to tests (agar overlay, agar plug, and distance growth co-growth tests), tailored for this aim, on Czapek yeast agar (CYA) and tryptic soy agar (TSA) media and incubated at 26 ± 1 °C for 10 days. BF growth, shape of colonies, area covered on plate, and inhibition capacity were evaluated. Most BF strains still exhibit their typical characters and the colonies separately persisted without inhibition (as Po-Sv) or with reciprocal confinement (as Th-Sv and Th-Pf). Even if apparently inhibited, the Po-Pf mix really merged, thus obtaining morphological traits representing a synergic co-growth, where both strains reached together the maturation phase and developed a sort of mixed biofilm. Indeed, bacterial colonies surround the mature fungal structures adhering to them without any growth inhibition. First data from in vivo experimentation with Po and Pf inocula in pot with metalliferous soils and hyperaccumulator plants showed their beneficial effect on plant growth. However, there is a lack of information regarding the effective co-growth between bacteria and fungi. Indeed, several studies, which directly apply the co-inoculum, do not consider suitable microorganisms consortia. Synergic rhizosphere BFs open new scenarios for plant growth promotion and soil bioremediation.

Leaf-associated fungal and viral communities of wild plant populations differ between cultivated and natural ecosystems.

Plants are colonized by diverse fungal and viral communities that influence their growth and survival as well as ecosystem functioning. Viruses interact with both plants and the fungi they host. Our understanding of plant-fungi-virus interactions is very limited, especially in wild plants. Combining metagenomic and culturomic approaches, we assessed the richness, diversity, and composition of leaf-associated fungal and viral communities from pools of herbaceous wild plants representative of four sites corresponding to cultivated or natural ecosystems. We identified 161 fungal families and 18 viral families comprising 249 RNA-dependent RNA polymerase-based operational taxonomic units (RdRp OTUs) from leaves. Fungal culturomics captured 12.3% of the fungal diversity recovered with metagenomic approaches and, unexpectedly, retrieved viral OTUs that were almost entirely different from those recovered by leaf metagenomics. Ecosystem management had a significant influence on both leaf mycobiome and virome, with a higher fungal community richness in natural ecosystems and a higher viral family richness in cultivated ecosystems, suggesting that leaf-associated fungal and viral communities are under the influence of different ecological drivers. Both the leaf-associated fungal and viral community compositions showed a strong site-specificity. Further research is needed to confirm these trends and unravel the factors structuring plant-fungi-virus interactions in wild plant populations.

Signaling in the Tomato Immunity against Fusarium oxysporum.

New strategies of control need to be developed with the aim of economic and environmental sustainability in plant and crop protection. Metabolomics is an excellent platform for both understanding the complex plant–pathogen interactions and unraveling new chemical control strategies. GC-MS-based metabolomics, along with a phytohormone analysis of a compatible and incompatible interaction between tomato plants and Fusarium oxysporum f. sp. lycopersici, revealed the specific volatile chemical composition and the plant signals associated with them. The susceptible tomato plants were characterized by the over-emission of methyl- and ethyl-salicylate as well as some fatty acid derivatives, along with an activation of salicylic acid and abscisic acid signaling. In contrast, terpenoids, benzenoids, and 2-ethylhexanoic acid were differentially emitted by plants undergoing an incompatible interaction, together with the activation of the jasmonic acid (JA) pathway. In accordance with this response, a higher expression of several genes participating in the biosynthesis of these volatiles, such as MTS1, TomloxC, TomloxD, and AOS, as well as JAZ7, a JA marker gene, was found to be induced by the fungus in these resistant plants. The characterized metabolome of the immune tomato plants could lead to the development of new resistance inducers against Fusarium wilt treatment.

ACTIVIDAD ENZIMÁTICA Y PROCESO DE INFECCIÓN INICIAL DE LA PLANTA DE GUARANÁ (Paullinia cupana) POR CEPAS PATOGÉNICAS Y ENDOFÍTICAS DE Colletotrichum guaranicola

Anthracnose of the guarana plant (Paullinia cupana) is a disease caused by Colletotrichum guaranicola Albuq. Few studies have analyzed the origin, the form of penetration and the colonization of endophytic fungi in the guarana plant. This study aimed to determine differences in the enzymatic activities of endophytic and pathogenic strains of C. guaranicola during the initial infection process in leaves of clones sensitive to guarana anthracnose. Fourteen pathogenic and nine endophytic strains of C. guaranicola were isolated from guarana leaves with and without anthracnose symptoms, respectively. The enzymatic activities of protease, amylase, polyphenol oxidase, lipase, pectinase, and cellulolytic activities were evaluated for each fungal strain. The experimental design for each enzymatic assay was completely randomized with five replicates. The enzymatic evaluation was based on the measurement of halo produced by the enzyme reaction in each assay. Conidia were evaluated during germination and appressoria formation. Results did not detect enzymatic difference between pathogenic and endophytic strains. Data prior to germination showed differences between endophytic and pathogenic strains. Colonization of plant tissues by pathogenic strain was evidenced after the appearance of disease symptoms 48 hours after inoculation (hai), while for endophytic strains the presence of appressoria was observed on the surface of the epidermis 48 hai, and colonization of cells was not observed.

Behind the scene: Critical role of reactive oxygen species and reactive nitrogen species in salt stress tolerance

AbstractSalinity is one of the most important abiotic factors which affects plant growth and development and reduces crop productivity. Plants have stress tolerance ability to respond to a particular type of stress. For salt stress alleviation, plants retain specific mechanisms, such as activation of signalling cascades, ion channels, receptors, hormonal stimulation, ion exchange, osmolytes and antioxidant enzymes which are involved either directly or indirectly in plant protection. In plants, reactive oxygen species (ROS) and reactive nitrogen species (RNS) are produced in different cell compartments and involved in the “oxidative signalling” mechanism. Based on the recent studies in signalling and mechanisms for salt tolerance in plant, we explored the role of the salt overly sensitive system (SOS) related to antiporters of plasma and mitogen‐activated protein kinase (MAPK) cascades. Considering the importance of ROS and RNS, the present review has focused on different aspects and mechanisms that play key role in plants cell signalling network in response to salinity stress. In addition, this review highlights the differential expression of ROS, RNS and various antioxidative enzymes in C3, C4 and CAM plants. Moreover, the strategies for alleviation of salt stress such as magnetopriming, nanopriming, biopriming and arbuscular mycorrhizal fungi (AMF) in plants to achieve improved salt tolerance in crops under field conditions and their effects through ROS and RNS is also discussed. We conclude the review with a discussion of unseen issues and suggestions for future researches.

Isolation and characterization of streptomycetes and pseudomonad strains with antagonistic activity against the plant parasitic nematode Pratylenchus penetrans and fungi associated with replant disease

Pratylenchus penetrans is one of the most important plant-parasitic nematodes causing losses in economically significant crops such as apple, cherry, corn, grapes, oat, onion, peach, potato, soybean, strawberry, and wheat. The objective of this study was to isolate and characterize plant growth promoting rhizobacterial (PGPR) strains from sweet cherry rhizospheres with biocontrol potential against P. penetrans, and to evaluate the antagonistic activity of the selected strains on a model plant (onion), in a growth chamber experiment. Five strains: three actinomycetes (Streptomyces fulvissimus A12, S. venezuelae A30, and S. annulatus A34) and two pseudomonads (Pseudomonas sp. P3 and P. donghuensis P17) with nematicidal activity were isolated. The selected PGPR strains decreased P. penetrans populations on onion roots and enhanced onion root length and dry weight. Among possible mechanisms of action, the strains displayed the capacity to produce nematicidal lytic enzymes such as chitinases and proteases, and form biofilms, which is an advantage in colonizing the plant rhizosphere. Some of them also showed antifungal activity against the phytopathogenic fungi Fusarium oxysporum C1-1, Ilyonectria macrodidyma C1-1, and Ilyonectria spp. C2-1 isolated from roots of cherry trees affected by replant disease. The multifunctionality of the strains, and the fact that they were isolated from the cherry rhizosphere, makes them good candidates to be used as biocontrol agents in sweet cherry orchards affected by P. penetrans.

The Abundance and Diversity of Fungi in a Hypersaline Microbial Mat from Guerrero Negro, Baja California, México.

The abundance and diversity of fungi were evaluated in a hypersaline microbial mat from Guerrero Negro, México, using a combination of quantitative polymerase chain reaction (qPCR) amplification of domain-specific primers, and metagenomic sequencing. Seven different layers were analyzed in the mat (Layers 1–7) at single millimeter resolution (from the surface to 7 mm in depth). The number of copies of the 18S rRNA gene of fungi ranged between 106 and 107 copies per g mat, being two logarithmic units lower than of the 16S rRNA gene of bacteria. The abundance of 18S rRNA genes of fungi varied significantly among the layers with layers 2–5 mm from surface contained the highest numbers of copies. Fifty-six fungal taxa were identified by metagenomic sequencing, classified into three different phyla: Ascomycota, Basidiomycota and Microsporidia. The prevalent genera of fungi were Thermothelomyces, Pyricularia, Fusarium, Colletotrichum, Aspergillus, Botrytis, Candida and Neurospora. Genera of fungi identified in the mat were closely related to genera known to have saprotrophic and parasitic lifestyles, as well as genera related to human and plant pathogens and fungi able to perform denitrification. This research suggests that fungi in the mat may participate in nutrient recycling, modification of community composition through parasitic activities, and denitrification.

CoGRIM19 is required for invasive hyphal growth of Colletotrichum orbiculare inside epidermal cells of cucumber cotyledons

Colletotrichum orbiculare, an anthracnose disease fungus of cucurbit plants, extends penetration hyphae inside the epidermal cells of host plants. Unlike vegetative hyphae formed on a nutrient rich medium, this pathogen initially develops biotrophic penetration hyphae, which acquire nutrient resources from living host cells and secret effector proteins to suppress host defense responses. Subsequently, the nature of penetration hyphae changes from biotrophy to necrotrophy in response to the interaction with a host plant. Hence, controlling the extension of penetration hyphae is crucial for C. orbiculare infection. Here, we identified CoGRIM19 encoding Nadh-ubiquinone oxidoreductase subunit as a pathogenicity gene. Pathogenicity assays showed that the cogrim19 mutant caused no visible symptoms on cucumber cotyledons. Microscopic observations revealed that the cogrim19 mutant developed an appressorium and penetration hyphae under artificial conditions such as on coverslips or cellulose membranes, but the penetration hyphae of the mutant were retarded in the cucumber cotyledons. Microscopic observations of biotrophy-specific expression fluorescent signals revealed that the biotrophic stage was maintained in the retarded penetration hyphae of the cogrim19 mutant as the penetration of the wild type. In addition to cytological observations, pathogenicity assays using wounded leaves showed that the cogrim19 mutant had an attenuated pathogenesis. Taking our results together, CoGRIM19 is required for invasive hyphal growth inside the epidermal cells of cucumber cotyledons in C. orbiculare.