Individual Fungal Species Research Articles

Micromorphology and thematic micro-mapping reveal differences in the soil structuring traits of three arbuscular mycorrhizal fungi

Arbuscular mycorrhizal (AM) fungi contribute to soil structure, but little is known about the effect of individual fungal species on soil aggregation. In this study, the influence of 3 AM fungi species on soil aggregation in a Vitric Andosol was determined using physical, micromorphological, and imaging analyses. We used a pipe of polyvinyl chloride (PVC) with a six-way connector, which was filled with soil plus AM fungal inoculum (Funneliformis mosseae, Rhizophagus intraradices, Gigaspora gigantea or non-inoculated -control-). Then lateral pipe connectors (experimental units) were covered with mesh systems (0.5, 0.25, and 0.034 mm), and PVC tubes filled with sterile soil were connected laterally using a clamp. The greenhouse experiment consisted of four treatments each with 32 experimental units. Four experimental units of each treatment were separated and collected at different times during the year: three were used to determine water-stable aggregates (disturbed soils), and one was preserved (undisturbed soil) to elaborate soil thin sections. Thematic micro-maps were constructed with image mosaics from a whole soil thin section, and micromorphological analyses were conducted using spatial operators. Our results showed that AM fungi affect soil aggregation forming micro-aggregates and macro-aggregates of different sizes. The most significant effects were observed with F. mosseae > R. intraradices >Gi. gigantea > control. Aggregation hierarchy was observed in micromorphological analysis, where F. mosseae and R. intraradices start binding organo-mineral particles and microaggregates to form macroaggregates, modifying soil structure from intergrain (apedal= without peds) to crumb aggregates (pedal= with peds). Gigaspora gigantea only promoted macroaggregation, by associating with pumice particles. The two AM fungi from Glomeraceae possess similar morphology compared to that isolate belonging to Gigasporaceae, which explain in part, their differential contribution traits on soil aggregation, as highlighted by using together physical and micromorphological analyses of soil thin sections based on high-resolution image mosaics.

Fungal diversity in homes and asthma morbidity among school-age children in New York City

BackgroundAsthma development has been inversely associated with exposure to fungal diversity. However, the influence of fungi on measures of asthma morbidity is not well understood. ObjectivesThis study aimed to test the hypothesis that fungal diversity is inversely associated with neighborhood asthma prevalence and identify specific fungal species associated with asthma morbidity. MethodsChildren aged 7–8 years (n = 347) living in higher (11–18%) and lower (3–9%) asthma prevalence neighborhoods were recruited within an asthma case-control study. Fungal communities were analyzed from floor dust using high-throughput DNA sequencing. A subset of asthmatic children (n = 140) was followed to age 10–11 to determine asthma persistence. ResultsNeighborhood asthma prevalence was inversely associated with fungal species richness (P = 0.010) and Shannon diversity (P = 0.059). Associations between neighborhood asthma prevalence and diversity indices were driven by differences in building type and presence of bedroom carpet. Among children with asthma at age 7–8 years, Shannon fungal diversity was inversely associated with frequent asthma symptoms at that age (OR 0.57, P = 0.025) and with asthma persistence to age 10–11 (OR 0.48, P = 0.043). Analyses of individual fungal species did not show significant associations with asthma outcomes when adjusted for false discovery rates. DiscussionLower fungal diversity was associated with asthma symptoms in this urban setting. Individual fungal species associated with asthma morbidity were not detected. Further research is warranted into building type, carpeting, and other environmental characteristics which influence fungal exposures in homes.

Endophytic Fungi Associated with Aquilaria sinensis (Agarwood) from China Show Antagonism against Bacterial and Fungal Pathogens.

Agarwood is the most expensive non-construction wood product in the world. As a therapeutic agent, agarwood can cure some diseases, but few studies have been carried out on the antagonistic abilities of endophytic fungi associated with agarwood. Agarwood is mainly found in the genus Aquiaria. The objectives of this study are to understand the antimicrobial activities and their potential as biocontrol agents of the endophytic fungi of Aquilaria sinensis. First, fresh samples of A. sinensis were collected from Yunnan and Guangdong Provinces in 2020-2021, and the endophytic fungi were isolated and identified to genus level based on the phylogenetic analyses of the Internal Transcribed Spacer (ITS) region. In this bioassay, 47 endophytic strains were selected to check their bioactivities against three bacterial pathogens viz. Erwinia amylovora, Pseudomonas syringae, and Salmonella enterica; and three fungal pathogens viz. Alternaria alternata, Botrytis cinerea, and Penicillium digitatum. The antibiosis test was carried out by the dual culture assay (10 days), and among the 47 strains selected, 40 strains belong to 18 genera viz. Alternaria, Annulohypoxylon, Aspergillus, Botryosphaeria, Colletotrichum, Corynespora, Curvularia, Daldinia, Diaporthe, Fusarium, Lasiodiplodia, Neofusicoccum, Neopestalotiopsis, Nigrospora, Paracamarosporium, Pseudopithomyces, Trichoderma, Trichosporon and one strain belongs to Xylariaceae had antimicrobial activities. In particular, Lasiodiplodia sp. (YNA-D3) showed the inhibition of all the bacterial and fungal pathogens with a significant inhibition rate. In addition, the strains viz; Curvularia sp. (GDA-3A9), Diaporthe sp. (GDA-2A1), Lasiodiplodia sp. (YNA-D3), Neofusicoccum sp. (YNA-1C3), Nigrospora sp. (GDA-4C1), and Trichoderma sp. (YNA-1C1) showed significant antimicrobial activities and are considered worthy of further studies to identify individual fungal species and their bioactive compounds. This study enriches the diversity of endophytic fungi associated with agarwood, and their potential antagonistic effects against bacterial and fungal pathogens.

The nature of the fungal cargo induces significantly different temporal programmes of macrophage phagocytosis

Phagocytosis is an essential component of our immune defence against fungal pathogens. Differences in the dynamics of phagocyte migration, recognition, uptake and phagolysosome maturation are dependent on the characteristics of the fungal cargo, and in particular to differences in cell wall composition and cellular morphology. However, studies that have focused on phagocyte interactions with individual fungal species have not enabled comparisons in the kinetics of these interactions to be made between these different species. We therefore used live cell video microscopy to examine the temporal dynamics of phagocytosis for a range of fungal cargoes by thioglycollate–elicited peritoneal macrophages from C57BL/6 mice. Uniform populations of macrophages were challenged at the same time with yeast cells of Candida albicans, Candida glabrata, Saccharomyces cerevisiae and Cryptococcus neoformans (wild–type and an acapsular mutant, cap59Δ), and spores of Aspergillus fumigatus and Mucor circinelloides to enable standardized comparative interactions to be quantified from different stages of phagocytosis. Differences in the rate of uptake of fungal cells varied by up to 26–fold, whilst differences in time to induce phagosome acidification varied by as much as 29–fold. Heat-killing or opsonizing the fungal targets markedly affected the kinetics of the interaction in a species–specific manner. Fungal and macrophage killing assays further revealed cargo–specific differences in phagocytosis and diversity in fungal evasion mechanisms. Therefore, simultaneous assessment of the interaction of macrophages with different fungal pathogens highlighted major differences in the kinetics and growth responses during fungus–phagocyte interactions that are likely to impact on pathogenesis and virulence.

Cell Wall Integrity and Its Industrial Applications in Filamentous Fungi.

Signal transduction pathways regulating cell wall integrity (CWI) in filamentous fungi have been studied taking into account findings in budding yeast, and much knowledge has been accumulated in recent years. Given that the cell wall is essential for viability in fungi, its architecture has been analyzed in relation to virulence, especially in filamentous fungal pathogens of plants and humans. Although research on CWI signaling in individual fungal species has progressed, an integrated understanding of CWI signaling in diverse fungi has not yet been achieved. For example, the variety of sensor proteins and their functional differences among different fungal species have been described, but the understanding of their general and species-specific biological functions is limited. Our long-term research interest is CWI signaling in filamentous fungi. Here, we outline CWI signaling in these fungi, from sensor proteins required for the recognition of environmental changes to the regulation of cell wall polysaccharide synthesis genes. We discuss the similarities and differences between the functions of CWI signaling factors in filamentous fungi and in budding yeast. We also describe the latest findings on industrial applications, including those derived from studies on CWI signaling: the development of antifungal agents and the development of highly productive strains of filamentous fungi with modified cell surface characteristics by controlling cell wall biogenesis.

First Report of Entomopathogenic Fungi Occurrence in Forest Soils in Croatia

Entomopathogenic fungi (EPF) in Croatian forests are known only from observations of insect cadavers that show obvious signs of disease. To date, their presence in soils has not been investigated. The aim of this study was to investigate their occurrence, diversity, and distribution, and to assess their density in tested soils. Soil samples were collected during 2018, 2019, and 2020 at different localities throughout the country, and analyzed by using a method of isolation of fungi on selective culture media. To assess the density of EPF in tested soils, colonies of individual fungal species were counted and recorded; the results were expressed as the number of colony-forming units (CFU) per gram of dry soil. After morphological and molecular analysis, five entomopathogenic fungal genera were identified: Beauveria spp., Metarhizium spp., Purpureocillium spp., Lecanicillium spp., and Paecilomyces spp. Results also showed that the range of a total EPF colony density in the soil varies from 4 × 103 to 27.4 × 103 CFU g−1. The most common were EPF of the genus Beauveria, which were recorded at four of five locations, and at 16 of 25 sampling points, but the highest average number (density) of colonies belonged to the genus Metarhizium. Since this type of research was never conducted in Croatia previously, this is the first evidence that insect pathogenic fungi are present in soils of different natural forest habitats. Such research can be useful in selecting and utilizing entomopathogens that are suitable for biological pest control in certain target areas.

Fungal-fungal and fungal-bacterial interactions in aquatic decomposer communities: bacteria promote fungal diversity.

Fungi produce a variety of extracellular enzymes, making recalcitrant substrates bioavailable. Thus, fungi are central for the decomposition of dead organic matter such as leaf litter. Despite their ecological importance, our understanding of relationships between fungal species diversity and ecosystem functioning is limited, especially with regard to aquatic habitats. Moreover, fungal interactions with other groups of microorganisms such as bacteria are rarely investigated. This lack of information may be attributed to methodological limitations in tracking the biomass of individual fungal species in communities, impeding a detailed assessment of deviations from the overall performance expected from the sum of individual species' performances, so-called net diversity effects (NDEs). We used fungal species-specific biomolecular tools to target fungal-fungal and fungal-bacterial interactions on submerged leaves using four cosmopolitan aquatic fungal species and a stream microbial community dominated by bacteria. In microcosms, we experimentally manipulated fungal diversity and bacterial absence/presence and assessed functional performances and fungal community composition after 14d of incubation. Fungal community data were used to evaluate NDEs on leaf colonization. The individual fungal species were functionally distinct and fungal cultures were on average more efficient than the bacterial culture. In absence of bacteria, NDEs correlated with growth rate (negatively) and genetic divergence (positively), but were predominantly negative, suggesting that higher fungal diversity led to a lower colonization success (niche overlap). In both absence and presence of bacteria, the overall functional performances of the communities were largely defined by their composition (i.e., no interactions at the functional level). In the presence of bacteria, NDEs correlated with genetic divergence (positively) and were largely positive, suggesting higher fungal diversity stimulated colonization (niche complementarity). This stimulation may be driven by a bacteria-induced inhibition of fungal growth, alleviating competition among fungi. Resulting feedback loops eventually promote fungal coexistence and synergistic interactions. Nonetheless, overall functional performances are reduced compared to bacteria-free cultures. These findings highlight the necessity to conduct future studies, investigating biodiversity-ecosystem functioning relationships using artificial systems, without exclusion of key organisms naturally co-occurring in the compartment of interest. Otherwise, study outcomes might not reflect true ecological relationships and ultimately misguide conservation strategies.

Assessment of Airborne Fungi in Childrens Hospital Located in Kolkata India

Fungal spores contribute significant concentration in the bioaerosol of various environmental conditions which may have potential health threats. Our study was aimed at determining the presence of disseminating airborne fungi in a pediatric government hospital in Kolkata. The study was started from the post-monsoon to the middle winter (August to December 2008) in the indoor and outdoor environment of the hospital with temperature and humidity ranges of 11.2 °C-35.2 °C and 70 per cent-90 per cent, respectively. Air sampling was performed at 14 days intervals during the daytime following the gravitation settling method, and the fungal colonies were identified based on micro and macro morphological characteristics. The percentage contribution of individual fungal species from the outdoor section and indoor units (Newborn Baby Ward, Respiratory Care Unit, Step Down Ward, Thalassemia Care Unit) of the hospital environment was calculated. We observed profound aeromycofloral diversity where the outdoor environment was mostly colonised by sterile hyphae (16.43 %) along with the allergenic Aspergillus fumigatus (13.6 %) and Penicillium sp. (12.32 %). Conversely, an abundance of Cladosporium herbarum (24.7 %) and Penicillium sp. (17.85 %) followed by Aspergillus sp. (12.9 %) and sterile hyphae (14.51 %) were found in different indoor units. Our results showed the diversity of airborne mycoflora which promotes the trend to health difficulties and thus the hospital environment monitoring along with proper control measures is essential.

The abundance of arbuscular mycorrhiza in soils is linked to the total length of roots colonized at ecosystem level.

Arbuscular mycorrhizal fungi (AMF) strongly affect ecosystem functioning. To understand and quantify the mechanisms of this control, knowledge about the relationship between the actual abundance and community composition of AMF in the soil and in plant roots is needed. We collected soil and root samples in a natural dune grassland to test whether, across a plant community, the abundance of AMF in host roots (measured as the total length of roots colonized) is related to soil AMF abundance (using the neutral lipid fatty acids (NLFA) 16:1ω5 as proxy). Next-generation sequencing was used to explore the role of community composition in abundance patterns. We found a strong positive relationship between the total length of roots colonized by AMF and the amount of NLFA 16:1ω5 in the soil. We provide the first field-based evidence of proportional biomass allocation between intra-and extraradical AMF mycelium, at ecosystem level. We suggest that this phenomenon is made possible by compensatory colonization strategies of individual fungal species. Finally, our findings open the possibility of using AMF total root colonization as a proxy for soil AMF abundances, aiding further exploration of the AMF impacts on ecosystems functioning.

Trichoderma Species Differ in Their Volatile Profiles and in Antagonism Toward Ectomycorrhiza Laccaria bicolor.

Fungi of the genus Trichoderma are economically important due to their plant growth- and performance-promoting effects, such as improved nutrient supply, mycoparasitism of plant-pathogens and priming of plant defense. Due to their mycotrophic lifestyle, however, they might also be antagonistic to other plant-beneficial fungi, such as mycorrhiza-forming species. Trichoderma spp. release a high diversity of volatile organic compounds (VOCs), which likely play a decisive role in the inter-species communication. It has been shown that Trichoderma VOCs can inhibit growth of some plant pathogens, but their inhibition potentials during early interactions with mutualistic fungi remain unknown. Laccaria bicolor is a common ectomycorrhizal fungus which in symbiotic relationship is well known to facilitate plant performance. Here, we investigated the VOC profiles of three strains of Trichoderma species, Trichoderma harzianum, Trichoderma Hamatum, and Trichoderma velutinum, as well as L. bicolor by stir bar sorptive extraction and gas chromatography – mass spectrometry (SBSE-GC-MS). We further examined the fungal performance and the VOC emission profiles during confrontation of the Trichoderma species with L. bicolor in different co-cultivation scenarios. The VOC profiles of the three Trichoderma species were highly species-dependent. T. harzianum was the strongest VOC emitter with the most diverse compound pattern, followed by T. hamatum and T. velutinum. Co-cultivation of Trichoderma spp. and L. bicolor altered the VOC emission patterns dramatically in some scenarios. The co-cultivations also revealed contact degree-dependent inhibition of one of the fungal partners. Trichoderma growth was at least partially inhibited when sharing the same headspace with L. bicolor. In direct contact between both mycelia, however, L. bicolor growth was impaired, indicating that Trichoderma and L. bicolor apply different effectors when defending their territory. Multivariate analysis demonstrated that all examined individual fungal species in axenic cultures, as well as their co-cultivations were characterized by a distinct VOC emission pattern. The results underline the importance of VOCs in fungal interactions and reveal unexpected adjustability of the VOC emissions according to the specific biotic environments.

Temperature niche position and breadth of ectomycorrhizal fungi: Reduced diversity under warming predicted by a nested community structure.

Species with narrow niche breadths are assumed to be more susceptible to environmental changes than those with wide niche breadths. Although information on niche properties is necessary for predicting biological responses to environmental changes, such information is largely missing for soil microbes. In this study, we present the temperature niche positions and breadths of a functionally important group of eukaryotic soil microbes, ectomycorrhizal (EM) fungi. We compiled high-quality EM fungal sequence data from 26 forested sites in Japan (with mean annual temperatures ranging from 1.6 to 23.6°C) to create temperature niche profiles for each individual fungal species. Nested theory and a newly developed weighted-randomization null model were applied to 75 fungal operational taxonomic units (OTUs) with high occurrence records to examine potential preferences for certain temperature positions and breadths. Our analyses revealed that (a) many EM fungal OTUs were restricted to habitats with low mean annual temperatures, (b) fungal OTUs observed at colder sites exhibited narrower temperature breadths than expected by chance, (c) the composition of EM fungal OTUs exhibited a nested pattern along the temperature gradient, and (d) EM fungal richness was highest at colder sites, where the greatest degree of overlap in OTU occurrence was observed. These findings imply that future warming may limit the distribution of many EM fungal species that are currently adapted to only cold climates. This could eventually reduce EM fungal biodiversity, which is linked to forest function through symbiotic associations with trees. This study demonstrates the distribution and environmental ranges of various EM fungal species and can contribute to develop species distribution models with the aim of conserving microbes in the face of climate change.

Fungal mitochondrial genomes and genetic polymorphisms.

Mitochondria are the powerhouses of eukaryotic cells, responsible for ATP generation and playing a role in a diversity of cellular and organismal functions. Different from the majority of other intracellular membrane structures, mitochondria contain their own genetic materials that are capable of independent replication and inheritance. In this mini-review, we provide brief summaries of fungal mitochondrial genome structure, size, gene content, inheritance, and genetic variation. We pay special attention to the relative genetic polymorphisms of the mitochondrial vs nuclear genomes at the population level within individual fungal species. Among the 20 species/groups of species reviewed here, there is a range of variation among genes and species in the relative nuclear and mitochondrial genetic polymorphisms. Interestingly, most (15/20) showed a greater genetic diversity for nuclear genes and genomes than for mitochondrial genes and genomes, with the remaining five showing similar or slower nuclear genome genetic variations. This fungal pattern is different from the dominant pattern in animals, but more similar to that in plants. At present, the mechanisms for the variations among fungal species and the overall low level of mitochondrial sequence polymorphisms are not known. The increasing availability of population genomic data should help us reveal the potential genetic and ecological factors responsible for the observed variations.

Mycobiomes of sympatric Amorphophallus albispathus (Araceae) and Camellia sinensis (Theaceae) – a case study reveals clear tissue preferences and differences in diversity and composition

Multiple biotic and abiotic parameters influence the dynamics of individual fungal species and entire communities. Major drivers for tropical plant endophytes are undoubtedly seasonality, local habitat conditions and biogeography. However, host specialization and tissue preferences also contribute to the structuring of endophytic mycobiomes. To elucidate such specializations and preferences, we sampled two commercially important, unrelated plant species, Amorphophallus albispathus and Camellia sinensis (tea plant) simultaneously at close proximity. The mycobiomes of different tissue types were assessed with high-throughput amplicon sequencing of the internal transcribed spacer DNA region. Both plants hosted different fungal communities and varied in α- and β-diversity, despite their neighboring occurrence. However, the fungal assemblages of Amorphophallus leaflets shared taxa with the mycobiomes of tea leaves, thereby suggesting common driving forces for leaf-inhabiting fungi irrespective of host plant identity. The mycobiome composition and diversity of tea leaves was clearly driven by leaf age. We suggest that the very youngest tea leaves are colonized by stochastic processes, while mycobiomes of old leaves are rather similar as the result of progressive succession. The biodiversity of fungi associated with A. albispathus was characterized by a large number of unclassified OTUs (at genus and species level) and by tissue-specific composition.This study is the first cultivation-independent high-throughput assessment of fungal biodiversity of an Amorphophallus species, and additionally expands the knowledge base on fungi associated with tea plants.

Evaluation of individual fungal species and their co-culture for degrading a binary mixture of dyes under solid-state fermentation

Description of the subject. In recent years, biological methodologies, such as solid-state fermentation, have acquired a great relevance for bioremediation of complex molecules because of their efficiency and low environmental impact. Specifically, the use of white-rot fungi in different biotechnological processes has emerged as a promising strategy given their broad enzymatic potential. Objectives. Evaluation of three individual fungal species, as well as various fungal consortia of these species, for the degradation of a mixture of dyes, brilliant blue – allura red, through solid-state fermentation. Method. The species Pleurotus pulmonarius, Pleurotus ostreatus and Trametes versicolor were assessed, both individually, and in their binary consortia. The interaction between the mycelia of the different white-rot fungi was taken into account as a criterion for using their consortia to degrade the mixture of pollutants under solid conditions. The dyes were adsorbed onto the agro-industrial by-products flower stems and corncob. The fermentative process was carried out over 20 days, after which the degradation percentage was quantified by UV-Vis spectroscopy. Results. The highest degradation percentage was obtained after fermentation by T. versicolor alone. This species reached an average degradation of 79.57% of the binary mixture of dyes, brilliant blue – allura red. Meanwhile, the best consortium, composed of P. ostreatus and T. versicolor, achieved a degradation of 63.24%. Conclusions. These results suggest that the use of fungal consortia, in solid media, does not always lead to a synergy between species for improved dye degradation by the integrated strategy that includes the processes of adsorption and solid-state fermentation. Instead, competition for space and nutrients associated with growth on a solid substrate could decrease the degradation efficiency.

Microbial Tools in Agriculture Require an Ecological Context: Stress‐Dependent Non‐Additive Symbiont Interactions

Core IdeasLeaf fungal symbionts represent a potential new tool in agriculture.Effective fungal application requires an understanding of their interactions.Fungal interactions resulted in non‐additive plant growth and wilt responses.Fungal metabolites indicated qualitative additive, synergistic, or antagonistic plant responses.Fungal trait dissimilarity predicted the size of plant response deviations.Fungal symbionts are increasingly targeted as tools for crop management, but their use in the field requires an understanding of how fungi interact in a community context. Fungal interactions may result in additive effects on the host plant, which could be predicted simply based on individual fungal behavior. Alternatively, interactions among fungi may result in non‐additive synergistic or antagonistic effects on plant performance that are more challenging to predict. Here, we hypothesized that the effects of fungal interactions on the plant host could be predicted from their niche overlap. To test this idea, we used foliar fungal endophytes with a range of niche overlap based on trait dissimilarities to examine the effects of six fungal species pairs compared to the corresponding individual fungal species on switchgrass (Panicum virgatumL.) in water‐stressed and well‐watered conditions. Mixtures of endophytes had either no effect or predictable, additive effects on plant tiller number, but effects on plant growth rate and wilting were largely non‐additive. Moisture level, fungal stress, and metabolic trait dissimilarity predicted 51 to 92% of the deviation of fungal effects from additive, with less similar fungi likely to have more synergistic effects on the plant host. Furthermore, we identified indicator metabolites for fungal interaction outcomes. However, the effects of endophyte interactions on the plant host were environment dependent making single community applications more challenging. Overall, future development of microbial tools for use in agriculture must consider their interactions to optimize application.

Molecular Identification of Fungal Contamination in Date Palm Tissue Cultures.

Fungal contamination of in vitro cultures of date palm (Phoenix dactylifera L.) is the major constraint to their initiation and maintenance. Different molecular approaches have been applied successfully to analyze both inter- and intraspecific variation among fungal species as well as determine their identity. This chapter describes step-by-step procedures of molecular identification of fungal contaminants by internal transcribed spacer (ITS) products of the most common fungal contaminants of date palm tissue culture. To begin with, samples of genera Alternaria, Aspergillus, Cladosporium, Epicoccum, and Penicillium were collected to isolate each fungal genus and extraction of genomic DNA. Polymerase chain reactions were accomplished by ITS primers (ITS1 and ITS4) for each fungal contaminant as well as for sequencing. Subsequently, they are analyzed by Basic Local Alignment Search Tool (BLAST) search of ITS sequence to reveal the identity of each individual fungal contaminant species. The molecular identification herein is a rapid and reliable procedure to identify date palm fungal contaminants which is very important in their control and treatment.

Fungi associated with dieback of Abies alba seedlings in naturally regenerating forest ecosystems

Abstract Dieback of young Abies alba seedlings was identified as an important limitation for natural regeneration of this species in the mountain regions of Central Europe. Approximately 2–4 weeks after emergence, during cool and wet weather, necrotic spots developed on seedling cotyledons. Later they expanded and merged to finally cover all above-ground tissues. Symptomatic seedlings of A. alba were sampled at 16 stands, and fungi were isolated from the cotyledons, stems, and roots. Morphological and molecular methods based on ITS rDNA sequencing were then used for isolate identification. In total, 105 distinct taxa were identified, with Ascomycota dominating, representing 97.4% of the isolates. The most frequently isolated taxa were Allantophomopsis lycopodina, Gyoerffyella rotula, Leptosphaeria sp., Phialocephala fortinii, Pseudaegerita sp., Scirrhia aspidiorum, Sydowia polyspora, Peyronellaea sp., Phomopsis sp., and Varicosporium elodeae. The frequency of colonization by individual fungal species differed among the three plant organs and among forest types. In symptomatic cotyledons, the dominant species were G. rotula, S. polyspora, and Pseudaegerita sp. whose pathogenicity, together with that of Gyoerffyella sp., V. elodeae, and Hormonema carpetanum, was tested on young A. alba seedlings. Only G. rotula and Gyoerffyella sp. caused serious dieback of above-ground seedling tissues and necrotic symptoms on cotyledons. This study is one of the few comprehensive reports showing that aquatic hyphomycetes commonly occur in forests beyond their preferred habitat.

Evolution and Functional Insights of Different Ancestral Orthologous Clades of Chitin Synthase Genes in the Fungal Tree of Life.

Chitin synthases (CHSs) are key enzymes in the biosynthesis of chitin, an important structural component of fungal cell walls that can trigger innate immune responses in host plants and animals. Members of CHS gene family perform various functions in fungal cellular processes. Previous studies focused primarily on classifying diverse CHSs into different classes, regardless of their functional diversification, or on characterizing their functions in individual fungal species. A complete and systematic comparative analysis of CHS genes based on their orthologous relationships will be valuable for elucidating the evolution and functions of different CHS genes in fungi. Here, we identified and compared members of the CHS gene family across the fungal tree of life, including 18 divergent fungal lineages. Phylogenetic analysis revealed that the fungal CHS gene family is comprised of at least 10 ancestral orthologous clades, which have undergone multiple independent duplications and losses in different fungal lineages during evolution. Interestingly, one of these CHS clades (class III) was expanded in plant or animal pathogenic fungi belonging to different fungal lineages. Two clades (classes VIb and VIc) identified for the first time in this study occurred mainly in plant pathogenic fungi from Sordariomycetes and Dothideomycetes. Moreover, members of classes III and VIb were specifically up-regulated during plant infection, suggesting important roles in pathogenesis. In addition, CHS-associated networks conserved among plant pathogenic fungi are involved in various biological processes, including sexual reproduction and plant infection. We also identified specificity-determining sites, many of which are located at or adjacent to important structural and functional sites that are potentially responsible for functional divergence of different CHS classes. Overall, our results provide new insights into the evolution and function of members of CHS gene family in the fungal kingdom. Specificity-determining sites identified here may be attractive targets for further structural and experimental studies.

In-Vitro Efficacy of Certain Essential Oils and Plant Extracts against Three Major Pathogens of Jatropha curcas L.

Antifungal activity of plant extracts and essential oils of six different plant species was tested against three pathogenic fungi, viz., Alternaria alternata, Colletotrichum gloeosporioides and Fusarium moniliforme isolated from Jatropha curcas L. using Poison Food Technique. All the samples tested were found effective in-vitro. More than 60% inhibition of growth of individual fungal species was observed at 100 ppm. Maximum inhibition was observed at concentration of 1000 ppm. However, among the essential oils tested Cinnamomum impressinervium exhibited the strongest activity (80%) in the case of Colletotrichum gloeosporioides and Alternaria alternate and 78.6% in the case of Fusarium oxysporum at concentration of 1000 ppm followed by Cinnamomum tamala, Cymbopogon jwarancusa and Cymbopogon citratus respectively. Among the plant extracts tested, Catharanthus roseus exhibited stronger activity in comparison to Tithonia diversifolia. Inhibition percentage of all the essential oils and plant extracts increased with the increase in concentration.

Comparisons of ectomycorrhizal colonization of transgenic american chestnut with those of the wild type, a conventionally bred hybrid, and related fagaceae species.

American chestnut (Castanea dentata [Marsh.] Borkh.) dominated the eastern forests of North America, serving as a keystone species both ecologically and economically until the introduction of the chestnut blight, Cryphonectria parasitica, functionally eradicated the species. Restoration efforts include genetic transformation utilizing genes such as oxalate oxidase to produce potentially blight-resistant chestnut trees that could be released back into the native range. However, before such a release can be undertaken, it is necessary to assess nontarget impacts. Since oxalate oxidase is meant to combat a fungal pathogen, we are particularly interested in potential impacts of this transgene on beneficial fungi. This study compares ectomycorrhizal fungal colonization on a transgenic American chestnut clone expressing enhanced blight resistance to a wild-type American chestnut, a conventionally bred American-Chinese hybrid chestnut, and other Fagaceae species. A greenhouse bioassay used soil from two field sites with different soil types and land use histories. The number of colonized root tips was counted, and fungal species were identified using morphology, restriction fragment length polymorphism (RFLP), and DNA sequencing. Results showed that total ectomycorrhizal colonization varied more by soil type than by tree species. Individual fungal species varied in their colonization rates, but there were no significant differences between colonization on transgenic and wild-type chestnuts. This study shows that the oxalate oxidase gene can increase resistance against Cryphonectria parasitica without changing the colonization rate for ectomycorrhizal species. These findings will be crucial for a potential deregulation of blight-resistant American chestnuts containing the oxalate oxidase gene.