Mycologia最新文献

Sexual compatibility in the Basidiomycota is governed by genetic identity at one or two loci, resulting in compatibility systems called bipolar and tetrapolar. The loci are known as HD and P/R, encoding homeodomain transcription factors and pheromone precursors and receptors, respectively. Bipolarity is known to evolve either by linkage of the two loci or by loss of mating-type determination of either the HD or the P/R locus. The ancestor to basidiomycete fungi is thought to have been tetrapolar, and many transitions to bipolarity have been described in different lineages. In the diverse genus Marasmius (Agaricales), both compatibility systems are found, and the system has been shown to follow the infrageneric sections of the genus, suggesting a single origin of bipolarity. Here, we tested this hypothesis using a comprehensive phylogenetic framework and investigated the mode by which bipolarity has evolved in this group. We utilized available genomic data and marker sequences to investigate evolution of sexual compatibility in Marasmius and allied genera. By generating a concatenated multilocus phylogeny, we found support for a single transition to known bipolarity within Marasmius. Furthermore, utilizing genomic data of the bipolar species Marasmius oreades, we found that the HD and P/R loci likely have remained unlinked through this transition. By comparing nucleotide diversity at the HD and P/R loci in Ma. oreades, we show that the HD locus has retained high diversity, and thus likely the function of determining sexual identity, as similarly in other bipolar mushroom-forming fungi. Finally, we describe the genomic architecture of the MAT loci of species of both sexual compatibility systems in Marasmiaceae and related families.

The endolichenic Fusarium solani (EF5), known to show induced metabolite production when exposed to red and green lights, was selected for characterization of their putative light-regulated bioactive compounds. To achieve this, fractionation was first performed for crude extracts from cultures of F. solani (EF5) incubated in green, red, white-fluorescent light and dark conditions. The extract yielded 12 (dark condition) to 15 (exposed to green, red, and white-fluorescent lights) fractions, and each of the fractions was tested for antimicrobial activities. The fraction (fraction 5) that showed the most promising antimicrobial activity was then subjected to high-performance liquid chromatography (HPLC) and liquid chromatography-mass spectrometry (LC-MS) to identify the bioactive compounds. Results revealed detection of two new metabolites from endolichenic F. solani, putatively identified as 8-deoxyjavanicin and fusolanone A, which are known to have antimicrobial properties. This study revealed that red and green lights trigger the production of 8-deoxyjavanicin and fusolanone A, which likely contributed to the antimicrobial properties demonstrated by endolichenic F. solani.

Plastics are a prevalent and persistent pollutant in the environment. As plastic production increases, finding ways to degrade these recalcitrant polymers is paramount. Many terrestrial fungi, across the kingdom, degrade various types of plastic. Plastics are the fastest-growing habitat in the oceans, and we hypothesized that fungi isolated from the ocean would demonstrate high success rates in degrading polyurethane (PU). To test this, visual degradation assays were performed by inoculating 1% PU medium with 68 different fungal strains cultured from marine habitats. The area of clearance of the fungus was measured periodically, to determine a relative degradation rate. Of the 68 fungal strains, 42 demonstrated the ability to degrade PU. We conditioned the nine fastest PU degraders through serial inoculations into liquid media with increasing concentrations of PU, starting at 1% and going up to 12%. The growth rates of the original and conditioned fungi were then compared in new inoculation trials, and results show that three of the nine conditioned fungi demonstrate higher PU degradation rates than their unconditioned counterparts. Marine fungi, coupled with conditioning, show promise for developing novel mycoremediation technologies.

Epichloë species are systemic, often seed-transmissible symbionts (endophytes) of cool-season grasses (Poaceae subfam. Poöideae) that produce up to four classes of bioprotective alkaloids. Whereas haploid Epichloë species may reproduce sexually and transmit between host plants (horizontally), many Epichloë species are polyploid hybrids that are exclusively transmitted via seeds (vertically). Therefore, the generation of, and selection on, chemotypic (alkaloid) profiles and diversity should differ between haploids and hybrids. We undertook a genome-level analysis of haploids and polyploid hybrids, emphasizing hybrids that produce lolines, which are potent broad-spectrum anti-invertebrate alkaloids that can accumulate to levels up to 2% of plant dry mass. Prior phylogenetic analysis had indicated that loline alkaloid gene clusters (LOL) in many hybrids are from the haploid species Epichloë bromicola, but no LOL-containing E. bromicola strains were previously identified. We discovered LOL-containing E. bromicola from host grasses Bromus tomentellus and Melica persica in a Mediterranean-climate region (MCR) in Isfahan Province, Iran, and from Thinopyrum intermedium in Poland. The isolates from B. tomentellus and M. persica were closely related and had nearly identical alkaloid gene profiles, and their LOL clusters were most closely related to those of several Epichloë hybrids. In contrast, several LOL genes in the isolate from T. intermedium were phylogenetically more basal in genus Epichloë, indicating trans-species polymorphism. While identifying likely hybrid ancestors, this study also revealed novel host ranges in central Iran, with the first observation of E. bromicola in host tribe Meliceae and of Epichloë festucae in host tribe Bromeae. We discuss the possibility that MCRs may be hotspots for diversification of grass-Epichloë symbioses via extended host ranges and interspecific hybridization of the symbionts.

Polymorphic yeasts can switch between unicellular division and multicellular filamentous growth. Although prevalent in aquatic ecosystems, such as the open ocean, we have a limited understanding of the controlling factors on their morphological variation in an aquatic ecology context. Here we show that substrate concentration regulates cell morphogenesis in a cosmopolitan polymorphic yeast, Aureobasidium pullulans, isolated from the pelagic open ocean and analyzed in liquid batch culture. Filamentous cell development was triggered only under high initial substrate conditions, suggesting that hyphal growth could be more advantageous under eutrophic conditions and may influence pelagic fungal interactions with particulate organic matter. Filamentous growth proportionally declined before the exhaustion of substrate and before budding yeast-type cell division entered stationary phase, possibly modulated by quorum sensing as previously evidenced in other polymorphic yeasts. We also found that budding yeast-type unicells decreased in size and became more elongated in shape in response to substrate depletion, resulting in higher cell surface area to volume ratios, which could affect yeast dispersal and/or provide a nutrient uptake advantage under oligotrophic conditions. Our results demonstrate resource-responsive morphological plasticity in a marine-derived polymorphic yeast, providing mechanistic insight into the ability of fungi to survive fluctuating environmental conditions such as in the open ocean.

Some species of Tilletia are responsible for diseases in economically important crops, such as wheat and rice. In this study, we sequenced, assembled, and annotated 22 new genomes for Tilletia, with a focus on species causing dwarf bunt (DB; T. controversa), common bunt (CB; T. caries and T. laevis), and rice kernel smut (RKS; T. horrida). We present the first genomes for four other species (T. bromi, T. fusca, T. goloskokovii, and T. rugispora), resulting in the largest and most diverse sample of Tilletia genomes studied to date. Depending on the species and strain, the assembly size ranged from 24.3 to 30.5 Mb and gene prediction resulted in 7138 to 8261 gene models per genome. Phylogenomic analyses with hundreds to thousands of genes revealed significant support for the relationships among certain Tilletia taxa and validated findings of previous molecular studies that employed a small number of genes. Further population-level analyses showed two distinct populations of DB and CB: T. controversa (DB) as a single population and another intermixed population of T. caries and T. laevis (CB). No evidence of geographic isolation was observed within these populations. Our phylogenomic analyses also supported previous multigene hypotheses that multiple lineages of Tilletia may cause RKS. Collectively, our results suggest that taxonomic revisions are needed for the RKS-causing pathogens and provide convincing evidence for formally recognizing the CB-causing taxa as one species, named T. caries (synonym T. laevis). Overall, our study significantly enhances genomic resources for Tilletia, offers insights into phylogenetic relationships and population structure, and provides whole genome sequences for future studies.

While a lot is known about cytokinins (CKs) and their actions at the molecular and cellular levels in plants, much less is known about the function of CKs in other kingdoms such as fungi. CKs have been detected in a wide range of fungal species where they play roles ranging from enhancing the virulence of phytopathogens to fortifying plant growth when secreted from fungal symbionts. However, the role of CKs where they concern fungal physiology, apart from plant associations, remains largely uncharacterized. Profiling by UHPLC-HRMS/MS (ultrahigh-performance liquid chromatography-high-resolution tandem mass spectrometry) revealed that Pleurotus ostreatus (oyster mushroom) produces CKs in vitro in both liquid and solid cultures. During fungal growth, CK profiling patterns were consistent with previous suggestions that tRNA degradation products might play a role in the physiological development of fungi. It confirms that those products are CKs that act as fungal growth regulators. Moreover, P. ostreatus was shown to respond to exogenous applications of aromatic and isoprenoid CKs, and their effects were dependent on the dose and CK type in a biphasic manner consistent with hormone action. N⁶-benzyladenine (BAP), kinetin (KIN), N⁶-isopentenyladenine (iP), and trans-zeatin (tZ) bioassays all revealed hormesis-type responses. Accordingly, at low doses, mycelium colony diameter, biomass accumulation, and changes in morphology were stimulated, whereas at high doses only inhibitory effects were observed. Thus, CKs may act as "mycohormones" and consequently have potential for applications in fungal agriculture and medicinal compound production.

Two species of Blackwellomyces (Clavicipitaceae, Hypocreales, Ascomycota) were discovered during an investigation of the diversity of entomopathogenic fungi. A new fungus and one known fungal species that were gathered from Yunnan Province were described in this study. Blackwellomyces changningensis, sp. nov. was described using morphology and phylogenetic evidence from 14 mitochondrial protein-coding gene (PCG) data sets (atp6, atp8, atp9, cob, cox1, cox2, cox3, nad1, nad2, nad3, nad4, nad5, nad6, and nad4L) and six nuclear genes (ITS [ITS4 and ITS5], 18S nuc rDNA [18S], 28S nuc rDNA [28S], tef1-α, rpb1, and rpb2). B. changningensis were found parasitic to Lepidoptera larvae and to produce filiform ascospores with septations. The asexual conidia were ovoid to ellipsoid in shape. Phylogenetic analysis and morphological observations concurred that the fungus belonged to a different species within the genus of Blackwellomyces. The foundation for further taxonomic, genetic, and evolutionary biological studies of the genus Blackwellomyces was laid by this work.

Ectomycorrhizal fungi in the genus Tuber form hypogeous fruiting bodies called truffles. Many Tuber species are highly prized due to their edible and aromatic ascomata. Historically, there has been attention on cultivating and selling European truffle species, but there is growing interest in cultivating, wild-harvesting, and selling species of truffles endemic to North America. North America has many endemic Tuber species that remain undescribed, including some that have favorable culinary qualities. Here, we describe two such Tuber species from eastern North America. Maximum likelihood and Bayesian phylogenetic analyses of ITS (internal transcribed spacer), tef1 (translation elongation factor 1-alpha), and rpb2 (second largest subunit of RNA polymerase II) sequences were used to place these species within a phylogenetic context. We coupled these data with morphological analyses and volatile analyses based on gas chromatography-mass spectrometry. Tuber cumberlandense, sp. nov. (previously referred to as Tuber sp. 66), is a member of the Rufum clade that has been opportunistically harvested for commercial sale from T. melanosporum orchards across eastern North America. Tuber canirevelatum, sp. nov. belongs in the Macrosporum clade and thus far is only known from eastern Tennessee, USA. Both new species were discovered with the assistance of trained truffle dogs. The volatile profiles of T. canirevelatum and T. cumberlandense were measured in order to characterize aromas based on the chemical compounds produced by these fungi. Ascomata from both species were enriched in acetone, dimethyl sulfide, 1-(methylthio)-1-propene, and 1-(methylthio)propane. In this work, we celebrate and encourage the use of trained truffle-hunting dogs for fungal biodiversity discovery and research.

Morchella helvetica, sp. nov. (Morchella sect. Distantes) is a new species of true morels discovered in Switzerland. It is formally described in the present study using an integrative approach based on micro- and macromorphological characteristics, multilocus phylogenetics, and a brief description of its habitat. Molecular analyses clearly indicated that Morchella helvetica is a sister species to M. eximioides, M. angusticeps, and M. confusa. It can be distinguished by the two phylogenetic markers RNA polymerase II subunit 2 (RPB2) and translation elongation factor-1 alpha (TEF1-α). In addition, M. helvetica exhibits particular morphological features, notably the presence of pale hairs on the pileus, a mealy stipe, and darkening ridges when aging.