Secondary metabolite biosynthetic diversity in the fungal family Hypoxylaceae and Xylaria hypoxylon

Paclitaxel - a Product of Fungal Secondary Metabolism or an Artefact?

Taxol (common name: paclitaxel) is an extremely important component of drugs for the treatment of various cancers. Thirty years after the discovery of its effectiveness, a metabolic precursor of Taxol (10-deacetylbaccatin III) is still primarily extracted from needles of European yew trees. In order to meet the considerable demand, hopes were pinned on the possibilities of biotechnological production from the very beginning. In 1993, as if by chance, Taxol was supposedly discovered in fungi that grow endobiotically in yew trees. This finding aroused hopes of biotechnological use to produce fungal Taxol in large quantities in fermenters. It never came to that. Instead, a confusing flood of publications emerged that claimed to have detected Taxol in more and more eukaryotic and even prokaryotic species. However, researchers never reproduced these rather puzzling results, and they could certainly not be applied on an industrial scale. This paper will show that some of the misguided approaches were apparently based on a seemingly careless handling of sparse evidence and on at least questionable publications. Apparently, the desired gold rush of commercial exploitation was seductive. Scientific skepticism as an indispensable core of good scientific practice was often neglected, and the peer review process has not exerted its corrective effect. Self-critical reflection and more healthy skepticism could help to reduce the risk of such aberrations in drug development. This article uses this case study as a striking example to show what can be learned from the Taxol case in terms of research ethics and the avoidance of questionable research practices.

Cultures as types and the utility of viable specimens for fungal nomenclature

The debates over the requirement of the International Code of Nomenclature for algae, fungi, and plants (ICNafp) for a viable specimen to represent the name-bearing type material for a species or infraspecific taxon have a long history. Taxonomy of fungi commonly studied as living cultures exemplified by yeasts and moulds, strongly depend on viable reference material. The availability of viable cultures is also particularly useful for several groups of filamentous and dimorphic fungi. While the preservation of metabolically inactive cultures is permitted and recommended by the ICNafp, there is room for improvement. Below, we review the history and current status of cultures as the name-bearing type material under the Code. We also present a roadmap with tasks to be achieved in order to establish a stable nomenclatural system that properly manages taxa typified by viable specimens. Furthermore, we propose setting up rules and defining the nomenclatural status of ex-type cultures under Chapter F, the section of the ICNafp that includes provisions specific to names of fungi.

Molecular networking and computational NMR analyses uncover six polyketide-terpene hybrids from termite-associated Xylaria isolates

Fungi constitute the Earth's second most diverse kingdom, however only a small percentage of these have been thoroughly examined and categorized for their secondary metabolites, which still limits our understanding of the ecological chemical and pharmacological potential of fungi. In this study, we explored members of the co-evolved termite-associated fungal genus Xylaria and identified a family of highly oxygenated polyketide-terpene hybrid natural products using an MS/MS molecular networking-based dereplication approach. Overall, we isolated six no yet reported xylasporin derivatives, of which xylasporin A (1) features a rare cyclic-carbonate moiety. Extensive comparative spectrometric (HRMS2) and spectroscopic (1D and 2D NMR) studies allowed to determine the relative configuration across the xylasporin family, which was supported by chemical shift calculations of more than 50 stereoisomers and DP4+ probability analyses. The absolute configuration of xylasporin A (1) was also proposed based on TDDFT-ECD calculations. Additionally, we were able to revise the relative and absolute configurations of co-secreted xylacremolide B produced by single x-ray crystallography. Comparative genomic and transcriptomic analysis allowed us to deduce the putative biosynthetic assembly line of xylasporins in the producer strain X802, and could guide future engineering efforts of the biosynthetic pathway.

Isolation and Identification of Pigment-Producing Endophytic Fungi from the Amazonian Species Fridericia chica

Pigments of fungal origin have aroused increasing interest in the food dye and cosmetic industries since the global demand for natural dyes has grown. Endophytic microorganisms are a source of bioactive compounds, and Amazonian plant species can harbor fungi with a wide range of biotechnological applications. Popularly known in Brazil as crajiru, Fridericia chica is a medicinal plant that produces a red pigment. In this study, a total of 121 fungi were isolated in potato dextrose agar from three plants. We identified nine pigment-producing endophytic fungi isolated from branches and leaves of F. chica. The isolates that showed pigment production in solid media were molecularly identified via multilocus analysis as Aspergillus welwitschiae, A. sydowii, Curvularia sp., Diaporthe cerradensis (two strains), Hypoxylon investiens, Neoscytalidium sp. (two strains) and Penicillium rubens. These isolates were subjected to submerged fermentation in two culture media to obtain metabolic extracts. The extracts obtained were analyzed in terms of their absorbance between 400 and 700 nm. The pigmented extract produced by H. investiens in medium containing yeast extract showed maximum absorbance in the red absorption range (UA700 = 0.550) and significant antioxidant and antimicrobial activity. This isolate can thus be considered a new source of extracellular pigment.

Metabolomics insights into the polyketide-lactones produced by Diaporthe caliensis sp. nov., an endophyte of the medicinal plant Otoba gracilipes

IMPORTANCE

The integration of metabolomics-based approaches into the discovery pipeline has enabled improved mining and prioritization of prolific secondary metabolite producers such as endophytic fungi. However, relying on automated untargeted analysis tools might lead to misestimation of the chemical complexity harbored in these organisms. Our study emphasizes the importance of isolation and structure elucidation of the respective metabolites in addition to deep metabolome analysis for the correct interpretation of untargeted metabolomics approaches such as molecular networking. Additionally, it encourages the further exploration of endophytic fungi from traditional medicinal plants for the discovery of natural products.

Rapid discovery of terpene tailoring enzymes for total biosynthesis

Twenty oxygenated aristolochene congeners were rapidly synthesised by combining genes from four different fungal pathways in the fungal host organism Aspergillus oryzae. Compounds produced in a single step include the natural product hypoxylan A and an epimer of guignaderemophilane C. A new fungal aromatase was discovered that produces phenols by oxidative demethylation.

Sporothioethers: deactivated alkyl citrates from the fungus Hypomontagnella monticulosa

Submerged cultivation of Hypomontagnella monticulosa MUCL 54604 resulted in formation of a stereoisomeric mixture of new sulfur-containing sporothriolide derivatives named sporothioethers A and B. The presence of the 2-hydroxy-3-mercaptopropanoic acid moiety attenuates the antimicrobial activity in comparison to the precursor sporothriolide suggesting a detoxification mechanism. However, moderate effects on biofilms of Candida albicans and Staphylococcus aureus were observed for sporothriolide and sporothioethers A and B at concentrations below their MICs.

Inhibitory Effects of the Fungal Pigment Rubiginosin C on Hyphal and Biofilm Formation in Candida albicans and Candida auris

The two fungal human pathogens, Candida auris and Candida albicans, possess a variety of virulence mechanisms. Among them are the formation of biofilms to protect yeast against harsh conditions through the development of (pseudo)hyphae whilst also facilitating the invasion of host tissues. In recent years, increased rates of antifungal resistance have been associated with C. albicans and C. auris, posing a significant challenge for the effective treatment of fungal infections. In the course of our ongoing search for novel anti-infectives, six selected azaphilones were tested for their cytotoxicity and antimicrobial effects as well as for their inhibitory activity against biofilm and hyphal formation. This study revealed that rubiginosin C, derived from stromata of the ascomycete Hypoxylon rubiginosum, effectively inhibited the formation of biofilms, pseudohyphae, and hyphae in both C. auris and C. albicans without lethal effects. Crystal violet staining assays were utilized to assess the inhibition of biofilm formation, while complementary microscopic techniques, such as confocal laser scanning microscopy, scanning electron microscopy, and optical microscopy, were used to investigate the underlying mechanisms. Rubiginosin C is one of the few substances known to effectively target both biofilm formation and the yeast-to-hyphae transition of C. albicans and C. auris within a concentration range not affecting host cells, making it a promising candidate for therapeutic intervention in the future.

Eremoxylarins D-J, Antibacterial Eremophilane Sesquiterpenes Discovered from an Endolichenic Strain of Xylaria hypoxylon

An endolichenic strain of the Ascomycetaceous Xylaria hypoxylon, cultivated alone or in coculture with another endolichenic fungus Dendrothyrium variisporum, produced seven new bioactive eremophilane sesquiterpenes eremoxylarins D-J (1-7). The isolated compounds disclosed a high similarity with the eremophilane core of the bioactive integric acid, and structures were elucidated by 1D and 2D NMR spectra and electronic circular dichroism (ECD) analyses. Eremoxylarins D, F, G, and I showed a selective activity against Gram-positive bacteria such as methicillin-resistant Staphylococcus aureus with minimum inhibitory concentration (MIC) values between 0.39 and 12.5 μg/mL. Eremoxylarin I, the most antibacterial active sesquiterpene, was also active against HCoV-229E at a concentration nontoxic to the hepatoma Huh-7 cell line with an 50% inhibitory concentration (IC₅₀) of 18.1 μM and a 50% cytotoxic concentration (CC₅₀) of 46.6 μM.

Assembly and comparative genome analysis of a Patagonian Aureobasidium pullulans isolate reveals unexpected intraspecific variation

Aureobasidium pullulans is a yeast-like fungus with remarkable phenotypic plasticity widely studied for its importance for the pharmaceutical and food industries. So far, genomic studies with strains from all over the world suggest they constitute a genetically unstructured population, with no association by habitat. However, the mechanisms by which this genome supports so many phenotypic permutations are still poorly understood. Recent works have shown the importance of sequencing yeast genomes from extreme environments to increase the repertoire of phenotypic diversity of unconventional yeasts. In this study, we present the genomic draft of A. pullulans strain from a Patagonian yeast diversity hotspot, re-evaluate its taxonomic classification based on taxogenomic approaches, and annotate its genome with high-depth transcriptomic data. Our analysis suggests this isolate could be considered a novel variant at an early stage of the speciation process. The discovery of divergent strains in a genomically homogeneous group, such as A. pullulans, can be valuable in understanding the evolution of the species. The identification and characterization of new variants will not only allow finding unique traits of biotechnological importance, but also optimize the choice of strains whose phenotypes will be characterized, providing new elements to explore questions about plasticity and adaptation.

Redisposition of apiosporous genera Induratia and Muscodor in the Xylariales, following the discovery of an authentic strain of Induratia apiospora

BACKGROUND

The genus Induratia is based on Induratia apiospora, a xylarialean pyrenomycete from New Zealand with clypeate uniperitheciate stromata, hyaline apiospores and a nodulisporium-like anamorph. However, because of the lack of DNA data from the generic type, its phylogenetic affinities have remained unresolved. Recently, two fungal species with teleomorphs strikingly similar to Induratia were discovered in Thailand. However, they did not produce an anamorph and were found to be phylogenetically close to the species classified within the hyphomycete genus Muscodor, which was described after Induratia. Therefore, in 2020 the species of Muscodor were transferred to Induratia, and a new family Induratiaceae was proposed.

RESULTS

We have encountered an unpublished ex-holotype strain of Induratia apiospora among the holdings of the ATCC collection, enabling detailed morphological and molecular phylogenetic investigations. We observed the characteristic nodulisporium-like anamorph described in the original publication. Phylogenetic analyses of multigene sequence data revealed a close relationship of Induratia apiospora to the Barrmaeliaceae, while a close relationship to the Induratia species formerly classified within Muscodor was rejected.

CONCLUSIONS

We here classify Induratia apiospora within the Barrmaeliaceae and consider Induratiaceae to be synonymous with the former. As the holotype specimen of Induratia apiospora is apparently lost, an isotype specimen from WSP is selected as lectotype. We also propose that the genus Muscodor is resurrected within the Xylariaceae, and formally transfer several Induratia species to Muscodor.

Studies on the Genus Pyrenopolyporus (Hypoxylaceae) in Thailand Using a Polyphasic Taxonomic Approach

Over the past two decades, hypoxylaceous specimens were collected from several sites in Thailand. In this study, we examined their affinity to the genus Pyrenopolyporus using macroscopic and microscopic morphological characters, dereplication of their stromatal secondary metabolites using ultrahigh performance liquid chromatography coupled to diode array detection and ion mobility tandem mass spectrometry (UHPLC-DAD-IM-MS/MS), and molecular phylogenetic analyses. We describe and illustrate five novel species and a new record for the country, present multi-locus phylogenetic analyses that show the distinction between the proposed species, and provide proteomic profiles of the fungi using matrix associated laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF/MS) for the first time. Based on our findings, this strategy is useful as a complementary tool to distinguish species between Daldinia and Pyrenopolyporus in a consistent way with the phylogenetic analysis.

Adaptations of Pseudoxylaria towards a comb-associated lifestyle in fungus-farming termite colonies

Characterizing ancient clades of fungal symbionts is necessary for understanding the evolutionary process underlying symbiosis development. In this study, we investigated a distinct subgeneric taxon of Xylaria (Xylariaceae), named Pseudoxylaria, whose members have solely been isolated from the fungus garden of farming termites. Pseudoxylaria are inconspicuously present in active fungus gardens of termite colonies and only emerge in the form of vegetative stromata, when the fungus comb is no longer attended ("sit and wait" strategy). Insights into the genomic and metabolic consequences of their association, however, have remained sparse. Capitalizing on viable Pseudoxylaria cultures from different termite colonies, we obtained genomes of seven and transcriptomes of two Pseudoxylaria isolates. Using a whole-genome-based comparison with free-living members of the genus Xylaria, we document that the association has been accompanied by significant reductions in genome size, protein-coding gene content, and reduced functional capacities related to oxidative lignin degradation, oxidative stress responses and secondary metabolite production. Functional studies based on growth assays and fungus-fungus co-cultivations, coupled with isotope fractionation analysis, showed that Pseudoxylaria only moderately antagonizes growth of the termite food fungus Termitomyces, and instead extracts nutrients from the food fungus biomass for its own growth. We also uncovered that Pseudoxylaria is still capable of producing structurally unique metabolites, which was exemplified by the isolation of two novel metabolites, and that the natural product repertoire correlated with antimicrobial and insect antifeedant activity.

Segregation of the genus Parahypoxylon (Hypoxylaceae, Xylariales) from Hypoxylon by a polyphasic taxonomic approach

During a mycological survey of the Democratic Republic of the Congo, a fungal specimen that morphologically resembled the American species Hypoxylon papillatum was encountered. A polyphasic approach including morphological and chemotaxonomic together with a multigene phylogenetic study (ITS, LSU, tub2, and rpb2) of Hypoxylon spp. and representatives of related genera revealed that this strain represents a new species of the Hypoxylaceae. However, the multi-locus phylogenetic inference indicated that the new fungus clustered with H. papillatum in a separate clade from the other species of Hypoxylon. Studies by ultrahigh performance liquid chromatography coupled to diode array detection and ion mobility tandem mass spectrometry (UHPLC-DAD-IM-MS/MS) were carried out on the stromatal extracts. In particular, the MS/MS spectra of the major stromatal metabolites of these species indicated the production of hitherto unreported azaphilone pigments with a similar core scaffold to the cohaerin-type metabolites, which are exclusively found in the Hypoxylaceae. Based on these results, the new genus Parahypoxylon is introduced herein. Aside from P. papillatum, the genus also includes P. ruwenzoriensesp. nov., which clustered together with the type species within a basal clade of the Hypoxylaceae together with its sister genus Durotheca.

Curiouser and curiouser: progress in understanding the programming of iterative highly-reducing polyketide synthases

Covering: 1996-2022Investigations over the last 2 decades have begun to reveal how fungal iterative highly-reducing polyketide synthases are programmed. Both in vitro and in vivo experiments have revealed the interplay of intrinsic and extrinsic selectivity of the component catalytic domains of these systems. Structural biology has begun to provide high resolution structures of hr-PKS that can be used as the basis for their engineering and reprogramming, but progress to-date remains rudimentary. However, significant opportunities exist for translating the current level of understanding into the ability to rationally re-engineer these highly efficient systems for the production of important biologically active compounds through biotechnology.

A re-assessment of Taxomyces andreanae, the alleged taxol-producing fungus, using comparative genomics

The monotypic "bulbilliferous hyphomycete" genus Taxomyces was erected in 1993 for a fungal endophyte isolated from the Yew tree Taxus brevifolia and named Taxomyces andreanae. This fungus was reported to produce the plant-derived anti-cancer drug taxol. The original description of the fungus was not conclusive as to its taxonomic position because no sporulation or other salient morphological features were reported. Consequently, the taxonomic affinities of this fungus have remained obscure. However, a full genome sequence of this strain was generated by a German research group in 2013, in an unsuccessful attempt to detect the biosynthesis genes encoding for taxol. This prompted us to search for phylogenetic marker genes and compare those with the data that recently have become available from state-of-the-art polyphasic taxonomic studies. Surprisingly, the strain turned out to belong to the phlebioid clade of wood-destroying Basidiomycota as inferred from a comparison of its partial ITS, the 28S rDNA (LSU), the RNA polymerase II largest subunit (rpb1), the RNA polymerase II second largest subunit (rpb2), and the translation elongation factor 1-α (tef1) sequences. A multi gene genealogy based on these loci revealed that the closest relative is Ceriporiopsis (syn. Mycoacia) gilvescens. Even though such wood-destroying Basidiomycota are regularly encountered among the endophytic isolates after surface-disinfection of plant organs, the vast majority of the reported endophytic fungi belong to the Ascomycota. Nevertheless, the data available now allow for synonymizing Taxomyces with Ceriporiopsis, and the necessary new combination is made.

Ten decadal advances in fungal biology leading towards human well-being

Fungi are an understudied resource possessing huge potential for developing products that can greatly improve human well-being. In the current paper, we highlight some important discoveries and developments in applied mycology and interdisciplinary Life Science research. These examples concern recently introduced drugs for the treatment of infections and neurological diseases; application of -OMICS techniques and genetic tools in medical mycology and the regulation of mycotoxin production; as well as some highlights of mushroom cultivaton in Asia. Examples for new diagnostic tools in medical mycology and the exploitation of new candidates for therapeutic drugs, are also given. In addition, two entries illustrating the latest developments in the use of fungi for biodegradation and fungal biomaterial production are provided. Some other areas where there have been and/or will be significant developments are also included. It is our hope that this paper will help realise the importance of fungi as a potential industrial resource and see the next two decades bring forward many new fungal and fungus-derived products.

A genomic journey in the secondary metabolite diversity of fungal plant and insect pathogens: from functional to population genomics

Fungal pathogens produce a broad array of secondary metabolites (SMs), which allow the fungus to thrive in its natural habitat and gain competitive advantage. Analysis of the genetically encoded blueprints for SM assembly highlighted that only a small portion of the SMs these fungi are capable of producing are known, and even fewer have been investigated for their natural function. Using molecular tools, a lot of progress has been made recently in identifying the blueprint products and linking them to their ecological purpose such as the peptide virulence factor fusaoctaxin A released by Fusarium graminearum during infection of wheat or the F. oxysporum polyketide bikaverin that provides competitive advantage against bacteria in tomato. In addition, population genomics have given particularly important insights into the species-specific plasticity of the SM blueprint arsenal, showcasing the ongoing evolution and adaptation of fungal pathogens. This approach holds promise in inferring roles in pathogenicity of many more fungal SMs.

Microbial polyketides and their roles in insect virulence: from genomics to biological functions

Covering: May 1966 up to January 2022Entomopathogenic microorganisms have potential for biological control of insect pests. Their main secondary metabolites include polyketides, nonribosomal peptides, and polyketide-nonribosomal peptide (PK-NRP) hybrids. Among these secondary metabolites, polyketides have mainly been studied for structural identification, pathway engineering, and for their contributions to medicine. However, little is known about the function of polyketides in insect virulence. This review focuses on the role of bacterial and fungal polyketides, as well as PK-NRP hybrids in insect infection and killing. We also discuss gene distribution and evolutional relationships among different microbial species. Further, the role of microbial polyketides and the hybrids in modulating insect-microbial symbiosis is also explored. Understanding the mechanisms of polyketides in insect pathogenesis, how compounds moderate the host-fungus interaction, and the distribution of PKS genes across different fungi and bacteria will facilitate the discovery and development of novel polyketide-derived bio-insecticides.

Studies on the secondary metabolism of Rosellinia and Dematophora strains (Xylariaceae) from Iran

The xylariaceous genus Dematophora has recently been resurrected and segregated from Rosellinia based on a molecular phylogeny and morphological characters. This was an important taxonomic change because Dematophora in the current sense contains several important pathogens, while Rosellinia is limited to mainly saprotrophic species that have an endophytic stage in their life cycle and may even have beneficial effects on the host plants. During our ongoing work on the functional biodiversity of the Xylariales, we have encountered new strains of rosellinoid Xylariaceae from Iran and have studied their mycelial cultures for secondary metabolites in an attempt to establish further chemotaxonomic affinities. In the process, we isolated and identified 13 compounds, of which rosellisteroid (1), the cichorine derivative 2, and the alkaloid 3 are new. Out of these, nine were tested for their antimicrobial affinities with cytochalasin E (6) exhibiting weak activity against Schizosaccharomyces pombe. The cytotoxicity of three cytochalasin derivatives was examined and their effects on the F-actin cytoskeletal organization studied by fluorescence microscopy using fluorescent phalloidin. Cytochalasin E (6) and Δ6,12-cytochalasin E (7) showed strong and irreversible action on actin, while cytochalasin K (8) exhibited weaker, reversible effects.

Three New Species of Hypoxylon (Xylariales, Ascomycota) on a Multigene Phylogeny from Medog in Southwest China

During a survey of hypoxylaceous fungi in Medog county (Tibet Autonomous Region, China), three new species, including Hypoxylon damuense, Hypoxylon medogense, and Hypoxylon zangii, were described and illustrated based on morphological and multi-gene phylogenetic analyses. Hypoxylon damuense is characterized by its yellow-brown stromatal granules, light-brown to brown ascospores, and frequently indehiscent perispore. Hypoxylon medogense is morphologically and phylogenetically related to H. erythrostroma but differs in having larger ascospores with straight spore-length germ slit and conspicuously coil-like perispore ornamentation. Hypoxylon zangii shows morphological similarities to H. texense but differs in having Amber (47), Fulvous (43) and Sienna (8) KOH-extractable pigments and larger ascospores with straight spore-length germ slit. The multi-gene phylogenetic analyses inferred from the datasets of ITS-RPB2-LSU-TUB2 supported the three new taxa as separate lineages within Hypoxylon. A key to all known Hypoxylon species from China and related species worldwide is provided.

Brunneosporopsis yunnanensis gen. et sp. nov. and Allocryptovalsa xishuangbanica sp. nov., New Terrestrial Sordariomycetes from Southwest China

Three fungal taxa were collected on dead branches of wood during fieldwork in Sichuan and Yunnan Provinces, China. The new generic name Brunneosporopsis gen. nov. and species B. yunnanensis sp. nov. are introduced for a novel taxon characterized by globose to subglobose and dark olivacous-brown conidia. Phylogenetic analyses based on combined LSU, SSU and tef1-α loci strongly support the monophyly of this taxon and place it in the subclass Diaporthomycetidae. It could not be assigned to any currently recognized families in the subclass and was, therefore, placed in the Diaporthomycetidae genera incertae sedis. A second taxon represents a new species in Allocryptovalsa based on an analysis of the sequence datasets of ITS and btub loci of the novel, brown-spored sexual morphic species. This taxon is described here as A. xishuangbanica sp. nov. An interesting hypocrealean fungus producing synnemata, Stilbocrea gracilipes, was collected from dead wood of an unknown host from Sichuan Province and is reported here, with asexual morph from both the host and culture as well as LSU, ITS, tef1-α, rpb2 and rpb1 sequence data.

Diversity of biologically active secondary metabolites in the ascomycete order Sordariales

Ascomycetes belonging to the order Sordariales are a well-known reservoir of secondary metabolites with potential beneficial applications. Species of the Sordariales are ubiquitous, and they are commonly found in soils and in lignicolous, herbicolous, and coprophilous habitats. Some of their species have been used as model organisms in modern fungal biology or were found to be prolific producers of potentially useful secondary metabolites. However, the majority of sordarialean species are poorly studied. Traditionally, the classification of the Sordariales has been mainly based on morphology of the ascomata, ascospores, and asexual states, characters that have been demonstrated to be homoplastic by modern taxonomic studies based on multi-locus phylogeny. Herein, we summarize for the first time relevant information about the available knowledge on the secondary metabolites and the biological activities exerted by representatives of this fungal order, as well as a current outlook of the potential opportunities that the recent advances in omic tools could bring for the discovery of secondary metabolites in this order.

Multi-Gene Phylogeny and Taxonomy of Hypoxylon (Hypoxylaceae, Ascomycota) from China

The Hypoxylon species play an important ecological role in tropical rainforest as wood-decomposers, and some might have benefical effects on their hosts as endophytes. The present work concerns a survey of the genus Hypoxylon from Hainan Tropical Rainforest National Park of China. Four new species: H. wuzhishanense, H. hainanense, H.chrysalidosporum, and H.cyclobalanopsidis, were discovered based on a combination of morphological characteristics and molecular data. Hypoxylon wuzhishanense is characterized by Rust pulvinate stromata, amyloid apical apparatus and brown ascospores, with most of the perispore being indehiscent in 10% KOH. Hypoxylon hainanense has effused–pulvinate and Violet stromata, amyloid apical apparatus, light-brown to brown ascospores with straight germ slit and dehiscent perispore. Hypoxylonchrysalidosporum is distinguished by glomerate to pulvinate stromata, highly reduced or absent inamyloid apical apparatus, and light-brown to brown ascospores with very conspicuous coil-like ornamentation. Hypoxyloncyclobalanopsidis has Livid Purple pulvinate stromata, highly reduced amyloid apical apparatus, faint bluing, brown ascospores and dehiscent perispore, and it grows on dead branches of Cyclobalanopsis. Detailed descriptions, illustrations, and contrasts with morphologically similar species are provided. Phylogenetic analyses inferred from ITS, RPB2, LSU, and β-tubulin sequences confirmed that the four new species are distinct within the genus Hypoxylon.

Whole Genome Sequencing and Annotation of Naematelia aurantialba (Basidiomycota, Edible-Medicinal Fungi)

Naematelia aurantialba is a rare edible fungus with both nutritional and medicinal values and especially rich in bioactive polysaccharides. However, due to the lack of genomic information, researches on the mining of active compounds, artificial breeding and cultivation, genetics, and molecular biology are limited. To facilitate the medicinal and food applications of N. aurantialba, we sequenced and analyzed the whole genome of N. aurantialba for the first time. The 21-Mb genome contained 15 contigs, and a total of 5860 protein-coding genes were predicted. The genome sequence shows that 296 genes are related to polysaccharide synthesis, including 15 genes related to nucleoside-activated sugar synthesis and 11 genes related to glucan synthesis. The genome also contains genes and gene clusters for the synthesis of other active substances, including terpenoids, unsaturated fatty acids, and bioactive proteins. In addition, it was also found that N. aurantialba was more closely related to Naematelia encephala than to Tremella fuciformis. In short, this study provides a reference for molecular cognition of N. aurantialba and related researches.