Mushrooms to live or die: toxicity of some Basidiomycota using Artemia franciscana

Consumption of wild mushrooms has increased in recent years; however, not all of them are edible and there is no precise information on those that may cause poisoning. Therefore, studies to obtain data about their toxicity are needed. For this purpose, we used the brine shrimp Artemia franciscana, a crustacean employed in toxicity tests and with wide application in the toxin detection, including mycotoxins. Mushrooms were collected in the state of Jalisco, Mexico, with which aqueous extracts were prepared. Dilutions of the stock solution of each extract were made to final concentrations of 50, 100, 250, 500, and 1000 µg/mL. Potassium dichromate (PD) was used as positive control and artificial seawater as negative control. The median lethal dose (LD50) of extracts on nauplii of A. franciscana was calculated. The aqueous extracts obtained from Amanita amerivirosa, A. muscaria, Chlorophyllum molybdites, and Leucopaxillus amarus showed a LD50 < 70 µg/mL, similar to PD (LD50 = 37 µg/mL). This is the first indication of the probable toxicity of Leucopaxillus amarus in humans. Cantharellus cibarius and Scleroderma texense caused the lower toxicity to the nauplii. The brine shrimp bioassay was effective in evaluating the toxicity of Basidiomycota. Scleroderma texense has been reported to be toxic, but it was not for this crustacean nauplii, and probably not to humans either, as recent literature has reported.

Whole genome sequencing and annotation of Scleroderma yunnanense, the only edible Scleroderma species

Scleroderma yunnanense, an ectomycorrhizal fungus, is a popular edible mushroom within the Yunnan Province of Southwest China that holds great ecological and economic implications. However, despite its significance, there remains limited information about this species. Therefore, we sequenced S. yunnanense genome to identify the functional genes of S. yunnanense involved in secondary metabolite and carbohydrate production pathways. First, we present the 40.43 Mb high-quality reference genome for S. yunnanense, distributed across 35 contigs; moreover, the N50 contig size was found to reach 3.31 Mb and contained 8877 functional genes. Finally, genome annotation was conducted to compare the functional genes of S. yunnanense with protein sequences from different publicly available databases. Taken together, we identified 12 biosynthetic gene clusters across 10 contigs; among these were 13 key mevalonate (MVA) pathway enzymes, a key tyrosinase enzyme in the 3,4-dihydroxyphenylalanine (DOPA) pathway that is responsible for producing DOPA melanins, and 16 enzymes involved in uridine diphosphate glucose biosynthesis. Overall, this study presents the first genome assembly and annotation of S. yunnanense; ultimately, this information will be important in the elucidation of the biological activities and artificial domestication of this fungus.

Neotropical Clavulina: Two new species from Mexico and a re-evaluation of Clavulina floridana

Clavulina comprises ca. 90 described species distributed worldwide in both tropical and temperate regions. However, only one species (C. floridana) has been described so far from tropical North America. We used morphological and molecular data from three DNA loci (nuc rDNA internal transcribed spacer region ITS1-5.8S-ITS2 [ITS], a portion of nuc 28S rDNA [28S], and a fragment of DNA-directed RNA polymerase II second largest subunit [RPB2]) from basidiomata and ectomycorrhizas collected in tropical ecosystems from three biogeographic provinces of Mexico and one tropical province in the USA to investigate the phylogenetic and taxonomic diversity of Clavulina in the region. Nine new species-level clades were discovered, two of which are proposed as new species (C. arboreiparva and C. tuxtlasana). Specimens of C. floridana recently collected in Florida were included in our analyses, for which a modern description is provided. In addition, C. floridana is a new record for Mexico. The diversity of Clavulina in tropical North America is comparable to that found in lowland tropical South America. However, some of the species found in tropical deciduous forests produce small, rare, and inconspicuous basidiomata, which easily go unnoticed, and therefore are poorly represented in collections. Many species remain undescribed in tropical regions of North America.

The Limited Establishment of Native Ectomycorrhizal Fungi in Exotic Eucalyptus spp. Stands in Japan

Host specificity may potentially limit the distribution expansion of ectomycorrhizal (ECM) fungi into areas where their original host plants are absent. To test this hypothesis, we investigated whether populations of native ECM fungi may establish in stands of exotic host trees, namely those of the Eucalyptus species, in Japan. ECM fungal communities associated with eucalyptus and surrounding native host species (Pinus thunbergii and Fagaceae spp.) were investigated at two sites; one site in which eucalyptus and native trees were growing in isolation, and a second site in which these species were mixed. To identify fungal taxa, the nuclear ribosomal internal transcribed spacer region 1 was sequenced for the ECM fungi from the root tips and clustered into operational taxonomic units (OTUs). To confirm whether the retrieved OTUs were native to Japan, they were queried against the entire database of the National Center for Biotechnology Information, UNITE, and GlobalFungi, whereby sampling locations and associated hosts were obtained from sequences with ≥97% similarity. Eucalyptus trees were associated with seven and 12 ECM fungal OTUs, including putatively exotic OTUs in isolated and mixed sites, respectively. Among the 36 and 63 native ECM fungal OTUs detected from native hosts at isolated and mixed sites, only one OTU was shared with eucalyptus at the respective sites. This means that most native ECM fungi in Japan may be incapable of forming an association with exotic Eucalyptus spp. Notably, even ECM fungi associated with both Pinus and Quercus were not detected from eucalyptus, suggesting that host-fungus incompatibility is determined not only by host phylogenetic relatedness but also by host biogeographic affinities. Our findings show that the incompatibility with eucalyptus as well as dispersal limitation may prevent the distribution expansion of native ECM fungi in Japan into the distribution ranges of Eucalyptus spp., where the original hosts are absent.

Catálogo de la micobiota del Complejo Volcánico de Colima, México

Antecedentes y Objetivos: El Complejo Volcánico de Colima (CVC) forma parte del Eje Volcánico Transversal Mexicano, localizado en el sureste de Jalisco y norte de Colima. Comprende cinturones de vegetación que cambian a través de un gradiente altitudinal desde 1200 hasta poco más de 4000 m, en donde es posible observar bosques tropicales, bosques templados y zonas semiáridas, así como bosque mesófilo de montaña. Respecto a estudios previos sobre diversidad fúngica en esta región, solo se contaba con la cita de 140 especies registradas en los diferentes municipios que comprende el área del CVC. El objetivo del presente trabajo es actualizar el conocimiento de la micobiota registrada dentro de la zona de estudio.Métodos: Se recolectaron ejemplares fúngicos durante los meses de junio a octubre entre 2011 y 2018. Adicionalmente, se realizó la revisión de material de la colección micológica del herbario IBUG. El estudio macro y micromorfológico se realizó con las técnicas convencionales en micología y el uso de bibliografía especializada para la determinación del material.Resultados clave: Un total de 2082 ejemplares fueron determinados hasta especie, corresponden a 408 taxones; de ellos 360 son Basidiomycota y 48 Ascomycota. Se citan dos registros nuevos para la micobiota de México: Ductifera exidioidea y Psathyrella longistriata, y 11 para el estado de Jalisco: Bulgaria inquinans, Crepidotus applanatus, Gymnopilus sapineus, Hohenbuehelia spathulata, Hygrocybe spadicea, Inocybe obsoleta, Lepiota cristata, Pholiota lubrica, Rhizina undulata, Scleroderma aff. pseudostipitatum y Trichoderma alutaceum, mientras que para el estado de Colima se aportan 20 registros nuevos.Conclusiones: Se considera importante incrementar estudios sistemáticos y exploraciones micológicas que permitan conocer más sobre este recurso, su posible uso y manejo racional, así como el análisis de especies endémicas o en riesgo y aspectos ecológicos que puedan mostrar la distribución actual y diversidad fúngica en dicha región. 

Notes, outline and divergence times of Basidiomycota

The Basidiomycota constitutes a major phylum of the kingdom Fungi and is second in species numbers to the Ascomycota. The present work provides an overview of all validly published, currently used basidiomycete genera to date in a single document. An outline of all genera of Basidiomycota is provided, which includes 1928 currently used genera names, with 1263 synonyms, which are distributed in 241 families, 68 orders, 18 classes and four subphyla. We provide brief notes for each accepted genus including information on classification, number of accepted species, type species, life mode, habitat, distribution, and sequence information. Furthermore, three phylogenetic analyses with combined LSU, SSU, 5.8s, rpb1, rpb2, and ef1 datasets for the subphyla Agaricomycotina, Pucciniomycotina and Ustilaginomycotina are conducted, respectively. Divergence time estimates are provided to the family level with 632 species from 62 orders, 168 families and 605 genera. Our study indicates that the divergence times of the subphyla in Basidiomycota are 406–430 Mya, classes are 211–383 Mya, and orders are 99–323 Mya, which are largely consistent with previous studies. In this study, all phylogenetically supported families were dated, with the families of Agaricomycotina diverging from 27–178 Mya, Pucciniomycotina from 85–222 Mya, and Ustilaginomycotina from 79–177 Mya. Divergence times as additional criterion in ranking provide additional evidence to resolve taxonomic problems in the Basidiomycota taxonomic system, and also provide a better understanding of their phylogeny and evolution.

Microscopic characterization of orchid mycorrhizal fungi: Scleroderma as a putative novel orchid mycorrhizal fungus of Vanilla in different crop systems

Vanilla is an orchid of economic importance widely cultivated in tropical regions and native to Mexico. We sampled three species of Vanilla (V. planifolia, V. pompona, and V. insignis) in different crop systems. We studied the effect of crop system on the abundance, type of fungi, and quality of pelotons found in the roots using light and electron microscopy and direct sequencing of mycorrhizal structures. Fungi were identified directly from pelotons obtained from terrestrial roots of vanilla plants in the flowering stage. Root samples were collected from plants in crop systems located in the Totonacapan area in Mexico (states of Puebla and Veracruz). DNA was extracted directly from 40 pelotons and amplified using ITS rRNA sequencing. Peloton-like structures were observed, presenting a combination of active pelotons characterized by abundant hyphal coils and pelotons in various stages of degradation. The most active pelotons were observed in crop systems throughout living tutors (host tree) in comparison with roots collected from dead or artificial tutors. Fungi identified directly from pelotons included Scleroderma areolatum, a common ectomycorrhizal fungus that has not been reported as a mycorrhizal symbiont in orchids. Direct amplification of pelotons also yielded common plant pathogens, including Fusarium and Pyrenophora seminiperda, especially in those sites with low colonization rates, and where large numbers of degraded pelotons were observed. This research reports for the first time the potential colonization of Vanilla by Scleroderma, as a putative orchid mycorrhizal symbiont in four sites in Mexico and the influence of crop system on mycorrhizal colonization on this orchid.

Scleroderma areolatum ectomycorrhiza on Fagus sylvatica L

Despite its broad host range and distribution and its potential applications in commercial plantation forests, comprehensive descriptions of Scleroderma ectomycorrhizae are available only for Scleroderma citrinum, Scleroderma bovista and Scleroderma sinnamariense. This study provides a morphological and anatomical description of tree nursery derived ectomycorrhizae of Scleroderma areolatum on Fagus sylvatica, grown for several years in a climatized room. Ectomycorrhizae of S. areolatum were silvery white with abundant rhizomorphs; all mantle layers were plectenchymatous, rhizomorphs of type E, with prominent emanating hyphae with thick cell wall. The distal ends of emanating hyphae of rhizomorphs were inflated and often merged with other emanating hyphae. All parts of the mycorrhiza were clampless. In hyphae of the outer mantle layer, rhizomorphs and emanating hyphae, oily droplets were observed that did not stain in sulfo-vanillin and disappeared in lactic acid after a few hours. Although the phylogenetic analysis positioned the newly described ectomycorrhiza together with Scleroderma verrucosum and Scleroderma cepa in a single clade with a taxon name SH005470.07FU, the ectomycorrhizae of these three species can be morphologically well separated based on rhizomorph type.

Discovery or Extinction of New Scleroderma Species in Amazonia?

The Amazon Forest is a hotspot of biodiversity harboring an unknown number of undescribed taxa. Inventory studies are urgent, mainly in the areas most endangered by human activities such as extensive dam construction, where species could be in risk of extinction before being described and named. In 2015, intensive studies performed in a few locations in the Brazilian Amazon rainforest revealed three new species of the genus Scleroderma: S. anomalosporum, S. camassuense and S. duckei. The two first species were located in one of the many areas flooded by construction of hydroelectric dams throughout the Amazon; and the third in the Reserva Florestal Adolpho Ducke, a protected reverse by the INPA. The species were identified through morphology and molecular analyses of barcoding sequences (Internal Transcribed Spacer nrDNA). Scleroderma anomalosporum is characterized mainly by the smooth spores under LM in mature basidiomata (under SEM with small, unevenly distributed granules, a characteristic not observed in other species of the genus), the large size of the basidiomata, up to 120 mm diameter, and the stelliform dehiscence; S. camassuense mainly by the irregular to stellate dehiscence, the subreticulated spores and the bright sulfur-yellow colour, and Scleroderma duckei mainly by the verrucose exoperidium, stelliform dehiscence, and verrucose spores. Description, illustration and affinities with other species of the genus are provided.