Amanita subpallidorosea, a new lethal fungus from China

Polymerase chain reaction-based methods for the rapid identification of Amanita exitialis

Amanita exitialis, a deadly mushroom found in eastern Asia, causes the highest death rates among all poisonous mushrooms in China. The aim of the present study was to develop an efficient, accurate, and user-friendly PCR-based method for identifying A. exitialis that could facilitate the prevention, diagnosis, and treatment of associated food poisoning. A. exitialis-specific primers and probes were designed based on the internal transcribed spacer region variations of 27 mushroom species. Specificity was confirmed using conventional and real-time PCR for 23 non-target mushroom species, including morphologically similar and closely related species. Compared to conventional PCR, real-time PCR was more sensitive (detectable DNA concentration: 1.36 × 10-2 ng/μL vs. 1.36 × 10-3) and efficient (analysis time: 1 h vs. 40 min). Furthermore, the real-time PCR results could be immediately visualized using amplification curve analysis. The results present two robust PCR-based methods for A. exitialis identification that can facilitate food safety.

Diversity and taxonomy of the genus Amanita (Amanitaceae, Agaricales) in the Yanshan Mountains, Northern China

Globally, the species of Amanita are key components of ectomycorrhizal ecosystems. Some of them are widely known as poisonous or edible fungi. Although many new Amanita species from China have been described, the species diversity of Yanshan Mountains remains unknown. We here describe three new species, namely, A. borealis sp. nov. (Sect. Amanita), A. brunneola sp. nov. (Sect. Caesareae), and A. yanshanensis sp. nov. (Sect. Validae), based on morphological observations and molecular phylogenetic analyses. In addition, nine known species, namely, A. caesareoides (Sect. Caesareae), A. chiui (Sect. Vaginatae), A. muscaria (Sect. Amanita), A. oberwinklerana (Sect. Roanokenses), A. ovalispora (Sect. Vaginatae), A. subglobosa (Sect. Amanita), A. subjunquillea (Sect. phalloideae), A. vaginata var. vaginata (Sect. Vaginatae), and A. virosa (Sect. phalloideae), were reported from Yanshan Mountains for the first time. Our results emphasize that China has a high diversity of Amanita species and that additional studies are required to understand the exact species number. These findings play a crucial role in Amanita toxin research and ecological conservation. This study investigated the areas where Amanita species-related research is lacking. The study also attempted to better understand Amanita distribution and thus contribute to related research. This study enriches the species diversity of Amanita in Yanshan Mountains and offers additional data supporting the macrofungal systematics, toxin research, and diversity and ecological studies of Amanita in future studies.

Enlargement of the knowledge of Cortinarius section Anomali (Agaricales, Basidiomycota): introducing three new species from China

Cortinarius is a globally distributed agaricoid genus that has been well studied in Europe and America with over 1,000 described species. However, as part of an ongoing effort to investigate the diversity of Cortinarius section Anomali in China, the resource investigation and classification research are still limited, and the species diversity has not been clarified by far. During the re-examination of the Chinese Cortinarius specimens, C. cinnamomeolilacinus, C. subclackamasensis, and C. tropicus, belonging to the sect. Anomali, were described in China as new to science based on morphological examination and phylogenetic analysis. The three new species are described and illustrated in detail according to the Chinese materials. The phylogenetic analysis based on internal transcribed spacer sequences confirmed the placement of the three species in the Cortinarius sect. Anomali clade. Phylogenetically related and morphologically similar species to these three new species are discussed.

Morphology and phylogeny identify two new species and one new subspecies of Podoscypha from Yunnan Province, Southwest China

In this study, Podoscypha was taxonomically and phylogenetically evaluated. In total, five specimens collected from the tropical areas of Yunnan Province in Southwest China were studied. In combination with morphological observations and phylogenetic analyses based on ITS and LSU loci, two new species and one new subspecies, Podoscypha subinvoluta, P. tropica, and P. petalodes subsp. cystidiata, respectively, were discovered. The illustrated descriptions of the new species and subspecies are provided. Moreover, the main morphological differences between related species are discussed.

Morphology, Multilocus Phylogeny, and Toxin Analysis Reveal Amanita albolimbata, the First Lethal Amanita Species From Benin, West Africa

Many species of Amanita sect. Phalloideae (Fr.) Quél. cause death of people after consumption around the world. Amanita albolimbata, a new species of A. sect. Phalloideae from Benin, is described here. The taxon represents the first lethal species of A. sect. Phalloideae known from Benin. Morphology and molecular phylogenetic analyses based on five genes (ITS, nrLSU, rpb2, tef1-α, and β-tubulin) revealed that A. albolimbata is a distinct species. The species is characterized by its smooth, white pileus sometimes covered by a patchy volval remnant, a bulbous stipe with a white limbate volva, broadly ellipsoid to ellipsoid, amyloid basidiospores, and abundant inflated cells in the volva. Screening for the most notorious toxins by liquid chromatography-high-resolution mass spectrometry revealed the presence of α-amanitin, β-amanitin, and phallacidin in A. albolimbata.

Diversity of MSDIN family members in amanitin-producing mushrooms and the phylogeny of the MSDIN and prolyl oligopeptidase genes

Background

Amanitin-producing mushrooms, mainly distributed in the genera Amanita, Galerina and Lepiota, possess MSDIN gene family for the biosynthesis of many cyclopeptides catalysed by prolyl oligopeptidase (POP). Recently, transcriptome sequencing has proven to be an efficient way to mine MSDIN and POP genes in these lethal mushrooms. Thus far, only A. palloides and A. bisporigera from North America and A. exitialis and A. rimosa from Asia have been studied based on transcriptome analysis. However, the MSDIN and POP genes of many amanitin-producing mushrooms in China remain unstudied; hence, the transcriptomes of these speices deserve to be analysed.

Results

In this study, the MSDIN and POP genes from ten Amanita species, two Galerina species and Lepiota venenata were studied and the phylogenetic relationships of their MSDIN and POP genes were analysed. Through transcriptome sequencing and PCR cloning, 19 POP genes and 151 MSDIN genes predicted to encode 98 non-duplicated cyclopeptides, including α-amanitin, β-amanitin, phallacidin, phalloidin and 94 unknown peptides, were found in these species. Phylogenetic analysis showed that (1) MSDIN genes generally clustered depending on the taxonomy of the genus, while Amanita MSDIN genes clustered depending on the chemical substance; and (2) the POPA genes of Amanita, Galerina and Lepiota clustered and were separated into three different groups, but the POPB genes of the three distinct genera were clustered in a highly supported monophyletic group.

Conclusions

These results indicate that lethal Amanita species have the genetic capacity to produce numerous cyclopeptides, most of which are unknown, while lethal Galerina and Lepiota species seem to only have the genetic capacity to produce α-amanitin. Additionally, the POPB phylogeny of Amanita, Galerina and Lepiota conflicts with the taxonomic status of the three genera, suggesting that underlying horizontal gene transfer has occurred among these three genera.

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.

Universal identification of lethal amanitas by using Hyperbranched rolling circle amplification based on α-amanitin gene sequences

Hyperbranched rolling circle amplification (HRCA) with a padlock probe (PLP) targeting the α-amanitin (α-AMA) gene, as a screening tool for the universal identification of lethal amanitas, was established in this study. With the isothermal HRCA assay, all of the lethal Amanita species tested from Phalloideae (10) were positive, while the non-Phalloideae Amanita species (15) and three amanitin-containing Lepiota and Galerina species were negative. Furthermore, the PLP based on α-AMA sequences from lethal Amanita species was effective for Amanita α-AMA, but not Amanita β-AMA or non-Amanita α-AMA. HRCA sensitivity was 100-fold higher than conventional PCR with a detection limit of 100 copies (recombinant plasmid containing α-AMA), and 0.2% lethal amanitas could be detected in dry mushroom blends. The HRCA method presented provided a rapid, specific, sensitive and low-cost identification tool for lethal amanitas.

Two new species of Amanitasect.Phalloideae from Africa, one of which is devoid of amatoxins and phallotoxins

Two new species of Amanitasect.Phalloideae are described from tropical Africa (incl. Madagascar) based on both morphological and molecular (DNA sequence) data. Amanitabweyeyensissp. nov. was collected, associated with Eucalyptus, in Rwanda, Burundi and Tanzania. It is consumed by local people and chemical analyses showed the absence of amatoxins and phallotoxins in the basidiomata. Surprisingly, molecular analysis performed on the same specimens nevertheless demonstrated the presence of the gene sequence encoding for the phallotoxin phallacidin (PHA gene, member of the MSDIN family). The second species, Amanitaharkonenianasp. nov. was collected in Tanzania and Madagascar. It is also characterised by a complete PHA gene sequence and is suspected to be deadly poisonous. Both species clustered together in a well-supported terminal clade in multilocus phylogenetic inferences (including nuclear ribosomal partial LSU and ITS-5.8S, partial tef1-α, rpb2 and β-tubulin genes), considered either individually or concatenated. This, along with the occurrence of other species in sub-Saharan Africa and their phylogenetic relationships, are briefly discussed. Macro- and microscopic descriptions, as well as pictures and line drawings, are presented for both species. An identification key to the African and Madagascan species of Amanitasect.Phalloideae is provided. The differences between the two new species and the closest Phalloideae species are discussed.

Investigating and analyzing three cohorts of mushroom poisoning caused by Amanita exitialis in Yunnan, China

Amanita exitialis is a lethal mushroom found in China. Knowledge regarding taxonomic characterization, toxin detection, general poisoning conditions, clinical manifestations, laboratory examinations, and clinical treatments for this species is currently lacking. We investigated three A. exitialis mushroom poisoning cohorts in Yunnan Province in 2014 and 2015, involving 10 patients. Mushroom samples were identified by morphological and molecular studies. Ultra performance liquid chromatography-electrospray ionization tandem mass spectrometry was used to detect the peptide toxins in the mushroom samples. Epidemiological information, clinical data, and results of laboratory examinations were collected and analyzed. The mushroom samples were all identified as A. exitialis. The average toxin concentration decreased from the cap to the stipe to the volva, and the average concentration of the peptide toxins decreased in the order of α-amanitin > phallacidin > β-amanitin > γ-amanitin. The latency period between ingestion and the onset of symptoms was 13.9 ± 2.1 h, and the time from ingestion to hospitalization was 49.6 ± 8.5 h. The most common symptoms were nausea and vomiting (100%). Four patients died from fulminant hepatic failure. Laboratory examinations showed that the alanine transaminase, aspartate transaminase, prothrombin time, and activated partial thromboplastin time levels peaked on the third day post-ingestion. Total bilirubin and direct bilirubin values peaked on day 7. The death group and the survival group had a similar variation trend of serological indexes, but the death group had a greater change. A. exitialis is an extremely dangerous mushroom and there is a need to educate the public to avoid picking and eating wild mushrooms that have not been definitively identified.

Determination of cyclopeptide toxins in Amanita subpallidorosea and Amanita virosa by high-performance liquid chromatography coupled with high-resolution mass spectrometry

Amanita subpallidorosea is a recently discovered lethal Amanita sect. Phalloideae species found in China that is clustered with A. virosa in the same clade based on molecular phylogenetic analysis. However, the cyclopeptide toxin contents of these lethal mushrooms remain poorly studied. In this study, the cyclopeptide toxins in A. subpallidorosea were reported for the first time and the cyclopeptide compositions of A. subpallidorosea and A. virosa species were systematically analyzed. Thirteen cyclopeptides and two unknown compounds were identified or observed from these two lethal mushrooms by high-performance liquid chromatography coupled with high-resolution mass spectrometry. Of the known cyclopeptides, the virotoxins alaviroidin, viroisin, and viroidin, which were previously thought to be restricted to A. virosa, were identified in A. subpallidorosea. The cyclopeptide compositions showed that there are diversities in the kinds and levels of amatoxins, phallotoxins, and virotoxins between A. subpallidorosea and A. virosa species, and that the amount of total toxins in the tested A. subpallidorosea is significantly higher than that in the tested A. virosa. Furthermore, consistency of the cyclopeptide toxins with the molecular phylogenetic relationships was demonstrated.

Lethal Amanita species in China

Lethal amanitas (Amanita sect. Phalloideae) cause many casualties worldwide. Recent molecular phylogenetic studies revealed diverse lethal Amanita spp. in China. Here a 5-gene phylogeny (nuc rDNA region encompassing the internal transcribed spacers 1 and 2 with the 5.8S rDNA, the D1-D3 domains of nuc 28S rDNA, and partial RNA polymerase II second largest subunit, translation elongation factor 1-α and β-tubulin genes) is used to investigate the phylogenetic lineages and species delimitation in this section. Thirteen species are recognized, including four new species, namely A. griseorosea, A. molliuscula, A. parviexitialis, and A. subfuliginea They are documented with morphological, multigene phylogenetic, and ecological evidence, line drawings, and photographs and compared with similar species. A key to the Chinese lethal Amanita species is provided.

Cyclopeptide toxins of lethal amanitas: Compositions, distribution and phylogenetic implication

Lethal amanitas (Amanita sect. Phalloideae) are responsible for 90% of all fatal mushroom poisonings. Since 2000, more than ten new lethal Amanita species have been discovered and some of them had caused severe mushroom poisonings in China. However, the contents and distribution of cyclopeptides in these lethal mushrooms remain poorly known. In this study, the diversity of major cyclopeptide toxins in seven Amanita species from Eastern Asia and three species from Europe and North America were systematically analyzed, and a new approach to inferring phylogenetic relationships using cyclopeptide profile was evaluated for the first time. The results showed that there were diversities of the cyclopeptides among lethal Amanita species, and cyclopeptides from Amanita rimosa and Amanita fuligineoides were reported for the first time. The amounts of amatoxins in East Asian Amanita species were significantly higher than those in European and North American species. The analysis of distribution of amatoxins and phallotoxins in various Amanita species demonstrated that the content of phallotoxins was higher than that of amatoxins in Amanita phalloides and Amanita virosa. In contrast, the content of phallotoxins was significantly lower than that of amatoxins in all East Asian lethal Amanita species tested. However, the distribution of amatoxins and phallotoxins in different tissues showed the same tendency. Eight cyclopeptides and three unknown compounds were identified using cyclopeptide standards and high-resolution MS. Based on the cyclopeptide profiles, phylogenetic relationships of lethal amanitas were inferred through a dendrogram generated by UPGMA method. The results showed high similarity to the phylogeny established previously based on the multi-locus DNA sequences.