Background: Lethal amanitas (Amanita section Phalloideae) are a group of wild, fatal mushrooms causing many poisoning cases worldwide. However, the diversity and evolutionary history of these lethal mushrooms remain poorly known due to the limited sampling and insufficient gene fragments employed for phylogenetic analyses. In this study, five gene loci (nrLSU, ITS, rpb2, ef1-α and β-tubulin) with a widely geographic sampling from East and South Asia, Europe, North and Central America, South Africa and Australia were analysed with maximum-likelihood, maximum-parsimony and Bayesian inference methods. Biochemical analyses were also conducted with intention to detect amatoxins and phalloidin in 14 representative samples.

This study investigated the morphological characteristics and molecular phylogenetic relationships among lethal Amanita species occurring in East Asia. The results revealed that at least nine phylogenetic taxa exist in the region. Among them, five were identical to previously known morphological taxa including A. exitialis, A. fuliginea, A. subjunquillea, A. subjunquillea var. alba and A. virosa; three new taxa, A. fuligineoides, A. rimosa and A. pallidorosea were described and illustrated here. The remaining one was labeled "A. sp. 1" because no robust morphological evidence was found to distinguish it from A. subjunquillea var. alba. The occurrence of A. virosa in East Asia, a well-known lethally poisonous mushroom originally described from Europe, was confirmed by both ITS sequences and morphology. Another lethal species native to Europe, A. phalloides, was determined as closely related to A. subjunquillea from East Asia. Amanita oberwinklerana was treated in section Phalloideae from a morphological point of view, but appeared to be a member of section Lepidella by the analyses of sequences from both the ITS regions and the large subunit of nuclear ribosomal RNA gene. Distribution features of East Asian Phalloideae and the phylogenetic relationships of these species with their counterparts from Europe and North America were also discussed. A key to species of section Phalloideae in East Asia is furnished.

Background: Genomes of lethal Amanita and Galerina mushrooms have gradually become available in the past ten years; in contrast the other known amanitin-producing genus, Lepiota, is still vacant in this aspect. A fatal mushroom poisoning case in China has led to acquisition of fresh L. venenata fruiting bodies, based on which a draft genome was obtained through PacBio and Illumina sequencing platforms. Toxin-biosynthetic MSDIN family and Porlyl oligopeptidase B (POPB) genes were mined from the genome and used for phylogenetic and statistical studies to gain insights into the evolution of the biosynthetic pathway. Results: The analysis of the genome data illustrated that only one MSDIN, named LvAMA1, exits in the genome, along with a POPB gene. No POPA homolog was identified by direct homology searching, however, one additional POP gene, named LvPOPC, was cloned and the gene structure determined. Similar to ApAMA1 in A. phalloides and GmAMA1 in G. marginata, LvAMA1 directly encodes α-amanitin. The two toxin genes were mapped to the draft genome, and the structures analyzed. Furthermore, phylogenetic and statistical analyses were conducted to study the evolution history of the POPB genes. Compared to our previous report, the phylogenetic trees unambiguously showed that a monophyletic POPB lineage clearly conflicted with the species phylogeny. In contrast, phylogeny of POPA genes resembled the species phylogeny. Topology and divergence tests showed that the POPB lineage was robust and these genes exhibited significantly shorter genetic distances than those of the housekeeping rbp2, a characteristic feature of genes with horizontal gene transfer (HGT) background. Consistently, same scenario applied to the only MSDIN, LvAMA1, in the genome. Conclusions: To the best of our knowledge, this is the first reported genome of Lepiota. The analyses of the toxin genes indicate that the cyclic peptides are synthesized through a ribosomal mechanism. The toxin genes, LvAMA1 and LvPOPB, are not in the vicinity of each other. Phylogenetic and evolutionary studies suggest that HGT is the underlining cause for the occurrence of POPB and MSDIN in Amanita, Galerina and Lepiota, which are allocated in three distantlyrelated families.

Most species in the genus Amanita are ectomycorrhizal fungi comprising both edible and poisonous mushrooms. Some species produce potent cyclic peptide toxins, such as α-amanitin, which places them among the deadliest organisms known to mankind. These toxins and related cyclic peptides are encoded by genes of the “MSDIN” family (named after the first five amino acid residues of the precursor peptides), and it is largely unknown to what extent these genes are expressed in the basidiocarps. In the present study, Amanita rimosa and Amanita exitialis were sequenced through the PacBio and Illumina techniques. Together with our two previously sequenced genomes, Amanita subjunquillea and Amanita pallidorosea, in total, 46 previously unknown MSDIN genes were discovered. The expression of over 80% of the MSDIN genes was demonstrated in A. subjunquillea. Through a combination of genomics and mass spectrometry, 12 MSDIN genes were shown to produce novel cyclic peptides. To further confirm the results, three of the cyclic peptides were chemically synthesized. The tandem mass spectrometry (MS/MS) spectra of the natural and the synthetic peptides shared a majority of the fragment ions, demonstrating an identical structure between each peptide pair. Collectively, the results suggested that the genome-guided approach is reliable for identifying novel cyclic peptides in Amanita species and that there is a large peptide reservoir in these mushrooms.

Background: Most species in the genus Amanita are ectomycorrhizal fungi, and the cyclic peptide toxins that some species produce are notoriously deadly. In total, around 25 of these peptides were found in the fruiting bodies over the past 82 years, and whether any of them are present in the mycorrhizae is unknown. Reportedly, sequenced lethal Amanita genomes harbor a significant number of precursor genes of MSDIN family, indicating there could be a much larger capacity for cyclic peptide production in these mushrooms. However, it is largely unknown that to what extent these genes are transcribed, and further, translated into true cyclic peptides. Method:In this study, three poisonous Amanita species, A. rimosa, A. exitialis and A. subjunquillea, were sequenced through PacBio and Illumina techniques. For expression analysis, one strain of A.subjunquillea was sequenced through RNA-Seq. A genome-guided approach was adopted to identify cyclic peptides by coupling predicted toxin-biosynthetic genes with mass spectrometry (MS and MS/MS). To investigate whether any of the toxins were express in the microbiome, profiling of known major toxins was conducted on A. subjunquillea mycorrhizae via HRMS and gene cloning. Results:The resultant genomes showed significant potential to produce known and unknown cyclic peptides. Together with our 2 previously sequenced genomes, in total 37 unknown MSDIN genes were discovered. Expression of over 90% of the MSDIN genes was demonstrated in two strains of A. subjunquillea. Through the genome-guided approach, 12 MSDIN genes were found to produce true, novel cyclic peptides with no additional posttranslational modifications. When the ectomycorrhizae of A. subjunquillea were analyzed by MS, all major toxins were detected. The corresponding MSDINs for these cyclic peptides were successfully cloned directly from the mycorrhizae. Conclusions:The genome-guided approach provided a speedy method to identify cyclic peptides both in Amanita mushrooms and in the ectomycorrhizae. In this study, a significant number of novel MSDIN genes were discovered, most of which were found to be expressed in the tested species. The identification of the 12 novel cyclic peptides strongly suggests that Amanita species possess a much larger reservoir of these peptides than previously thought. This is the first report to demonstrate that the cyclic peptides in Amanita species are expressed in the mycorrhizal association. All four major