Speciation Underpinned by Unexpected Molecular Diversity in the Mycorrhizal Fungal Genus Pisolithus.

The mutualistic ectomycorrhizal (ECM) fungal genus Pisolithus comprises 19 species defined to date which colonize the roots of >50 hosts worldwide suggesting that substantial genomic and functional evolution occurred during speciation. To better understand this intra-genus variation, we undertook a comparative multi-omic study of nine Pisolithus species sampled from North America, South America, Asia, and Australasia. We found that there was a small core set of genes common to all species (13%), and that these genes were more likely to be significantly regulated during symbiosis with a host than accessory or species-specific genes. Thus, the genetic "toolbox" foundational to the symbiotic lifestyle in this genus is small. Transposable elements were located significantly closer to gene classes including effector-like small secreted proteins (SSPs). Poorly conserved SSPs were more likely to be induced by symbiosis, suggesting that they may be a class of protein that tune host specificity. The Pisolithus gene repertoire is characterized by divergent CAZyme profiles when compared with other fungi, both symbiotic and saprotrophic. This was driven by differences in enzymes associated with symbiotic sugar processing, although metabolomic analysis suggest that neither copy number nor expression of these genes is sufficient to predict sugar capture from a host plant or its metabolism in fungal hyphae. Our results demonstrate that intra-genus genomic and functional diversity within ECM fungi is greater than previously thought, underlining the importance of continued comparative studies within the fungal tree of life to refine our focus on pathways and evolutionary processes foundational to this symbiotic lifestyle.

A field-based investigation of simple phenol variation in Australian Agaricus xanthodermus.

Agaricus xanthodermus and other species of the yellow-staining section Xanthodermatei are responsible for mushroom-related poisoning cases that require treatment. However, longstanding anecdotal evidence indicates that this species appears to exhibit considerable variation in toxicity, resulting in gastrointestinal irritation of varying severity in most cases. We quantified the amount of phenol, hydroquinone, and catechol in mushrooms using a novel protocol for gas chromatography-mass spectrometry (GC-MS) and investigated their levels in different basidiomatal structures, different developmental stages, and on different nutritional substrates. Phenol concentration was greater in the pileus than the stipe, in mature compared with immature basidiomata, and in basidiomata occurring in woody mulch versus lawns. Variation in toxicity is suggested to be due in part to variation in phenol concentration, developmental stage and tissue type consumed, and substrate. Variation in human sensitivity to simple phenols may also play a role but was not formally investigated in this study.

Revision of the genus Restingomyces, including two new species from Mexico.

To document sequestrate fungal diversity in American tropical regions, we performed a series of field surveys in southeastern Mexico and discovered two new species in the phalloid genus Restingomyces (Trappeaceae, Phallales). Here, we describe them based on morphological and phylogenetic analyses of mitochondrial adenosine triphosphatase (ATPase) subunit 6 and nuc 28S rDNA. Restingomyces guzmanianus is characterized by the brownish peridium, yellowish brown gleba, and ellipsoid basidiospores, whereas R. yaaxtax is characterized by the white peridium, pale green gleba, and small ellipsoid basidiospores. Both species occur in medium-statured tropical dry forest. The original diagnosis of the genus Restingomyces is emended to include these novel species. Illustrations are provided.

Intra-species genetic variability drives carbon metabolism and symbiotic host interactions in the ectomycorrhizal fungus Pisolithus microcarpus.

Ectomycorrhizal (ECM) fungi are integral to boreal and temperate forest ecosystem functioning and nutrient cycling. ECM fungi, however, originate from diverse saprotrophic lineages and the impacts of genetic variation across species, and especially within a given ECM species, on function and interactions with the environment is not well understood. Here, we explore the extent of intra-species variation between four isolates of the ECM fungus Pisolithus microcarpus, in terms of gene regulation, carbon metabolism and growth, and interactions with a host, Eucalyptus grandis. We demonstrate that, while a core response to the host is maintained by all of the isolates tested, they have distinct patterns of gene expression and carbon metabolism, resulting in the differential expression of isolate-specific response pathways in the host plant. Together, these results highlight the importance of using a wider range of individuals within a species to understand the broader ecological roles of ECM fungi and their host interactions.

Continental-scale metagenomics, BLAST searches, and herbarium specimens: The Australian Microbiome Initiative and the National Herbarium of Victoria.

PREMISE: Motivated to make sensible interpretations of the massive volume of data from the Australian Microbiome Initiative (AusMic), we characterize the soil mycota of Australia. We establish operational taxonomic units (OTUs) from the data and compare these to GenBank and a data set from the National Herbarium of Victoria (MEL), Melbourne, Australia. We also provide visualizations of Agaricomycete diversity, drawn from our analyses of the AusMic sequences and taxonomy. METHODS: The AusMic internal transcribed spacer (ITS) data were filtered to create OTUs, which were searched against the National Center for Biotechnology Information Nucleotide database and the MEL database. We further characterized a portion of our OTUs by graphing the counts of the families and orders of Agaricomycetes. We also graphed AusMic species determinations for Australian Agaricomycetes against latitude. RESULTS: Our filtering process generated 192,325 OTUs; for Agaricomycetes, there were 27,730 OTUs. Based on the existing AusMic taxonomy at species level, we inferred the diversity of Australian Agaricomycetes against latitude to be lowest between -20 and -25 decimal degrees. DISCUSSION: BLAST comparisons provided reciprocal insights between the three data sets, including the detection of unusual root-associated species in the AusMic data, insights into mushroom morphology from the MEL data, and points of comparison for the taxonomic determinations between AusMic, GenBank, and MEL. This study provides a tabulation of Australian fungi, different visual snapshots of a subset of those taxa, and a springboard for future studies.

Phylogeny, biogeography and taxonomic re-assessment of Multifurca (Russulaceae, Russulales) using three-locus data.

Multifurca is a small genus newly established to accommodate lactarioid and russuloid species with some characters reminiscent of corticoid members of Russulaceae. It shows an amphi-pacific distribution with strong preference for the tropical zone of the Northern Hemisphere and thus has particular significance for biogeographical study. Using worldwide samples and three loci (ITS, 28S rDNA and rpb2), we demonstrated that Multifurca is split into two highly supported major clades that are here recognized at the subgeneric level: subg. Furcata subg. nov. exclusively includes lactarioid species, while subg. Multifurca includes species with a russuloid habit. Using phylogenetic species recognition and comparison of genetic distances we recognize five new and six previously described species, almost double the known number of species before this study. Molecular dating using a Bayesian method suggested that Multifurca originated in early Paleocene and diversified in the Eocene. The most recent interspecific divergences occurred both in Asia and America, roughly at the same time around the Pliocene. Ancestral area reconstruction and comparisons of genetic distances and morphology suggested an early divergence within Australasia or tropical Asia. From the early Miocene to Pliocene, multiple dispersals/migrations to Australasia and North America by island hopping or land bridge likely happened. Vicariance at the late Tertiary might be the most likely mechanism accounting for the eastern Asia-southeastern North America and Australasia-tropical Asia disjunct distributions. The shared polymorphisms in the ITS alignment, numerous degenerated base pairs in the rpb2 sequences and weak conflict between the ITS and LSU genealogies of M. subg. Furcata suggest recent speciation. Host specificity of Multifurca species or species pairs is relatively low. Host shifts are believed to have aided establishment in new territories during the dispersals and migrations.

Cryptic diversity in the sequestrate genus Stephanospora (Stephanosporaceae: Agaricales) in Australasia.

Historically a single name, Stephanospora flava, was applied to all collections of Stephanospora in Australasia. We used morphological characters with molecular support to differentiate and describe nine novel cryptic species, and refine the circumscription of S. flava. Stephanospora flava is herein restricted to bispored collections from Tasmania, and the quadrisporic Stephanospora tetraspora is raised to species level. Six species (four new) are endemic to Australia, S. flava s.s, S. tetraspora comb. nov., Stephanospora sheoak, Stephanospora cribbae, Stephanospora hystrispora, and Stephanospora occidentiaustralis. Three species Stephanospora poropingao, Stephanospora pounamu, and Stephanospora kanuka are endemic to New Zealand; and one species, Stephanospora aorangi occurs in both Australia and New Zealand. Two other new species, Stephanospora novae-caledoniae and Stephanospora papua, are endemic to New Caledonia or Papua New Guinea, respectively. Analyses of three nuclear gene regions (ITS, ef-1, and LSU) are consistent with current classifications of the family Stephanosporaceae. Athelidium aurantiacum is an outlier, with a strongly supported core of Cristinia (Clade I), Lindtneria (Clade II), Stephanospora, Mayamontana, and Lindtneria trachyspora (Clade III), and a novel lineage of environmental and sporocarp sequences (Clade IV). Taxonomic and nomenclatural issues raised by the presence of both type species of Stephanospora (Stephanospora caroticolor) and Lindtneria (L. trachyspora) in the same clade are discussed.

Sequestrate species of Agaricus and Macrolepiota from Australia: new species and combinations and their position in a calibrated phylogeny.

Australian collections of sequestrate Agaricaceae were examined with morphological and molecular data (nuclear DNA from ITS and LSU), and the majority were found to belong to the genera Agaricus and Macrolepiota. Previously described Australian species of Endoptychum are transferred to the appropriate agaricoid genera and several new combinations proposed. Descriptions and illustrations are provided for these and eight new species: Agaricus eburneocanus sp. nov., A. chartaceus sp. nov., A. erythrosarx sp. nov., A. inilleasper sp. nov., A. pachydermus sp. nov., Macrolepiota gasteroidea sp. nov., M. vinaceofibrillosa sp. nov. and M. turbinata sp. nov. The sequestrate genus Barcheria is retained as a distinct taxon. Timing of evolution of sequestrate sporocarp forms in Macrolepiota, Chlorophyllum and Agaricus seems to have occurred in the past 15 000 000 y, and a stem age is approximately 65 000 000 y for Barcheria.

Characterisation of ectomycorrhizal formation by the exotic fungus Amanita muscaria with Nothofagus cunninghamii in Victoria, Australia.

The occurrence of the exotic ectomycorrhizal fungus Amanita muscaria in a mixed Nothofagus-Eucalyptus native forest was investigated to determine if A. muscaria has switched hosts to form a successful association with a native tree species in a natural environment. A mycorrhizal morphotype consistently found beneath A. muscaria sporocarps was examined, and a range of morphological and anatomical characteristics in common with those described for ectomycorrhizae formed by A. muscaria on a broad range of hosts were observed. A full description is provided. The likely plant associate was determined to be Nothofagus cunninghamii based upon anatomy of the roots. Analysis of ITS-1 and ITS-2 regions of nuclear ribosomal DNA sequences confirmed the identities of both fungal and plant associates. These findings represent conclusive evidence of the invasion of a non-indigenous ectomycorrhizal fungus into native forest and highlight the ecological implications of this discovery.

Phenology of epigeous macrofungi found in red gum woodlands.

The timing of fruiting body production by epigeous macrofungi is thought to be mostly determined by substrate moisture and temperature. Understanding the environmental cues that influence fruiting can help when designing surveys, interpreting results, and predicting effects of an altered climate. Species fruiting in 22 river red gum (Eucalyptus camaldulensis) woodland sites in southeastern Australia was recorded at regular intervals over 2 y. Models were constructed to explain the phenology of 25 of the most common species, as well as the total number of species found fruiting on each survey occasion. We found that rainfall minus evaporation and the time of year each influenced fruiting of the common fungi, but to varying degrees depending on species. Using these same variables, the model predictions for the total number of species expected to be found on each survey occasion fit the observations reasonably well (R(2)=0.49). The models could be used to estimate the probability of presence for species of conservation interest, to optimise survey timing, or to predict effects of climate change on fruiting.

Establishment of ectomycorrhizal fungal community on isolated Nothofagus cunninghamii seedlings regenerating on dead wood in Australian wet temperate forests: does fruit-body type matter?

Decaying wood provides an important habitat for animals and forms a seed bed for many shade-intolerant, small-seeded plants, particularly Nothofagus. Using morphotyping and rDNA sequence analysis, we compared the ectomycorrhizal fungal community of isolated N. cunninghamii seedlings regenerating in decayed wood against that of mature tree roots in the forest floor soil. The /cortinarius, /russula-lactarius, and /laccaria were the most species-rich and abundant lineages in forest floor soil in Australian sites at Yarra, Victoria and Warra, Tasmania. On root tips of seedlings in dead wood, a subset of the forest floor taxa were prevalent among them species of /laccaria, /tomentella-thelephora, and /descolea, but other forest floor dominants were rare. Statistical analyses suggested that the fungal community differs between forest floor soil and dead wood at the level of both species and phylogenetic lineage. The fungal species colonizing isolated seedlings on decayed wood in austral forests were taxonomically dissimilar to the species dominating in similar habitats in Europe. We conclude that formation of a resupinate fruit body type on the underside of decayed wood is not necessarily related to preferential root colonization in decayed wood. Rather, biogeographic factors as well as differential dispersal and competitive abilities of fungal taxa are likely to play a key role in structuring the ectomycorrhizal fungal community on isolated seedlings in decaying wood.

The safety of edible fungi purchased at Melbourne markets.

OBJECTIVE: To determine if toxic mushroom species are sold at Melbourne fruit and vegetable markets. METHODS: We purchased a specimen of every mushroom on sale at six large Melbourne markets on four separate days evenly spread during the period April to June, 2005. These specimens were identified by a specialist mycologist at the Royal Botanic Gardens Melbourne. RESULTS: Ten edible mushroom species, but no toxic species, were identified. CONCLUSIONS: Mushrooms purchased from Melbourne markets appear to be safe. IMPLICATIONS: While this study provides no evidence that public health is at risk from mushrooms sold at Melbourne markets, it has important limitations. Ongoing periodic surveillance is warranted.

Parental predictors of pediatric panic disorder/agoraphobia: a controlled study in high-risk offspring.

Our objective was to evaluate parental risk factors for pediatric-onset panic disorder/agoraphobia (PD/AG) in offspring at high risk for PD/AG. Comparisons were made between parents with PD who had a child with PD or AG (N = 27) and parents with PD without children with PD or AG (N = 79). Comparisons were also made between the spouses of these parents with PD. Separation anxiety disorder, social phobia, obsessive-compulsive disorder, and bipolar disorder in the parents with PD and their spouses accounted for the risk for childhood onset PD/AG in the offspring. This risk was particularly high if both parents were affected with social phobia. These findings suggest that psychiatric comorbidity with other anxiety disorders and with bipolar disorder in parents with PD and their spouses confer a particularly high risk in their offspring to develop PD/AG in childhood.

Description and affinities of a new sequestrate fungus, Barcheria willisiana gen. et sp. nov. (Agaricales) from Australia.

A new sequestrate fungus, Barcheria willisiana gen. et sp. nov., is described and its affinities evaluated using nLSU rDNA sequence data. This unusual fungus has several characters that are reminiscent of species of Agaricus and Lepiota, but with a very reduced basidiome form. The nLSU rDNA of four Australian taxa, Barcheria willisiana, Agaricus xanthodermus, Leucoagaricus naucinus, and Lepiota discolorata, was sequenced for this study. Parsimony analysis of the sequences placed Barcheria within an Agaricus clade.

Type studies of sequestrate Russulales II. Australian and New Zealand species related to Russula.

Nomenclatural types of the basionyms of species of sequestrate relatives of Russula from Australia and New Zealand were studied and original descriptions emended. Illustrations of microscopic characters are provided for the first time for many species. Several recombinations are proposed, including: (i) Arcangeliella crichtonii comb. nov. (≡ Cystangium crichtonii), (ii) Arcangeliella hepaticus comb. nov. (≡ Elasmomyces hepaticus), (iii) Macowanites tomentosa comb. nov. (≡ Hydnangium tomentosum).