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BACKGROUND The sister yeast species Cryptococcus neoformans (serotype A) and Cryptococcus deneoformans (serotype D) are causative agents of deadly cryptococcosis and fungal meningoencephalitis. These haploid yeasts can hybridise in nature, giving rise to AD hybrids that are predominantly diploid or aneuploid. Despite their increasing prevalence in clinical settings, much remains unknown about the allelic distribution patterns in AD hybrid strains. OBJECTIVES This study aims to characterise allele distributions in AD hybrids derived from the same basidium as well as from multiple basidia in a laboratory-derived C neoformans × C deneoformans hybrid cross. METHODS We dissected a total of 1625 basidiospores from 31 basidia. The 297 basidiospores that successfully germinated were genotyped by molecular characterisation of 33 markers using PCR-RFLP, with at least two markers on each of the 14 chromosomes in the genome. RESULTS Of the 297 strains, 294 contained at least one heterozygous locus, with a mean heterozygosity of ~30% per strain. Most hybrid genomes and chromosomes displayed significantly distorted allele distributions, with offspring originating from the same basidium tended to have alleles at different loci from the same parent. More basidia were skewed in favour of C deneoformans alleles, the mitochondria-donor parent, than the C neoformans alleles. CONCLUSIONS The divergence between C neoformans and C deneoformans genomes has likely created co-adapted allelic combinations, with their co-segregation in hybrid offspring imparting a significant fitness benefit. However, the diversity of genotypes recovered here in a single hybridisation event indicates the enormous capacity of AD hybrids for adaptation and diversification.

The heterothallic basidiomycetous fungus Cryptococcus neoformans has two mating types, MATa and MAT&alpha, Morphological progression of bisexual reproduction in C. neoformans is as follows: yeast to hyphal transition, filament extension, basidium formation, meiosis, and sporulation. C. neoformans Cdk-related kinase 1 (CRK1) is a negative regulator of bisexual mating. In this study, we characterized the morphological features of mating structures in the crk1 mutant and determined the genetic interaction of CRK1 in the regulatory networks of sexual differentiation. In the bilateral crk1 mutant cross, despite shorter length of filaments than in the wild-type cross, dikaryotic filaments and other structures still remained intact during bisexual mating, but the timing of basidium formation was approximately 18 h earlier than in the cross between wild type strains. Furthermore, gene expression analyses revealed that CRK1 modulated the expression of genes involved in the progression of hyphal elongation, basidium formation, karyogamy and meiosis. Phenotypic results showed that, although deletion of C. neoformans CRK1 gene increased the efficiency of bisexual mating, filamentation in the crk1 mutant was blocked by MAT2 or ZNF2 mutation. A bioinformatics survey predicted the C. neoformans GATA transcriptional factor Gat1 as a potential substrate of Crk1 kinase. Our genetic and phenotypic findings revealed that C. neoformans GAT1 and CRK1 formed a regulatory circuit to negatively regulate MAT2 to control filamentation progression and transition during bisexual mating.

Entoloma clypeatum species complex (ECSC) forms ectomycorrhiza-like roots (EMLR) with host plant species of Rosaceae or Ulmaceae. The EMLR colonized with ECSC are characterized by a thick fungal mantle, absence of a Hartig net structure, and collapse of the apical meristem caused by hyphal invasion. Some researchers have suggested parasitism of ECSC because of this unique mode of colonization; however, the nature of the interaction between ECSC and host plants has not been investigated in co-culture because of the difficulty of culturing this group of fungi. We established a procedure to synthesize EMLR of ECSC on pear seedlings using fungal cultures. Three conspecific strains of ECSC isolated from basidiospores and one strain isolated from EMLR were tested. Cultured mycelia were inoculated onto a modified Norkrans’ C (MNC) or Hyponex-yeast-glucose (HYG) medium slant on the bottom of a polycarbonate jar and covered with autoclaved andosol or a vermiculite/sphagnum moss mixture (VSM); an axenically cultivated Pyrus betulifolia seedling was then planted in the jar. Five months after inoculation, the formation of EMLR with Hartig net-like hyphae was confirmed in all of the experimental plots. However, the rate of root colonization was significantly higher in experimental plots using andosol than in those using VSM. The growth of pear seedlings was similar irrespective of the level of root colonization, suggesting commensalism rather than parasitism of ECSC. One experimental plot using strain A3, an MNC slant, and andosol as a substrate produced ECSC fruiting bodies with mature basidia and basidiospores. The results suggested that our procedure enables the synthesis of EMLR of ECSC and cultivation of their fruiting bodies.

Species of Coleosporium (Pucciniales) are rust fungi that typically alternate between pines and angiosperms. In North America, species of Coleosporium often infect Solidago (goldenrods), although their taxonomy on these hosts is unresolved. Joseph. C. Arthur and George B. Cummins regarded these as a single species, Coleosporium solidaginis (fide Arthur) or C. asterum (fide Cummins), but later inoculation studies demonstrated the presence of more than one species, distinguishable by their aecial hosts. A more recent taxonomic study of Coleosporium found that specimens on Solidago identified as C. asterum in North America were not conspecific with the type, which is from Japan, prompting the present study. Herein, we conducted a systematic study on ca. 60 collections of Coleosporium infecting species of Asteraceae from North America using regions of ribosomal DNA and morphology of teliospores and basidia. Our data indicate at least three species of Coleosporium occur on Solidago in North America, C. solidaginis, C. montanum comb. nov., which is proposed for the taxon that has commonly been identified as C. asterum in North America, and C. delicatulum, all of which can be differentiated by morphology of their basidia. In addition, the challenges of marker selection for molecular barcoding of rust fungi is discussed.

The genus Bannoa consists of four described species associated with dead leaves in southwestern Japan. In this study, we describe three new species, Bannoa guamensis, B. rosea, and B. tropicalis, from the South Pacific island of Guam and Guyana in South America. Isolates were obtained from surfaces of diseased and healthy leaves of plants in the Euphorbiaceae, Asteraceae, and Poaceae. DNA sequences from four gene regions, including nuc rDNA internal transcribed spacer ITS1‐5.8S‐ITS2 (ITS), D1–D2 domains of nuc 28S rDNA (28S), nuc 18S rDNA (18S), and a portion of tef1, which encodes translation elongation factor 1-alpha, were produced for phylogenetic analysis. Intercompatibility tests were performed, and subsequent development of clamp connections and basidia were documented for B. tropicalis. Potential life history strategies and association with diseased leaves, including rust-infected leaves, were evaluated across the genus. This is the first report of a species of Bannoa from South America.

A Dacryopinax species that was cultured in Costa Rica and fruited in the laboratory provided DNA for the first sequenced genome for the Dacrymycetes. Here we characterize the isolate morphologically and cytologically and name it D. primogenitus Molecular sequences from the nuclear large subunit gene and internal transcribed spacer indicated that it is closely related to the South American D. indacocheae with which it agrees structurally. Both species form conidia on the basidiocarp, and D primogenitus also forms them on the mycelium. Unlike previous reports for the Dacrymycetales postmeiotic nuclear division results in uninucleate basidiospores and six residual nuclei in the basidium after basidiospore discharge. Ultrastructural analysis shows the characteristic septal-pore apparatus for the class and endogenous origin of the epibasidia/sterigmata, which may be a common occurrence in Dacrymycetes and the early diverging orders of its sister class, the Agaricomycetes.

Three new and one previously described species of Physalacria (Physalacriaceae, Agaricales) are reported from China. Specimens of two additional species described from Malaysia and North America were studied for comparison. Placements of these species were corroborated based on morphological observations and molecular evidence from partial sequences of the nuc rDNA internal transcribed spacer regions (ITS) and the 28S D1-D3 region, and genes for translation elongation factor 1-α (tef1α) and the second largest subunit of RNA polymerase II (rpb2). These new species of Physalacria distributed in subtropical China were found on rotten wood of broadleaf trees or bamboo and possess stipitate-capitate basidiomata with four-spored basidia, clamp connections and smooth, inamyloid basidiospores. To facilitate studies of the genus in Asia, a key is provided for all Physalacria species reported from this region.

In the human fungal pathogen Cryptococcus neoformans, sex can benefit its pathogenicity through production of meiospores, which are believed to offer both physical and meiosis-created lineage advantages for its infections. Cryptococcus sporulation occurs following two parallel events, meiosis and differentiation of the basidium, the characteristic sexual structure of the basidiomycetes. However, the circuit integrating these events to ensure subsequent sporulation is unclear. Here, we show the spatiotemporal coordination of meiosis and basidial maturation by visualizing event-specific molecules in developing basidia defined by a quantitative approach. Monitoring of gene induction timing together with genetic analysis reveals co-regulation of the coordinated events by a shared regulatory program. Two RRM family regulators, Csa1 and Csa2, are crucial components that bridge meiosis and basidial maturation, further determining sporulation. We propose that the regulatory coordination of meiosis and basidial development serves as a determinant underlying the production of infectious meiospores in C. neoformans., eLife digest Many microbes that cause disease form spores to survive during and between infections. These include the fungus Cryptococcus neoformans, which is the leading cause of fungal meningitis worldwide. This fungus produces spores via sexual reproduction, meaning the genes from two living strains of the fungi combine to create new lives with unique genetics. By diversifying the fungus’s genetics, sexual reproduction in Cryptococcus is considered to accelerate drug resistance. Several processes must be coordinated for Cryptococcus to reproduce sexually. Genetic information recombines through a process called meiosis, the spore-making cell (known as the sexual structure) matures and later spores are produced. Scientists have identified many genes involved in each of these processes. Yet it is not known how these processes are coordinated to ensure the proper sequence of events. Liu, He, Chen et al. studied the physical changes in Cryptococcus cells when they lost certain genes. Two genes, which the researchers named CSA1 and CSA2, were found to regulate the parallel progression of meiosis and maturation of the sexual structure. Both processes need to be complete before spore production begins. Further investigation showed that these genes are important across various strains of infectious Cryptococcus. This research highlights sexual reproduction as a target to stop Cryptococcus forming spores and starting infections. The results also show that these processes change little through evolution within a large group of fungi. The next step will be to see how these systems operate across species and the effect this has on spore production.

This study explores species limits of a group of Clavaria species with taxonomic and nomenclatural problems and discusses the phylogeny and circumscription of the genus. The nuc 28S rDNA (28S) and internal transcribed spacer region phylog- enies resolve species relationships, and the ITS is shown to be an adequate barcode marker for Clavaria. Yellow, clamped species of Clavaria are distributed in two clades, (i) C. flavostellifera, sister to C. incarnata and C. asterospora in ITS analyses, characterized by producing ornamented spores, and (ii) C. argillacea-C. citrinorubra-C. flavipes-C. sphagni- cola, with smooth spores. Clavaria flavostellifera is described as new species based on morphological and molecular characters. Molecular evidence that sup- ports C. sphagnicola as distinct from C. argillacea is provided. The usefulness of spore ornamentation as a taxonomic character is discussed; it is present only in some taxa and then only on spores trapped in the hymenium. Descriptions of C. argillacea, C. flavipes and C. sphagnicola are provided, along with color photographs and a key to yellow species of Clavaria with clamped basidia. Camarophyllopsis and Clavicor- ona are recovered within a paraphyletic Clavaria in our 28S phylogeny. Clampless contextual hyphae and narrow, slightly thick-walled mycelial hyphae are proposed as synapomorphies of Camarophyllopsis and Clavaria.

Pseudobaeospora wipapatiae is described as new based on material collected in alien wet habitats on the island of Hawaii. Unique features of this beautiful species include deep ruby-colored basidiomes with two-spored basidia, amyloid cheilocystidia and a hymeniderm pileipellis with abundant pileocystidia that is initially deep ruby in KOH then changes to lilac gray. Phylogenetic analysis of nuclear large ribosomal subunit sequence data suggest a close relationship between Pseudobaeospora and Tricholoma. BLAST comparisons of internal transcribed spacer and 5.8S nuclear ribosomal subunit regions sequence data reveal greatest similarity with existing sequences of Pseudobaeospora species. A comprehensive description, color photograph, illustrations of salient micromorphological features and comparisons with phenetically similar taxa are provided.

Using a heat-treatment method, two genera of heat-resistant and xerotolerant basidiomycetes were isolated from soil samples. These two genera, Basidioascus and Geminibasidium gen. nov., are morphologically similar and phylogenetically related. The genus Basidioascus originally was described as an ascomycete, but the structures originally interpreted as single-spored asci appear to represent basidiospores. Morphologically both genera are characterized by the lack of a fruiting body, conspicuously granular and deciduous basidia with a unique basal lateral projection and apparently double-walled basidiospores. The basidia, rather than the basidiospores, are forcibly discharged in Basidioascus species but not in Geminibasidium species. In Geminibasidium species a putative basidium arises from a primary cell. These are novel forms of basidia ontogenesis previously unseen in basidiomycetes. The rDNA (SSU + 5.8S + LSU) Bayesian phylogenetic analysis suggests that these fungi are distantly related to Wallemia, another xerotolerant basidiomycete genus commonly found in indoor air dust, dried foods and natural hypersaline environments. Given the physiological similarity and phylogenetic relationships, Basidioascus and Geminibasidium are classified in a new order, Geminibasidiales, and are taxonomically assigned to the class Wallemiomycetes. Based on morphological observations and molecular phylogeny of the internal transcribed spacer (ITS), two species of Basidioascus (B. undulatus, B. magus sp. nov.) and two species of Geminibasidium (G. donsium sp. nov., G. hirsutum sp. nov.) are described. A key to these species is provided using micromorphological and cultural characters.

We analyzed the DNA sequences of four gene regions, 28S and 18S rDNA, the ITS region and rpb2, to obtain a high resolution phylogenetic tree of Dacrymycetes. In addition, we comparatively studied micro- and macromorphological characteristics of representative species. The traditional generic classification based on morphological characteristics was not reflected by our molecular phylogenies. Ancestral state reconstructions indicated that the morphology of basidia and clamp connections are evolutionarily stable. In contrast, basidiocarps and basidiospore septation patterns appear variable. Dacrymyces unisporus shares the dolipores with non-perforate parenthesomes typical of other dacrymycetous taxa but is a unique species having predominantly non-bifurcate basidia and subglobose to ovoid basidiospores with transverse and longitudinal septa. In molecular phylogenies this species is a member of Dacrymycetes but always occupies a sister position in relation to the rest of the Dacrymycetes. Based on our results we propose a new genus, Unilacryma, for D. unisporus. For proper accommodation of this taxon, we introduce the family Unilacrymaceae and the order Unilacrymales.

The meiotic spindles of Phallus impudicus had a similar ultrastructure to those seen in other basidiomycetes. After meiosis the basidal apex differentiated to form a number of broadly based protuberances which subsequently developed into basidiospores (up to 9 per basidium). The nuclei then underwent a post-meiotic mitosis within the cytoplasm of each basidiospore. After this mitosis one nucleus remained in the basidiospore and a complete septum developed at the base. The significance of this arrangement of meiosis, spore production and post-meiotic mitosis is discussed with respect to the taxonomy and life cycle of this unusual basidiomycete.

The Tremellomycetes (Agaricomycotina, Basidiomycota, Fungi) are a nutritionally heterogeneous group comprising saprotrophs, animal parasites, and fungicolous species (fungal-inhabiting, including lichen-inhabiting). The relationships of many species, particularly those with a lichenicolous habit, have never been investigated by molecular methods. We present a phylogeny of the Tremellomycetes based on three nuclear DNA ribosomal markers (nSSU, 5.8S and nLSU), representing all main taxonomic groups and life forms, including lichenicolous taxa. The Cystofilobasidiales, Filobasidiales, Holtermanniales, and Tremellales (including the Trichosporonales) are recovered as monophyletic, but this is not the case for the Tremellomycetes. We suggest, however, that the Cystofilobasidiales tentatively continue to be included in the Tremellomycetes. As currently circumscribed, the Filobasidiaceae, Sirobasidiaceae, Syzygosporaceae and Tremellaceae are non-monophyletic. Cuniculitremaceae, Sirobasidiaceae and Tetragoniomycetaceae are nested within Tremellaceae. The lichenicolous species currently included within the Tremellomycetes belong in this group, distributed across the Filobasidiales and Tremellales. Lichen-inhabiting taxa do not form a monophyletic group; they are distributed in several clades and sometimes intermixed with taxa of other nutritional habits. Character state reconstruction indicates that two morphological traits claimed to characterize groups in the Tremellomycetes (the basidium habit and basidium septation) are highly homoplastic. Comparative phylogenetic methods suggest that the transitions between single and catenulate basidia in the Tremellales are consistent with a punctuational model of evolution whereas basidium septation is likely to have evolved under a graduational model in the clade comprising the Holtermanniales, Filobasidiales, and Tremellales.

Diplomitoporus rimosus is a white rot polypore widely distributed in western N America, collected once in Africa, and is reported here from Iran. Molecular phylogenetic analyses of partial nuclear ribosomal LSU and ITS revealed that, unlike the generic type D. flavescens nested within the polyporoid clade, D. rimosus is positioned in the hymenochaetoid clade. A new genus is introduced to accommodate the species. Cyanotrama gen. nov. is recognized by its resupinate habit, narrow and strongly cyanophilous skeletal hyphae, barrel-shaped to short clavate basidia, variable presence of hyphal pegs and growth on conifers, especially Juniperus. Comparisons are made with representatives of polypores having similar morphological characteristics especially with cyanophilous skeletals. The biogeography of Cyanotrama rimosa with regard to its association with Juniperus woodlands is discussed briefly.

Cryptococcus neoformans is a basidiomycete fungus that is found worldwide and causes disease in humans and animal species. The fungus grows asexually as a budding yeast. Under laboratory conditions it is capable of sexual reproduction between two mating types. After cell fusion a dikaryotic filament develops, at the tip of which a basidium gives rise to four chains of basidiospores. Because the chains each comprise 10–30 spores, rather than single spores, the analysis of individual meiotic events has not been attempted in C. neoformans in the style of tetrad analyses performed in other fungal species. Here, the basidiospores from >100 basidia were micromanipulated and the resultant >2500 progeny analyzed for three genetic markers to understand the sexual process in this fungus, leading to four observations: (i) Marker segregation provides genetic evidence for a single meiotic event within the basidium followed by multiple rounds of mitosis. (ii) Using each basidium as an unordered tetrad, the ADE2 and URA5 genes are linked to their centromeres, consistent with adjacent genomic regions rich in repetitive elements predicted to comprise Cryptococcus centromeres. (iii) Lack of germination of basidiospores is attributed to aneuploidy, rather than dormancy. (iv) Analysis of basidiospores derived from single chains demonstrates that each chain can contain different genotypes. This mechanism of sexual spore production would benefit the species with a high rate of dispersal and at the same time aid in simultaneous dissemination of both mating types to new locations in the environment.

Pisolithus microcarpus (Cooke and Massee) G. Cunn. is a model organism for the studies on the ecology, physiology, and genetics of the ectomycorrhizal associations. However, little is known about the basidiosporogenesis in this species and, in particular, the nuclear behavior after karyogamy. In this work, the events involved in basidiosporogenesis and meiosis in P. microcarpus were analyzed using fluorescence and scanning electron microscopy. The basidia are formed inside peridioles by the differentiation of the cells along the whole hyphae. Basidial cells measure 12–18 μm in length and 6–7 μm in diameter. P. microcarpus produces eight basidiospores per basidium imbibed in a gelatinous matrix in the basidiocarp. The basidiospores are globose, equinate, with blunt spines, and measure 6–8 μm. Karyogamy can take place inside basidia as well as in undifferentiated hyphal cells followed by nuclear migration to a newly developed basidium where meiosis takes place. After the formation of the meiotic tetrad, one round of post-meiotic mitosis occurs, resulting in the production of eight nuclei per basidium. The newly-formed nuclei migrate into the basidiospores asynchronously, resulting in the production of eight uninucleate spores. This corresponds to pattern A of post-meiotic mitosis. This work is the first report on meiosis and post-meiotic mitosis during basidiosporogenesis in P. microcarpus and contributes to clarify some aspects of the biology and genetics of this ectomycorrhizal species.

Russian knapweed (Rhaponticum repens) is a rangeland weed pest in the western United States. One candidate fungus for biological control of R. repens is Puccinia acroptili, which causes a rust disease. Understanding the life cycle of candidate rust fungi for weed biological control is an essential component in risk assessments and evaluations, and for P. acroptili such was unknown. For this reason greenhouse studies were undertaken to clarify the life cycle of P. acroptili under artificial conditions. Spermogonia with spermatia developed on R. repens following plant inoculation with teliospores. Artificial transfer of spermatia between spermogonia resulted in the development of aecia with uredinioid aeciospores. Inoculation with aeciospores or urediniospores resulted in uredinia containing urediniospores and occasional amphispores. Telia with teliospores and occasional mesospores developed later. Teliospores produced typical basidia with four basidiospores. These results suggest that the life cycle of P. acroptili is macrocyclic and autoecious. Inoculation with teliospores also frequently resulted in production of sori that were morphologically similar to aecia but which were not associated with spermogonia or the classical transfer of spermatia. The ontology of these sori is unknown. This is the first description of spermogonia and the first report and description of basidiospores, aecia, aeciospores, amphispores and mesospores of P. acroptili.

The relationship between Sporidiobolus johnsonii and S. salmonicolor was investigated using rDNA sequence data. Two statistically well-supported clades were obtained. One clade included the type strain of S. johnsonii and the other included the type strain of S. salmonicolor. However, some mating strains of S. salmonicolor were found in the S. johnsonii group. These strains belonged to mating type A2 and were sexually compatible with mating type A1 strains from the S. salmonicolor group. DNA–DNA reassociation values were high within each clade and moderate between the two clades. In the re-investigation of teliospore germination, we observed that the basidia of S. salmonicolor were two-celled. In S. johnsonii, basidia were not formed and teliospore germination resulted in direct formation of yeast cells. We hypothesize that the S. johnsonii clade is becoming genetically isolated from the S. salmonicolor group and that a speciation process is presently going on. We suspect that the observed sexual compatibility between strains of the S. johnsonii and S. salmonicolor groups and the possible genetic flow between the two species has little biological relevance because distinct phenotypes have been fixed in the two taxa and intermediate (hybrid) sequences for LSU and ITS rDNAs have not been detected.

Evidence derived from molecular studies in recent years has revealed that corticioid fungal genera are present in all major clades of Homobasidiomycetes. Brunneocorticium pyriforme, a corticioid fungus is proposed as a new species and placed in a new genus belonging to the euagarics clade. This fungus has been collected in subtropical-tropical Taiwan and southern Yunnan Province, China. Basidiocarps often occur on bark of living Murraya spp. (Rutaceae). Basidiocarps of B. pyriforme are resupinate with a smooth hymenial surface, a dimitic hyphal system, with nodose-septate generative hyphae and abundant yellowish brown skeletal hyphae, and leptocystidia. It has 2-sterigmate basidia and pear-shaped basidiospores. Phylogenetic analysis based on sequence data derived from LSU rDNA included Brunneocorticium in the euagarics clade of Homobasidiomycetes, allied to the agaricoid genera Marasmiellus, Campanella, etc. The molecular analysis indicated that the Brunneocorticium was independent from other corticioid genera with similar morphological features.

Teliospores, basidia, cultures, hyphal septations, cellular interactions and nucleotide sequences from the D1/D2 region of the nuclear large subunit ribosomal RNA gene of Entyloma ossifragi occurring on Narthecium ossifragum (Nartheciaceae ) were examined and compared with findings in the Georgefischeriales and other Ustilaginomycetes . The data show that Entyloma ossifragi is a member of the Georgefischeriales . Among the Georgefischeriales, Entyloma ossifragi morphologically is very similar to Jamesdicksonia species, but differs from this genus and all other Georgefischeriales by the formation of dolipores without striations that become closed during teliosporogenesis. In addition, in our molecular phylogenetic analyses Entyloma ossifragi stands well apart from Jamesdicksonia forming with some Tilletiopsis specimens a statistically supported cluster. Accordingly, the genus Gjaerumia gen. nov. and the family Gjaerumiaceae fam. nov. are proposed to accommodate Entyloma ossifragi in the Georgefischeriales . The new combination G. ossifragi (syn. Entyloma ossifragi ) is made.

Amauromyces farinaceous is investigated. The species is a rare corticiaceous Homobasidiomycete recently collected in Taiwan. The unique basidial morphology, cell walls and septal pores of the hyphae are studied by transmission electron microscopy. The study demonstrates the gradual thickening of cell walls in the lower parts of young basidia, leaving only a small asymmetric cytoplasmic channel in mature stages. Systematics of genus Amauromyces are discussed by comparing it with Athelia, Athelopsis, Chaetoderma, Columnocystis, Gloeosoma, Paullicorticium, Sistotremastrum, Trechispora, Tulasnella and Veluticeps.

Two fossil poroid hymenophore fragments, one from the Cretaceous Period and the other from the Eocene Epoch, are described. The permineralized specimens were obtained from marine calcareous concretions on Vancouver Island, British Columbia, Canada, and were studied using the cellulose acetate peel technique. Size and distribution of pores in the hymenophores, as well as the hyphal anatomy of the dissepiments and some hymenial elements, were examined. In the Cretaceous specimen, Quatsinoporites cranhamii sp. nov., pores are round to elliptical, three per mm, and 130-540 μm diam. Dissepiments consist of narrow, simple septate, hyphae. Neither basidia nor basidiospores are present, but acuminate hymenial cystidia, up to 54 μm in length, are common. The Eocene specimen, Appianoporites vancouverensis sp. nov., has a pore density of six per mm and pores are 130-163 μm in diam. Dissepiments consist of narrow, simple septate, thin-walled hyphae. Neither basidia nor basidiospores are present, but acuminate, thick-walled hymenial cystidia, up to 32 μm in length, are common. The poroid hymenophore is a characteristic of a number of extant basidiomycete taxa, including the Boletales, Polyporales and Hymenochaetales. It is unlikely that the fleshy, ephemeral, terrestrial basidiomata of the Boletales would be preserved in a marine environment, and thus the specimens are interpreted as belonging to basidiomycete lineages, with persistent, leathery or corky basidiomata. The simple septate hyphae, the minute pores and presence of cystidia most closely resemble taxa of the Hymenochaetales. These fossils unequivocally push back the minimum age of homobasidiomycetes and extend their paleogeographical range.

Monobasidiospore isolates were prepared from basidiocarps of Stereum sanguinolentum. Five isolates per basidiome were paired with each other and with isolates from the trama. Interbasidiome pairings of the trama isolates and of a selection of single-spore isolates also were performed. Thin sections of the hymenium were stained with DAPI and examined by fluorescence microscopy to study the nuclei in the basidia. Spore prints were stained with DAPI to count the number of nuclei per spore. SEM was used to determine the number of basidiospores per basidium. All intrabasidiome pairings were compatible. In contrast, interbasidiome pairings, except one, were incompatible, independent of whether single-spore or trama isolates were paired. Fertile basidiomes were formed in single-basidiospore cultures. Basidia were regularly four-spored. On average, 5% of the basidiospores possessed one nucleus, 82% two, 2% three and 1% four nuclei. Ten percent of the spores appeared to be empty. Karyogamy, meiosis and postmeiotic mitosis were observed in the basidia. Nuclei resulting directly from meiosis, i.e., without having undergone postmeiotic mitosis, sometimes were observed in the sterigmata or spore primordia. The high number of vegetative compatibility groups (VCG) of S. sanguinolentum observed in this study and earlier studies is difficult to explain without sexual or parasexual recombination. We suppose that the majority of spores with ≥2 nuclei are amphithallic, possessing at least one nucleus of each mating type. Recombination could occur by exchange of nuclei among VCGs via anastomoses between homothallic compartments. Transfer of nuclei from heterothallic to homothallic mycelia or matings between homothallic mycelia, which originate from monokaryotic spores, might be other paths for gene exchange.

Among 400 wild specimens of A. bisporus collected in Europe, only three were tetrasporic. In the case of two of them from France, a previous study showed that one was homokaryotic and hypothetically belonged to a homothallic entity while the other was heterokaryotic and possibly resulted from hybridization between a member of this entity and a classical bisporic strain. A third tetrasporic specimen recently was discovered in Greece. Morphological and genetic comparisons, using alloenzymatic markers, molecular markers and ITS polymorphisms, reveal that this third specimen is homokaryotic and belongs, with the homokaryotic specimen from France, to the same entity. Dissimilarity analysis confirms the hybrid origin of the heterokaryotic specimen. Varietal status is proposed for this homothallic, highly homogeneous entity, and A. bisporus var. eurotetrasporus is described. This novel variety clearly differs from var. bisporus by its tetrasporic basidia and from var. burnettii by its longer spores. It has a complex story because it can interbreed with var. bisporus and shares the same habitat; however, because of its homothallic life cycle and its partial intersterility, it is probably in the process of speciation.

A new genus, Heterorepetobasidium, is proposed to accommodate two new species, H. subglobosum and H. ellipsoideum, recently collected in Taiwan. These species have apically, partially septate basidia, strongly swollen sterigmata, and repetobasidia. The systematics of the new taxa and related ones, inclusive of Ceratobasidium and the Ceratobasidiaceae, are reinterpreted.

To gain insight in the phylogenetic relationships within the Exobasidiales, septal pore apparatus, host-parasite interactions, sori, hymenia, basidia, and nucleotide sequences from the 5′ terminal domain of the nuclear large subunit rRNA gene were studied and compared.

Five new species of Inocybe, I. iringolkavensis, I. keralensis, I. kuruvensis, I. muthangensis and I. wayanadensis, are described from Kerala state, India, based on morphological and molecular data. All are associated with trees belonging to Dipterocarpaceae. Inocybe iringolkavensis is characterized by nodulose to somewhat stellate basidiospores, 1-4-spored basidia, and caulocystidia restricted to the stipe apex. Inocybe keralensis has a yellowish brown pileus, lamellae with whitish, serrate edges, smooth, ellipsoidal basidiospores and a duplex pileipellis with the superficial hyphae devoid of encrustations and encrusted hyphae beneath. The diagnostic features of I. kuruvensis include a dark brown pileus, stipe with a whitish base and grayish brown, floccose-fibrillose surface, nodulose basidiospores with saddle-shaped projections and faintly encrusted paracystidia with refractive contents. Violet basidiomata with a rimose, hygrophanous pileus, densely pruinose stipe with a marginate-bulbous base, and nodulose basidiospores are the major features of I. muthangensis. Inocybe wayanadensis is characterized by small, whitish basidiomata, a viscid pileus with a rimulose surface, a densely pruinose and fibrillose stipe with a marginate-bulbous base, nodulose basidiospores, thick-walled pleuro- cheilo- and caulocystidia and an ixotrichoderm-type pileipellis. The phylogenetic relationships of these new species are inferred from an analysis of nuc rDNA sequences of the internal transcribed spacers (ITS1-5.8S-ITS2) and the 28S gene. Except I. keralensis, which belongs to the Pseudosperma clade, all other species belong to the Inocybe clade. This study represents the second report of an Inocybe species (I. muthangensis) that combines violet basidiomata with nodulose basidiospores.

The current knowledge of sexual reproduction of Cryptococcus gattii from a population genetics perspective is reviewed in this chapter. In genetic studies, cryptic species are usually detected as exclusive groups of organisms occupying strongly supported branches on phylogenetic trees that have been derived from different, independent loci. Assessing the relative numbers of α and a cells is therefore an important aspect of determining if populations are likely to have undergone sexual recombination. The initial studies of mating type in C. gattii found 84% of clinical isolates to be of the α mating type. Mating type was assessed by coculture with tester strains, and the majority of strains (~90%) were fertile, producing basidia and basidiospores. Amplified fragment length polymorphisms (AFLPs), which are highly discriminatory molecular markers, were therefore selected to establish multilocus genotypes. The population genetics of clinical collections is generally more complicated than the study of environmental populations as humans travel and may acquire an infection far from where they eventually present with clinical disease and an isolate is obtained. The pattern of pairwise compatibility among global VGII isolates presents a striking contrast to that seen in VGI. All VGII populations studied to date are heavily biased for one or the other mating type, and the most probable scenario is that mating occurs between isolates of the same sex.

The phylogenetic relationships of anasto- mosis groups (AG) of Rhizoctonia associated with Cer- atobasidium and Thanatephorus teleomorphs were de- termined by cladistic analyses of internal transcribed spacer (ITS) and 28S large subunit (LSU) regions of nuclear-encoded ribosomal DNA (rDNA). Combined analyses of ITS and LSU rDNA sequences from 41 isolates representing 28 AG of Ceratobasidium and Thanatephorus supported at least 12 monophyletic groupings within Ceratobasidium and Thanatephorus. There was strong support for separation of Cerato- basidium and Thanatephorus, however, six sequences representing different AG of Ceratobasidium grouped with certain sequences within the Thanatephorus clade. Phylogenetic analysis of ITS sequence data from 122 isolates revealed 31 genetically distinct groups from Thanatephorus (21 groups) and Cerato- basidium (10 groups) that corresponded well with previously recognized AG or AG subgroups. Al- though phylogenetic analysis of ITS sequences pro- vided evidence that several AG of Ceratobasidium may be more closely related with some AG from Thana- tephorus, these relationships were not as strongly sup- ported by bootstrap analysis.

Characteristics of hyphal septation, cellular interaction, sporulation, cultures and/or nucleotide sequences from the 5’ terminal domain of the nuclear large subunit rRNA gene of some species of Exobasidium, Microstroma and Muribasidiospora were examined and compared. Our analyses show that the order Microstromatales comprises Microstroma, Muribasidiospora triumfetticola and the anamorphic species Rhodotorula bacarum, R. phylloplana and Sympodiomycopsis paphiopedili , whereas Muribasidiospora hesperidium and Muribasidiospora indica are members of the Exobasidiales. Because of the high degree of morphological divergence between Muribasidiospora triumfetticola and Microstroma , a new genus, Volvocisporium , and a new family, Volvocisporiaceae , of the Microstromatales are proposed. Apart from the phylogenetic implications, the most interesting observations in the present work are the unusual development of the basidia, especially of the basidiospores, and the nutrient transport system from the host attacking hyphae to the basidia in Muribasidiospora triumfetticola.

The genus Tricholosporum is characterised by cruciate spores. The formation of these basidiospores and their subsequent growth until release from the sterigmata, is described from a sequence of SEM photographs. The spores on a basidium form either a diad, a triad or a tetrad during their development. The outer cell wall layer of the basidiospore enlarges, resulting in the cruciate shape of the spores and the ultimate calyptrate appearance after release when desiccated. The spores are seceded sequentially.

A suitable screening method for heterozygous DNA markers in shiitake,Lentinula edodes (Berk.) Pegler, is reported. Monokaryons were derived from a dikaryon by de-dikaryotization via protoplast formation. Compatibility of the monokaryons was determined by pairwise culture on agar plates. We selected the primers to amplify polymorphic fragments among the original strain (Hokken600∶H600) and two monokaryons (H600PP-39 and H600PP-67) showing compatibility. A total of 135 fragments were selected as specific random amplified polymorphic DNAs (RAPDs) resulting from 56 primers of the 147 primers tested. Furthermore, we tested whether the polymorphic fragments segregated into 2∶2 among four strains isolated from a basidium. Most of the polymorphic fragments (about 97.8%) showed 2∶2 segregation among the four strains. We concluded that the polymorphic fragments were heterozygous if they were detected in either of the monokaryons (H600PP-39 and H600PP-67) and segregated to 2∶2 among four meiotic strains (H600B-1,-2, -3, and -4). A total of 132 heterozygous DNA markers were therefore selected from a dikaryon of shiitake (Hokken600∶H600).

The development of the peridioles of a Mycocalia sp., and the primordia of Scleroderma verrucosum and S. areolatum, has been studied, particularly in view of the presence of metamorphosed basidia. In the Mycocalia sp. and S. verrucosum spore-like bodies were formed exclusively by transformation of whole basidia. The ontogeny of S. verrucosum has been compared with that of S. areolatum. The structure of the exoperidium of S. verrucosum is much more complicated: hyphal knots play an important part in its construction. The processes giving rise to the exoperidium may be homologous with those constituting universal veils in Agaricales.

Recent field work on smut fungi in Cuba yielded one new species and, among many new records, several poorly known species which are described and illustrated. The new species, Cintractia cubensis on Rhynchospora microcephala, is characterized by rather large, dark, and finely foveolate teliospores which can germinate with basidia of only two basidial cells. The poorly known C. samanensis was found on the new host Rhynchospora fascicularis ssp. fascicularis. Entyloma guaraniticum on Bidens pilosa differs from E. bidentis on the same host by thick-walled teliospores embedded in the mesophyll of leaves deforming them. Spores of E. bidentis are smaller and do not deform the leaf. Sphacelotheca everhartii on Andropogon virginicus, S. microspora on Paspalum notatum, and S. panici-leucophaei on Trichachne insularis are transferred into Sporisorium.

In order to examine the systematic posi- tion of Entyloma callitrichis Liro, morphological, ul- trastructural and molecular characters of E. callitri- chis and some species of the Entylomatales and Doas- sansiales were studied and compared. The results show that E. callitrichis belongs to the Doassansi- aceae, occupying a basal position within this family. In contrast with the other species of Doassansiaceae, the teliospores of E. callitrichis are not arranged in spore balls. Therefore, the new genus Doassinga is proposed to accommodate E. callitrichis.

We report results on a systematic study of the genus Tuber using isozyme analysis. Eighteen en- zyme loci were analyzed on numerous fruitbodies of various morphotaxa collected from different Spanish, French, Italian a -' lstrian locations. Fruitbodies were classified i-,to 20 electrophoretic types based on isozyme polyrmorphisms. Genetic distances were ana

The soilborne plant pathogenic basidiomycetous fungus Thanatephorus cucumeris (anamorph: Rhizoctonia solani) is composed of at least 12 anastomosis groups (AG), which seem to be genetically...

The process is described of teliospore germination in Tilletia opaca and T. sumatii leading to the production of basidiospores on basidia, and later the development of ballistospores and blastospores on agar. In both species the basidium shows some evidence of being a condensed dichotomously branched structure. The situation in these two smuts is discussed in relation to that in several other species of Tilletia , and some consideration is given to the origirt of the basidium and evolutionary trends within the genus.

Gigasperma americanum is described as a new species associated with Cercocarpus ledifolius from northern Utah. The species is characterized by large, smooth, globose to subglobose basidiospores with a basal pore which are produced on singlespored basidia. Species of Gigasperma have not previously been reported in North America.

A number of homothallic isolates in the Agaricus subfloccosus complex, designated W4, was obtained from basidiome collections at four separate locations in the U.K. The relative prominence of floccules on the pileus surface, the ring structure, stipe length and vivid discoloration of the cut or bruised flesh distinguished these isolates from Canadian and Swiss isolates of A. subfloccosus and a morphologically similar species, the cultivated mushroom A. bisporus. The mycelial extension growth rates of the A. subfloccosus W4 isolates on agar and in composted substrate were less than those of Swiss and Canadian isolates of A. subfloccosus, which in turn were less than those of wild and commercial strains of A. bisporus. Basidiomes of all A. subfloccosus isolates were obtained from culture in composted substrates. There were significant differences in basidiome yield and mycelial extension growth rate between different sources of the A. subfloccosus W4 isolates, but the two parameters were not correlated. Single spore isolates from the same parent culture and same basidium were found to have significant differences in basidiome yield. The culture of A. subfloccosus isolates on a range of composted substrates was examined and their potential as a commercial edible mushroom is discussed.

In Exidia recisa basidiospores germinated on agar to give a branched mycelium with prostrate conidiophores forming bacilliform conidia in succession as from a phialide. The situation is compared with that in other heterobasidiomycetes. In Sirobasidium intermediae basidia were formed in basipetal succession. The basidia liberated spore-like epibasidia (sterigmata) which accumulated in large numbers as a surface slime on the basidiocarp. The very few epibasidia that germinated in situ gave rise to aerial ballistosporic basidiospores which, on agar, germinated to give a yeast phase. Spread thinly on agar, most epibasidia germinated in a variety of ways; many gave rise to aerial ballistospores; others to a yeast phase; and a few underwent repetition to form sessile blastospores. Yeast-like colonies, arising from discharged basidiospores, developed occasional aerial tufts of clamped hyphae which, on isolation, grew slowly and soon reverted to the yeast phase. In forming a yeast-like phase and in not producing conidia as from a phialide, Sirobasidium seems closer taxonomically to Tremella than to other tremellaceous fungi.

The genus Rugosospora (Agaricales, Basidi? omycota) comprises two species R. ochraceobadia, de? scribed from Africa, and R. pseudorubiginosa, de? scribed from Mexico and Colombia. In this paper, the morphology, taxonomy, and nomenclature of R. pseu? dorubiginosa is discussed and its geographical distri? bution extended. Comparison of the basidiospore or? namentation of both species is based on scanning elec? tron microscopy studies. A key to the species of the

The objective of this work was to study the basidiosporogenesis and the intraspecific variation in the number of basidiospores produced per basidium in Agaricus brasiliensis with transmission (TEM) and scanning electron microscopy (SEM). A. brasiliensis produces predominantly tetrasporic basidia, but this trait may vary depending on the strain. For certain strains, such as CS2 and CS7, the frequency of bisporic and trisporic basidia was similar to, or greater than, that of tetrasporic strains. These results suggest that some strains of A. brasiliensis may be amphithallic; however, this behavior is variable and strain dependent. The development of basidia and basidiospores occurs asynchronously during basidiocarp production. The basidiospore cell wall is composed of three distinct layers and presents variable thickness. The conspicuous presence of lipid bodies also was observed in the basidiospores, while nuclei, mitochondria, vacuoles and dolipore septa could be visualized only in the basidia. The basidiospores generally are produced free but also may be enveloped by an extracellular matrix with unknown chemical composition. The presence of connection hyphae linking the basidia was observed for the first time in A. brasiliensis. This characteristic, so far not reported for other fungi, may represent a specific strategy of A. brasiliensis for exchanging nuclei and other cell material between basidial cells during basidiosporogenesis.

Ustilago maydis (DC) Cda., a phytopathogenic Basidiomycota, is the causal agent of corn smut. During its life cycle U. maydis alternates between a yeast-like, haploid nonpathogenic stage, and a filamentous, dikaryotic pathogenic form that invades the plant and induces tumor formation. As all the members of the Subphylum Ustilaginomycotina, U. maydis is unable to form basidiocarps, instead it produces teliospores within the tumors that germinate forming a septate basidium (phragmobasidium). We have now established conditions allowing a completely different developmental program of U. maydis when grown on solid medium containing auxins in dual cultures with maize embryogenic calli. Under these conditions U. maydis forms large hemi-spheroidal structures with all the morphological and structural characteristics of gastroid-type basidiocarps. These basidiocarps are made of three distinct hyphal layers, the most internal of which (hymenium) contains non-septate basidia (holobasidia) from which four basidiospores develop. In basidiocarps meiosis and genetic recombination occur, and meiotic products (basidiospores) segregate in a Mendelian fashion. These results are evidence of sexual cycle completion of an Ustilaginomycotina in vitro, and the demonstration that, besides its quasi-obligate biotrophic pathogenic mode of life, U. maydis possesses the genetic program to form basidiocarps as occurs in saprophytic Basidiomycota species.

We investigated nuclear behavior during basidiosporogenesis in Lentinw, Panus, and Neolenti- nus in an attempt to discover characters for taxonomic segregation of lentinoid-pleurotoid fungi. In Lentinus tigrinus and Panus lecomtei somatic hyphae are binu- cleate. Karyogamy and meiosis occur in the basidia, meiotic products migrate into spores and postmeiotic mitosis occurs; this is followed by back-migration of one nucleus from each spore into the basidium. Ma- ture spores are consequently uninucleate and dis- charged basidia are quadrinucleate. In Neolentinus le- pideus many somatic cells are multinucleate. Karyogamy, meiosis, and postmeiotic mitosis occur as in L. tigrinus and P. lecomtei, but there is no back- migration, mature spores are binucleate, and dis- charged basidia are anucleate. The patterns of nuclear behavior in L. tigrinus and P. lecomtei correspond to type C nuclear behavior as defined by Duncan and Galbraith, whereas that of Neolentinus corresponds to type D nuclear behavior. Lentinus and Panus cannot be distinguished on the basis of postmeiotic nuclear behavior, but both can be distinguished from Pleurotus

Puccinia rutainsulara recently was described as a microcyclic rust on Melicope (= Pelea) spp. (Ru- taceae) endemic to Hawaii. Spermogonia are not pro? duced, and teliospores are extruded from deep-seated telia in tightly compacted bristle-like columns. Telio? spores produced an elongate basidium, typically with one, but rarely two, basidiospores. Following kary- ogamy, the nucleus migrated into the basidium and divided one or more times to produce variably two, three, or four daughter nuclei. While the other nuclei remained apparently functionless in the basidium, the distal-most nucleus migrated into the developing ba? sidiospore and divided to produce a tetranucleate ba? sidiospore. The observed nuclear behavior and pro? duction of a single basidiospore are not typical of rust fungi elsewhere, but similar unusual teliospore ger? mination and nuclear behavior have been observed in other Hawaiian rusts.

Recent studies indicate that numerous tet? rasporic Suillus species have both binucleate and uni? nucleate spores. If the binucleate spores are homo? karyotic, resulting from postmeiotic mitotic divisions in the spores, then the breeding system is primarily determined by the heterothallic mating system of the fungus, be that bipolar or tetrapolar. Alternatively, if the postmeiotic mitoses occur in the basidia prior to nuclear migration, then some proportion ofthe spores could also be secondarily homothallic (heterokaryot? ic), this proportion being determined by the pattern of nuclear migration into the spores. The secondary mycelia of many Suillus species do not regularly pro? duce clamp connections, thus complicating the deter? mination of the genetic constituencies of the binucle? ate spores. In this paper we report the results of genetic analyses using randomly amplified polymorphic DNA markers which suggest that the binucleate spores of Suillus granulatus from eastern North America may result from postmeiotic mitotic divisions in the basidia, prior to nuclear migration into the spores. Binucleate spores of S. granulatus are thus potentially secondarily homothallic. The implications of a functionally diverse mating system, resulting from heterothallic uninucle? ate spores and secondarily homothallic binucleate spores, are discussed for this cosmopolitan ectomy? corrhizal basidiomycete.

The course of germination of teliospores in 8 species of Sporisorium is illustrated. In 5 species (S. tricholaenae, S. themedae-arguentis, S. cornutum, S. bursum and S. erythraeense) germination soon leads to a structure that can readily be interpreted as a 4-celled basidium; but that in S. catharticum is 2-celled. In S. moniliferum and S. tripogonis the corresponding structure cannot easily be related to a basidium. In S. tricholaenae germination of the basidiospores (sporidia) leads to the formation of haplophase hyphae some of which may generate relatively large sporidia both on the surface of the medium and in an aerial situation. S. themedae-arguentis behaves in a similar manner but no aerial spores are formed. It is suggested that, because of the great variety in the patterns of teliospore germination, Sporisorium cannot be regarded as a ‘natural’ genus.

Item does not contain fulltext Populations of Armillaria mellea (Basidiomycota, Agaricales) across much of its range are heterothallic; homothallic populations occur only in Africa (A. mellea ssp. africana), China (China Biological Species CBS G), and Japan (A. mellea ssp. nipponica). Monosporous isolates of heterothallic A. mellea are haploid and their mating behaviour is consistent with the requirement of two different alleles at two mating-type loci (tetrapolar mating system) to create a diploid individual. In contrast, monosporous isolates of homothallic A. mellea are putatively diploid; they bypass the haploid phase by undergoing karyogamy in the basidium (a unique type of secondary homothallism/pseudohomothallism). In order to determine the genetic origin of this homothallism, we analyzed genetic variation of 47 heterothallic isolates from China, Europe, and North America, and 14 homothallic isolates from Africa, China, and Japan. Gene trees and mutational networks were constructed for partial mitochondrial gene ATP synthase subunit 6 (ATP6) and for the following nuclear genes: actin (ACTIN), elongation factor subunit 1-alpha (EFA), glyceraldehyde 3-phosphate dehydrogenase (GPD), and the RNA polymerase subunit II (RPB2). Homothallic isolates from Africa and Japan shared a common mitochondrial ATP6 haplotype with homothallic isolates from China, and are likely introductions. Homothallic isolates from China that shared a common mitochondrial haplotype with all European isolates did not share European nuclear haplotypes, as revealed by median-joining networks, but instead clustered with haplotypes from China or were intermediate between those of China and Europe. Such mitochondrial-nuclear discordance in homothallic isolates from China is indicative of hybridization between lineages originating from China and Europe. 01 juni 2012