This issue of Mycological Research News features: An Amanita muscaria fruit body with a pored hymenium; and Aspergillosis in sea fans. A review article considers the chemistry, biology , toxicology and ethnomycology of A. muscaria, and fast-tracked is a paper reporting double-stranded RNA elements in Agaricus bisporus mushrooms affected by MVX disease.

Molecular papers consider the population structure in Fomitopsis rosea, and the relationships of Sclerotium rolfsii and S. delphinii, present evidence for recombination in ‘asexual’ Alternaria spp., examine the genetic diversity in Rhizoctonia isolates from Lotus, and demonstrate polymorphisms in biosynthesis genes in Fusarium graminearum. DNA fingerprinting reveals differences in Pochonia chlamydosporia from different nematode hosts, and primers for the detection of P. chlamydosporia var. catenulate effective in soil have been devised.

Ascospore release and survival in Sclerotinia sclerotiorum has been studied in depth, and the anaerobic conditions for the production of the yeast-like morph of Rhizopus circinelloides described. The effects of tropical Xylariaceae as wood decay agents of hard- and soft-woods are compared.

Systematic papers consider Beverwykella and similar tropical aeroaquatic hyphomycetes, report the rediscovery of Basidiobolum fimbriatum, and describe a fossil Metacapnodium species from Baltic amber.

The following new scientific names are introduced in this part: Ramicephala gen. nov.; Beverwykella clathrata and R. sphaerospora spp. nov.; and Metacapnodium succinum comb. nov. (syn. Rosaria succina).

The fly agaric is a remarkable mushroom in many respects; these are its bearing, history, chemical components and the poisoning that it provokes when consumed. The ‘pantherina’ poisoning syndrome is characterized by central nervous system dysfunction. The main species responsible are Amanita muscaria and A. pantherina (Amanitaceae); however, some other species of the genus have been suspected for similar actions. Ibotenic acid and muscimol are the active components, and probably, some other substances detected in the latter species participate in the psychotropic effects. The use of the mushroom started in ancient times and is connected with mysticism. Current knowledge on the chemistry, toxicology, and biology relating to this mushroom is reviewed, together with distinctive features concerning this unique species.

Double-stranded RNA (dsRNA) has been isolated from Agaricus bisporus fruit bodies exhibiting a wide range of disease symptoms. The symptoms which occurred singularly or in combination included; bare cropping areas on commercial beds (primordia disruption), crop delay, premature veil opening, off- or brown-coloured mushrooms, sporophore malformations and loss of crop yield. All symptoms were associated with loss of yield and/or product quality. Collectively, these symptoms are described as mushroom virus X (MVX) disease. The dsRNA titre was much lower than that previously encountered with the La France viral disease of mushrooms and a modified cellulose CF11 protocol was used for their detection. A broad survey of cultivated mushrooms from the British industry identified dsRNA elements ranging between 640 bp and 20.2 kbp; the majority have not previously been described in A. bisporus. 26 dsRNA elements were identified with a maximum of 17, apparently non-encapsidated dsRNA elements, in any one sample. Three dsRNAs (16.2, 9.4 and 2.4 kbp) were routinely found in mushrooms asymptomatic for MVX. Previously, La France disease was effectively contained and controlled by minimising the on-farm production and spread of basidiospores. Our on-farm observations suggest that MVX could be spread by infected spores and/or mycelial fragments.

The genetic structure of five Fennoscandian populations of the threatened wood-decay fungus Fomitopsis rosea (Basidiomycota) was investigated using codominant PCR–RFLP, allele specific amplification (ASA) markers, inter simple sequence repeat (ISSR) markers and mating studies. Sequence analyses of a subset of single spore isolates revealed sequence variation in four target sequences; internal transcribed spacer (ITS) and intergenic spacer (IGS1) of the nuclear ribosomal DNA, the translation elongation factor 1 alpha (efa) gene and the super oxide dismutase (sod) gene. No sequence variation was found in amplified portions of the mitochondrial large and small rRNA genes. Genotype distributions were mostly (90%) in accordance with Hardy–Weinberg expectations, and the nrDNA markers (ITS/IGS1), efa and sod were in most cases (87%) in linkage equilibrium, indicating an outcrossing reproductive mode, panmictic conditions and large population sizes of the fungus. Mating tests confirmed that F. rosea exhibits an outcrossing bipolar heterothallic mating system. Mating allele richness was high in two investigated populations. Phylogenetic analyses of ITS and IGS1 sequences from the five geographic populations revealed some geographic sub-structuring of the ITS sequences, but no sub-structuring of IGS1. The nrDNA (ITS/IGS1), efa and sod markers gave a low overall FST (0.013). The ISSR markers gave no clustering of the populations in UPGMA, and the between-population variance component was very low in AMOVA (0.4%), indicating a high level of gene flow.

The phylogenetic relationships of the stem rot pathogens Sclerotium rolfsii and S. delphinii were examined, based on their rDNA ITS sequences. The ITS regions were cloned and sequenced to identify three distinct ITS types: r-1, r-2, and r-3. Two different ITS types exist within S. rolfsii and S. delphinii strains. Japanese strains and one strain of S. rolfsii from the USA contain types r-1 and r-2, whereas another strain from the USA and one from Chile have only one ITS type, r-2. S. delphinii strains have types r-1 and r-3. We discuss the implications of the common presence of ITS type r-1 for the taxonomy and evolution of this species complex.

About 15000 species of ascomycete fungi lack a known sexual state. For fungi with asexual states in the anamorph genera Embellisia, Ulocladium, and Alternaria, six species have known sexual states but more than 50 species do not. In sexual filamentous ascomycetes, opposite mating type information at the MAT1 locus regulates mating and the opposite mating type genes each have a clonal, non-recombining phylogenetic history. We used PCR to amplify and sequence fragments of the opposite mating type genes from three supposedly asexual species, A. brassicae, A. brassicicola and A. tenuissima. Each haploid fungal isolate had just one mating type, but both mating types were present in all the three species. We sequenced the ribosomal ITS regions for isolates of opposite mating type, for the three asexual species and four known related sexual species. In a phylogenetic analysis including other ITS sequences from GenBank®, the three asexual species were not closely related to any of the known sexual species. Isolates of opposite mating type but the same species had identical ITS sequences. During any period of asexual evolutionary history, lineages of each mating type would have had a separate evolutionary history and any ITS substitutions shared between isolates of opposite mating type would have had to accumulate by convergence. Allowing for varying substitution rates and assuming a Poisson distribution of substitutions, the probability that isolates of opposite mating type shared an ITS substitution through convergence was low. This suggests that isolates of opposite mating type of A. brassicae, A. brassicicola and A. tenuissima were exchanging substitutions through sexual or parasexual reproduction while the ITS was evolving. If sexuality was lost, it was lost after the period of evolutionary history represented by the shared substitutions.

Species of Rhizoctonia cause a blight of Lotus corniculatus, a perennial forage legume. We characterized genetic variation and virulence in populations of R. solani and binucleate Rhizoctonia's associated with diseased L. corniculatus in field plantings over several years. Isolates of anastomosis groups AG-1 and AG-4 accounted for the R. solani recovered from diseased leaf and shoot tissues. Isolates of binucleate Rhizoctonia were recovered predominantly from soil and associated plant debris. Isolates of R. solani were more virulent on leaves and shoots of L. corniculatus than were binucleate Rhizoctonia isolates. Numerous unique DNA restriction patterns were observed among binucleate isolates and anastomosis groups of R. solani. Variation in restriction patterns was greater among isolates of AG-1 from the lower plant canopy than from the upper canopy. No restriction pattern was shared by any isolate from AG-1 and AG-4. Allelic and genotypic heterogeneity of AG-1 isolates were also greater in the lower plant canopy. Binucleate isolates exhibited greater heterogeneity than AG-1 isolates from either canopy region. L. corniculatus offers significant opportunities for investigating temporal and spatial dynamics of genetic structure of Rhizoctonia populations in perennial plant systems.

Diversity in trichothecene mycotoxin production by 167 isolates of Fusarium graminearum was examined by chemical and molecular methods. Isolates from barley, corn, and wheat grown in Korea produced either deoxynivalenol (DON) or nivalenol (NIV), whereas isolates from corn grown in the United States produced DON only. Southern blotting of MseI-digested genomic DNA's from these isolates was performed using a 0.6-kb fragment of Tri5, a key enzyme for trichothecene production, as a probe. This technique revealed a single-band polymorphism between these isolates, with 1.8- and 2.2-kb bands arising from DON and NIV producers, respectively. The same set of isolates was subjected to previously developed PCR assays using primers derived from Tri7 or Tri13. These assays also revealed a single-band polymorphism between NIV- and DON-producing chemotypes. The polymorphisms at Tri5, Tri7, or Tri13 in all of the US isolates were consistent with their chemotypes as identified by GC–MS. However, for seven Korean isolates, chemical and molecular analyses yielded seemingly inconsistent results. This issue was resolved by Southern blot analysis with the Tri5 probe using two other restriction enzymes and sequence comparison of a 3.8-kb region spanning Tri5. In addition, one of these exceptional isolates was found to carry both DON and NIV chemotype-specific regions, possibly resulting from recombination between the two chemotypes.

The mitosporic fungus Pochonia chlamydosporia is a potential biocontrol agent for cyst (Heterodera spp. and Globodera spp.) and root knot (Meloidogyne spp.) nematodes, which are important agricultural plant pests. 54 isolates from diverse geographical regions and several nematode hosts were used in this study. Genetic variation was examined using enterobacterial repetitive intergenic consensus (ERIC) primed PCR and sequences from the internal transcribed spacer (ITS) rRNA region. ERIC PCR yielded 35 scorable binary characters from all the fungi tested and cluster analysis of the data showed that isolates from cyst nematodes were more genetically variable than those from root knot nematodes. The ITS regions were highly conserved, the only significant difference being an extra thymidine in isolates from Meloidogyne spp. Assays with nematode eggs indicated that isolates differ in their ability to infect different nematode genera. The results indicate host related variation in P. chlamydosporia. This finding has significant implications for the application of P. chlamydosporia as a biocontrol agent.

Pochonia chlamydosporia var. catenulata is a potential biocontrol agent against root-knot nematodes. Diagnosis of isolates has relied on morphological identification, and is both time-consuming and difficult. β-tubulin primers have been developed for the identification of this fungus that were specific enough to distinguish between varieties of the fungus within the same species. Separate primers have been developed for the specific detection of P. chlamydosporia var. catenulata based on ITS sequences, which were able to detect the fungus in soil from various sites in Cuba where the biocontrol agent had been added. When the PCR diagnosis was combined with serial dilution of soil samples on selective medium, colonies were rapidly identified. The fungus was still present, albeit at low densities, in soils inoculated five years previously. The development of a baiting method allowed quick in situ screening of the isolates' ability to infect nematode eggs, and when combined with PCR diagnosis both varieties of the fungus could be detected in infected eggs. RFLP analysis of ITS sequences from P. chlamydosporia provided an extra level of discrimination between isolates.

The release and survival of ascospores of a UK Sclerotinia sclerotiorum isolate were studied. Apothecia placed in a spore clock apparatus with different lighting regimes at 15 °C released ascospores continuously with an increasing rate for the duration of experiments (72–84 h). Spore release was not confined to light or dark periods in alternating regimes and occurred in continuous dark or light. Ascospores were released in both saturated air (90–95% rh) and at 65–75% rh. High temperature and rh were detrimental to ascospore survival but spore viability was maintained for longer periods than previously reported. The significance of these results in relation to disease control is discussed.

The dimorphic Mucor circinelloides requires an anaerobic atmosphere and the presence of 30% CO2 to grow as a multipolar budding yeast, otherwise hyphal growth predominates. Establishing other means to control the morphology would be a distinct advantage in the development of a fermentation process for this organism for the production of heterologous proteins. Thus, conditions suppressing polarised growth while at the same time abolishing the CO2 requirement were investigated in submerged cultivations. It was found that supplementing cultures with mixtures of ergosterol and Tween 80 resulted in yeast-like growth under 100% N2. Their impact on growth and morphological development was assessed at a range of concentrations. Maximum biomass levels and the specific growth rate decreased at elevated levels of ergosterol and Tween 80. Possible effects of carbon dioxide and the added fatty acid/sterol mixture on supporting yeast growth by influencing the fluidity of the plasma membrane or affecting polarised growth are discussed.

Tropical xylariaceous taxa in the genera Biscognauxia, Hypoxylon and Xylaria were evaluated for their ability to produce wood-decay enzymes and effect mass loss and lignin solubilization in angiosperm and gymnosperm wood. All xylariaceous taxa were capable of cellulose and xylan hydrolysis, but few produced enzymes involved in lignin breakdown. Xylariaceous fungi were incapable of causing mass loss in gymnosperm wood, but several caused significant mass loss in angiosperm wood during a six month in vitro exposure. Mass loss values obtained were low at approx. 20% of those obtained for basidiomycetes. Lignin was solubilized at similar rates to mass loss by Hypoxylon and Xylaria species, resulting in indices of lignin solubilization between 0.88 and 1.11, which were similar to those obtained for white-rot basidiomycetes and higher than those previously reported for any other xylariaceous fungi.

Two new aeroaquatic fungi, Ramicephala sphaerospora gen. sp. nov. and Beverwykella clathrata sp. nov., are described and illustrated from tropical and subtropical latitudes. B. clathrata, a species similar to B. cerebriformis, deviates from the latter in having a clathrate outermost cell layer instead of tightly appressed cells, a feature unique in Beverwykella. The second species, Ramicephala sphaerospora gen. sp. nov., has a unique combination of features concerning conidial ontogeny and morphology, and is therefore placed in a new genus. The genus most similar to Ramicephala is Beverwykella, from which it differs in having: (1) globose, non-flattened conidia; (2) a large central globose cell giving rise to centrifugally branching, tightly packed chains of cells; and (3) a compact peripheral cell layer, the cells of which are tightly interlocked in a zipper-like form. Similarities of R. sphaerospora to species of Pseudaegerita, Candelabrum and Cristulariella are discussed. Illustrations of and a key to all described species of Ramicephala and Beverwykella are provided.

An obscure parasitic fungus, Basidiolum fimbriatum, was found on Amoebidium parasiticum (Amoebidiales) associated with Caenis sp. (mayfly) nymphs, during a survey of gut fungi (Trichomycetes) from a small stream in northeastern Kansas, USA. The hindguts of the nymphs harboured a species of Legeriomycetaceae and Paramoebidium sp. This is the first report of the ectocommensal protozoan, A. parasiticum, associated with the gills of Caenidae (Ephemeroptera), and of B. fimbriatum in the 142 years since its original documentation from Wiesbaden, Germany. B. fimbriatum is recorded from two midwestern USA states (Kansas and Iowa) and the morphological and developmental features of the parasite on its host are compared with Cienkowski's original observations and interpretation. B. fimbriatum is characterized as a parasitic fungus possessing merosporangia that form on a simple pyriform thallus that penetrates and consumes its host via a haustorial network. The hypothesis that B. fimbriatum is most closely related to members of the order Zoopagales sensu Benjamin (1979) is proposed. The importance of future collections and molecular-based phylogenetic approaches to place this parasitic fungus within a current system of classification are highlighted.

Sooty moulds are described and illustrated from European amber dating back to 22–54 Myr. All the fossils are fragments of superficial subicula composed of brown moniliform hyphae with markedly tapering distal ends. The subglobose cells are identical to those of extant Metacapnodium (Metacapnodiaceae, Capnodiales) species. Also other preserved features, like the type of apical growth, wide-angled branching and the production of two distinctive conidial states, supports a placement in this genus. The fossils demonstrate that Metacapnodium hyphae have remained unchanged for tens of millions of years. This confirms that hyphal morphology and conidial states should be accorded considerable classificatory significance in this group of fungi. The following nomenclatural change is made: Metacapnodium succinum comb. nov. (syn. Rosaria succina). The type specimen was initially described as a filamentous cyanobacterium, due to similarities with Rosaria ramosa. Also the systematic position of this attribute is shortly discussed.