This month Mycological Research News features group sex in New England, the recovery of viable fungal spores from 140 000 year old glaciers, and the role of ericoid mycorrhizas in conveying arsenate resistance to their plant partners.

The lead paper in this issue is an historical and morphological critique of the supposed differences of gasteromycetes from other basidiomycetes. Amongst the other 17 papers in this issue are molecular studies on Ganoderma in Australia, Melampsora on Salix, Phaeosphaeria sexual progeny, endomycorrhizal Pisolithus isolates, and cultured and in situ wood decomposing fungi. Complementary isozyme studies on Ganoderma in Australia are also presented. Adhesion and infection in Pestalotiopsis conidia has been examined, the yeasts associated with ant mounds in Texas analyzed, dual infections of grasses with different Neotyphodium endophytes studied experimentally, the detection of Botrytis cinerea by monoclonal antibodies raised by different immunogens assessed, the action of Verticillium fungicola on Agaricus bisporus hyphae examined, and the efficacy of Fusarium tumidum isolates with biocontrol potential against gorse and broom compared. A long-fruiting population of Morchella conica is documented, and numerous isolates of nematophagous fungi have been found in sheep faeces in Brazil.

The following new scientific names are introduced: Hebeloma radicosoides, Ramularia byrsonimatis, and Rhizosphaera pseudotsugae spp. nov.; and Pseudocercospora byrsonimatis (syn. Cercospora byrsonimatis) comb. nov.

Comparison of all presently available data on gasteromycetoid structure and development allows reassessment and leads to rectification of some questionable ideas about the relation of gasteromycetes to Agaricales. The gasteroid features which are dealt with are those which are particularly relevant to this subject. Some important, but specifically taxonomic, features are left out of the discussion. The loss of violent spore discharge is the only criterion to characterise basidiomycetes which have been united under the term gasteromycetes. Gasteromycetoid adaptations have probably arisen in the distant past at successive levels of basidiomycete evolution. Sometimes the shape of gasteromycetes is reminiscent of one of the groups from which they have descended and in other cases they have been subjected to an unique evolution in response to challenge by particular ecological requirements regarding spore dispersal.

Genetic variability among isolates of the ectomycorrhizal fungus genus Pisolithus collected in Brazil, USA and France was examined, based on nucleotide sequence of ITS from rDNA genes and restriction polymorphism of the mitochondrial DNA (mtDNA). Alignment of the ITS sequences showed 97.0% homology among isolates from Brazil, 97.8% homology among isolates from USA and France and 75.7–78.5% among the isolates from Brazil and USA/France. These sequences were aligned with ITS sequences of Australian, Brazilian and Kenyan Pisolithus isolates described in the literature. A consensus tree generated by sequence data of all Pisolithus isolates showed the presence of a number of species among the isolates. The mtDNA analysis was carried out by total DNA restriction analysis with different enzymes (Dra I, EcoR I, EcoR V, Hha I–Xba I, Hind III and Rsa I) and probing with purified mtDNA labelled with fluorescein d-UTP. The size of the mitochondrial genome of isolates Pt 90A, Pt 185R and PF cleaved with EcoR I was estimated to be, approx. 40.5, 47.2 and 47.6 kb, respectively. Cluster analysis based on the mtDNA restriction fragments grouped the isolates into two distinct groups, which coincide with their host specificity and geographical origins. PCR-RFLP analysis of mitochondrial rDNA (mt rDNA) from 12 Pisolithus isolates did not show any polymorphism. These data corroborate previous results obtained in our laboratory with RAPD-PCR and rDNA PCR-RFLP markers and support recent taxonomic studies where a number of Pisolithus species were described.

Segregation and recombination in sexual progeny of Phaeosphaeria spp. were analysed using three PCR based techniques which targeted arbitrary DNA sequence (random amplified polymorphic DNA, RAPD–PCR), microsatellites (microsatellite primed PCR, MP–PCR) and dispersed repetitive DNA elements (rep-PCR). Polymorphic DNA markers were not detected in three sets of P. avenae f. sp. triticea ascospores isolated sequentially from single asci. It is hypothesised that ascospores of P. avenae f. sp. triticea were produced from a sexual process in which fusion of genetically identical nuclei took place. On the other hand, polymorphic DNA fragments were found in three sets of eight P. nodorum isolates recovered from ascospores sequentially liberated from single asci produced by in vitro mated ‘+’ and ‘−’ strains. Among 172 polymorphic markers identified in two sets of isolates (ascospores) of the fungus, 171 segregated in a ratio 1[ratio ]1. We have demonstrated for the first time that the inheritance of PCR based markers in P. nodorum progeny follows Mendelian genetics. Thereby, a molecular proof for bipolar heterothallism of the fungus was provided. In contrast, of 48 polymorphic markers detected in the third cross, only 26 segregated in an expected Mendelian frequency 4[ratio ]4 and the other 22 demonstrated either aberrant segregation pattern or possessed new DNA fragments amplified in PCR which were not detected previously in parental DNA profiles. The reasons underlying the high frequency PMS type markers identified almost exclusively in one cross have yet to be conclusively determined. If such recombinants were found in the progeny of in vitro mated P. nodorum isolates it is obvious that they also occur under natural conditions. Thus, the study provides a molecular evidence for generation of novel genotypes of the pathogen.

Four different primer pairs were designed for the preferential PCR amplification of fungal SSU rDNA directly from environmental samples. Most of the amplification products obtained from a reference collection of 46 wood-decomposing fungi could be separated by denaturing gradient gel electrophoresis (DGGE) using 1650 bp rDNA fragments produced by primer pair FR1+NS1. A relatively high level of resolution was also achieved using 390 bp products amplified with primer pair FR1+FF390. In contrast, the separation of amplification products obtained by the remaining two primer pairs (FR1+FF700 and FR1+FF1100; 700 bp and 1100 bp, respectively) was inadequate when applied to our fungal collection. Differentiation between all the species tested was achieved by combined analysis of the rDNA fragments produced by primer pairs FR1+NS1 and FR1+FF390. The DGGE analysis of environmental samples collected from Norway spruce stumps showed that the analysis of fungal DNA extracted directly from wood was usually in accordance with the investigation of mycelial cultures isolated from the same decay column. In some cases, however, disagreement was observed, which suggests that these two fundamentally different techniques present different views about fungal diversity. The investigation of fungal species profiles directly from environmental samples using DGGE analysis of PCR-amplified SSU rDNA molecules can be used to improve the detection of fungal groups that are difficult to cultivate.

Amplified fragment length polymorphism (AFLP) was used to examine genetic variation in two forms of Melampsora rust on Salix viminalis, the ‘stem-infecting form’ (SIF) and the f. sp. larici-epitea typica (LET) of M. epitea. A simple two-tube method was used to obtain genomic DNA suitable for AFLP. Eleven SIF and 26 LET isolates from the UK were tested using two primer combinations. Of the 215 AFLP markers scored, 93% were polymorphic. AFLP profiles were distinct between SIF and LET (Nei & Li's similarity coefficients between SIF and LET isolates = 22–35%). Within SIF, AFLP patterns were very similar (similarity > 98–9%), indicating that SIF is an asexual population and may have a clonal lineage. Within LET, similarities were > 69%. LET isolates collected from a site at Long Ashton in 1991–1993 were closely related and, therefore, may have come from the same local source. Similarity data from AFLP were in good agreement (Spearman's rank correlation = 0.85) with that of RAPD when both SIF and LET isolates were included, but the correlation was less obvious (= 0.49) when only LET isolates were included. Identical banding patterns were obtained when AFLP was performed using either a Perkin–Elmer 480 or a Perkin–Elmer 9700 Thermocyclers, each programmed with a different PCR profile.

Phylogeny inferred from ITS DNA sequence resolved isolates of Australian Ganoderma into five terminal clades. The phylogenetic analysis was considered superior to sequence variation statistics for delineating species as intra and inter-specific variation were dissimilar across the taxa studied. The analysis also revealed that a number of isolates had been misnamed. Phylogeny inferred from the sequence data supported the retention of Elfvingia and Ganoderma as subgenera of Ganoderma, and the placement of the G. chalceum complex within subgenus Ganoderma. These findings were, however, poorly supported by decay analysis. G. adspersum, a European species considered to be a synonym of G. australe (a species which is in need of neotypification) by some authors, was not synonymous with G. australe from Australia. G. incrassatum from Northern Australia formed a clade with isolates named G. gibbosum from China and an isolate named G. australe from Taiwan. G. weberianum from Australia, originally identified by R. L. Steyaert, formed a terminal clade that was closely related to a second terminal clade comprised of two G. weberianum isolates and an isolate of G. microsporum from Asia. It was concluded that the clades represented two allopatric populations of G. weberianum and that G. microsporum was a synonym of G. weberianum. Isolates determined as G. chalceum by R. L. Steyaert and referred to here as G. cupreum formed a distinct terminal clade most closely related to material identified as G. sinense. A species mistaken for G. lucidum from Australia and Indonesia, a species from temperate and South East Asia containing commercially cultivated strains, and an Argentinean species showed evidence of allopatric speciation. Nomenclatural problems and the implications of our study on the pharmaceutical and commercial exploitation of Ganoderma in Australia are discussed.

Isozymes of five Australian Ganoderma species were studied using cellulose acetate gel electrophoresis (CAGE) and PAGE. Phenetic analysis supported the distinction between the five species, which were separated by unbiased genetic distances of between 0.532 and 3.330. Estimates of heterozygosity and polymorphisms identified considerable genetic variability within populations and species. The putative saprotrophic G. australe, G. incrassatum and G. cupreum had the lowest genetic variability while the pathogen Ganoderma sp. Group 6.3, morphologically similar to G. lucidum, had the highest, followed by G. weberianum. Isolates of G. adspersum, G. applanatum from Europe and G. australe from Australia differed at most loci, thus the commonly accepted synonymy between G. australe and G. adspersum was not supported. Pectic isozymes alone were sufficient to distinguish three laccate (possessing a cutis surface consisting of a palisade of inflated hyphal ends) Australian species, G. weberianum, Ganoderma sp. Group 6.3 and G. cupreum, but they did not distinguish between the non-laccate G. australe and G. incrassatum. The laccate group contains species of greatest economic importance. Australian species were resolved by a single isozyme (glucose-6-phosphate dehydrogenase) using CAGE, demonstrating the potential for this method as a rapid diagnostic tool for identifying species of Ganoderma. This is the first reported population genetics based study of Ganoderma using isozymes.

The adhesion of conidia of Pestalotiopsis neglecta occurs in four stages in a specific manner which allows the first cell most likely to germinate to become firmly attached its substrate while leaving the other two fertile cells free to be dispersed further, thereby increasing the chance of further successful infections. The first stage of adhesion involves the mucilaginous coating acquired from the conidial matrix and appears weak. The second stage of adhesion is also relatively weak and occurs at the bases of the pedicel. The third stage occurs with the release of a fibrillar adhesive substance from along the length of the pedicel to the top of the basal cell and at times a lesser amount of fibrillar material is released from the apical appendages. The fourth stage involves the release of fibrillar material at the point of germtube emergence. The third and fourth stages provide strong attachment.

Soil yeast occurrence and abundance was studied in brood chambers within mounds of the red imported fire ant, Solenopsis invicta, and adjacent non-mound soil from Texas. Ten yeast species were isolated from fire ant brood chamber soil and 13 from non-mound soil. Relative frequencies of Candida parapsilosis and C. lipolytica were greater in brood chamber soil, and Cryptococcus terreus occurred more frequently in non-mound soil. Rhodoturula rubra, R. minuta, and Candida vini only occurred in non-mound soil. Mean cfu g−1 of soil was greater in brood chamber soil. Fire ants alter the community composition and relative abundance of yeasts within mounds due to creation of unique microhabitat patches.

Individual tall fescue (Festuca arundinacea) plants infected with both Neotyphodium coenophialum and N. lolii endophytes, and individual perennial ryegrass (Lolium perenne) plants infected with both N. lolii and Neotyphodium LpTG-2, were obtained following inoculation of naturally infected seedlings with the second endophyte. Differences in the ability of the endophytes to produce conidia, together with colony characteristics, enabled the endophytes in plants to be identified following incubation of excised leaf tissue on potato dextrose agar. Most tillers of dually infected plants were infected with just a single endophyte, but tillers infected with two endophytes were identified in three tall fescue plants. In these tillers one endophyte was always present at a much higher concentration than the other. Over time the incidence of dually infected tillers decreased and no tillers with both N. coenophialum and N. lolii were present 5 months after the associations were established. No evidence was obtained of exchange of nuclei between different endophytes present in dually infected tillers giving rise to heterokaryons or interspecific hybrids.

A panel of monoclonal antibodies (MAbs) was raised to Botrytis cinerea using four different immunogens. Co-immunization with cross-reactive monoclonal antibodies helped to increase the percentage of specific hybridoma cell lines produced. The abilities of the MAbs to detect fungal antigens in extracts from infected tissue was correlated with their taxonomic specificities and with the localization of the antigens on the surfaces of the hyphae and conidia. Four distinct groups were identified: taxonomically unrelated, near-genus-, genus- and near-isolate-specific. Genus-specific antibodies gave the highest absorbance values in ELISAs with extracts from infected plant tissues. MAbs from this group all recognized heat-stable epitopes on antigens expressed along the length of the extracellular matrix of the hyphae and surface of the conidia. Antibodies from this group were all IgG1 antibodies.

Host-parasite interactions of Agaricus bisporus and Verticillium fungicola were studied in paired-cultures. Different growth reactions were found according to the culture medium used, but no apparent alterations could be detected by light and electron microscopy in A. bisporus vegetative mycelia. In vitro, different hydrolytic enzymes are produced by V. fungicola in cultures with A. bisporus vegetative mycelial cell walls as the only carbon source. In vitro, this enzyme preparation is able to partially digest isolated A. bisporus vegetative mycelial cell walls. These results suggest that although apparent attachment of the mycoparasite to the host cell surface seems to occur, there is no in vivo A. bisporus vegetative mycelial cell wall degradation.

The relationship between trichothecene production and pathogenicity was investigated for 29 isolates of Fusarium tumidum, a potential bioherbicide for gorse (Ulex europaeus) and broom (Cytisus scoparius) in New Zealand. All isolates originally derived from broom produced high levels of T-2 tetraol derivatives when grown on ground maize kernels and pearl barley grains, compared with isolates from gorse. Low amounts of scirpentriol derivatives were also produced by both groups of isolates. No nivalenol and deoxynivalenol derivatives were detected in any of the culture extracts. A subset of isolates cultured on gorse and broom tissue produced only small amounts of T-2 tetraol derivatives relative to the amounts produced in grain cultures. Overall, isolates from broom were more aggressive towards both hosts than isolates from gorse, but the pathogenicity of isolates was not correlated with their capacity to produce large amounts of T-2 tetraol derivatives in culture. Two isolates from gorse were highly aggressive towards both weeds. These isolates offer prospects for the development of a safe bioherbicide that could target two major weeds in New Zealand, as trichothecenes were not detected from them at the higher concentrations.

Morels are known to produce ascocarps during a few weeks in the spring. Here we present findings about a Morchella conica population which produces ascocarps during a period of 8–10 months, from early spring until mid-winter. To the best of our knowledge, this phenomenon has not been described previously. Field investigations correlated the ascocarp appearance with gradual drying of the soil. DNA–PCR fingerprinting indicated that these Morchella shared a similar genetic background.

Few studies have examined faeces as a substratum for nematophagous fungi, and no information is available about colonisation of faeces in tropical regions. Sheep faeces were deposited on a Brachiaria decumbens pasture in the Mata Region of Minas Gerais, Brazil. Up to 2 wk after deposition, samples were collected and cultivated on water agar (2 %) with free-living nematodes as bait. From 150 samples, 130 isolates were recovered after 3 wk. More than 70% were predators and Arthrobotrys and Monacrosporium spp. predominated. Endoparasitic species of Drechmeria, Harposporium, Myzocytium, Nematoctonus and Verticillium were also isolated.

Type collections of Cercospora byrsonimatis and Ramularia ligustrina have been re-examined. Cercospora byrsonimatis is transferred to Pseudocercospora while a second hyphomycete, found on the type material, is described as Ramalia byrsonimatis sp. nov. Ramularia ligustrina is redescribed and its status as a true member of Ramularia is confirmed.