Protostelids, dictyostelids and myxomycetes are well known from terrestrial ecosystems in temperate regions but poorly known from the tropics. This study examined the distribution and ecology of these three groups of ‘slime moulds’ in the forest floor litter microhabitat of five different forest types (tabonuco forest, secondary tabonuco forest, palo colorado forest, palm forest, and elfin forest) within the Luquillo Experimental Forest in Puerto Rico. Protostelids associated with aerial litter (dead but still attached plant parts) also were studied. At least 13 species of protostelids, 13 species of dictyostelids and 24 species of myxomycetes were recovered. Both species richness and abundance of dictyostelids and myxomycetes were higher in the secondary tabonuco forest than in any of the other forest types. The tabonuco forest yielded the most species of protostelids, but the next highest total was recorded from the secondary tabonuco forest. Both of these forest types are located at the low end of the elevation gradient. Lowest levels of species richness and abundance occurred in the elfin forest, located at the high end of the elevation gradient. The general pattern observed was that of decreasing diversity with increasing elevation.

Non-pathogenic binucleate Rhizoctonia species (BNR) belonging to the anastomosis group AG-G are commonly associated with members of the Rhizoctonia solani complex. They provide effective protection to young bean seedlings against root rot caused by R. solani AG-4. Both fungi are morphologically similar and it is difficult to differentiate between them without using laborious conventional techniques. RAPD assays were carried out on a large range of isolates of binucleate Rhizoctonia species to identify markers common to all AG-G isolates. Two fragments of 1368 bp and 882 bp were isolated, cloned and used to probe Southern blots of DNA from: AG-G isolates; isolates from other AGs of binucleate and multinucleate Rhizoctonia species; various heterogeneous pathogens known to infect bean plants; and co-inoculated bean plants with BNR AG-G and R. solani AG-4. The fragments hybridized only to DNA from AG-G isolates. Both fragments were nucleotide sequenced and two pairs of SCAR (sequence characterized amplified region) primers (BR1a F/R and BR1b F/R) were generated for use in PCR. Two fragments of anticipated size were generated following PCR of all isolates of AG-G and not from any range of other fungal species associated with root and leaf diseases of beans. The SCAR primers were also used to detect AG-G isolates in DNA extracted from bean and soil samples co-inoculated with binucleate and multinucleate Rhizoctonia species. The assays were capable of detecting as little as 2·6 pg of fungal DNA in extracts of soil samples. This system offers the potential to determine the presence of AG-G isolates in infected soil and plant samples.

We studied the occurrence of genotypes of Gnomonia setacea by RAPD-PCR analysis at two natural sites in SW Finland to study site-, tree- and leaf-level genetic diversity. The analysis was performed with two primers by using 40 isolates from a total of 250 colonies isolated from two trees from each of two sites. Genetic diversity of G. setacea was found to be very high: every isolate studied was a unique genotype, even within the same leaf. This is probably due to sexual reproduction and the horizontal transmission system of airborne spores. Genotype distribution exhibited site-level similarity, indicating limited spore deposition and the ability to form local populations.

Phenotypes of species hybrids created from in vitro fusion of zoospores from Phytophthora nicotianae and P. capsici were characterized and compared. The species hybrids were created as part of a study of sources of genetic variation in populations of the parent species that are pathogenic over a similar range of plants. Four isolates of species hybrids proved to be similar to both P. capsici and P. nicotianae in relation to vegetative and reproductive morphologies. As in a previous study, DNA of P. capsici was detected more readily than that of P. nicotianae in all hybrid isolates. In the present study, DNA of P. nicotianae was detected in three of four hybrids by hybridization of RAPD-PCR products with species-specific DNA from P. nicotianae. By thermal denaturation analyses, DNA melting temperatures and GC contents of parent species and species hybrids were similar. The mean GC content of 47·2% was similar to GC contents reported for other Phytophthora spp. Additionally, the distributions of GC-rich regions of hybrids were more similar to the distribution in P. capsici than in P. nicotianae. By these molecular analyses, the hybrids were shown to be more similar to P. capsici than to P. nicotianae. Even though interspecific somatic fusion is likely to occur rarely under natural conditions, it could contribute to the genetic diversity of heterothallic species of Phytophthora.

A new freshwater ascomycete Micropeltopsis quinquecladiopsis sp. nov. was collected on submerged twigs in a stream in Thailand. The fungus is described at the light microscope, scanning and transmission electron microscope level. Distinctive features are the appendaged 1-septate hyaline ascospores. The appendage arises as an outgrowth of the episporium from a basal stalk, then divides into five arms (three long and two short). The episporium and appendages are surrounded by an indistinct (at light microscope level) mucilaginous layer. The fungus is assigned to the Dothideales (Trichothyriaceae). Ascospore appendage ontogeny is compared with those of marine Ascomycota (Halosphaeriales).

Anastomoses between hyphae, leading to both successful cell fusions and death of fused cells (vegetative incompatibility) were observed by video microscopy. Anastomosis was seen only to occur between tip cells from side branches, never main runner hyphae, and tip to side fusion was never observed. Perfect hyphal fusion was only observed following pre-contact tropism between the hyphae involved. The time taken for the process of cell wall dissolution and reformation following contact was 15 min.

A new freshwater ascomycete genus Proboscispora is introduced to accommodate P. aquatica collected on wood submerged in streams in Australia and the Philippines. Proboscispora is characterized by having immersed, ellipsoidal, papillate ascomata, septate tapering paraphyses, cylindrical unitunicate asci with a refractive apical ring, and 3-septate, hyaline ascospores provided with coiled or proboscis-like bipolar filamentous appendages. Proboscispora aquatica is illustrated at the electron microscope level and is compared with Annulatascus, Ceratosphaeria, Ceriospora, Ceratostomella and Rivulicola, with which it shares some common characters.

The genetic variability within 600 bp of DNA sequence from the ribosomal internal transcribed spacers (ITS 1 and ITS 2) and the 5·8 S rRNA gene was examined in 52 strains belonging to 29 terverticillate taxa in Penicillium subg. Penicillium from diverse sources and locations. The sequenced region is extremely conserved within the terverticillate penicillia, with only 29 positions differing in one or more taxa. The highest degree of ITS variability was seen among the species close to Penicillium roqueforti (P. roqueforti, P. carneum and P. paneum) whereas the ITS variability was very low between closely related taxa, e.g. among the taxa near P. aurantiogriseum. The relationships among the terverticillate penicillia, and related teleomorphs in Eupenicillium, were analysed from bootstrapped ITS sequence data sets using the neighbour-joining method. The terverticillate penicillia form a well supported clade with Eupenicillium crustaceum. Sequence analysis generally confirmed the overall taxonomy in Penicillium subg. Penicillium but relationships between all the terverticillate taxa could not be clearly established due to the low degree of ITS variability. Nevertheless, clades of Penicillium species sharing environmental characteristics did emerge, e.g. species growing on protein and lipid rich substrates (e.g. P. crustosum and P. commune), species prevalent in dry habitats (e.g. P. chrysogenum and P. nalgiovense), and those prevalent on carbohydrate rich substrates (e.g. P. aurantiogriseum and P. freii).

The vascular wilt pathogen currently causing severe die-back and mortality of takamaka in the Seychelles has morphological and physiological characters inconsistent with its placement in Verticillium. Features of the pathogen warrant its transfer to Leptographium and Leptographium calophylli comb. nov. is proposed. L. calophylli is described in detail based on new collections.

Gymnomyces dominguezii, a gasteroid fungus belonging to the Russulales, is described and illustrated as a new species. Its main taxonomic characters are discussed and compared with other species in the genus and those in Martellia and Zelleromyces.

Three isolates each, of nine different Trametes and five other wood inhabiting basidiomycetes, were collected from the indigenous forests of Zimbabwe, and the impact of temperature (20–60 °C), osmotic and matric potential (−0·5 to −8·0 MPa), and their interactions on in vitro growth compared. Generally, there was no significant difference between growth of isolates of the same species in relation to temperature. Temperature relationships of the species studied correlated well with their geographic distributions. Species occurring in hot, dry regions tolerated a wide temperature range, with some showing unusually high thermotolerance (55°, T. socotrana, T. cingulata and T. cervina). There were significant intra-strain differences for individual species in relation to solute potential on glycerol-modified media. Generally, growth of all species was better on glycerol- and KCl-modified osmotic media than on a matrically-modified medium (PEG 8000) at 25, 30 and 37°. The limits for growth on the osmotic media were significantly wider than matric medium, being −4·5 to −5·0 and −2·5 to −4·5 MPa, respectively. An Irpex sp. grew at lower water potentials than all other species, with good growth at −7·0 MPa. This study suggests that the capacity of these fungi for effective growth over a range of temperatures, osmotic and matric potentials contributes to their rapid wood decay capacities in tropical climates.

The hydrophobin SC4 was isolated from the medium of a dikaryon from Schizophyllum commune with disrupted SC3 genes. Although not glycosylated, its biophysical properties were similar to those of SC3. As the hydrophobins SC3 from S. commune and ABH1 and ABH3 from Agaricus bisporus, SC4 self-assembled at hydrophilic-hydrophobic interfaces into an SDS insoluble amphipathic film with a typical rodlet structure at its hydrophobic face, and also proved to be a powerful surfactant. Similar rodlet structures were observed in the fruiting body plectenchyma. By immunodetection SC4 could be localized lining air channels within this tissue. A similar localization was found for the ABH1 hydrophobin in fruiting bodies of A. bisporus. Probably, these hydrophobin coatings prevent collapse of air channels allowing efficient gas exchange even under wet conditions.

A numerical taxonomic analysis of 272 specimens and strains of Leptoxyphium, Caldariomyces and Aithaloderma was undertaken. Analysis was carried out on two data sets: characters from the form of the hyphal cells, shape of conidiomata and the presence of ascospores were coded and 34 binary variables encoded for all strains; 29 living cultures of Leptoxyphium and Caldariomyces were characterized for colony morphology, micromorphology and physiological characters encoded as 168 binary variables. Cluster analysis, principal components analysis and discriminant analysis was carried out. Three main groups are identified. A group comprising mainly Aithaloderma specimens is most clearly resolved. Another group comprises a mixture of Caldariomyces and Leptoxyphium specimens. The third group comprised mainly Leptoxyphium specimens with some Aithaloderma specimens. Physiological characters provide no evidence for the separate recognition of Caldariomyces and Leptoxyphium.

Muskmelon crops have sustained serious losses in Spain since 1980, due to a disease characterized by a sudden collapse of the plant as the fruit approaches maturity. The cause has been attributed to Acremonium cucurbitacearum. To evaluate the genetic variation of A. cucurbitacearum in Spain and its relationship with other species of Acremonium, a study of vegetative compatibility groups (VCGs) and random amplified polymorphic DNA (RAPD-PCR) was carried out on 29 isolates from diseased muskmelon plants. The species used in comparison with A. cucurbitacearum were A. charticola, A. strictum, A. kiliense, A. sclerotigenum and A. crotocinigenum. Spanish isolates of A. cucurbitacearum were grouped in eight different VCGs, with two isolates belonging to more than one VCG. In only two of the reference species was it possible to complete all of the complementation tests: A. charticola (VCG 100) and A. crotocinigenum (VCG 200). The isolates of A. sclerotigenum and A. kiliense appeared to be naturally resistant to chlorate and could not be tested for VCG. All strains of A. strictum assayed were heterokaryon self-incompatible. The RAPD data showed considerable genetic variation, with 14 isolates grouped in 11 haplotypes. They also supported the recognition of A. cucurbitacearum as a new species, as the genetic similarity between A. cucurbitacearum and the reference species was less than 0·05.

Fifty-eight fungi from different physio-ecological groups were compared for their capacity to oxidize five polycyclic aromatic hydrocarbons (PAH) with three to five benzene rings (R), and produce the appertaining extracellular oxidoreductases in liquid culture. In 14 d, wood- and straw-associated basidiomycetes converted 19–90% of the original PAH compounds. The groups of wood- and straw-degrading, wood-degrading, terricolous, ectomycorrhizal, and mitosporic fungi converted PAH at a proportion of 100[ratio ]75[ratio ]34[ratio ]19[ratio ]18. All fungi preferred fluoranthene and pyrene (4R). Anthracene (3R) was preferred by wood-associated fungi. Phenanthrene (3R) and perylene (5R) were sufficiently converted by wood-associated and terricolous, but poorly by ectomycorrhizal and mitosporic fungi. Nevertheless, fungi that converted the entire set of PAH satisfactorily were found in all five groups. PAH conversion was correlated with the production of manganese peroxidase (r=0·98), peroxidase (r=0·89), and laccase (r=0·85), but not with monophenol monooxygenase (r=0·07). Mn(III) ions oxidized all PAH with preference to anthracene. Hydrogen peroxide converted PAH possibly by the products of Fenton's reaction. Limiting factors were shortages in peroxidases and H2O2. Gymnopilus sapineus and Agrocybe praecox converted top quantities of PAH in the absence of peroxidases, manganese peroxidases, and lignin peroxidases. The relative contributions of intra- and extracellular enzymes to the conversion of PAH and the possible role of the fungi in the long-term detoxification of soil xenobiotics are discussed.

Thirty-three strains of Fusarium species from clinical sources including F. solani, F. oxysporum, F. moniliforme, F. proliferatum, F. subglutinans and F. chlamydosporum were examined for their physiological characteristics and mycotoxin production. Of this collection 29 exhibited growth at 37 °C and 21 were resistant to cycloheximide. Two strains of F. moniliforme and two strains of F. proliferatum produced fumonisins. No strains in this collection produced detectable amounts of trichothecenes. All 18 strains of F. solani tested produced the immunosuppressive agent cyclosporin A. The cyclosporin A-producing ability of clinical isolates of F. solani may influence their pathogenic potential.

The effect of xyloglucan on spore germination, hyphal length and mycorrhizal colonization of alfalfa plants was studied. The presence of high concentrations of xyloglucan in the rooting medium inhibited mycorrhizal colonization in plants inoculated with Glomus mosseae. Intermediate xyloglucan concentrations had no effect on arbuscular mycorrhizal (AM) colonization, but a low concentration increased mycorrhization of host plants. The effects of these doses on spore germination and hyphal length of G. mosseae were similar to those observed for mycorrhizal colonization. Production of xyloglucanase was assayed during colonization by the AM fungus G. mosseae in lettuce and onion. Endoxyloglucanase activity peaked 15 d after inoculation, whereas exoxyloglucanase activity peaked at 30 and 50 d. Extracts from external mycelia of G. mosseae showed endo- and exoxyloglucanase activities. Some of the endoxyloglucanase activities detected in AM colonized plant roots may be derived from the AM fungus, as endoxyloglucanase proteins found in the external mycelia of G. mosseae and in mycorrhizal root extracts showed similar electrophoretic mobility. These results suggest that xyloglucanase is involved in the process of colonization of plants by G. mosseae.

Spores of Tetrachaetum elegans were isolated in early autumn from submerged leaves which were randomly collected at a single site from a small stream in southwestern France. In order to investigate potential substrate preferences, spores were sampled in four leaves from seven different plant genera. A total of 96 monosporic isolates were screened for genetic variation in RAPD patterns using nine different primers. Fifty-two fragments were identified and used for calculation of similarity coefficients. A large number of fragments were shared across all isolates, suggesting that the population was genetically homogeneous. The combination of 11 polymorphic fragments contributed to the delineation of 13 RAPD types. Colonization of a single leaf by multiple genotypes was frequently encountered. Fungal genetic assemblages differed between plant genera. Variations in the frequency of occurrence of the various genotypes are discussed in terms of ecological strategies and in reference to previous work at the community level. We suggested two hypotheses: first, substrate preferences are found among aquatic hyphomycete genotypes, and secondly, sequential occupation by distinctive populations may result in different assortments of genotypes on leaf litters of different plants at any given time of sampling.

An agar plate test is described to determine the growth inhibition of dermatophytes by fungicides applied to fabrics. Trichophyton rubrum and Epidermophyton floccosum, two major causative agents of tinea pedis (athlete's foot), were used as test organisms. The assay was capable of distinguishing between direct contact effects and diffusion of fungicide into the agar medium, and could be used semi-quantitatively. The method included an essential sterilization stage to prevent interference by micro-organisms contaminating the test materials. Loss of fungicide efficacy due to the sterilization procedure required careful control.

A new genus of freshwater ascomycetes, Cataractisopora, with three new species: C. aquatica, C. appendiculata and C. viscosa, are described. These fungi occur on decaying wood and possess similar characteristics including coriaceous globose ascomata, wide septate paraphyses, cylindrical asci with a relatively massive refractive apical ring and ascospores with polar chambers and filamentous appendages. Appendage material accumulates within the polar chambers and, on release from the ascus, the ascospore appendage unfurls to form long threads. The appendage material is fibrillar at the ultrastructural level, and is derived from episporial projections at the ascospore tip. Although these three fungi are similar to species of Annulatascus, they are assigned to a new genus – Cataractispora based on their unique appendage ontogeny. Annulatascus bipolaris is also assigned to Cataractispora on the basis of its ascospore appendage ontogeny.