This paper describes the use of a monoclonal antibody-based ELISA for the quantification of the effects of Trichoderma harzianum on the saprotrophic growth dynamics of Rhizoctonia solani in unsterile compost-based microcosms. Quantification of R. solani was based on the immunological detection of a constitutive, extracellular, water soluble glycoprotein antigen (the copper-containing enzyme catechol oxidase) which is secreted by actively growing mycelium of the fungus only. Extracts derived from lyophilized mycelium (FDM) were used as a quantifiable and repeatable source of the antigen in order to prepare calibration curves that accounted for incomplete extraction of the antigen from compost samples. These curves were used to convert the absorbance values of extracts in ELISA to FDM biomass equivalents, which allowed comparisons of the saprotrophic growth dynamics of R. solani to be made in the presence and absence of T. harzianum. The high pH (9·6) of the buffer used to extract the antigen from microcosm samples also resulted in the extraction of humic components of the compost which interfered with the sensitivity of the assay. A protocol, based on the determination of optimal ELISA absorbance[ratio ]extract dilution ratios, was used in order to reduce the interference and improve the sensitivity of the quantitative assay.

Helicobasidium mompa is a clampless basidiomycete and binucleate both in secondary and primary hyphae. Single basidiospore isolates were paired in sibling and non-sibling combinations. We did not observe any alterations in colony morphology, such as tuft formation, but mycelial incompatibility, as indicated by the presence of a dark demarcation line between colonies, occurred in a unifactorial manner. Techniques using DNA molecular markers, such as internal transcribed spacer-restriction fragment-length polymorphism (ITS-RFLP), inter–simple-sequence-repeat polymerase chain reaction (PCR), and universally primed PCR, failed to identify nuclear migration to opposite single basidiospore isolates in all but one of the 92 pairings. These results imply that single basidiospore isolates of H. mompa may be incompetent to mate under laboratory conditions and that a single mycelial incompatibility factor operates in single basidiospore isolates.

Two pathogenic special forms (f. sp.) of the Fusarium oxysporum species complex f. sp. lycopersici (Fol) and f. sp. radicis-lycopersici (Forl) are morphologically indistinguishable. Although they are pathogenic to the same host genus Lycopersicon (tomato), and infect the same tomato cultivar, they form distinct diseases; Fol causes wilt and Forl causes crown rot and root rot. These two special forms apparently exist as genetically isolated populations, based on vegetative compatibility and molecular variation at the DNA level. In seeking efficient diagnostic tools for differentiating Fol and Forl isolates, we examined three techniques: isozyme analysis, mitochondrial DNA (mtDNA) RFLP by HaeIII-digestion of total genomic DNA, and an osmotic method using high performance liquid chromatography (HPLC) to detect fungal pigments. The isolates were collected from geographically widespread locations. Distinct HPLC-profile differences were found between an endophytic non-pathogenic isolate and the other pathogenic isolates. However, the direct mtDNA RFLP technique proved to be an efficient diagnostic tool for routine differentiation of Fol and Forl isolates.

Arbuscular mycorrhizal fungi are common in moderately saline soil (colonized by Distichlis stricta) in an inland boreal salt pan in north-central Manitoba, but are absent from adjacent soil that is extremely saline (colonized by Puccinellia nuttalliana). In order to determine if this absence was due to the lack of suitable plant hosts or to edaphic factors, mycorrhizal colonization, vegetation composition, soil salinity and water content were examined along transects between the two vegetation zones. Correlation and principal component analyses revealed that mycorrhizal colonization of P. nuttalliana was positively linked to cover of Distichlis stricta and soil water content, and negatively linked to bare ground. The area closest to the point of salt seepage was uncolonized by mycorrhizal fungi. A transplant experiment confirmed that mycorrhizal fungi are unable to sustain colonization in this area of the salt pan. In this inland salt pan, colonization by mycorrhizal fungi is limited by edaphic factors, and not by the absence of suitable host plants, suggesting that mycorrhizal fungi have a lower limit of salinity tolerance than halophytes such as P. nuttalliana.

The sequence variation within the genus Letharia in the Caucasus and Morocco was investigated. Twelve thalli from each area were sequenced at eight different loci. Phylogenetic analysis of the multiple loci data revealed the cryptic species Letharia ‘lupina’ in Morocco, previously known only from western North America. The two cryptic species L. vulpina and L. ‘lupina’ locally share the same ecology but are genetically isolated from each other. In the Caucasus, five different haplotypes of L. vulpina were detected, and in Morocco four L. vulpina haplotypes and six L. ‘lupina’ haplotypes were found. For L. vulpina, allelic differences were detected at five of the eight loci in the Caucasus and Morocco. The populations of L. vulpina in both the Caucasus and Morocco contain more genetic variation than those previously investigated in Europe, which indicates that the Caucasus and Morocco acted as refugia during quaternary glaciations, and that central and northern Europe may have been recolonised from one or both of these areas.

This first contribution of a planned series on the morphology of the Ingoldian fungi discusses three aspects useful for conidial identification, something needed principally in stream ecology and biodiversity surveys: (1) types of propagules found; (2) release organ remnants found on propagules; and (3) conidial tails (or caudal appendages).

(1) Propagules can be unexpectedly varied, and difficulty may be encountered in distinguishing, for example, misshapen conidia from expected ranges in conidial form, or in recognizing the outcome of post-release morphogenesis (involving elongation, branching or fragmentation, the latter resulting in part-conidia of several kinds); autonomous hyphal branching systems resembling branched conidia may undergo disorganized in situ fragmentation; propagules may be compound, the components covering more than one generation of the same morph or even more than one morph; conidial aggregations may behave as single dispersal units; and in one case it may be difficult to distinguish between thalli and propagules.

(2) Conidia secede by means of various specialized structures (release organs) which leave behind remnants of diagnostic value. Among ascomycetous anamorphs are scars (half-septa resulting from schizolysis of release septa), basal collars (portions of lateral walls resulting from rhexolysis or fracture of release or separation cells), and in one case mucilaginous masses (probably the result of the gelification of release cells). The location of scars can sometimes only be inferred by means of other diagnostic characters, and in some instances it cannot even be inferred. This may lead to problems in orientating conidial and consequently in their identification. In the case of release cells, the remnants on the conidium frequently disappear or become indistinct. Among basidiomycetous anamorphs are twin scars (the result of paired schizolysis of the two septa, i.e. the axial and bridge septa, in the release clamp), excentric collars (seemingly the result of a combination of schizo- and rhexolysis of clamp components) and basal collars (the outcome of lysed evacuate conidiogenous cells).

(3) The presence of tails is often inconstant, but where recognizable three types occur which may significantly aid in conidial orientation and hence identification.

In addition, three methodological aspects are emphasized: the effect of the position of the conidium on the appreciation of some diagnostic characters, the need to observe spent conidiogenous structures, and in some cases the necessity of directly observing morphogenesis in order to interpret the conidial form.

The morphology of gametangia was examined in 43 pairs of isolates (mating types A1×A2; 11 A1 and 24 A2 isolates; five isozyme/electrophoretic types) of Phytophthora cinnamomi. An amphigynous antheridium always formed with each oogonium. However, in 41 of the crosses a proportion (39 had 0·2–10% and two had >30%) of oogonia also consistently had single or multiple paragynous antheridia. Single or multiple paragynous antheridia formed concurrently with amphigynous ones during the period of gametangial production in paired colonies. Where there were multiple paragynous antheridia associated with an oogonium, sometimes additional antheridia formed after fertilization or even after oospores were visible. Developmental studies showed that when meiosis in amphigynous and paragynous antheridia was simultaneous, fertilization tubes developed synchronously from both. However, cytological examination indicated that either a nucleus from an amphigynous or a paragynous antheridium fertilized the oosphere. Observations of paragynous and amphigynous, and amphigynous-only associations suggested that fertilization from either type of antheridium only occurred when meiosis in the oogonium was nearly synchronous with that of the antheridium. Asynchronous meiosis between oogonia and antheridia may contribute to failed fertilization and aborted oospore development. This appears to be the first description of paragynous antheridia in P. cinnamomi and the second observation of oogonia with both paragynous and amphigynous antheridia in a heterothallic Phytophthora species. Moreover, the development of both paragynous and amphigynous antheridia with an oogonium is rare in Phytophthora, as is the development of multiple antheridia. Antheridial variation is a characteristic to be taken into account in isolate identification. Nuclei from paragynous antheridia appear able to fertilize oospheres and therefore, have a role in sexual reproduction.

Eight species of ectomycorrhizal (ECM) fungi in the genera Amanita, Gymnoboletus, Lactarius, and Russula were isolated from subtropical plant communities in eastern Australia. Two species were isolated from each of rainforest, Nothofagus forest, Eucalyptus forest, and Eucalyptus dominated wallum (heath) forest. These communities differ strongly in their soluble soil nitrogen (N) composition. The ability of the fungi to use inorganic (nitrate, ammonium) and organic (amide, peptide, protein) nitrogen sources was determined. As the fungi did not grow in liquid culture, a ‘floating culture’ technique was devised that allows hyphal growth on a screen floating on liquid medium. With some exceptions, fungal biomass production in floating culture closely reflected fungal growth on solid media assessed by total colony glucosamine content. Most isolates grown in floating culture had similar glucosamine concentrations on all N sources, with isolate specific concentrations ranging from 6 to 12 μg glucosamine g−1DW. However, Russula spp. had up to 1·7-fold higher glucosamine concentrations when growing with glutamine or ammonium compared to nitrate, glutathione or protein. Floating cultures supplied with 0·5, 1·5, 4·5, or 10 mM N mostly produced greatest biomass with 4·5 mM N. In vitro nitrate reductase activity (NRA) ranged from very low (0·03 μmol NO2 g−1 fw h−1) in Russula sp. (wallum) to high (2·16 μmol NO2 g−1 fw h−1) in Gymnoboletus sp. (rainforest) and mirrored the fungi's ability to use nitrate as a N source. All Russula spp. (wallum, Nothofagus and Eucalyptus forests), Lactarius sp. (rainforest) and Amanita sp. (wallum) utilized ammonium and glutamine but had little ability to use other N sources. In contrast, Amanita species (Nothofagus and Eucalyptus forests) grew on all N sources but produced most biomass with ammonium and glutamine. Only Gymnoboletus sp. (rainforest) showed similar growth with nitrate and ammonium as N sources. Fungal N source use was not associated with taxonomic groups, but is discussed in the context of soil N sources in the different habitats.

Palaeoclavaria burmitis gen. et sp. nov. (Palaeoclavariaceae fam. nov., Hymenomycetes) is described from a series of fruit bodies and hyphae in Cretaceous amber from Burma (about 100 Myr). This is the first fossil record of the Aphyllophorales and establishes certain basic morphological and ecological characters for the group.

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.

Oidiodendron maius is accepted widely as an ericoid mycorrhizal endophyte because it is isolated primarily from the roots of ericaceous plants. Reports of the species from other materials are much fewer, suggesting a limited role as a free-living saprobe. We show that assumptions concerning the prevalence of O. maius in a common substrate (i.e. peat) are affected by isolation protocols. Oidiodendron maius was observed on 99.6% of peat samples incubated in moist chambers but only 0–9% of the peat fragments plated on different isolation media. These results, and previous studies showing ability to degrade Sphagnum, indicate that O. maius could inhabit a much broader niche than previously suspected. Sterile ascocarps with peridia morphologically similar to Myxotrichum arcticum were observed on moist incubated peat and in a series of controlled crosses. These observations provide evidence that the teleomorph of O. maius is a species of Myxotrichum.

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.

Genetic variability in Crinipellis perniciosa, the causal organism of witches' broom disease in Theobroma cacao, was determined in strains originating from T. cacao and other susceptible host species Heteropterys acutifolia and Solanum lycocarpum in Brazil, in order to clarify host specificity and geographical variability. RFLP analysis of the ribosomal DNA ITS regions (rDNA ITS), and the mitochondrial DNA small subunit ribosomal DNA gene (mtDNA SSU rDNA) did not reveal any genetic variability in 120 tested strains, possibly serving only as species level markers. Genetic variability was observed in the ribosomal DNA IGS spacer region, in terms of IGS size, RFLPs and sequence data. Phylogenetic analyses (using CLUSTAL W, PHYLIP and TREEVIEW) indicated considerable differences between C. perniciosa strains from T. cacao and those from H. acutifolia (85–86%) and S. lycocarpum (95–96%). Sequence differences also indicated that C. perniciosa from T. cacao in Bahia is less variable (98%) when compared to the pathogen on T. cacao in Amazonas (97–98%), perhaps reflecting a recent introduction to T. cacao in Bahia.

Hyphae of Saprolegnia ferax recovered from intracellular acidification with variable degrees of apical vacuolation and migration of cytoplasm out of the apex, prior to apical refilling and resumption of growth. The response was not due to alkalinization, but was generalized to recovery from diverse growth inhibitors including procaine, latrunculin B and the kinase inhibitor 6-dimethylaminopurine. The vacuoles apparently arise from expansion and fusion of apical tubular vacuoles. This process is mediated by microtubules, since their disruption suppresses apical vacuolation. The shape of the vacuoles appears to be F-actin imposed, because their expansion is enhanced by F-actin disruption. The accompanying, often bidirectional, cytoplasmic migrations are independent of tip growth, require F-actin, and probably represent part of a hypothetical generalized cytoplasmic avoidance response.

Duddingtonia flagrans was grown in shake flask culture on Sabouraud's dextrose medium with and without the addition of agar (to form a slightly more viscous medium). The addition of agar increased the number of chlamydospores produced in late stationary phase, with 8.6×105 chlamydospores ml−1 being obtained on a medium containing 5 g agar l−1. The pH optimum for growth was between 5.5–7.5 but colonies formed on plate cultures buffered at pH 10.5. When grown in shake flask culture at 25 °C and pH 7 on malt extract–yeast extract–peptone–glucose medium (MYPG), D. flagrans had a specific growth rate of 0.21 h−1 (doubling time 3.3 h) and produced 5.1±0.07 mg biomass ml−1. To increase chlamydospore production in a liquid medium, D. flagrans was also grown in a two phase culture system in which late exponential phase biomass produced in MYPG medium was transferred to Vogel's mineral salts medium containing various nitrogen (mycological peptone, casein) and carbon (sodium acetate, starch and glycerol) sources. The highest chlamydospore concentrations (6.2×105 and 5.6×105 ml−1) were observed when the biomass was transferred to Vogel's medium containing 10 g starch or glycerol l−1, respectively.

Eudarluca caricis, the teleomorph of Sphaerellopsis filum, was found on blackberry rust (Phragmidium violaceum) in south west England and its morphology is described. Cultures derived from ascospores produced pycnidial conidiomata and conidia typical of S. filum, confirming the connection between the meiotic and mitotic stages of the fungus. Microconidia were also found in the cultures derived from ascospores. Conidiomata developed on the majority of uredinial pustules of P. violaceum 10 d after inoculating detached, uredinia-bearing blackberry leaves with the conidia from the cultures derived from ascospores.

Perenniporiella gen. nov. is segregated from Perenniporia. The new combinations Perenniporiella neofulva and Perenniporiella micropora, and the new species Perenniporiella pendula are proposed. Perenniporia piperis and Perenniporia albida are considered as taxonomic synonyms of P. neofulva. The three species are described and their taxonomic position is discussed. A key to the neotropical Perenniporiella and Perenniporia species with pileate basidiomes is presented.

A fossilised fungal colony is described and illustrated from Dominican amber dating back 15–45 Myr. Many hyphae in the coenocytic mycelium had produced terminal or intercalary protuberances resembling the sporangia of some extant zygomycetes and oomycetes. Other hyphae had produced cylindrical arthroconidia similar to those of Geotrichum and related extant yeasts. Many fossilised diaspores had germinated prior to preservation. The fungus seems to have been a rapidly growing saprophyte, utilising fluid substrates, possibly plant exudate. The palaeoenvironment proposed for the mycelium, namely that of a moist epiphytic or epixylic microhabitat, supports earlier conclusions that the original Dominican amber forest possessed a tropical moist forest biome.

A method for the observation of the three-dimensional structure of intact ectomycorrhizal rhizomorphs is described. The method is based on a combination of clearing the material with KOH followed by staining with congo red and subsequent imaging under a laser scanning confocal microscope (LSCM). The images obtained are of a much higher three-dimensional resolution than those obtained previously by use of conventional light microscopical techniques. The structure of highly differentiated and undifferentiated rhizomorphs is described. Applications of the method are briefly discussed.

The PCR technique based upon randomly amplified polymorphic DNA (RAPD) markers using 10-mer oligonucleotide primers was used to investigate the phylogenetic relationships among 33 isolates of Heterobasidion annosum belonging to the intersterility groups F and S. The F isolates originated from Italy, the S isolates from the Italian Alps, northern Europe and North America. The presence or absence of some bands was shown to be population-specific. The North American S group and the European S group differed significantly from each other, but within the latter group there were no significant differences between the Italian S and the northern European S populations, with as much similarity within these populations as between them. More DNA polymorphisms appeared within European F and S groups than in the North American S group. The North American S group appeared to be more closely related to the European S group than to the F group. The isolates of the Italian F population seemed to be most closely related to the Italian S isolates and then, in decreasing order, to the northern European S and North American S isolates. The order of genetic similarity was inversely correlated with the mating frequency in vitro obtained in an earlier study.