Perhaps like many other mycologists, my initial encounters with fungi filled me with a desire to engage with mysteries: mysteries embedded in the diversity of form and function in fungi and how this diversity might be related to the life of the forest in which so many of these organisms appear to find their homes. In all good mysteries, the resolution of underlying causes at one level of comprehension only serves to reveal deeper levels for exploration.This can open the way into a cascade that nourishes a growing empathy with fellow beings and so assuages that most fundamental need to have a sense of belonging – to be as one; to be at peace; secure in the knowledge of idiosyncrasies embraced in the fondness of others. I dreamt that fungi would somehow eventually lead me and my fellow travellers down that cascade. I still do.

Armillaria species are amongst the most important pathogens of trees and have a world-wide distribution. In recent years, the taxonomy of Northern Hemisphere Armillaria spp. has been extensively treated, but those occurring in Africa are poorly known. Previously, isolates of Armillaria from Zimbabwe have been grouped based on morphology and biochemical tests. In this study, six isolates representing the three previously characterized groups of Armillaria spp. occurring in Zimbabwe were analysed using DNA-based techniques. Three distinct clusters emerged from both PCR–RFLP and analysis of sequence data for the IGS-1 rRNA operon. The three groups corresponded to those previously identified based on morphology and biochemical tests. Differences in IGS-1 sequences strongly suggest that the Zimbabwean groups represent three distinct taxa. Isolates belonging to Group I, previously assumed to be to A. heimii, were similar to those identified as A. fuscipes from South Africa and La Reunion. Group II isolates resided in a clade apart from all other isolates and appear to represent A. heimii. The remaining isolates residing in Group III clustered with isolates from Zambia and Cameroon. These are different from A. heimii and A. fuscipes and apparently represent an undescribed taxon.

A new powdery mildew infecting papaya (Carica papaya) in Brazil, Streptopodium caricae sp. nov., is described. The species is compared with other anamorphic Erysiphales known to infect papaya: Oidiopsis sicula, Ovulariopsis papayae, Oidium caricae, O. papayae, O. caricicola, O. indicum, O. caricae-papayae, Podosphaera (syn. Sphaerotheca) spp., and Erysiphe spp. An emended description Streptopodium and a key to the anamorphs of powdery mildews on papaya are also presented. A re-examination of the type material of Phyllactinia caricaefolia showed that conidia in this material are dimorphic, indicating that its anamorph does not belong to Ovulariopsis and that the teleomorph is not conspecific with Phyllactinia guttata. Oidium caricae, the common powdery mildew of papaya, was re-examined, recognized as a member of subgenus Pseudoidium, an emended description was prepared, and a new type was indicated. O. papayae was recognized as a synonym of O. caricae, and many of the records of this fungus are considered to be doubtful or incorrect, either omitting a description of the fungus or including a description or illustration of an euodium conidiophore morphology.

Annulatascus species are common freshwater ascomycetes in the tropics. In this paper, the type species, Annulatascus velatisporus, and a new species, A. triseptatus, are described and illustrated at light and electron microscope levels. Annulatascus triseptatus differs from A. velatisporus in having three-septate ascospores surrounded by a thin sheath. The asci of both species have bilamellate ascus walls and a bipartite apical ring. The upper part of the apical ring differentiates from the inner ascus wall layer and the lower part elongates downwards during maturation. The mesosporium is the first formed ascospore wall layer followed by the episporium, which is covered with verruculose ornamentations. The mucilaginous sheath of the ascospores is fibrillar or amorphous depending on the fixation methods employed, and appears to be derived from the episporial verruculose ornamentations.

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.

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.

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.

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.

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.

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.

Economic mass production is a crucial stage in the development of biocontrol agents. This paper compares different solid substrates with and without preceding liquid culture for efficacy and economics in the scaled-up production of the mycoparasitic biocontrol agent Clonostachys rosea. In a basic liquid medium (BLM) containing (in g l−1): molasses (80), neopeptone (10) and yeast extract (2), Clonostachys rosea produced 107 conidia ml−1 after 4 d in agitated culture. Spore viability was 99% and did not differ from that of conidia derived from potato dextrose agar plates. Guata, an inert polyester fibre, coated with BLM and cassava starch (30 g l−1), was the best solid matrix yielding 109 conidia g−1 after 20 d. On a volume basis after extraction and on a production unit basis, Guata was in a similar range to Biodac®, a granular cellulose complex, which had also been enriched with BLM, producing up to 107 conidia ml−1 or over 1010 conidia per 23×28 cm polypropylene bag, the production unit in which all solid matrices were incubated. Rice was the lowest-yielding solid matrix regardless of quality. Chlamydospores were not observed in liquid or on solid media. All conidia produced on solid matrices had a viability >90%. Conidia produced on Biodac had a higher viability (95.6%) than spores produced on Guata (93.1%) after 24 h on potato-dextrose plates. However, production on Biodac was more variable and negatively affected by prefermentation in liquid culture, whereas production on Guata and rice was unaffected by the origin of the starting inoculum. Guata of medium thickness (1.27 cm) was superior to thicker (2.54 cm) or thinner (0.64 cm) sheets with respect to both yield per gram and per production unit. Although prefermentation neither improved yield nor reduced cost, it increased throughput by a factor five and may be advantageous where fermentor and/or incubator space is limited. Biodac and Guata were the most economical solid matrices; inoculum to treat one hectare (3×1012 conidia) cost US $ 27, whereas rice-based production cost US $ 613 under Costa Rican conditions. Liquid culture alone would be fast but too costly: US $ 1078 ha−1. Experiments to further reduce costs in the Guata system are suggested.

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.

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.

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.

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.

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.

The ability of an unidentified mycobiont from Pisonia grandis mycorrhizas to utilize organic nitrogen and phosphorus sources was determined in axenic liquid cultures. The fungus utilized inorganic phosphate and both freely- and poorly-soluble salts of inositol hexaphosphate as sole phosphorus sources. With the exception of uric acid which did not support growth, the yield of the mycobiont on all organic nitrogen sources tested was significantly greater than the yield on either NH4+ or NO3−. It is suggested that the major ecological role of the Pisonia mycobiont in stands of P. grandis on coral cays may be rapid absorption of allantoin and urea produced during degradation of uric acid by the soil microflora. This may be important in retaining nitrogen in the soil[ratio ]plant system prior to loss from the coral cay by further degradation, volatilization and/or leaching.

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.

Corky root of tomato caused by Pyrenochaeta lycopersici is a disease of concern in Italy and for many tomato growing areas in the world. Isolates of the fungus were characterized at both the physiological and molecular level. The optimal in vitro growth temperature for all isolates was 23 °C. All Italian isolates of P. lycopersici showed similar RAPD and esterase banding patterns. No relevant polymorphisms were detected after enzymatic digestion of PCR-amplified ITS and IGS regions. The overall results indicate a low degree of genetic variability within a collection of 43 Italian isolates. These data are of interest in breeding programs for resistance against corky root of tomato and they provide useful information for the development of molecular diagnostic tools for the rapid identification and detection of P. lycopersici.