The wood of one Picea abies stump, including its roots (1·3 m in length), was sliced into 2 cm thick discs. The stump originated from a thinning conducted 7 yr prior to the investigation in a 30 yr old spruce stand planted on previous farmland that became heavily infected by Heterobasidion annosum. After incubation of the wood discs, interaction zones were observed on the surfaces and H. annosum was isolated from the areas between the zones and from the zone lines, resulting in 296 isolates. The isolates were tested with somatic incompatibility to detect 35 different genets. Of the 27 genets colonising the upper part of the stump (excluding the roots), 12 had proceeded into the roots. Seven genets found in the roots were not found in the upper part of the stump and one genet isolated from an interaction zone on the top of the stump was not found elsewhere in the stump or in the roots. Two of the genets had grown into root contact with other trees.

Serpula lacrymans is a basidiomycete cord-forming wood decay fungus which reallocates nitrogen within an extensive perennial mycelial system in response to spatial discontinuities in external nutrient supply. Intracellular stored protein is mobilised by conversion to amino acids at nutrient-poor sites within a mycelium or when a whole mycelium is starved. Intracellular peptidase and proteinase activities of the mycelium were investigated with the aim of identifying proteases specifically activated in response to a nitrogen demand. Mycelium for enzyme extraction grown as surface mats in static liquid culture was homogenised, and the extract used in assays for proteinase and peptidase with various synthetic peptide substrates conjugated to 4-nitroaniline. Activities against different substrates were characterised with respect to pH, inhibitor sensitivity, requirements for divalent metal ions, isoelectric point, and by changes in activities in starved mycelium. Four different activities were found, comprising two peptidases one of which had metalloprotease characteristics, a serine-type proteinase, and a proteinase active at pH 2.5 which was not affected by any of the inhibitors tried. Both the latter were most active in starved mycelium. Isoelectric focusing showed peaks with activities corresponding to the serine-type proteinase and one of the manganese-activated peptidases. Possible roles for these enzymes in nitrogen reallocation during mycelial foraging are discussed.

Genetic variation was found between isolates of Botrytis elliptica from the USA and Taiwan based on 22 polymorphic markers from five RAPD primers. Among these 69 isolates, there were 43 different genotypes. One clonal genotype was found spanning Oregon and Washington, USA, and in a population from Hsinshe, Taiwan, clonal genotypes were frequent, demonstrating the importance of asexual spread of this pathogen. However, when only unique genotypes were considered, gametic disequilibrium among putative RAPD loci of the genotypes from Taiwan (33) or Hsinshe (23) was not detected, suggesting an underlying sexual recombination system for this population of B. elliptica. A weak level of cultivar specialization was detected among B. elliptica isolates from the Hsinshe population based on analysis of genetic distances between isolates.

Green moulds caused by Trichoderma harzianum biotypes Th2 and Th4 are responsible for important economic losses on mushroom farms producing Agaricus bisporus, whereas other biotypes present in farms have only slight effects on the cultivated mushroom. Adaptation of Th2 and non-Th2 strains of Trichoderma to grow in compost prepared for mushroom cultivation was compared through extracellular enzyme activities and competition with bacteria isolated from compost. No specific differences between Th2 and non-Th2 strains were observed for the activities of the 17 secreted enzymes tested. Confrontations of 27 bacterial isolates with 4 Trichoderma strains revealed that the aggressive Th2 strains were affected by a lower number of bacterial isolates than the non-Th2 strains. Capacities of T. harzianum, biotype Th2, to colonise mushroom compost are not due to a specific ability to produce enzymes necessary for compost degradation but to their tolerance to the inhibitory effect of bacteria present in compost.

To attract insects for sexual reproduction, some fungi can induce the formation of pseudoflowers on their hosts. Pseudoflowers are rosettes of yellow host leaves upon which the fungus presents gametes in sweet nectar. Eleven species of the fungus complex Uromyces pisi can induce pseudoflowers on the host Euphorbia cyparissias. The taxonomy of these species is based on the choice of the alternate host, a species of Fabaceae, as well as on teliospore morphology on the Fabaceae hosts. Morphological identification of the fungi on E. cyparissias is impossible. To identify the fungal species on infected E. cyparissias, we compared sequences from the ITS region of the rDNA to the DNA from five identified fungal species on Fabaceae. From 43 specimens on E. cyparissias, collected in 1997–99 in Switzerland, 24 specimens could be identified as U. pisi s. str. and 16 specimens as U. striatus. Two specimens were identified as U. laburni and U. loti, respectively, and one specimen could not be identified. We therefore conclude that fungal pseudoflowers are typically induced by U. pisi s. str. on U. striatus in Switzerland, although other species do sometimes occur. The ITS sequences were then used to reconstruct the phylogenetic relationship among species in the U. pisi complex and two closely related microcyclic rust species of the complex Uromyces scutellatus. Phylogenetic analyses indicated that the microcyclic species may be descendants from macrocyclic U. pisi s.l. ancestors. The ITS region sequenced in this study was found to be appropriate for answering phylogenetic, as well as ecological questions, and provided valuable markers for future studies.

This paper develops field data analysis and theoretical hypotheses concerning the role of climatic factors and fungal interactions in the control of fungal populations. We studied three ‘resource unit restricted fungi' colonizing Pinus sylvestris needles along a climatic gradient. We investigated both competition and succession. A general linear model was used for statistical analysis. Despite interference competition at the scale of the individual needle, the first two colonizers, Lophodermium pinastri and Cyclaneusma minus, coexisted and the frequencies of both increased with altitude. This increase seemed to be related to the greater humidity at altitude. The initial stages of development of the final colonizer, Verticicladium trifidum, were strongly dependent on the first two colonizers on the individual needles. The observed decrease in frequency of V. trifidum with increasing altitude may be due to interactions with the early colonizers, with no direct effect of altitude on V. trifidum. Fungal colonization at low and high altitudes can be interpreted by accounting for both climatic effects and fungal interactions expressed as interference and succession.

The identity of strains identified as Trichoderma aureoviride/Hypocrea aureoviridis was reconsidered. Trichoderma aureoviride was isolated originally from a specimen identified as H. aureoviridis and thus is H. aureoviridis. The morphological and molecular characters of most strains identified as T. aureoviride differ from those of the ex-type but are more typical of T. harzianum, a member of sect. Pachybasium. Molecular data do not support inclusion of T. aureoviride in sect. Trichoderma, nor was there strong phenotypic similarity between H. aureoviridis and H. rufa. In the ITS phylogeny the T. aureoviride ex-type and other collections of H. aureoviridis form a strongly supported clade that is separate from any other recognized section of Trichoderma. Hypocrea vinosa, which was originally included in the T. aureoviride aggregate species concept, is distinct from T. aureoviride, but closely allied with H. rufa/T. viride. Trichoderma aureoviride/H. aureoviridis is a rare species, restricted to the UK and the Netherlands. We redefine T. aureoviride, limiting it to strains with very slow growth rate, effuse conidiation, and the ITS-1 and 2 sequence type D.

We screened a cDNA library generated from harvested and stored sporophores of Agaricus bisporus and identified 19 genes with higher transcript levels than at the time of harvest. Five of these genes had no detectable mRNA levels prior to detachment from the mycelium. Sequence analysis of ten clones revealed significant similarities to known genes, these code for proteins involved in polymer breakdown and metabolism, cell wall synthesis, stress tolerance, cytochrome P450 activity and DNA binding. The diversity of functions of these genes suggests the changes in the sporophore after harvest involve several different physiological processes.

The genera Hobsonia, Illosporium, and Marchandiomyces include several common lichenicolous (lichen-inhabiting) species that have been taxonomically linked in the past. These mitosporic genera are frequently misidentified because of a paucity of morphological characters, which has led to some confusion about their relationships. We examined the phylogenetic positions of species in these genera using complete sequences of the small subunit (SSU) and internal transcribed spacer (ITS) ribosomal DNA (rDNA), and portions of the mitochondrial (mt) SSU rDNA obtained from isolated cultures of freshly collected specimens. Phylogenetic analysis of the sequence data indicated that Marchandiomyces corallinus and M. aurantiacus are closely related members of a basidiomycete clade. In addition, the clade includes an undescribed non-lichenicolous species that is morphologically similar to M. corallinus. Another undescribed species with marchandiomyces-like sclerotia, appears to be in a separate basidiomycete clade. The three recognized species of Hobsonia are unrelated, with H. christiansenii appearing to be a hypocrealean ascomycete closely related to a sample of Illosporium carneum, H. santessonii an ascomycete of unknown affinity, and H. mirabilis a basidiomycete. The latter, a plant pathogen, is the type species of Hobsonia. The new generic names Illosporiopsis and Hobsoniopsis gens. nov. are described for the lichenicolous species H. christiansenii and H. santessonii, respectively, and the necessary new combinations made.

Random amplified polymorphic DNA polymerase chain reaction (RAPD–PCR) was used to assess the genetic diversity in twelve populations (a total of 144 isolates) of the Pleurotus eryngii complex, sampled in Israel. Our results show a higher level of diversity of RAPD polymorphism in the populations, especially in the drier, stressful climates. Twelve primers used in this study amplified 164 scorable RAPD loci, of which 163 (99.4%) were polymorphic and only 1 monomorphic. Out of the 164 loci, 123 (75%) varied significantly (P < 0.05) in allele frequencies among populations. This total proportion (75%) of significant polymorphic loci far exceeds the 5% level expected by chance (binomial test, P < 0.000001). The levels of polymorphism and gene diversity appeared to be highly significantly different between the populations. Sixty-eight per cent of the RAPD diversity was within populations and 32% was between populations. Inter-population genetic distances showed positive association with geographic distance, which was confirmed with spatial autocorrelation analysis of RAPD frequencies. Spearman rank correlation revealed a strong positive association between high polymorphism and the aridity index. In multiple regression, the coefficient of determination of polymorphism and gene diversity was explained by climatic variables linked to temperature and humidity. Our findings further demonstrate the validity of the ‘environmental theory of genetic diversity' hypothesis within P. eryngii populations in Israel. We suggest that natural selection develops a high level of RAPD polymorphism as adaptation to cope with stressful and temporally heterogeneous environments.

The saprobic microfungi associated with endemic plants of Mauritius have been studied. Over 200 taxa were identified of which approximately 90% are new records for Mauritius including one genus and 38 new species. The mycobiota encountered on the monocotyledonous genus Pandanus is more distinct than that on three dicotyledonous hosts Sideroxylon, Cordemoya and Olea. Arguments are presented to support the inclusion of microfungi in in situ conservation management policies.

The occurrence of fungi and slime moulds on 70 decaying beech logs was surveyed based on the presence/absence of sporocarps. In total 277 species of fungi and 25 of slime moulds were recorded and summarised in a log/species datamatrix. The structure of the datamatrix was analysed using detrended correspondance analysis (DCA). The ecological nature of the gradients expressed by the first three DCA-axes was then investigated by environmental and log related variables. The first and strongest gradient corresponded to changes in the community development during the decay process. The second gradient was complex and corresponded to both decay rate and microclimatic stress. The third, rather weak, gradient was influenced by soil conditions. The gradients are discussed in a context of fungal ecological strategy theories. A model generalised from the community development on the studied logs is proposed.

To understand the mechanism of wood discolouration employed by the staining fungus Ophiostoma floccosum, a gene involved in dihydroxynaphthalene (DHN) melanin biosynthesis was cloned from this organism and its function was examined. Degenerate oligonucleotide primers were designed according to conserved regions of hydroxynaphthalene (HN) reductases and used to PCR-amplify a 380 bp fragment from genomic DNA of O. floccosum. The amplified product was used as a probe to screen an O. floccosum genomic phage library. A genomic clone containing a full-length HN reductase gene was retrieved and a total of 1681 bp of its nucleotide sequence was determined. The determined sequence contained 673 bp of 5′ untranslated sequence, 807 bp of putative open reading frame (ORF) encoding a protein of 269 amino acids and 197 bp 3′ untranslated sequence. The ORF contained a 76-bp intron. Based on the similarity of the inferred amino acid sequence to other known fungal HN reductases, the cloned O. floccosum gene was considered an HN reductase gene. Disruption of the O. floccosum reductase gene was unsuccessful due to integration anomalies during homologous recombination. As an alternative, we complemented an HN reductase deficient buf mutant of the rice blast fungus Magnaporthe grisea by introducing the cloned O. floccosum reductase gene using hygromycin B resistance plasmid pCB1004. The complemented M. grisea buf mutants produced a black pigment like a wild type strain, indicating that the O. floccosum reductase is functionally homologous to other fungal HN reductases. These results suggest that O. floccosum uses the DHN pathway for pigmentation.

Single-strain biocontrol agents often look promising when tested against single-strain pathogens. When confronted with a biodiverse field population, however, biocontrol is inconsistent. This study implies that biodiversity of the crown rot pathogen Colletotrichum musae leads to strain discrimination by antagonists which results in variable biocontrol of the disease. Broad host-range mycoparasites of fungi of the crown rot disease complex of banana (C. musae, Fusarium moniliforme and Botryodiplodia theobromae) which attacked at least two of the pathogen genera, exhibited significant differences in aggression against different strains of C. musae, the main pathogen. Antagonists acted via several different mechanisms, i.e. parasitism, antibiosis or competition, simultaneously. The relative importance of each mechanism differed with the individual mycoparasites. Strain discrimination was correlated to differential susceptibility to one or more minor mechanism(s). When as many as four antagonists were combined into one inoculum, they complemented rather than antagonised each other. Biocontrol efficiency increased with the number of antagonist strains combined. Therefore, strain mixtures should be sought to control the crown rot disease complex of banana.

The effect of air-dry storage environment on the longevity of conidia from seven isolates of Beauveria bassiana produced at different times and locations was determined by estimating the parameters of a viability equation. Conidia were stored hermetically at six to 11 moisture contents between 2.3 and 32.0% with one (50±0.5 °C) to five constant temperatures (10, 20, 30, 40 and 50±0.5 °) for various periods up to 372 d and then tested for viability. All isolates behaved similarly (P > 0.25) in terms of the relative effect of moisture content (CW) and temperature (CH and CQ) on conidial longevity; common values were CW = 3.05 (SE = 0.07), CH = 0.0293 (SE = 0.0078), and CQ = 0.00081 (SE = 0.00011). Estimates of the low-moisture-content limit to the negative logarithmic relation between conidial moisture content and longevity were 4.6 and 5.0% at 50° and 40°, respectively, for isolate I98-1140ss, and 5.2 and 5.1% moisture content, respectively, for isolate I97-1111. Absolute longevity (KE) varied considerably (P < 0.005) among isolates, even within an isolate when conidia were produced at different locations. Among the eight samples of seven isolates, two cohorts were identified with respect to KE (P < 0.005): conidia of three isolates which were produced at Ascot had a common estimate of KE of 6.696 (SE = 0.170), whereas those produced at Nairobi or Carolina provided a lower estimate (6.203, SE = 0.029). This difference in KE means that for any given viability period in any given environment, the conidia produced in Ascot provided about three times the longevity of the other samples.

The South African Cape Floral Kingdom is the world’s smallest and most diverse plant Kingdom, but is greatly under threat from urbanisation and agriculture. It covers only 90000 km2 and has a Mediterranean climate. This area has a long history of botanical studies, but little research has been undertaken on the associated fungi. Therefore, a biodiversity study of the fungi has been initiated. The catalyst for this study has been the diversity of unusual fungi encountered whilst studying the fungal pathogens of Proteaceae. These pathogens include species, or entire genera of fungi that are specific to genera of Proteaceae. The diversity and uniqueness of the Proteaceae pathogens may indicate a similar diversity in saprobic fungi in this unusual habitat. Therefore, microfungi associated with genera of Proteaceae in various habitats are being systematically sampled over a two-year period. The initial results of this study are presented.

A thermostable intracellular lipoxygenase from Thermomyces lanuginosus was purified to sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) homogeneity by ion-exchange chromatography on diethylaminoethyl (DEAE)-Sepharose, ion-exchange chromatography on carboxymethyl (CM)-Sepharose and Phenyl-Sepharose hydrophobic interaction chromatography. The molecular weight of the enzyme was estimated to be 100 kDa by SDS-PAGE. The lipoxygenase exhibited maximal activities at pH 6.0. The optimum temperature for the activity was 55 °C. The enzyme was thermostable at 50 ° with half-lives at 60 ° of 20 min and 70 ° of about 7 min. The lipoxygenase activity was completely lost by heating at 80 ° for 5 min. The lipoxygenase catalyzed the oxidation of linoleic acid into 13-L-hydroperoxy-9,11(Z,E)-octadecadienoic acid(13-HPOD) as the major product. The enzyme had an apparent Km of 8.5 μM and Vmax of 10.8 μmol mg−1 min−1 with linoleic acid as substrate.

Gondwanan vegetation, and the Australian region in particular, is species rich for ectomycorrhizal fungi in epigeous and hypogeous forms with over 100 species recorded in small (1 ha) patches of forests. Distinguishing co-occurring ectomycorrhizal fungi as root associations in native (natural or wildlands) vegetation or plantations and discriminating them from other larger basidiomycetes, e.g. wood and leaf litter decomposer fungi, places large demands on molecular identification, especially if interspecific similarities and intraspecific variation occur in target sequences. One hundred and nine species of larger basidiomycetes from a single forest location were characterised by PCR–RFLP profiles of two genomic regions (nuclear rDNA ITS and mtLSU). Over one-third of the species for which multiple isolates were tested showed intraspecific variation in either one or both genomic regions. This remarkably high variation questions previous assumptions about intraspecific ITS sequence variation and highlights the value of integrated molecular and morphological databases including voucher specimens. It also emphasises the value of molecular investigations that use more than one genomic region. Interspecific similarities were common among the Cortinariaceae, especially in the ITS region. Discrimination of most Cortinariaceae species was achieved using variation in the mtLSU region in conjunction with the ITS. This new information raises the possibilities that the ITS sequence is more conserved and the mtLSU more variable than among species of the other 23 families. In the other families, interspecific ITS variation was greater and the mtLSU profiles grouped species within families. The high variation in the two genomic regions indicated possible differences in the fungal population structure between two adjacent, differently managed blocks of Eucalyptus marginata forest. The significance of this variation to ecology, biodiversity assessment and ecosystem management are discussed.

Sporocarps of Arcangeliella borziana, a hypogeous russuloid fungus, were found in a subalpine spruce forest in the Swiss Alps. We identified the ectomycorrhizas formed by this species using the ITS–PCR–RFLP method and described them in terms of morphological, anatomical, and molecular features. Phylogenetic placement of A. borziana was studied by comparing nucleotide sequences of the mitochondrial large subunit rRNA gene and the ITS region of nuclear rRNA, respectively, with existing sequence databases, and by comparing the ITS–RFLP pattern with a reference library of approx. 180 mainly basidiomycetous fungi. Sequence analysis of the mitochondrial large subunit rRNA gene confirmed the affiliation of A. borziana to the Russulaceae. Sequence as well as RFLP pattern comparison of the ITS region revealed a close affinity of this species to Lactarius sect. Russularia. This is in accordance with morphological and anatomical studies of the ectomycorrhizas, which share many features with ectomycorrhizas of Lactarius sect. Russularia.

The development of apothecia of Pyrenopeziza brassicae (anamorph Cylindrosporium concentricum) on oilseed rape debris and compost malt agar was observed by scanning electron and light microscopy. On oilseed rape debris, apothecia developed directly beneath the epidermis as small globular structures of dense mycelium, which protruded through the epidermis as they increased in size. The apices of erumpent immature apothecia then developed small ostiolar openings which increased in diameter to expose the hymenia of mature apothecia containing dome-shaped asci interspersed with filiform paraphyses. On compost malt agar, hyphae of one mating type grew towards hyphae of the opposite mating type 3–4 d after inoculation of conidia onto agar surfaces. The subsequent development of apothecia on compost malt agar was similar to that on oilseed rape debris.