Phylogenetic analysis of the ITS rDNA region was carried out with two economically important downy mildews, Pseudoperonospora cubensis, which infects species of Cucumis, Cucurbita, and Citrullus belonging to Cucurbitaceae, and P. humuli, which infects plants of the genus Humulus belonging to Cannabaceae. Two closely related species, P. cannabina and P. celtidis, were also included to reveal taxonomic relationships with the first two mildews. All four species formed a well-resolved clade when compared with the ITS sequences of other downy mildew genera, using Bayesian inference and maximum parsimony. The P. cubensis isolates obtained from different hosts and (or) geographical origins in Korea, exhibited no intraspecific variability in the ITS sequences. The phylogenetic analyses of P. cubensis and P. humuli showed that they share a high level of sequence homology; the morphology of the sporangiophores, sporangia, and dehiscence apparatus confirmed the similarity of the two species. We therefore reduce P. humuli to the status of a taxonomic synonym of P. cubensis.

Ectomycorrhizal and saprobic macrofungi growing in the wild were collected from non-auriferous and unpolluted areas and analyzed for gold. Gold was determined using long-term instrumental neutron activation analysis (INAA). In total, 154 samples, including 67 species of ectomycorrhizal fungi and 22 species of terrestrial saprobes, were examined. Gold contents of the both groups were mostly less than 20 ng g−1 of D.W. The highest concentrations (expressed in D.W.) were found in the ectomycorrhizal species Amanita strobiliformis (136 ng g−1), Russula claroflava (148 ng g−1), Cantharellus lutescens (156 and 210 ng g−1), and Boletus edulis (235 ng g−1). Among the saprobic fungi, the highest values were found in Langermannia gigantea (160 ng g−1) and Morchella esculenta (189 ng g−1). Species of Agaricus commonly had relatively high gold values, 10s of ng g−1. The gold content of macrofungal fruit bodies was considerably higher than that of vascular plants, and parallels concentrations found in plants growing in auriferous areas.

The ITS region including the 5.8S rRNA gene as well as the 5′ end of the 28S rRNA gene of hypogeous Pezizaceae and Tuberaceae were studied to clarify the generic placement of two southern African desert truffles, Terfezia pfeilii and Choiromyces echinulatus. The results show that neither species belongs in the genus to which it has been assigned on the basis of morphological characters. As expected, two Choiromyces spp. grouped close to the representative of the Tuberaceae (Tuber melanosporum). However, C. echinulatus diverged from the other Choiromyces species and emerged near members of the genus Terfezia, being even closer to that genus than T. pfeilii. Two new genera and new species combinations, Kalaharituber gen. nov. with K. pfeilii (syn. T. pfeilii) comb. nov. and Eremiomyces gen. nov. with E. echinulatus (syn. C. echinulatus) comb. nov. are therefore introduced to accomodate these taxa. Both genera are closely related to Terfezia, and thus are placed in the Pezizaceae.

Accurate identification of Alternaria spp. is dependent upon the production of diagnostic morphological characters under defined cultural conditions and the proper assessment of character variation. This process is often compromised by variation in laboratory facilities and technical expertise. To assist taxon identification and phylogenetic studies, restriction site information from the intergenic spacer (IGS) region of nuclear rDNA was evaluated. Restriction maps were constructed from 15 species of Alternaria and Stemphylium botryosum (telemorph Pleospora herbarum) for 11 restriction enzymes using a new method for restriction mapping based on differential priming of IGS amplicons. IGS fragment size varied among species from 2.2–3.9 kb. Based upon restriction site homology among closely-related and more distantly related species, the IGS region could be divided into conserved and variable domains. The conserved domain was approximately 0.75 kb in size and was located at the 3′ end of the IGS region. Restriction site homology within this region was very high, especially among closely related taxa. The remainder of the region comprised the variable domain, which encompassed considerable differences in size and restriction sites among taxa. The presence or absence of restriction sites among taxa was analyzed using methods of neighbor-joining. Phylogenetic relationships based on this method were concordant with those previously resolved based upon other methods and other genomic regions.

21 cactus species occurring in various localities within Arizona were screened for the presence of fungal endophytes. 900 endophyte isolates belonging to 22 fungal species were isolated. Cylindropuntia fulgida had the maximum endophyte species diversity, while C. ramosissima harboured the maximum number of endophyte isolates. Alternaria sp., Aureobasidium pullulans, and Phoma spp. were isolated from several cactus species. The diversity of the endophyte assemblages was low and no host specificity among endophytes was observed. However, the frequencies of colonization of the few endophyte species recovered were high and comparable to those reported for tropical plant hosts. Species of Colletotrichum, Phomopsis, and Phyllosticta, which are commonly isolated as endophytes from plants of more mesic habitats, were absent from these cacti.

A piece of Baltic amber (Tertiary, Eocene) contains an inclusion of a springtail (Collembola) which is overgrown by an Aspergillus species. The fossil fungus is described as A. collembolorum sp. nov. The excellent mode of preservation of the numerous conidiophores is remarkable and can be explained by sporulation in liquid resin. This is the second report of a fossil Aspergillus, the first being from Dominican amber.

Maple, linden and oak leaves were immersed in a stream for 1–21 d. Cumulative mass loss, ergosterol content, and species richness of released aquatic hyphomycete conidia increased with time. Numbers and richness of attached conidia were highest on days 1 and 2. Denaturing gradient gel electrophoresis revealed up to seven fungal phylotypes on the leaves before their immersion in the stream and after one day of stream exposure. After 5 d of immersion the contribution of these terrestrial fungi decreased and that of aquatic hyphomycetes increased. The dominant phylotypes belonged to Anguillispora filiformis, Articulospora tetracladia and Flagellospora curvula, which also dominated the community of released spores. The molecular diversity was highest on day 2 and 3 on all substrates. This may be due to a few species of terrestrial fungi, later outcompeted by aquatic hyphomycetes, and to many different conidia of aquatic hyphomycetes, some of which may germinate but are unable to establish themselves and reproduce.

Podosphaera tridactyla (Ascomycota: Erysiphales) is a morphologically variable species occurring on Prunus s. lat. In order to assess the genetic variation within this species, the rDNA ITS region was amplified from 29 specimens from a range of Prunus species collected in Australia, Switzerland, and Korea. RFLP analysis of the PCR products revealed six groups, and a comparison of sequences from representatives of these groups revealed three clades: Clade 1 contained all specimens from Prunus subgen. Prunus; Clade 2 specimens from a variety of Prunus subgenera, except subgen. Prunus, and Podosphaera longiseta was closely allied to this clade; and Clade 3 contained two specimens, from Japan and Korea. Phylogenetic analysis comparing P. tridactyla with of a range of Podosphaera species suggests that P. tridactyla is paraphyletic.

The endophytic behaviour of Sclerotinia pseudotuberosa, cause of black rot of fruits of Castanea sativa, was investigated in asymptomatic tissues of the host, including nuts, buds and bark. A nested polymerase chain reaction (PCR) assay was developed for the specific detection of S. pseudotuberosa. Two specific primers, RAC1 and RAC2 were designed within the ITS1-5.8S-ITS2 region of rDNA by comparison of sequences of 24 isolates of S. pseudotuberosa and related species. Specificity of primers was tested against isolates of related and unrelated genera and the total DNA of C. sativa. The assay proved to be highly sensitive and capable of detecting picograms of S. pseudotuberosa DNA. Our study showed that S. pseudotuberosa was present asymptomatically in all the chestnut tissues tested. It is discussed that latency of S. pseudotuberosa in chestnut tissues may represent a adaptive strategy of the pathogen for rapid and massive host colonization in favourable environmental conditions.

Although Plasmopara viticola causes grape downy mildew in most, if not all, wine producing countries, many basic biological or chemical aspects are still unknown and thus the histopathological changes during development of this oomycete pathogen were studied. The fluorochromes Aniline blue and Uvitex 2B were successfully used in whole leaf stainings to visualise intercellular hyphae and to investigate septal-development in sporangiophores. The occurrence and transfer of cytoplasm in sporangiophores was studied with the aid of Chlorazole Black E and Phloxin B. Application of Chlorazole Black E was the most reliable method to differentiate between cytoplasm and septa in sporangiophores due to a high contrast between the dark cytoplasm and the pale septa. In P. viticola, septa were found in the stem and branches of the sporangiophores, but not in the intercellular hyphae, which was in contrast to other oomycetes, such as P. tabacina, Pseudoperonospora cubensis and P. humuli, where septa were frequently found in the mycelium. In order to verify chemical composition of septa, sporangiophores were digested using chitinase and β-1,3-glucanase. After staining with Aniline blue and Uvitex 2B, the intense fluorescence of septa was conserved after the application of chitinase but not after β-1,3-glucanase, indicating that septa are mainly composed of β-1,3-glucans. Pretreatments of infected vine leaves with 2-deoxy-D-glucose (2-DOG) at low concentrations (1–5 mM) led to a disorganisation of the sporangiophore structure of P. viticola, whereas the production of septa was unaffected. Application of 2-DOG at higher concentrations resulted in a reduced length of intercellular hyphae (10 mM) or total inhibition (50 mM) of the intercellular mycelium. Thus, 2 DOG or its analogues interferes with morphogenesis in Plasmopara viticola and may have a deleterious effect on the spread of this downy mildew between plants.

Fungal endophytes of the genera Neotyphodium and Epichloë are important mutualistic symbionts and pathogens of many cool-season grass species. Here we report the characterization of a secreted N-acetylglucosaminidase from the Neotyphodium sp. endophyte that infects the grass Poa ampla. The enzyme was expressed at low levels within the host, and activity could be detected in the apoplastic protein fraction. Low-level expression could also be detected in endophyte-infected perennial ryegrass (Lolium perenne), Chewings fescue (Festuca rubra subsp. fallax), and tall fescue (L. arundinaceum). The enzyme may function in the recycling of chitin oligomers generated from turnover of the fungal cell wall. This is the first report of a secreted N-acetylglucosaminidase expressed by an endophytic fungus in the infected host plant.

A list of the 242 scientific publications authored, co-authored, or edited by John Webster from 1951 to the end of 2004 is presented. The list includes papers, books, book chapters, films, and videos.

Amphipathic glucose derivatives 3-O-octyl- and 3-O-decyl-D-glucose were synthesized, and the ability to induce fruit bodies on Pleurotus ostreatus was examined. Surfactants such as CHAPS, CHAPSO, MEGA-8, MEGA-9, and MEGA-10 were also assayed. The result was that both glucose derivatives could stimulate fruiting on P. ostreatus, while none of the surfactants assayed in this study stimulated the fruiting of P. ostreatus. These results suggest that sugar moiety is necessary for amphipathic compounds to work as a fruiting signal for P. ostreatus.

The aim of this study was to test the usefulness of direct PCR-amplification in analysing fungal diversity in stumps. The analysis was conducted on stumps treated against Heterobasidion spp. using a commercial formulation of Phlebiopsis gigantea (Rotstop), and carried out using denaturing gradient gel electrophoresis (DGGE) of small subunit (SSU) ribosomal DNA (rDNA) fragments PCR-amplified directly from wood DNA samples using two separate fungus-specific primer pairs. On average, two (range 0–9) different amplification products were observed by DGGE in single wood samples of approximately 500 mm3. The PCR products were classified into operational taxonomical unit (OTU) groups based on their DGGE mobility. Six OTUs could be affiliated with a known species based on a reference fungal collection of 37 species: Heterobasidion annosum, H. parviporum. Hypholoma capnoides, P. gigantea, Resinicium bicolor and Stereum sanguinolentum. Sequence analyses did not give further identifications. OTU profiles from old (6 yr-old) and fresh (1-year-old) Scots pine and Norway spruce stumps from treated and untreated forest plots were compared statistically, and some significant differences were observed in the species composition between the treated and untreated plots. However, the frequency of most of the OTUs did not seem to be affected, and the treatment did not seem to have reduced the overall level of fungal diversity. Based on these results, direct PCR-amplification seems to be useful in analyses of fungal communities in decaying conifer stumps.

Lignin peroxidase and laccase gene-specific PCR primers were used to screen 38 diverse basidiomycetes and xylariaceous fungi. Lignin peroxidase gene-specific sequences were obtained for basidiomycetes only and were highly divergent. Possession of laccase genes was relatively widespread among basidiomycetes, and is shown for the first time in Xylariaceae. All sequences were highly conserved with no variation resulting in changes to predicted amino acid sequence. Those basidiomycetes shown to possess lignin peroxidase and laccase genes also produced the enzyme in vitro. Conversely none of the xylariaceous fungi shown to possess laccase genes were able to do so, whilst others decolorized Poly R yet yielded no PCR amplicons.

In the mushrooms Pleurotus ostreatus and Agrocybe aegerita, expression of the hemolytic proteins ostreolysin and aegerolysin, which belong to the aegerolysin family, has been shown to be initiated specifically during formation of primordia and fruiting bodies. We used rabbit anti-ostreolysin and fluorescent rhodamine-labelled secondary goat antibodies for monitoring ostreolysin and aegerolysin in situ during the mushrooms' development. In parallel, the protein level in developing tissues was monitored with SDS-PAGE and hemolytic assay. Immunolocalization of ostreolysin, visualized by epifluorescence, together with biochemical tests, confirmed specific expression of ostreolysin and aegerolysin in the primordia and fruiting bodies but not in the vegetative mycelia. In the primordia, the proteins were disposed diffusely. In growing and mature fruit bodies they persisted in the lower part of the pileus, in particular in basidia and basidiospores, while in other parts only a few focal remains were observed. Confocal microscopy of immunolabelled sections showed that intracellular ostreolysin was located specifically along the inner edges of hyphae. Since both proteins were found preferentially in the rapidly growing primordia, and in the basidia and basidiospores of maturing fruit bodies, it is suggested that they might play a role in the processes of fructification and/or sporulation.