Pycnidiospores of Phyllosticta ampelicida germinate only after they become attached to a hydrophobic substratum. They do not readily attach or germinate on hydrophilic surfaces or on nutrient-rich media. The properties of the spore surface that function in attachment and signal mediation for germination were investigated in this study. Pycnidiospores were surrounded by a sheath that bound Concanavalin A (Con A)-TRITC and only weakly bound wheat germ agglutinin (WGA)-FITC. Galanthus nivalis lectin-FITC selectively bound primarily to the apical region of the sheath associated with the appendage. Con A, but not WGA or GNL, disrupted spore attachment. The Con A effect on spore attachment was significantly reduced when the lectin was pre-mixed with methyl-D-α-mannoside. The sheath as well as the associated appendage was removed with either Novozym 234 or crude β-glucuronidase. Such sheathless spores were initially adhesion incompetent but, by 40 min, the spores regained their ability to adhere to hydrophobic surfaces through the secretion of material that had an affinity toward colloidal gold. Non-treated pycnidiospores surrounded by sheath remained spatially separate; however, sheathless spores readily agglutinated. Addition of cations enhanced attachment to both hydrophobic and hydrophilic surfaces presumably through the masking of electronegative groups on the sheath or by reduction of the ordered water-shell surrounding the sheath. In particular, Ca2+ induced both attachment and germination on normally non-inductive hydrophilic surfaces, suggesting an additional role for Ca2+ in signal mediation for germination.

A Melampsora lini β-tubulin gene and flanking sequence has been isolated and characterised. The gene contains 8 introns, is expressed in germinating urediospores and vegetative mycelia and encodes a 448 amino acid protein that is similar to other fungal β-tubulin genes. Evidence for a second β-tubulin gene within the M. lini genome is also presented. The predicted M. lini β-tubulin protein was compared with 34 other fungal β-tubulin proteins in a phylogenetic analysis and, in general, good agreement was observed between the derived β-tubulin based phylogeny and the current taxonomic status of these species. However, a second β-tubulin protein found in five fungal species is atypical when compared to other fungal β-tubulin proteins. Analysis of intron positions within 33 fungal β-tubulin genes showed that intron location was generally characteristic of the fungal class, with euascomycete fungi showing particularly striking conservation of intron position, although intron number was variable and intron sequences showed little conservation.

The mitosporic fungus Pochonia chlamydosporia is a potential biocontrol agent for cyst (Heterodera spp. and Globodera spp.) and root knot (Meloidogyne spp.) nematodes, which are important agricultural plant pests. 54 isolates from diverse geographical regions and several nematode hosts were used in this study. Genetic variation was examined using enterobacterial repetitive intergenic consensus (ERIC) primed PCR and sequences from the internal transcribed spacer (ITS) rRNA region. ERIC PCR yielded 35 scorable binary characters from all the fungi tested and cluster analysis of the data showed that isolates from cyst nematodes were more genetically variable than those from root knot nematodes. The ITS regions were highly conserved, the only significant difference being an extra thymidine in isolates from Meloidogyne spp. Assays with nematode eggs indicated that isolates differ in their ability to infect different nematode genera. The results indicate host related variation in P. chlamydosporia. This finding has significant implications for the application of P. chlamydosporia as a biocontrol agent.

Sequential effects of colonisation by the wood decaying Fistulina hepatica were examined microscopically in naturally infected and artificially inoculated heartwood of pedunculate oak (Quercus robur). For 6 mo, the deposition of brown materials within parenchyma cells containing hyphae was the only visible effect of colonisation. After 12 mo degradation occurred but was initially confined to parenchyma of xylem rays, in which the secondary cell walls showed helically orientated internal cavities containing hyphae, as in a soft rot. The hyphae were covered with a resinous material and persisted in a herringbone pattern after the secondary walls became heavily degraded. The adjacent libriform wood fibres also showed cavity formation. By contrast fibre-tracheids were mainly affected by a brown rot. uv-microscopy indicated that cell types in which the soft rot mode occurred were rich in syringyl lignin, whereas the brown rot was associated with cells rich in guaiacyl lignin. Thus, the present study shows that F. hepatica possesses dual modes of degradation which appear to correlate with the different lignin composition within cell types of oak.

This study investigates the potential of emissions from a zinc smelter to induce oxidative damage to DNA and lipids in Boletus edulis, the king bolete. Concentrations of cadmium, zinc, copper, and mercury were determined in 16 fruit bodies collected near the smelter (exposed group), as well as in 15 reference samples. Frequency of apurinic/apyrimidinic (AP) sites in DNA (a pre-mutagenic DNA base modification) and concentration of lipid hydroperoxides were chosen as damage parameters. Concentrations of the four metals, as well as oxidative damage to DNA and lipids were significantly elevated in the exposed group (Mann–Whitney, P<0.001). Both damage parameters correlated positively with concentrations of cadmium, zinc or copper in fruiting bodies (Spearman's P<0.01). Frequency of AP sites correlated significantly with mercury in the fruit bodies (P<0.05), whereas the association between lipid hydroperoxides and mercury was insignificant. Frequency of AP sites correlated positively with concentration of lipid hydroperoxides (P<0.001). Negative trends for the associations between concentrations of metals and AP sites or lipid hydroperoxides in the reference group (significant only for mercury and lipid hydroperoxides; P<0.05) suggest that in B. edulis low concentrations of mercury, possibly also of other of the metals determined in the present study, may induce dose-response relationships of a hormetic (‘J-shaped’) nature.

The Ophiostoma piceae species complex incorporates several economically important species, including serious tree pathogens and agents of bluestain. The species in the complex are morphologically similar, but can be distinguished from each other based on morphology, biology, mating type studies and molecular data. At present, all the species in the complex are considered to be native to the Northern Hemisphere, most of them with a very wide distribution. Only a few sporadic reports of members of the complex are available from the Southern Hemisphere, where they are believed to have been introduced, including New Zealand, Australia, Chile, Brazil and Uruguay. This study aims to confirm the identity of isolates resembling O. piceae originating from three Southern Hemisphere countries, using mating compatibility and rDNA sequencing. Our results show that O. quercus is widely distributed throughout South Africa on both native and exotic hardwoods. O. quercus is also reported for the first time from Brazil, again from a native host. O. floccosum is reported for the first time from South Africa, but from an exotic Pinus sp. These results suggest that species of the O. piceae complex are common in the Southern Hemisphere, and that current views on the origins of especially O. quercus need to be reconsidered.

The ITS regions of 14 isolates of endophytic fungi obtained from the root systems of four Woollsia pungens plants were sequenced and compared to sequences of Hymenoscyphus ericae, Oidiodendron maius and to sequences from other fungal taxa currently available in the GenBank and EMBL nucleotide databases. Sequence data suggested that six distinct taxa were present in the root systems of the four plants and that up to four of these were present in the root system of a single plant. One of the endophytes was identified as an Oidiodendron species, while most other isolates probably belong to the Leotiales.

Interactions between the mycoparasite Cladosporium tenuissimum and the bean rust Uromyces appendiculatus were studied through light and electron microscopy in vitro at the host–parasite interface. Urediniospore germination decreased on contact with ungerminated C. tenuissimum conidia, possibly due to antibiosis mechanisms. C. tenuissimum grew towards the bean rust spores and coiled around their germ tubes. Penetration of the urediniospores occurred either enzymatically and/or mechanically, through appressorium or infection cushion structures, from which a thin penetrating hypha was generated. Enzyme production by the mycoparasite was suggested by the loosening of the matricial components of the spore wall, which sometimes left chitin fibrils visible. Mycoparasite hyphae grew within the host spore, emptied its content, and emerged profusely forming conidiophores and conidia. C. tenuissimum was able to grow on media containing laminarin, suggesting the ability of producing glucanases, but not when chitin was used as the sole carbon source. Conidia that had been grown on a sugar-rich medium, filtered, and extracted with organic solvents, were found to contain cladosporol and related compounds. Complete control of the bean rust disease was achieved by application of C. tenuissimum culture filtrates but not by conidial suspensions. This is the first report of parasitism by C. tenuissimum on U. appendiculatus. These investigations provide additional observations on a genus besides Melampsora and Cronartium from which this fungus has been isolated and tested to date. The possible role of environmental factors for the exploitation of this organism as a biocontrol agent is also mentioned.

Phylogenetic trees of 16 Claviceps species were constructed based on alignments of 5.8S rDNA and the adjacent ITS1 and ITS2 spacers. Two highly supported clades were found: (1) C. paspali, C. zizaniae, C. grohii, C. sulcata, C. fusiformis, and C. purpurea; and (2) C. citrina, C. phalaridis, two unidentified Claviceps spp. (isolates PM and SG), C. sorghicola, C. gigantea, C. sorghi, C. africana, C. viridis, and C. pusilla. No relationship was found between the species placement and its morphological markers. The probe from C. purpurea gene cpd1 for dimethylallyl tryptophan synthase, the first enzyme of alkaloid biosynthesis, was hybridized to Pst I digested genomes of the above species under non-stringent conditions. Hybridizing DNA was present in all species of clade 1, although the signal of the C. paspali gene was weaker. In clade 2, only C. africana, C. gigantea, and C. pusilla gave weak positive signals. Colorimetric detection found small amounts of alkaloids in cultures of Claviceps sp. SG and PM but despite that, no cpd1 hybridizing bands were found. The occurrence of two major clades of Claviceps and their biogeography suggests, that the genus originates from South America and that the evolution of its species was influenced by comigration with their hosts and with the global climatic changes that influenced spreading of grass subfamilies.

36 fungal β-tubulin sequences were analysed to study the evolution of this gene and the phylogeny of basidiomycetes. The analysis comprises a representative selection of all major lineages of basidiomycetous fungi and some selected ascomycetes for comparison. Intron positions vary between the different lineages, but seem to be conserved in the Hymenomycetes and Ustilaginomycetes. The most conserved regions seem to be highly susceptible for introns. Splicing and branching sites of the introns are more variable in basidiomycetes than reported from other fungal groups so far.

Basidiomycete monophyly was confirmed with our data in respect to the ascomycetes studied. By analysing amino acid sequences, the Hymenomycetes and the Ustilaginomycetes were resolved as monophyletic groups. The phylogeny within these two groups is similar to that obtained with other genes. Based on β-tubulin data Naohidea sebacea, Chionosphaera apobasidialis, Jaculispora submersa, Platygloea pustulata, Platygloea disciformis and Melampsora lini, representing the Urediniomycetes, are not resolved in most analyses. The early radiation of major basidiomycetous lineages seems to be reflected in the highly conserved β-tubulin gene.

The temporal pattern of release and dispersal of inoculum of plant and insect pathogenic fungi play an important role in the spread of disease. Airborne concentrations of primary and secondary conidia of Erynia neoaphidis released from the rose-grain aphid Metopolophium dirhodum were monitored at the edge of two winter wheat crops on IACR-Rothamsted Experimental Farm between May and September in 1996 and 1997. Hourly average temperature and humidity were recorded at each spore trap site and daily totals of rain and sunshine hours and daily average wind speed recorded about 1.6 km from the monitoring sites. No airborne conidia were found in 1996, but large numbers were trapped at the two sites in 1997. They were present from mid-June until early August, reaching peak concentrations on 17–18 July. Concentrations were usually highest during the night and in the early morning (01:00–07:00 h GMT) and were generally low during the day. On the 3 days when significant numbers of conidia were caught in the afternoon, daytime relative humidity was high (about 89%) and day-time temperature low (about 16 °C). Night-time conditions nearly always favoured the production of conidia. This suggests day to day variation in airborne conidium concentrations may be affected more by underlying biological factors than environmental conditions.

The infection of round-leaved mallow (Malva pusilla) leaves by Colletotrichum gloeosporioides f. sp. malvae was studied using light and confocal microscopy. Conidia germinated and produced appressoria within 24 h after inoculation. An infection peg arose from the base of the appressorium and directly penetrated an epidermal cell. An intracellular infection vesicle appeared beneath the penetration site by 48 h after inoculation. Large primary hyphae (LPH, approx. 4 μM diam.) emerged from the vesicle and grew intracellularly through several adjacent epidermal cells and then intercellularly between mesophyll cells. Epidermal cells infected by LPH maintained their viability, as shown by their ability to plasmolyse and accumulate neutral red stain. No visible disease symptoms appeared during this biotrophic stage of infection. Thin secondary hyphae (TSH, approx. 2 μM diam.) developed from LPH in 4–5 days after inoculation and were associated with the appearance of necrotic lesions. Host cell wall maceration was visible only during the necrotrophic stage. The duration of the biotrophic stage decreased as mallow leaves became older or were senesced by placing them in the dark. TSH and host cell necrosis developed as soon as 48 h after inoculation of the most senescent leaves, and TSH were observed directly emerging from the infection vesicle. Application of thiol reagents, such as glutathione and dithiothreitol, lengthened the biotrophic stage and delayed symptom development, whereas an antioxidant, ascorbate, enhanced infection and promoted symptom development.

Gaeumannomyces graminis var. graminis produces 1,8-dihydroxynaphthalene (DHN) melanin in its hyphal and hyphopodial cell walls. We isolated G. graminis mutants that were affected in their melanin biosynthesis. One was unable to synthesize DHN-melanin and, because it accumulated 2-hydroxyjuglone, a DHN melanin pathway shunt product, it is most likely to be defective in the reductase that catalyzes the conversion of 1,3,8-trihydroxynaphthalene to vermelone, the penultimate reaction in DHN synthesis. Genetic crosses with our wild-type strain indicated that this trihydroxynaphthalene reductase deficiency was the result of a single mutation. Another mutant constitutively synthesized DHN melanin and genetic crosses with our wild-type strain suggested that this heavily melanized mutant had a single mutation responsible for its phenotype. This mutant produced more melanin than the wild-type strain as measured by Azure A binding to melanin. The wild type and constitutively melanized mutant hyphae were more hydrophobic and more resistant to lytic enzymes, benomyl, restrictive temperature, and uv light than the non-melanized mutant, which also autolysed more readily. The non-melanized mutant was not more sensitive to heavy metal than the melanized strains. In addition, the non-melanized mutant was unaltered in pathogenicity to rice, whereas the constitutively melanized mutant was less pathogenic. The constitutively melanized mutant produced less extracellular lytic enzymes than the wild-type and the non-melanized mutant, which may explain its reduced virulence.

Genetic variation of 42 isolates of Corynespora cassiicola, a destructive fungal pathogen of many economically important crop plants including rubber, was investigated using RAPD–PCR analysis. Five genetic groups were identified using RAPD–PCR profiles generated by eight random primers. Results indicate that there is a significant genetic variation among C. cassiicola isolates collected from different host plants. These results should facilitate the development of rubber clones with enhanced resistance against all genetic groups of C. cassiicola.

Species of Mycosphaerella and their anamorphs are commonly found on the leaves of Myrtaceae, many of which are defoliated by these pathogens. The taxonomy of these fungi has been based on minute morphological differences, and virtually nothing is known regarding their relatedness to each other. In this study, we present a phylogeny of 30 species of Mycosphaerella or their anamorphs from myrtaceous hosts, based on sequence data from the ITS regions of the ribosomal RNA operon. Fifteen of the species were also analysed for the 5′ end of the large subunit (28S), which produced a phylogeny similar to that obtained for the ITS data set. The Mycosphaerella species included in this analysis are all regarded as representatives of section Plaga, and appear to represent a monophyletic assemblage. Mycosphaerella lateralis was the only species shown to have a wide host range. In general, species clustered together based on their anamorph genera. Species with Colletogloeopsis and Stenella anamorphs always grouped in two respective clusters. However, species with Mycovellosiella, Phaeophleospora, Pseudocercospora and Uwebraunia anamorphs occurred separately, suggesting that they have evolved more than once within Mycosphaerella. Based on the ITS data set, all morphospecies were also shown to be phylogenetic species, although too few isolates were available to address questions relating to intraspecies variation. Nevertheless, ITS sequence data proved sufficient to distinguish morphologically similar taxa that have hitherto only been distinguished based on ascospore germination patterns and anamorph characteristics. Sequence data presented in this study should facilitate the identification of Mycosphaerella species occurring on Myrtaceae in the future.

The illudins are a family of fungal sesquiterpenes that have been studied as anti-tumor agents, and they also have antibacterial activity. Over a four-year period, 25304 fungal isolates (approximately 97% ascomycetes and 3% basidiomycetes), were screened for antibacterial activity against methicillin-resistant Staphylococcus aureus. Illudin-like compounds with antibacterial and cytotoxic activity against tumor cell lines were observed in 10 basidiomycete strains. The isolates were recovered from different types of substrata using indirect methods and only formed sterile mycelia in pure culture. The isolates were genetically related but not identical, based on PCR-based fingerprinting techniques. DNA sequencing of the ITS1-5.8 S-ITS2 region of the strains revealed that nine had identical sequences, indicating that they were conspecific. The sequence of the remaining isolate was 96.34% similar, suggesting that it was a closely related species. The D1–D2 region of the 25 S rRNA gene of the two strain types was also sequenced. Both sequences were 99.39% similar, and Coprinopsis gonophylla (syn. Coprinus gonophyllus) was the closest match for both. Strains were grown in pure culture on a rice-based medium that allowed the development of basidiomata from one culture of the main strain type, which was identified as C. episcopalis, a close relative of C. gonophyllus. Both species (or strain types) produced different types of illudin-like compounds. Three novel illudins (I, I2 and J2) were found to be produced by the cultures identified as C. episcopalis, while only illudinic acid was produced by the other Coprinopsis sp. The taxonomical relationships of the Coprinopsis species identified in this study with other illudin producers previously reported in the literature are discussed.

Neurospora and Gelasinospora are traditionally distinguished by the ornamentation pattern of the surface of their ascospores, which are ribbed in the former and pitted in the latter. However, a detailed examination of the morphology of numerous strains of most of the species of both genera confirm the hypothesis that there are not enough criteria to distinguish them from each other. The names Neurospora and Gelasinospora are synonymized and the circumscription of the genus Neurospora amended. Partial sequences of the 28S rDNA gene from 27 species of both genera were analysed to infer their phylogenetic relationships. Species of the two genera were interspersed in the different clades and confirmed that they are genetically very similar. The grouping obtained demonstrates that the morphology of the episporial-layer of the ascospores is an informative phylogenetic character. Two recent isolates from soils of Nigeria and Spain, which could not be classified as any known species of Neurospora are described, illustrated, and recognized as new: N. nigeriensis and N. uniporata spp. nov. A synopsis and key to the 49 species of Neurospora now recognized in the genus is presented, and the new genus Pseudogelasinospora described to accommodate P. amorphoporcata (syn. Gelasinospora amorphoporcata comb. nov.).

The macro- and micromorphology of 45 specimens and 19 holotypes of the subgenus Ganoderma (=G. lucidum complex) were examined, together with isoenzymic data. The objective was to evaluate relationships by analysing numerically morphological and isoenzymic data to discern the number of species occurring in southern South America, and their delimitation. A total of 73 isozymic bands and 26 morphological characters were considered. Spore ornamentation was studied under SEM. Nine taxa appear to be represented in the region (G. lucidum var. lucidum, G. multiplicatum, G. sessiliforme, G. praelongum, G. subincrustatum, G. platense, G. zonatum, G. sessile and G. tuberculosum) and the presence of another eight is doubtful (G. argillaceum, G. bibadiostraum, G. chaffangeonii, G. lucidum var. capense, G. lucidum var. dorsale, G. subamboinense var. laevisporum, G. resinaceum and G. tropicum). Three major cutis types were defined and illustrated. Although congruence between dendrograms derived from both data sets was low, some similar groupings were formed. Species descriptions and a key for identification are provided.

Gel-based and spectrophotometric assays were used to demonstrate expression of a manganese-dependent peroxidase (MnP) activity in culture filtrates of the ectomycorrhizal basidiomycete Tylospora fibrillosa. PCR amplification using a primer pair specific for a 260 bp fragment from the 5′-end of a gene encoding an H3-like MnP isozyme in Phanerochaete chrysosporium, produced single amplification products of 260 bp from DNA extracted from two isolates of T. fibrillosa. The amplified fragment from T. fibrillosa had a 93·7% nucleotide overlap (over 201 bases) with a published sequence for a 260 base amplification product from the P. chrysosporium H3 MnP isozyme gene, strongly suggesting the presence of a homologous gene in the ectomycorrhizal fungus. The results are discussed in the context of lignin degradation by ectomycorrhizal fungi.

The effects of the structural features of the thallus and the lichen–substratum interface on soil water infiltration were investigated using low temperature scanning electron microscopy and scanning electron microscopy with backscattered electron imaging. Two morphologically different lichen species were examined, the crustose Diploschistes diacapsis and the squamulose Squamarina lentigera. Water distribution within lichen-forming soil crusts explains the results of earlier infiltration studies. Several anatomical features of the upper cortex gave rise to similar impervious characteristics of the thallus. The fungal material comprising the lichen thallus showed significant hydrophobic features and only when in contact with calcium oxalate crystals or minerals in the soil was this material able to retain water. The lichen–substratum interface appears to play an important role in the hydric strategy of these lichens which in turn affects the penetration of water into the soil.