The white rotting Armillaria mellea induced a spatially very distinctive pattern of degradation in sycamore wood, under both natural and artificial conditions. Degradation began preferentially within groups of fibres containing intercellular spaces, whereas fibre regions lacking such spaces were undegraded and remained largely intact even when decay had become advanced elsewhere. The two types of fibre region differed not only in the presence of intercellular spaces, and hence in the potential for gas exchange, but also in their degree of lignification. This was higher in the more resistant type, as shown by staining of undecayed wood with toluidine blue-O, by microspectrometry after staining for the Mäule colour reaction, and by uv-microscopy. A spatially similar pattern of cellulose degradation was induced by the brown rotting Laetiporus sulphureus, which is known to cause preferential degradation of less strongly lignified cell walls. By contrast, the white-rotting Ganoderma pfeifferi showed a tendency to degrade the stronger lignified cell walls. Thus, in combination with the application of conventional histological methods, the wood degradation modes observed give additional evidence for stronger and weaker lignified fibre regions within the wood of sycamore.

The fungi associated with diseased and healthy shoots of young, planted Betula pendula were studied at five sites in Scotland where crown die-back of birch is occurring. At each site, 30 diseased and 30 healthy shoots were sampled twice, with 1 yr-old shoots collected in May 2002, and 4–5-month-old shoots collected in September/October 2002. Overall, 34 different fungal species were recorded, with 92% and 60% of all diseased and healthy shoot pieces, respectively, colonised by at least one fungal species. The main colonisers of both diseased and healthy shoots were Melanconium bicolor, Discula betulina and Godronia urceolus, and the fungi most frequently found on diseased shoots only included Marssonina betulae and Fusarium avenaceum. The pathogenicity of these fungi was tested on seedlings of B. pendula and B. pubescens. Melanconium bicolor required a wound for lesion development on both birch species and caused larger lesions on B. pubescens than on B. pendula. Discula betulina caused lesions on stems and shoots of both birch species, including non-wounded current shoots. Marssonina betulae caused lesions and die-back of wounded and non-wounded current shoots of B. pendula seedlings. This fungus was not pathogenic on B. pubescens. Fusarium avenaceum caused restricted lesions on the main stems of both birch species. Godronia urceolus was not pathogenic on either birch species. Further work needs to focus on the role of these fungi in causing crown die-back of young, planted B. pendula in Scotland.

Isolates of Verticillium lecanii, from insects and other substrates, were tested for vegetative compatibility by observing heterokaryon formation among complementary nitrate-nonutilizing (nit) mutants, Among 33 V. lecanii isolates, 17 were self-incompatible. The 16 self-compatible isolates were divided into 13 vegetative compatibility groups (VCGs). Eleven VCGs were single-member VCGs, and the remaining two included two or three isolates each. Self-incompatibility occurred more frequently among isolates with abundant aerial mycelium, whereas most of the isolates with short or reduced aerial mycelium were self-compatible. Virulence to larvae of Bemisia tabaci ranged from 0 (four isolates) to 83% mortality 4 d after treatment with conidial suspensions. There was no correlation between the capacity of isolates to anastomose and their virulence to larvae of Bemisia tabaci: highly virulent isolates were found at similar frequencies among self-compatible and self-incompatible isolates. Those with abundant aerial mycelium were collectively more virulent (28·5% mortality) than those with reduced mycelium (10·7% mortality). Three isolates belong to VCG VL-11 were all highly virulent.

All isolates of Rhizoctonia solani (teleomorph Thanatephorus cucumeris) anastomosis group (AG) 3 from potato tubers in commercial fields in Scotland were found to contain more than one double-stranded RNA (dsRNA) element ranging in size from 0·3 to 15 kb. Strains of other AGs (2-1, 3, 4, 5) from culture collections also contained dsRNA elements. Isolates of AG 3 from different black scurf lesions on single tubers showed similar dsRNA profiles and, when opposed on agar plates, underwent compatible hyphal fusion where the colonies met. Isolates from different tubers in the same commercial field often showed somatic incompatibility (mean 44%) leading to cytoplasmic death when colonies fused. Isolates from different fields always showed somatic incompatibility after hyphal fusion, suggesting that the complex population structure of AG 3 could significantly limit the transmission of dsRNA between strains. The incidence of different dsRNA elements in AG 3 isolates could not be related to pathogenicity in seedling tests on tomato, carrot, lettuce, radish, cress or onion. Double-stranded RNA elements could not be eliminated from AG 3 isolates by repeated hyphal-tip subculture or extended (8 week) incubation on agar containing cycloheximide. Some isolates lost the smaller dsRNA elements (1·0 to 1·6 kb) during these procedures, and one isolate (of AG 4) lost a 6·5 kb dsRNA element, but the larger elements (up to 9·5 or 12 kb) were always retained. When assessed by low stringency hybridisation, the dsRNA elements of R. solani AG 3 and of strains from AGs 2-1, 4 and 5 showed no homology with a plasmid containing cDNA of the complete hypovirus dsRNA genome of Cryphonectria parasitica.

The distinctiveness of the European Galerina marginata and the American G. autumnalis is tested with analyses of DNA sequences from the internal transcribed spacer (ITS-2) of the nuclear ribosomal repeat and RFLP analysis of the entire ITS region. European and North American material from six taxa described in Galerina subgenus Naucoriopsis are included along with out-group material of six taxa representing two other subgenera of Galerina. The results do not indicate any genetic difference between species by Smith & Singer (1964) referred to the two ‘stirpes’ Marginata and Autumnalis of Naucoriopsis, i.e. G. autumnalis, G. marginata, G. oregonensis, G. pseudomycenopsis, G. unicolor, and G. venenata and all except G. pseudomycenopsis are considered later synonyms of G. marginata. Galerina badipes (syn. G. cedretorum var. bispora of ‘stirps’ Cedretorum is well supported as a distinct species. Subgenus Naucoriopsis appears as a distinct infrageneric unit well separated from the infrageneric units represented by the out-group species.

To understand the nature of recombination processes in Beauveria bassiana, double-auxotrophic complementary mutant strains were used to produce six heterokaryons by three different methods. Conidia from these heterokaryons were plated on selective media and stable haploid (but not diploid) recombinants were isolated. Single colony recombinants were recovered with both parental and non-parental random amplified polymorphic DNA (RAPD) profiles. These results suggest that a range of different recombination mechanisms may be occurring in B. bassiana.

The avidity of conidia and 48-h-old germlings of Coniothyrium minitans for FITC-conjugated lectins was characterised by flow cytometry and digital microscopy. Six isolates of C. minitans representing three morphological types were compared. Binding of Con A, SBA and WGA by conidial populations varied markedly in extent and pattern between isolates, however, with increasing culture age, conidia from all isolates demonstrated a significant reduction in lectin avidity. Germling isolates bound significantly different amounts of lectins and lectin binding differed significantly with locality. Spore walls of all germlings from all isolates bound more Con A compared with hyphal apices and mature hyphal walls. In contrast, hyphal apices of the majority of germling isolates, readily bound SBA and mature hyphal walls of germling isolates bound more WGA than other regions of the germlings. Such differential lectin binding by conidia and germlings may influence their specific surface interactions and adherence characteristics.

The devastating dry rot fungus, Serpula lacrymans, has a worldwide occurrence in buildings. We investigated the genetic variation in European isolates belonging to five vegetative compatibility groups (VCGs) by AFLP analysis. Our results indicate that S. lacrymans in Europe is genetically extremely homogenous; only five out of 308 scored AFLP fragments (1.6%) were polymorphic. In contrast, S. himantioides, the closest relative of S. lacrymans, possessed 31.3% polymorphic fragments (84 out of 268). AFLP polymorphisms observed in S. lacrymans were distributed independently of the VCG boundaries, indicating that the VCGs do not represent clones but that different genets of S. lacrymans frequently share similar vic alleles due to low genetic variation. Thus, although the European S. lacrymans is genetically extremely homogeneous, and our results suggest that the species reproduces and spreads mainly sexually and not by clones.

Stilbohypoxylon is resurrected. The type species, S. moelleri, is redescribed and S. samuelsii is described as new. The third species, S. quisquiliarum, represents a new combination. A key to these taxa is provided.

An α-L-arabinofuranosidase gene (abf1) from Penicillium purpurogenum was identified and sequenced. abf1 has an open reading frame of 1518 bp, does not contain introns and codes for a protein of 506 amino acids. The deduced mature protein has a molecular mass of 49.6 KDa, and its sequence is homologous to arabinofuranosidases of glycosyl hydrolase family 54. Southern blots suggest that abf1 is a single copy gene. Putative sequences for the binding of the transcriptional regulators XlnR, CreA, PacC, AlcR and AreA are present in the promoter. Northern-blot analysis shows that abf1 is expressed at neutral but not at alkaline or acidic pH values. The presence of binding sites for regulatory elements in the promoter region has been compared to the genes of other fungal enzymes belonging to the same family. This is the first characterization of an abf gene from a Penicillium species.

A Coniothyrium minitans strain (T3) co-transformed with the genes for β-glucuronidase (uidA) and hygromycin phosphotransferase (hph), the latter providing resistance to the antibiotic hygromycin B, was used to investigate the survival and infection of sclerotia of Sclerotinia sclerotiorum by C. minitans over time in four different soils. Infection of sclerotia was rapid in all cases, with the behaviour of transformant T3 and wild type parent A69 being similar. Differences were seen between the soils in the rate of infection of sclerotia by C. minitans and in their indigenous fungal populations. Amendment of agar with hygromycin B enabled the quantification of C. minitans in soil by dilution plating where there was a high background of other microorganisms. In Lincoln soil from New Zealand, which had a natural but low population of C. minitans, the hygromycin B resistance marker allowed the umambiguous discrimination of the applied transformed isolate from the indigenous hygromycin B sensitive one. In this soil, although the indigenous C. minitans population was detected from sclerotia, none were recovered on the dilution plates, indicating the increased sensitivity of C. minitans detection from soil using sclerotial baiting. C. minitans was a very efficient parasite, being able to infect a large proportion of sclerotia within a relatively short time from an initially low soil population. The addition of hygromycin B to agar also allowed the detection of C. minitans from decaying sclerotia by inhibiting secondary fungal colonisers. This is the first report to show that fungi colonising sclerotia already infected by C. minitans mask the detection of C. minitans from sclerotia rather than displacing the original parasite.

The occurrence of Lophodermium on fallen needles and Leptostroma, the mitosporic state of Lophodermium, on living needles of Japanese black pine trees treated with simulated acid rain (SAR, pH 3) or tap water (control, pH 6·3) were studied. The amount of fallen needles was also examined. Significantly more needles fell from SAR-treated trees than from control trees, though there were no visible symptoms in the needles of SAR-treated trees. The detection frequency of Lophodermium on fallen needles, and that of endophytic Leptostroma on 2 year old and 3 year old needles, was lower in SAR-treated than control trees. The reduction in the detection of Lophodermium/Leptostroma on needles implied the reduction in the density of endophytic fungi with air pollution.

At a high arctic, polar semi-desert site (79°N) in Svalbard, nitrogen, phosphorus and potassium fertilizers were added to the soil for 5 yr to simulate increases in decomposition and nutrient mineralization which may occur as a result of increases in soil temperature and soil moisture caused by environmental change. Abundance of decomposer fungal species, isolated from standing-dead leaves of Dryas octopetala, varied between fertilized and unfertilized plots. Fungal biodiversity, as indicated by the Brillouin index, was lower in dead Dryas leaves from the fertilized plots, although more colonies were isolated from leaves of plants which had been fertilized. The fungi were cosmopolitan and not restricted to tundra areas. The dead leaves from the fertilized plots contained more nitrogen and phosphorus than those of the unfertilized plants. Leaves in the fertilized plots appeared to have been killed by winter injury resulting from an extended growing season in an atypically mild and wet autumn, which was followed quickly by extreme subzero temperatures.

Growing fruit bodies of Agaricus bisporus and Amanita muscaria responded with regenerating white hyphae to cell and tissue injuries caused by intrapileal needle insertion and leucofuchsin injection. We point out reserve cells as a possible source of regenerating hyphae in the wound repair. Such reserve cells were not found in the partial veil and in the surface covering. Damage of the partial veil remained unrepaired and caused lamellar dysplasia. Hydrophilic, somatic tissues reacted immediately and strongly with leucofuchsin, whereas hyphae of the surface covering and partial veil showed a delayed and weak reaction. We explain this by the presence of an extracellular matrix, which consists of hydrophilic mucilaginous substances around tissue-forming hyphae. Transmission and scanning electron microscopical studies revealed that white hyphae were deprived of such matrix material. We conclude that for fungal tissue formation the hyphae have to be capable of producing a substantial amount of extracellular matrix material beyond the cell wall.

The formal taxonomy of the new family Myzocytiopsidaceae, with three new genera Myzocytiopsis, Chlamydomyzium and Syzygangia, is presented. The family also includes Gonimochaete.

Intact ungerminated spores or germinating swollen spores of Mucor circinelloides were biolistically transformed to leucine prototrophy with the autonomous replicating plasmids pLeu4 and pMCL1302. The former developmental stage was efficiently transformed with both plasmids. The existence of pLeu4 sequences, as selfreplicating elements, within Leu+ transformants was established by Southern analysis and by the recovery of plasmid pLeu4 in bacteria transformed with total DNA from M. circinelloides transformants. This is the first report of the transformation of intact cells of a member of the Zygomycetes.

The diversity of Eutypa lata was studied in 56 isolates collected from Languedoc-Roussillon, France. The pathogenicity of isolates varied within a very broad range and was not influenced by the cultivar from which they originated. Using 27 RAPD markers, each isolate was identified as an unique genotype. Gene diversity averaged 0·292 for the regional population. Lack of gametic disequilibrium between RAPD loci supported the hypothesis of random mating. The RAPD analysis did not allow subdivision of the population according to geographic location, vine cv. or pathogenicity of E. lata. The composition of the community of fungi was studied in 116 vines showing eutypa dieback symptoms collected at several localities in the region. E. lata was recovered from 80% of the samples, from the sectorial brown lesion characteristic of the disease. This lesion was associated in half of the vines with a central zone of discoloured hard wood and/or a light-coloured lesion of soft consistency. E. lata was isolated alone from 124% of the vines and was associated in 67% of the vines with one, two or three of the following fungi: Sphaeropsis malorum, Phomopsis viticola, Gliocladium roseum, Phaeoacremonium chlamydosporum, P. aleophilum and Phellinus igniarius. The variation in symptoms observed in the vineyard may be partly explained by the wide genetic diversity in E. lata and differences in the composition and functioning of the fungal community.

Creolophus cirrhatus, Hericium erinaceus and H. coralloides were paired against over 20 other wood decay fungi from beech (Fagus sylvatica) covering a range of ecological strategies, on 2% malt agar (MA), 0.5% MA, 0.5% MA adjusted to −1.25 MPa by addition of KCl, 0.5% MA adjusted to pH 4 with KOH/H3PO4 and 0.5% MA under 5% O2/30% CO2 all at 20 °C. Creolophus cirrhatus and H. coralloides were also paired against 17 other species in wood, incubated at 20 ° for 36–38 wk. They were average to good combatants, deadlocking with or replacing over half of the antagonists, H. erinaceus being slightly more combative than the other two species. Outcomes in wood were representative of those in agar. Abiotic conditions altered the outcomes slightly, reduced water potential favouring C. cirrhatus and H. erinaceus. Overall extension rate of C. cirrhatus and H. erinaceus often increased in the presence of antagonists. There was prolific production of fruit bodies in controls and interactions, though notably not under altered gaseous regime. Results are discused in an ecological context.

The yeast–mycelial dimorphic Aureobasidium pullulans var. pullulans was grown in chemostat culture under zinc-limitation at pH values in the range 2–7. Steady state was obtained and the growth yield with respect to zinc was independent of pH. The culture grew entirely as yeast, independently of the pH in the pH interval 3–7. The exopolysaccharide (EPS) production from the yeast cells was highest in the pH range 3–6 with a maximum at pH 4·0. Only little EPS was produced at pH 7·0 and no EPS was produced at pH 2·1. At pH 2·1 about 20% of the total biomass was in the filamentous growth form and some chlamydospores were present. A change in the carbon source from glucose to sucrose resulted in a more than doubling of the steady-state EPS concentration from 3·1 to 6·9 g l−1. A simple mass balance on carbon was constructed which could account for more than 95% of the carbon.