The importance of pneumocandin B0 as the fermentation-derived starting material for the antifungal drug candidate, MK-991, along with the identification of our production strain as Z. arboricola (ATCC 20868) as CBS prompted a search for other strains of Z. arboricola or Zalerion species with improved titres or that might produce natural pneumocandin analogues. Analysis of morphology, secondary metabolites profiles, and DNA fingerprinting demonstrated that ATCC 20868 was not congeneric with Z. arboricola. Ribosomal DNA sequences were compared among Zalerion species and pneumocandin-producing fungi and with rDNA sequences in GenBank. No good matches with sequences in GenBank were obtained for Z. arboricola or Z. maritimum, but for Z. varium, P. carpinea and ATCC 20868, relevant similarities were observed with ITS1 sequences from fungi of Leotiales. ATCC 20868 was phylogenetically more akin to P. carpinea, another pneumocandin producer, than initially suspected. The closest relative of ATCC 20868 seemed to be Hymenoscyphus monotropae. We conclude that the genus Zalerion is artificial; its species bear no phylogenetic relation among themselves. ATCC 20868 and Z. varium were related to fungi of the Leotiales. We propose a new anamorph genus and species, Glarea lozoyensis, to accommodate ATCC 20868.

Various substrates and temperatures were evaluated for their effect on the sporulation and virulence of F. avenaceum, a potential biological control agent for marsh reed grass (Calamagrostis canadensis). Prior to assessing sporulation, growth was optimal on potato dextrose agar (PDA) between 15°–28°C, and minimal on malt extract agar (MEA). Temperature predisposed sporulation of 15 d old cultures, with refrigeration of PDA stock cultures of 4° causing a nearly ten-fold decrease in sporulation. Sporulation increased when PDA was juxtaposed with MEA or vice versa. In juxtaposed media, inoculation with MEA stock cultures significantly reduced macroconidial production. Although juxtaposition of MEA with PDA enhanced conidial production, there was no clear relationship between maltose-based substrates and conidial abundance. In 30 d old cultures, sporulation levels were higher when daytime temperatures were 30° versus 20°. The high daytime temperature also caused a greater proportion of macroconidia to form, and lowered the abundance of mesoconidia. In comparisons of bag cultures incubated at 20°, inoculum produced on puffed wheat was twice as virulent as that produced on marsh reed grass straw amended with malt extract. Mesoconidial production was maximal (2·6×108 mesoconidia g−1) using a 1:1 mixture of puffed wheat and wheat straw with malt extract. Straw cultures without malt extract produced the most virulent inoculum. Straw cultures generally produced a higher proportion of macroconidia but virulence was not a directly related to conidial morphology. While conditions favouring abundant sporulation did not favour virulence, bag cultures were a suitable method for production of F. avenaceum conidia.

Confocal laser scanning microscopy was used for in vivo observations of autofluorescent fungal structures of Glomus mosseae in intact, living rye-grass roots. Clear images of hyphae and collapsed arbuscules could be obtained without staining or sectioning roots. As rye-grass roots are highly transparent, with only a few cell layers above the vascular cylinder, they provide an excellent in vivo system for microscopical confocal laser scanning studies of arbuscular mycorrhizal structures.

The ultrastructure of the dimorphic ascospores of Mamillisphaeria dimorphospora are illustrated. The small brown ascospores differ from the larger hyaline ascospores in having a thick melanin layer in the ascospore wall. They are also 2–3 times smaller and do not germinate on PDA. The significance of these observations with respect to dispersal of aquatic fungi is discussed. The large hyaline ascospores may be morphologically adapted to dispersal in streams, while the smaller brown ascospores are thought to be adapted to aerial dispersal. The reasons for this are discussed. The method by which two spore types can be produced in separate asci in one ascoma is hypothesised.

The phylogenetic relationships among fungi that cause spring dead spot disease of Bermuda grass in Australia and the United States were studied from nucleotide sequence data of the ITS region of the rDNA. High levels of sequence similarity were observed among Ophiosphaerella herpotricha, O. korrae and Leptosphaeria narmari. These species clustered into a distinct clade that was distant from other Leptosphaeria and Phaeosphaeria species. Based on sequence data and previous descriptions of the ascoma and ascospore characteristics of these species, we propose a taxonomic transfer of L. narmari to O. narmari. Oligonucleotide primers specific for O. narmari were developed from ITS1 and ITS2 regions to help identify non-sporulating isolates. These primers amplified all isolates of O. narmari, including those from the United States, but not those of O. herpotricha, O. korrae or other ectotrophic root-inhabiting fungi. This is the first report of O. narmari in North America. Two Group I introns were found in the small subunit rDNA of some isolates of O. korrae and O. narmari, but not O. herpotricha. A 425-nucleotide intron in O. narmari and O. korrae was inserted two nucleotides downstream from the ITS5 conserved primer sequence. These introns exhibited an 80% sequence identity. In addition, a second 431-nucleotide intron in O. narmari was similar in size and location to one in O. korrae.

The cultivated mushroom Agaricus bisporus was grown and fruited in wheat straw compost. RNA was extracted from samples of mycelium growing in compost during colonization and fruit body development. Laccase gene (combined lcc1 and lcc2) expression and cel3 gene (cellobiohydrolase) expression were determined by Northern blot analysis and by competitive RT-PCR. The level of laccase transcripts was highest in colonized compost (prior to the onset of fruiting), declined during the period of fruit body enlargement and increased again after harvesting and during the second flush of fruit body production. No transcripts of the cel3 gene were detectable in colonized or pre-fruiting cultures, but the level became detectable and rose to a maximum at the veil-break stage of fruiting, declined after harvesting and rose again during the second flush. Gene expression for laccase and cellobiohydrolase correlated with the known changes of laccase and cellulase enzyme activities during the fruiting life cycle.

Genetic divergence among 57 isolates of Colletotrichum lindemuthianum collected in north, central and south America and The Netherlands was assessed on the basis of PCR-RFLP analysis and sequencing of the nuclear rDNA region of the two internal transcribed spacers (ITS 1 and ITS 2) and the 5·8S rRNA gene. A reproducible 0·58 kb fragment was amplified in all 57 isolates. Races of C. lindemuthianum formed two groups based on the restriction of the PCR-amplified ITS regions. Group I consisted mainly of Middle American races (65%), whereas 85% of Andean races belonged in group II. Genetic distances calculated from the sequence polymorphism in the rDNA region ranged from 0·2 to 1·8% among 14 isolates of C. lindemuthianum. The neighbour-joining and parsimony analyses of the sequence data showed no association of any particular ITS genotype with host gene pool, virulence or geographic origin of races. These data suggest that virulence can arise in different geographic areas at different times, independent of genetic background. Molecular polymorphism among isolates of races 7, 17, 31 and 73 collected in different countries was demonstrated by RFLP analysis of the ITS regions. A similar lack of agreement was observed in the sequence data between isolates of race 73 from Mexico and the United States and the Jukes–Cantor genetic distance between the isolates was large (0·9%). These findings support a level of molecular variability within C. lindemuthianum greater than the variability previously characterized by virulence analysis and suggest independent evolution of specific virulence patterns.

Byssosphaeria, Chaetosphaeria and Niesslia are discussed and illustrated in relation to their occurrence on palms. New collections of B. schiedermayeriana are reported including Chaetosphaeria exima, which is a new synonym. Chaetosphaeria arecacensis, C. hongkongensis and C. palmicola spp. nov. are described and new collections of C. callimorpha are reported. Cryptophiale is reported as a new anamorph connection for Chaetosphaeria. Niesslia palmicola sp. nov. is described and new collections of N. exosporioides are recorded. Ornatispora gen. nov. is introduced to accommodate several Chaetosphaeria-like species from palms. In Ornatispora, ascomata are superficial, black, papillate, smooth-walled or covered in setae and paraphyses are filiform, non-septate and deliquesce in dried material. Asci are 8-spored, clavate, and lack an apical apparatus and deliquesce at maturity, while ascospores are ellipsoidal, 1-septate, hyaline, verrucose and surrounded by a mucilaginous sheath. One species is closely associated with Didymostilbe aurantiospora, which is considered to be the anamorph. Three new species of Ornatispora, and one new combination are described and illustrated. Ornatispora is compared with Bertia, Chaetosphaeria, Peethambara and Niesslia.

The Amphisphaeriaceae (sensu lato) presently includes 36 genera and 23 synonyms and is a heterogeneous assemblage of ascomycetes. In this paper molecular and morphological data and teleomorph–anamorph connections are examined and confirm that the Amphisphaeriaceae (sensu stricto) should be confined to ten teleomorphic genera and their Pestalotia-like anamorphs. These include Amphisphaeria, Broomella, Discostroma, Ellurema, Griphosphaerioma and Neobroomella which are described and illustrated; and Blogiascospora, Lepteutypa, Paracainiella and Pestalosphaeria which are discussed.

A method to identify the earliest stages (initials) of Pleurotus pulmonarius and Coprinus cinereus fruit body formation was developed. Light microscopy and Cryo-SEM were used to confirm that even the smallest structures to take up stain were initials of fruit bodies. An approach combining histological staining (flooding the Petri dish with 1% toluidine blue in 1% boric acid (w/v) for 15 min) and image analysis allowed the number of fruit bodies formed on Petri dishes to be quantified easily. Use of the vital stain Janus green (0·001% aqueous, w/v) allowed continued observation of living tissue so that the proportion of fruit bodies that matured (30%) could be established. The method was also effective on wheat straw cultures and could be used to monitor development of mature fruit bodies. It is a promising tool in the study of physiological processes involved in fruit body initiation.

Strains of Hebeloma representative of different climatic zones were grown in axenic culture at either 2°C and 22° or 6° and 22°. Culture filtrates were assayed for proteolytic activity using FITC labelled BSA as a substrate. Assays were run between 0–37°. Growth at low temperature induced greater proteolytic activity (g−1D.W. mycelium). Many of the strains produced protease(s) which retained significant activity at temperatures as low as 0°, and a thermal optimum between 0–6° with a second optimum at higher temperature. The results are discussed in relation the nutrient acquisition potential of ectomycorrhizal fungi at low temperature and the contribution such cold active proteases might make to the soil enzyme pool.

The endophytic mycobiota of healthy twigs and the assemblage of species associated with twig lesions of Eucalyptus globulus and E. grandis planted at the same site in the central west region of Uruguay was examined. Twig segments from E. grandis and E. globulus were plated on 2% malt agar. The diversity of endophytes isolated was low, as was the number of host-specific species. E. globulus endophytes of healthy xylem were different from the colonizers of cracked lesions and healthy bark. Conversely, in E. grandis characterized by black spots, the main difference in species composition was between xylem and bark. Cytospora chrysosperma was isolated from healthy bark and symptomatic twigs of E. globulus, suggesting that symptomatic tissues, such as cracks produced under drought were favourable to saprotrophic expansion.

Hyphae of Saprolegnia ferax recovered from intracellular acidification with variable degrees of apical vacuolation and migration of cytoplasm out of the apex, prior to apical refilling and resumption of growth. The response was not due to alkalinization, but was generalized to recovery from diverse growth inhibitors including procaine, latrunculin B and the kinase inhibitor 6-dimethylaminopurine. The vacuoles apparently arise from expansion and fusion of apical tubular vacuoles. This process is mediated by microtubules, since their disruption suppresses apical vacuolation. The shape of the vacuoles appears to be F-actin imposed, because their expansion is enhanced by F-actin disruption. The accompanying, often bidirectional, cytoplasmic migrations are independent of tip growth, require F-actin, and probably represent part of a hypothetical generalized cytoplasmic avoidance response.

Diplocladium gregarium was described almost one hundred years ago, later transferred to Cylindrocladium, and finally excluded from this genus. It has recently been rediscovered from bark beetle galleries in the bark of Picea abies and Pinus sylvestris in Germany. The fungus is redescribed and a new genus is proposed to accommodate it.

Six species of Mycosphaerella and eight anamorphs with unknown Mycosphaerella states occurring on myrtaceous hosts other than Eucalyptus are treated in the present study. Eight additional species that have recently been described elsewhere are discussed, while a further six species remain unconfirmed, and two are excluded from Mycosphaerella. New species are described in Mycosphaerella, Mycovellosiella, Passalora, Pseudocercospora and Stenella, and new combinations proposed in Eruptio and Microthyrium. Keys are provided to distinguish the accepted species occurring on Myrtaceae other than Eucalyptus, while their morphological similarities with taxa known from this host are discussed.

Macro- and micromorphology of 124 specimens and 11 holotypes of South American taxa of subgenus Elfvingia (= G. applanatum complex) were examined, and were compared with isoenzymic data previously obtained. Two major dermis types were defined and illustrated. Spore ornamentation was inspected under SEM. Sixty-four per cent of the specimens had an anamixodermis, 80% had spores with longitudinal furrows under SEM and 83% had a context layer without streaks of melanoid deposits. Some of our South American collections could be ascribed to G. lipsiense, G. tornatum, G. testaceum and G. lobatum. Other taxa are critically discussed. The position adopted in this work was to join under synonymy closely related taxa on the grounds of morphology and geographical distribution. In general, correlation between morphological features and isoenzymic patterns could not be established. In this group, phenotypic plasticity appears to be great.

Nine ascomycetes, 1 basidiomycete and 15 mitosporic fungi are reported from submerged wood, collected from a single English river site. Ascotaiwania pallida, Neta angliae and Trichocladium englandense spp. nov. and Frigidispora colnensis gen. & sp. nov. are described and illustrated. Most of the species present on the submerged wood appear to have been identified, for the single date and location sampled, because the asymptote of the accumulative curve was reached between 80–100 substrata. The results of this study are compared with those from collections, using similar collection techniques in tropical regions. Results suggest that temperate streams appear to have a lower fungal diversity than in the tropics. Only Acrogenospora sphaerocephala was common to tropical (Seychelles) and temperate (U.K., River Coln) sites.

Crossing and selfing experiments were carried out with six field collections and five isolates belonging to three formae speciales, larici-epitea typica (LET), larici-daphnoides (LD), and larici-retusae (LR), of willow rust, Melampsora epitea. European larch (Larix decidua) was inoculated with basidiospores produced on overwintered telial leaves and the resulting spermagonial lesions on larch needles subsequently paired in vitro. In two crosses between LR and LD involving a total of 439 lesion pairs, only two cultures obtained were identified as hybrids. These two cultures were non-pathogenic to the maternal host Salix burjatica cv. Korso and weakly pathogenic to the paternal host S. daphnoides cv. Meikle. No identifiable hybrids were obtained from 56 lesion pairs between LET and LD. In a cross between LET as receptor and LD as donor, one-third of the lesions formed aecia. In the reciprocal combination, however, less than 1% developed aecia. All F1 cultures between LET and LR were weakly pathogenic to the parental hosts S. viminalis cv. Mullatin and S. burjatica cv. Korso. When three of the F1 cultures were used to produce telia, only one developed mature teliospores. Subsequent selfing experiments showed that this culture was predominantly self-sterile, with only 1% of lesions producing aecia. In selfing and crossing two pathotypes within the same f. spp., 20–40% of needles produced aecia and the rate of aecial formation was similar in both directions. The results obtained suggest that M. epitea is heterothallic and the sexual compatibility is controlled by a pair of alleles at a locus. It is concluded that the three f. spp. are genetically different populations and ecologically fit new pathotypes cannot arise easily as a result of hybridization between them. Within a f. sp., however, many pathotypes exist or will occur due to exchange of genes for virulence during the sexual life-cycle.

Twelve wood decaying species of Phlebia and Phanerochaete were analysed by RFLP (restriction fragment length polymorphism) analysis of an 18S rRNA gene fragment and an ITS region. The data obtained by different restriction endonucleases were used to construct phenograms based on the UPGMA algorithm. PCR-RFLP within the 18S rRNA gene was sufficient to distinguish between Phlebia species but did not show variation among Phanerochaete spp. ITS region amplified from Phlebia spp. varied in length from 570–745 bp. The smallest ITS fragment was amplified from P. subcretacea and the longest from P. hydnoides. The size of ITS fragments amplified from Phanerochaete spp. was uniform (635 bp), except for the ITS from two P. sanguinea strains (690 bp). RFLP analysis within ITS amplified from Phanerochaete spp. distinguished between them. Results from PCR-RFLP of 18S rRNA and ITS strongly suggest that Phiebia gigantea is closely related to Phanerochaete. Morphological characteristics (lack of clamp connections in hymenium, well developed subiculum) further support this hypothesis.

Observations on cytological and ultrastructural changes in Plasmopara viticola oospores were carried out during the overwintering period. Three types of oospores were observed. Type I, characterized by a thin inner oospore wall (IOW), large lipid globules and two nuclei, was recovered only in samples collected in October. These oospores were considered to be immature. Maturation occurred during November and involved a noticeable increase in thickness of the IOW, fusion of nuclei, formation of an ooplast and break up of large lipid globules into smaller ones (type II oospores). A few oospores (type III) showed abnormal organization with very large lipid globules and less frequently discernible nuclei. IOW solubilization, dissolution of the ooplast and lipid globules and nuclear division were the first detectable events during oospore germination. Germinating oospores produce a germ tube which was terminated by a sporangium. In its young stage, the sporangium had a thick wall and an unusual multi-layered membrane. During this phase, nuclear divisions took place in the sporangium. While sporangium development progressed, the ribosome density in the cytoplasm decreased and mitochondria, initially roundish with evident cristae, became their usual tubular profile. The plasma membrane had a typical structure and storage organelles, such as finger print vacuoles and lipid globules, became more numerous in the cytoplasm. Larger vacuoles contained the flagella of differentiating zoospores.