Evidence that chemical changes in litter exposed to elevated CO2 might alter the composition and function of fungal communities in soil is presented. Some potential effects of elevated atmospheric CO2 on the decomposition of Fraxinus excelsior leaf litter and the interactions of the colonizing fungi, growing singly or in simple associations in microcosms, were investigated. Fungal colonization was monitored by analysis of the ergosterol content of litter and specific PCR-amplified ribosomal DNA spacer products. After < 42 d, fungal colonization was less on litter with a higher C[ratio ]N ratio when obtained from seedlings grown in elevated CO2 (600 ppm). After triple-species inoculation percentage α-cellulose and, in some combinations, nitrogen content was reduced on litter from seedlings grown in elevated CO2.

Nine new species of Phanerochaete from Taiwan are described and illustrated: P. argillacea, P. capitata, P. eburnea, P. flavidogrisea, P. fulva, P. hyphocystidiata, P. reflexa, P. rubescens, and P. suballantoidea. A key to 30 species of Phanerochaete from Taiwan is given.

Venturia populina, first described on European Populus nigra, has been thought to be the only species of Venturia in Europe and North America to cause leaf and shoot blight of balsam poplars and cottonwoods in Populus sects. Tacamahaca and Aigeiros. The species of Venturia occurring on introduced P. nigra and native P. trichocarpa in the Pacific northwest were examined. Venturia populina was consistently found on P. nigra (i.e. the widespread P. nigra cv. ‘italica’) in the region, but V. inopina sp. nov. was present on native P. trichocarpa and its hybrids. There were neither examples of V. populina on P. trichocarpa and its hybrids nor of V. inopina on P. nigra cv. ‘italica’ (27 collections from 16 sites in Oregon, Washington, and Vancouver Island were made during 1995–2002). In an inoculation study, host-range separation was confirmed in that V. inopina caused sporulating leaf lesions on P. trichocarpa and its hybrids, but only non-sporulating lesions on P. nigra cv. ‘italica’. These two species of Venturia can readily be distinguished by conidial septation; V. populina is primarily 2-septate, whereas V. inopina is primarily 1-septate. Growth rates on PDA at 15 °C, and ITS sequences (2.3% divergence) were also distinct in isolates of these congeners. Conidial shape was of more value in discriminant analysis than conidial length. Venturia inopina is homothallic, given the sexual fertility of cultures of single ascospores that were overwintered under ambient conditions. Its geographic range appears to be restricted even within the Pacific northwest, leaving open the possibility that still other undescribed, native species of Venturia occur elsewhere in North America on sects. Tacamahaca and Aigeiros.

During a survey of 375 strains of the Xylariales, one isolate (F127076) was observed to have an ITS1 size of 833 bp. This size exceeds the average ITS1 size in the Xylariales (mean=209±57 bp). Comparison of the DNA sequence with GenBank and with a proprietary DNA database revealed low homology with Xylaria hypoxylon ATCC 42768, and with one undescribed Xylaria species. When the ITS2 sequence was compared, these isolates were 96–98% homologous. Sequences of other variable genes confirmed the relatedness among these strains. A closer observation of the ITS sequence of this isolate revealed the presence of three repeated domains of 250 bp plus one truncated domain, showing 52–75% homology. Sequence similarity suggests that the repeated domain is derived from the fusion of the ITS1 with a DNA fragment derived from the γ-glutamyltranspeptidase gene. This example suggests that the rate of evolution of ITS1 can be independent of the rate of evolution of other genes, even when this variability is not a result of slipped strand misspairing events like in other Xylariales. This observation also indicates that recombination with other nuclear genes could participate in the evolution of the internal transcribed spacer.

Xylem tissues of eight pip fruit, two stone fruit and one willow cv. exhibited similar seasonal variations in susceptibility to colonisation by hyphae of Chondrostereum purpureum following monthly inoculation and incubation of cuttings in the laboratory. Xylem tissues of all hosts exhibited maximum resistance during May/June/July. Generally, susceptibility increased in spring/early summer, peaked in November and declined over late summer to autumn. During June, cv. Golden Delicious apple cuttings prevented host colonisation by immersion of hyphae in tannin-like deposits in xylem vessels. Such deposits were not observed in Nashi pear where hyphae in vessels were also severely disrupted. Hyphae of C. purpureum were bi-nucleate, contained glycogen deposits and readily penetrated starch granules and cell walls.

Spatial distributions and species diversity of ectomycorrhizal fungi were studied. Epigeous fungal fruit bodies and mycorrhizas were investigated in a reforested stand of Pinus densiflora aged 45 yr. Forty species of fruit bodies, including the dominant genera, Russula and Inocybe, were recorded throughout the three-year investigation. A species–area curve of the fruit bodies indicated that mean species number in 1.5 m2 was ca 1.0. Pine ectomycorrhiza, which were randomly sampled throughout the same investigation period, were assigned to 51 morphotypes microscopically. Although the dominant morphotypes were not manifested due to the sampling method used, a species–area curve of the mycorrhizas indicated the mean species number in 1.5 m2 was ca 25. Thus, spatial distributions among fruit bodies and mycorrhizas were quite different, and the mycorrhizas showed more complex distributions than fruit bodies. Several species abundance and diversity coefficients changed in relation to both the calculation method and fungal material used, which suggested the necessity for a uniform method of characterizing ectomycorrhizal fungal community structure.

AFLP (amplified fragments length polymorphism) and ISSR (inter simple sequence repeat) analyses were used to detect genetic diversity among 46 Phialophora gregata isolates including 41 from soybean, four from mung bean, and one from adzuki bean. Five AFLP primers amplified 55 fragments, of which 20 bands were polymorphic. Thirteen ISSR primers amplified 66 fragments, of which 45 bands were polymorphic. The ISSR technique detected more polymorphism than the AFLP technique did. A UPGMA (unweighted pair-group arithmetic mean) dendrogram was constructed based on the 121 amplified fragments with AFLP and ISSR primers to depict genetic diversity and relationships among the 46 isolates. Various levels of DNA polymorphism were detected among P. gregata isolates from soybean and mung bean. The estimated average genetic diversity is 0.079 for the population of 45 isolates from soybean and mung bean. The ISSR technique was shown to be more effective and economic than the AFLP technique in detecting genetic variation in P. gregata.

Torrentispora fibrosa gen. sp. nov. (Ascomycota, Annulatascaceae) is described based on specimens from submerged wood collected from streams in Tai Po Kau Forest Reserve, Hong Kong. T. fibrosa is characterized by immersed to superficial ascomata with a peridium of black cells arranged in irregular rows, wide septate paraphyses, long cylindrical asci with a relatively massive refractive apical ring, and unicellular ascospores with a fibrillar sheath. Illustrations from light and scanning electron microscopy are provided. It is compared with species in the genus Annulatascus, from which it differs in ascoma peridium and ascospore sheath morphology, and with other aquatic ascomycetes possessing ascospores with a similar fibrillar sheath structure.

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.

The effect of xyloglucan on spore germination, hyphal length and mycorrhizal colonization of alfalfa plants was studied. The presence of high concentrations of xyloglucan in the rooting medium inhibited mycorrhizal colonization in plants inoculated with Glomus mosseae. Intermediate xyloglucan concentrations had no effect on arbuscular mycorrhizal (AM) colonization, but a low concentration increased mycorrhization of host plants. The effects of these doses on spore germination and hyphal length of G. mosseae were similar to those observed for mycorrhizal colonization. Production of xyloglucanase was assayed during colonization by the AM fungus G. mosseae in lettuce and onion. Endoxyloglucanase activity peaked 15 d after inoculation, whereas exoxyloglucanase activity peaked at 30 and 50 d. Extracts from external mycelia of G. mosseae showed endo- and exoxyloglucanase activities. Some of the endoxyloglucanase activities detected in AM colonized plant roots may be derived from the AM fungus, as endoxyloglucanase proteins found in the external mycelia of G. mosseae and in mycorrhizal root extracts showed similar electrophoretic mobility. These results suggest that xyloglucanase is involved in the process of colonization of plants by G. mosseae.

Motile zoospores of species of oomycetes encyst rapidly to form walled cysts that germinate and infect host plants. Differences in the protein composition of the plasma membrane and endomembranes of zoospores and cysts of the oomycete Phytophthora nicotianae have been explored by comparing patterns of polypeptides in one- and two-dimensional gels of microsomal fractions. Against a backdrop of common components, this comparison revealed that at least 53 proteins were specific to, or occurred preferentially in, the microsomal fraction of one spore type or the other. In addition, proteins common to zoospore and cyst plasma membranes were further investigated by immunocytochemical labelling with a panel of 10 monoclonal antibodies raised against P. nicotianae spore components. The results of immunolocalisation studies and immunoblotting showed that the antibodies reacted with four different sets of membrane proteins, and were grouped accordingly. Group 1 antibodies bound preferentially to the bladder of the water expulsion vacuole or a region of the cell surface associated with it. Group 2 antibodies reacted with a protein of high relative molecular weight (>200 kDa) found in zoospores and cyst plasma membranes and in the cleavage membranes of sporangia. Group 3 antibodies reacted with a set of proteins occurring in the plasma membrane of zoospores and cysts, in the peripheral cisternae, in the spongiome membranes of the water expulsion vacuole, in the cleavage membranes of sporangia, and in the plasma membrane and apical vesicle membranes in hyphae and germinating cysts. Group 4 antibodies bound to a set of proteins present in the zoospore and cyst plasma membrane, in sporangial cleavage membranes and in the spongiome but not present in the peripheral cisternae, hyphae or germinating cysts. The results document the presence of proteins that are common to the plasma membrane of all stages of the asexual life cycle of P. nicotianae, of proteins that occur in the plasma membrane of the asexual spores but not of hyphae, and of proteins that occur in the membranes of either zoospores or cysts. The results also indicate that zoospore and cyst plasma membrane proteins may be present in specific subsets of other membranes within the zoospores.

Oidiophores with uninucleate oidia are produced on the aerial mycelium of Coprinus cinereus and occasionally also on the submerged mycelium. Oidiophore development starts with the formation of a stem cell and proceeds with stem cell elongation, followed by the formation of oidial hyphae at the tip of the stem cell and subsequent release of matured oidia. However, analysis of more than 20 different C. cinereus strains revealed that oidiophore formation is a flexible process. Based on morphological variations, we defined four main types of oidiophores. Types 1 and 2 oidiophores produced oidia at the tip(s) of simple (type 1) or branched stems (type 2). Types 3 and 4 oidiophores were characterized by the absence of stem cell elongation (type 3) or stem cell formation (type 4). All strains examined produced types 1 and 2 oidiophores and some produced also types 3 and 4 oidiophores but the frequency of the different oidiophore types varied strongly from strain to strain.

Inocybe inexpectata sp. nov., from Spain, is described and illustrated. It is characterized by its small size, brown–argillaceous tinges, strongly decurrent gills, absence of metuloid cystidia, cylindrical to suballantoid spores and a well-developed trichoderm.

The mycoparasite Sphaerellopsis filum (teleomorph Eudarluca caricis) was applied simultaneously with Melampsora larici-epitea on to willow leaf discs using eight concentrations of conidia. Inoculum densities were quantified and the numbers of uredinia of the rust, pycnidia and conidia of S. filum and rust spores produced per leaf disc were measured 13 d after inoculation (first assessment). Higher S. filum inoculum densities resulted in more rust uredinia being infected, but did not reduce the number of uredinia produced. The ratios of infected rust pustules: S. filum conidia applied were in a range of 0.25–0.31 when less than 20 S. filum spores were inoculated on to a leaf disc (0.95 cm2). Suppressive effects of S. filum on rust spore production were more obvious in the second assessment, carried out 23 d after inoculation. Inoculum densities of S. filum were significantly (P<0.001) correlated with the frequency of uredinia infected (% variance accounted for [VAF]=85.8), the number of S. filum pycnidia (%VAF=81.4), S. filum spores produced (%VAF=72.3) and rust spore production (%VAF=48.6). Rust spore production was significantly (P<0.001) negatively correlated with the frequency of uredinia infected (%VAF=51.1), the number of S. filum pycnidia (%VAF=42.0) and the number of S. filum spores produced (%VAF=40.6). The best correlation was found between the number of pycnidia and the number of S. filum spores produced (%VAF=88.8).

Mycosphaerella contains some of the most damaging foliar pathogens of Eucalyptus. Identification of the species has relied mainly on characters such as ascospore morphology and the mode of ascospore germination. Wide variation and overlap in morphological characters, especially ascospore shape and size, has lead to confusion in species concepts. This study examines the potential of RAPD–PCR to differentiate Mycosphaerella species that cause leaf diseases of Eucalyptus in Australia. RAPD–PCR was conducted on 39 isolates representing 10 species of Mycosphaerella collected from southern Australia. Primers were chosen mainly to distinguish between the two most common and damaging species in Australia, M. cryptica and M. nubilosa. The RAPD analysis revealed five groups within the 39 isolates, four of which represent distinct species: M. cryptica, M. gregaria, M. nubilosa and M. marksii. For these four species, the cluster analysis and RAPD patterns gave results that fitted well with classical taxonomic criteria. Variation within M. cryptica, M. nubilosa and M. marksii was low, even though the isolates within these species originated from diverse hosts and locations. The remaining species in this study grouped together and could not be easily separated using the RAPD data here.

Four species of Linocarpon on Pandanus are described and illustrated. L. spathulatum and L. sulcatum spp. nov. have ascospores with grooved appendages and ascomata with eccentric ostioles. L. fasciatum sp. nov. is similar to L. pandanicola, but its ascospores lack appendages and the ascomata are smaller. A collection of L. elaeidis, not previously reported from Mauritius, has ascomata with distinct black papillate necks, in contrast to the type material which lacks these structures.

Botrytis cinerea secreted low levels of a constitutive acid phosphatase into liquid culture when grown in the condition of phosphate starvation or in the presence of high concentrations (4 mM) of organic phosphate esters or inorganic phosphate. During phosphate starvation the overall acid phosphatase activity secreted into the culture fluid was increased up to 80-fold due to the appearance of a second (phosphate-repressible) enzyme form. On native polyacrylamide electrophoresis gels, the constitutive enzyme displayed size heterogeneity, whereas the repressible enzyme was resolved as a discrete band. Both forms of the enzyme reacted with p-nitrophenylphosphate under such conditions, but only the constitutive form was found to hydrolyse β-glycerophosphate. Histochemical staining with these two substrates with the Gomori lead-capture method revealed significant staining of secretory vesicles in the hyphal tip region only in phosphate-starved mycelium with p-nitrophenylphosphate as the substrate. By contrast, vacuolar structures were stained with both substrates under conditions of phosphate starvation as well as abundance of inorganic phosphate. The implications of these observations for the likely exit route of the two acid phosphatase forms are discussed.

A new genus, Halorosellinia, is introduced to accommodate the lignicolous mangrove inhabitant Hypoxylon oceanicum. A detailed illustrated account of the teleomorphic and anamorphic states is given. Halorosellinia oceanica comb. nov., is compared with Stilbohypoxylon quisquiliarum and Nemania confluens (a reduced form of Nemania) and the reasons for introducing a new genus are discussed. Data on the ecology and geographical distribution of H. oceanica are presented.

Rhynchosporium alismatis, a pathogen of several Alismataceae species, is being studied in Australia as a potential weed biocontrol agent for Alisma lanceolatum, A. plantago-aquatica and Damasonium minus. Chlamydospores of R. alismatis are described for the first time. Large numbers (5.34×105 cm−2) were produced on potato dextrose agar within 8–15 d and range in size from 4.7 to 14 μm. There was variability between isolates in mean diameter but size was not related to the host of origin. Within 24 h at 30 °C 60% of chlamydospores, 8 d to 3 months old, germinated. Each germinated chlamydospore produced up to four germ-tubes. Chlamydospores were detected in leaf lesions on naturally-infected A. plantago-aquatica. One-month-old chlamydospores were pathogenic to leaf discs cut from mature leaves of A. lanceolatum and Damasonium minus. The relative robustness of chlamydospores is an advantage over conidia for the future production of a biological control agent if they can be produced and harvested in broth culture.

The amount of Gaeumannomyces graminis var. tritici inoculum was quantified by slot-blot hybridization assay, using a specific DNA probe, pG158. Estimates of the amount of G. graminis var. tritici DNA in naturally infested and inoculated soils were made and correlated with take-all disease severity as determined by a conventional soil bioassay (expressed as a percentage of seminal roots with G. graminis var. tritici lesions). Disease severity in the glasshouse assay and DNA levels were highly correlated. The level of take-all disease severity in naturally infested soil can be predicted using the equation yi=53·078 log (xi)+88·866, where yi=the predicted value of the disease severity (%) and xi=amount of G. graminis var. tritici DNA (ng) in 100 g soil. The DNA-based assay for quantifying the amount of G. graminis var. tritici has been further developed and improved in terms of the sampling techniques and efficiency. Soils of different types were collected to a depth of 10 cm and organic matter between 0·5–1·4 mm in size was separated from this soil. Using a slot-blot hybridization assay, it was found that G. graminis var. tritici was mostly present in the organic matter fraction greater than a size of 0·5 mm and in soil at a depth of 5 cm. This rapid and reliable DNA-based assay is being used in conjunction with a model of take-all disease development to predict disease levels in the field due to G. graminis var. tritici.