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.

Helicodendron fuscum is described and compared with the similar species H. cumbriense and H. pinicola. Helicondron websteri, formerly confused with H. fuscum, is described as a new species. The anamorph of Tyrannosorus pinicola, Helicodendron pinicola, which has not been validly published is validated. A key for identification and illustrations are provided for all species treated.

The genus Piricauda comprises eight species characterized by monotretic conidiogenous cells and micronematous arched conidiophores: P. cochinensis, P. cubensis, P. longispora, P. mexicana, P. paraguayensis, P. pseudarthriae, P. taiwanensis, and P. vulcanensis sp. nov. P. caribensis is transferred to Acrodictys. Species usually colonize dead petioles and rachides of palms in tropical and subtropical areas, but can also be found on branches and leaves of different trees. The species are illustrated and briefly described, and a key to them is provided.

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.

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 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.

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.

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.

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.

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.

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.

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.

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.

Primordia formation and basidiocarp maturation have separate requirements for light. Both show maximum activity in the 440–470 nm range but with slightly different peak values. Maturation requires over 2 orders of magnitude longer exposures to light than does initiation. Fluence–response relationships of primordia initiation are complex and do not show reciprocity.

Rimularia insularis forms an photosynthetic thallus on lichens of the Lecanora rupicola group. In the thalli of R. insularis, some hyphae of the host are detectable, and they are situated mainly in the basal part of the Rimularia's medulla. No Lecanora hyphae were present in the Rimularia's algal layer and they were indistinct in the upper parts of its medulla, from where we obtained clean ITS-sequences of Rimularia. Direct PCR from various sections of the algal layer detected only one photobiont genotype, although the algal cells could be assigned to two morphologically different types. Calcium deposits were found in the upper parts of the medulla, while abundant rock substrate fragments with different mineral compositions were present in the lower parts. Cavities and fissures in the rock below the infected thalli were filled by fungal cells, PCR analyses of such parts indicated that the Rimularia hyphae extend below the host, and into the rock.

The taxonomic status and relationship of Tricholoma sulphureum and the similar T. bufonium were investigated using different sets of characters. These included morphological data on fruit bodies, ecological and chorological data, and analysis of the sequence data obtained for the ITS of basidiomes of different ecological and geographic origin. Moreover, the ectomycorrhizas formed by T. bufonium on Abies alba and Quercus sp. were characterised, and anatomical features compared with those of T. sulphureum mycorrhizas on coniferous and broad-leaved host trees. Our results revealed extensive ITS variation in members of the T. sulphureum group, but this variation was not correlated with morphology, ecology, or geographical distribution. We conclude that T. bufonium cannot be maintained as an autonomous taxon and should be treated as an infraspecific variant of T. sulphureum.

A preliminary physiological characterization of osmoregulation in an Aspergillus nidulans salt sensitive mutant carrying cotransformed DNA sequences from the marine hyphomycete Dendryphiella salina is described. A genomic DNA library made in lambda EMBL3 was cotransformed with the plasmid pDJB3 into an A. nidulans host carrying a selectable marker for transformation (pyrG89) and a salt sensitivity mutation (sltA1). In some cases D. salina clones appeared to directly complement the salt sensitivity mutation by restoring salt and arginine insensitivity. Other clones gave marked increases in salt tolerance and yet the hosts remained arginine sensitive. Improvements in salt tolerance correlated with an enhanced ability to induce polyol biosynthesis during salt challenge.

Isolates of Fusarium oxysporum from different habitats were compared with respect to intra- and extracellular isozymes. Five intracellular enzymes: esterase, superoxide dehydrogenase, malate dehydrogenase, dihydrolipoamide dehydrogenase and succinate dehydrogenase were extracted from the mycelium, and four extracellular enzymes: protease, cellulase (endoglucanase), amylase and lipase were obtained from the culture medium. Proteins were separated either by discontinuous PAGE or by IEF, and isozymes were detected by specific staining. The intracellular enzyme data were analysed by an unweighted paired group method analysis (UPGMA), which separated the isolates into three main clusters. The clusters generated from the intracellular enzymes were weakly correlated with the electrophoretic types based on the extracellular enzymes. These results suggest that extracellular enzymes may be of limited value for classification within F. oxysporum.

Rhynchosporium secalis isolates E97-2 and H97-2, represented the major pathotypes in populations on barley in Alberta, Canada, but differed widely in their virulence. Following greenhouse co-inoculation with the two pathotypes, E97-2, originally isolated from resistant cv. ‘CDC Earl’, predominated over H97-2, isolated from the susceptible cv. ‘Harrington’, from the first to the last of four infection cycles on both ‘CDC Earl’ and ‘Harrington’. These results indicated that the host can rapidly influence pathotype composition and that pathotype E97-2 may have a competitive advantage over H97-2 on these cultivars. DNA polymorphisms were found between isolates from single or mixed inoculations on cvs ‘CDC Earl’ and ‘Harrington’ for four successive cycles. Co-inoculation with the two isolates resulted in a shift to a molecular phenotype more similar to E97-2 than H97-2. The competitive advantage of E97-2 over H97-2, combined with the selective pressure exerted by the host, would explain the increased susceptibility of cv. ‘CDC Earl’ and other cultivars with similar sources of scald resistance, in fields across Alberta. However, H97-2 will likely remain one of the major pathotypes in Alberta due to the relatively large acreage of cv. ‘Harrington’ in this province.