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.

Epifluorescence microscopy and low temperature scanning electron microscopy were used to document the development of Uncinula necator on vine leaves and the antifungal effects of kresoxim-methyl and penconazole. Post-germinational growth and development followed a regular time course which was classified into 10 stages.

Kresoxim-methyl was applied at a range of concentrations and at different times before and after inoculation. In glasshouse trials at moderate relative humidity (60%), all pre-infectional applications completely inhibited conidial germination. Lower efficacies were observed with detached leaves at high humidity in Petri dishes. Post-infectional applications of at least 8 mg a.i. l−1 inhibited sporulation and mycelial growth and 67 mg a.i. l−1 caused a partial collapse of surface structures.

Penconazole applied at 17 mg a.i. l−1 did not inhibit germination, but prevented hyphal development and caused growth distortion with hyphal tip swelling. Pre- and post-infectional treatments had similar effects. Applications made 3 d after inoculation increased multiple appressoria and conidiophore formation.

When isolate NIOI of self-inducing Phytophthora boehmeriae was grown on medium containing the fungicide ethazol, the fungus produced oospore-free sectors from which self-sterile cultures were recovered. Self-sterile cultures were also recovered from three of six other isolates tested. Single hyphal fragment cultures and single zoospore cultures derived from these self-sterile cultures were of A1A2, A1, A2, and A0 types. Conversion of self-fertile species of Phytophthora to A1 and A2 types is suggested as another possible evolutionary origin of the two sexes in lower organisms, in addition to previously reported mating type change as a possible origin of sexes.

Monoclonal antibodies were raised against the mycelium of a litter-decomposing basidiomycete, Mycena galopus, for use in an autecological study of the fungus in forest litter. Two clones (3E12 and 6D8), produced using particulate and whole-cell extracts of the fungus respectively, cross-reacted with several species including other Mycena species, non-Mycena basidiomycetes, zygomycetes and anamorphs or mitosporic fungi. Of these clones, 3E12 appeared to be directed against an unidentified β-glucan and 6D8 against chitin. A third clone (6E1), using as immunogen latex collected in the field from stipes of the basidiomes, was specific to M. galopus mycelium in ELISA and immunofluorescence tests and was probably directed against an unidentified polysaccharide.

Seven hundred and eighty two isolates corresponding to 52 fungal taxa have been obtained from 920 segments of healthy and symptomatic twigs of Eucalyptus grandis, incubated on media with water potential −0·138 MPa and −4·19 MPa. Only thirty taxa were isolated at frequencies of 2% and greater. The composition of species isolated from bark of healthy twigs incubated on media with both water potentials was similar, with Aureobasidium pullulans being dominant. Sistrotrema brikmannii was the main species isolated from xylem of healthy twigs at −0·138 MPa whereas Pleospora sp. and Sphaeropsis eucalyptus were the dominant species isolated from this material on medium at −4·19 MPa. Fusicoccum eucalypti and Cytospora chrysosperma were most commonly isolated from bark and xylem of symptomatic twigs. Correspondence analysis showed the fungal species associated with each tissue. Summer drought followed by frequent frost in early autumn may have incited wounds allowing fungal invasion of the bark of twigs.

The PCR technique based upon randomly amplified polymorphic DNA (RAPD) markers using 10-mer oligonucleotide primers was used to investigate the phylogenetic relationships among 33 isolates of Heterobasidion annosum belonging to the intersterility groups F and S. The F isolates originated from Italy, the S isolates from the Italian Alps, northern Europe and North America. The presence or absence of some bands was shown to be population-specific. The North American S group and the European S group differed significantly from each other, but within the latter group there were no significant differences between the Italian S and the northern European S populations, with as much similarity within these populations as between them. More DNA polymorphisms appeared within European F and S groups than in the North American S group. The North American S group appeared to be more closely related to the European S group than to the F group. The isolates of the Italian F population seemed to be most closely related to the Italian S isolates and then, in decreasing order, to the northern European S and North American S isolates. The order of genetic similarity was inversely correlated with the mating frequency in vitro obtained in an earlier study.

Pycnidial hyperparasites of powdery mildew fungi, often used in biological control experiments, are currently considered as belonging to a single species, Ampelomyces quisqualis. However, RFLP analysis of the nuclear rDNA ITS region in a worldwide collection of Ampelomyces isolates showed the existence of seven RFLP groups. Cultural characters, e.g. growth rate of isolates, correlated with the exhibited restriction patterns. The results suggested that A. quisqualis should be regarded as a problematic species complex. The geographical distribution of genetically distinct isolates showed that (i) isolates belonging to the same RFLP group were present even in different continents in their fungal hosts, and (ii) isolates representing various RFLP groups were found in the same geographical region, in the same species of the Erysiphaceae and on the same host plants. The detected genetic differences could influence the applicability of various isolates in biological control.

Two new tropical species of Lachnum with red or reddish hymenia are described. Lachnum euterpes occurs on fronds of the palm Prestoea (= Euterpe) and L. victoriani is described from coriaceous leaves of dicotyledonous trees. A full description of each new species is given along with a brief discussion of the morphological differences distinguishing it from other species with which it could be confused. New combinations in Lachnum are made for the tropical fern-inhabiting species Dasyscyphus ulei and D. chermisinus.

Forty-seven isolates of Verticillium albo-atrum, 35 from hop (Humulus lupulus), seven from lucerne (alfalfa, Medicago sativa) and five from four other hosts, were analysed for DNA polymorphisms. Restriction fragment length polymorphisms (RFLPs) were detected in ribosomal RNA genes (rDNA) using Southern hybridization. Polymorphisms in mitochondrial DNA (mtDNA) were detected in ethidium bromide stained gels after digestion of total genomic DNA with restriction enzymes which recognize four bases containing only G and C. Amplified polymorphic DNA (APD) was analysed using primers based on rDNA sequences from the intergenic spacer (IGS) and 25S regions. These data were used to construct phenograms using either squared Euclidean dissimilarity coefficients (SEDC) and cluster analysis, or unweighted pair grouping with arithmetic averaging (UPGMA). rDNA RFLPs revealed one group with 44 isolates, a second group with two atypical hop isolates, and a third group containing a single avirulent lucerne isolate. mtDNA RFLPs separated rDNA group one into two subgroups, one group containing 38 isolates from different hosts and the other containing all six virulent lucerne isolates. APD analysis divided the isolates into 16 phenotypes, 12 of which contained most of the hop isolates, but there was no correlation with origin, hop cultivar, pathogenicity or year of isolation. One APD phenotype contained all six virulent lucerne isolates, indicating the genetic differentiation between hop and lucerne isolates. Two further APD phenotypes coincided with the second atypical group containing two hop isolates and a distinct avirulent lucerne isolate, respectively. The three methods revealed that three isolates differed markedly from those of the main group.

Dictyoporthe cinnamomi sp. nov., Pseudomassaria cyclobalanopsidis sp. nov. and Splanchnonema verruculospora sp. nov. are described and illustrated from Taiwan and compared with closely related species. A key to species of Dictyoporthe is also provided.

Melanographium palmicolum sp. nov. is described and illustrated based on a specimen collected on a decaying rachis of Archontophoenix alexandrae in Hong Kong. It differs from other previously described species of Melanographium by its moderately dense and widely divergent conidiophore fascicles, and the shape and size of its conidia. A key to the eight species currently accepted in the genus is provided, based on the literature.

Banksia brownii plants treated with a range of potassium phosphonate solutions were examined histologically to determine the mechanism of resistance to invasion by Phytophthora cinnamomi. Reaction zones in plants treated with the chemical compartmentalized P. cinnamomi in both bark and woody tissues, similar to acquired host resistance. Compartmentalization corresponded with the CODIT model of decay in trees. Reaction zones analogous to walls 2 and 3 of CODIT were actively rather than passively formed, and were associated with the ray and axial parenchyma, respectively. While the anatomical evidence of resistance in Australian native flora to this pathogen has been reported previously, this is the first report of enhanced compartmentalization responses of a susceptible native species after treatment with phosphonate.

Hyalorhinocladiella and Sporothrix are two common mycelial anamorphs of Ophiostoma that are difficult to distinguish from each other. Sporothrix spp. differ visibly from Hyalorhinocladiella by the presence of denticles on the conidiogenous cells. Graphium and Sporothrix are often synanamorphs of the same Ophiostoma species and the aim of this study was to determine whether a relationship exists between sympodial conidium development in Sporothrix and annellidic development in Graphium. Conidium development was examined in Sporothrix schenckii, Ophiostoma nigrocarpum and Ophiostoma piceae. Using fluorescence microscopy, as well as scanning and transmission electron microscopy, distinct denticles were observed on the conidiogenous cells in Sporothrix spp. In some cases, these conidiogenous cells were reduced, giving them a Hyalorhinocladiella-like appearance. Results of this study suggest that a continuum in patterns of conidium development exists between Sporothrix, Hyalorhinocladiella and Graphium. The linear extent, and the angle of the proliferation stage with reference to the long axis of the conidiogenous cell, appear to determine the form of conidium development.

DNA fingerprinting with a set of synthetic oligonucleotides complementary to simple repetitive sequences was used to develop molecular markers for Ascochyta rabiei, the most important fungal pathogen of chickpea (Cicer arietinum). Two compatible mating type isolates (MatI and MatII) from the U.S. Pacific Northwest with the same low level of aggressivity were compared to highly virulent isolates from the Mediterranean region and Pakistan to find suitable mating partners for the production of a mapping population. After Hinf I or Taq I restriction, electrophoresis and in-gel hybridization with ten different simple repetitive oligonucleotides, all tested single-spored isolates exhibited unique fingerprint patterns. The analysis revealed that the two U.S. mating types share a considerable amount of genetic variability. A total of 77 polymorphic marker bands were detected. A higher number of polymorphic bands (up to 104) was observed between these isolates and those from different geographical regions. The isolates from the Mediterranean region and Pakistan shared a lower degree (between 80 and 90 bands) of detectable genetic diversity. These data permit selection of highly virulent crossing partners for the different mating types with a high degree of detectable polymorphism.

A sexual cross was performed to prove the Mendelian segregation of fingerprint bands for future linkage analysis. Additionally, the fingerprint data based on 268 informative characters combined with phenetic and phylogenetic algorithms allow determination of the genetic identity, relatedness and diversity of the different isolates. To confirm the phylogenetic data, two outgroupers Ascochyta fabae and Ascochyta pisi, were included. Results indicate that A. pisi is more closely related to A. rabiei than A. fabae.

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.

A study of the lichenicolous fungi occurring on species of the lichenized genus Peltigera has resulted in six new species: Libertiella curvispora, L. didymospora, L. fennica Alstrup, Polycoccum superficiale, Roselliniella peltigericola, and Zwackhiomyces kiszkianus. A key to the five known species of Libertiella is included. This paper brings the number of fungi known on this host to 87, of which 61 are not known from any other host genus, providing additional evidence for the richness of Peltigera thalli as a host for novel fungi. The possible hypotheses to explain the richness of this host genus for lichenicolous fungi are enumerated; these are not mutually exclusive.

The ability of Hymenoscyphus ericae to produce 12 carbohydrolytic activities has been investigated during growth under solid-state fermentation conditions. The fungus produced a complete cellulase enzyme complex (cellulase, cellobiohydrolase and β-D-glucosidase) along with components of the hemicellulolytic (endoxylanase, β-D-xylosidase, α-L- and β-L-arabinosidase and glucoronidase) and mannanolytic (mannanase, β-D-mannosidase, α-D- and β-D-galactosidase) complexes. Specific activities were greatest for endo-acting enzymes and lower for exo-acting and side-branch removing activities in each case. The data indicate that H. ericae possesses a considerable ability to degrade plant polymeric material and are discussed in relation to establishment of the symbiosis and interaction of mycelium with moribund plant organic matter in soil.

After purification by thin-layer chromatography (tlc) several fatty acids stimulated oospore formation in Phytophthora cactorum but not in Phytophthora parasitica. Palmitoleic acid was the most effective and was the only fatty acid tested that promoted oospore formation in P. parasitica. Purification of palmitoleic acid by Florisil column chromatography resulted in a two-fold increase in activity over that purified by tlc. When 0·01 to 100 ng of cholesterol was added to basal medium containing palmitoleic acid, the added cholesterol did not significantly change oospore production by P. cactorum. Oospore formation in P. cactorum was slightly stimulated by tlc-treated aliphatic hydrocarbons, or derivatives of hydrocarbons, but was strongly stimulated by geraniol and squalene. Vitamin A and vitamin A esters stimulated oospore formation in both P. cactorum and P. parasitica. tlc treatment also significantly increased the activity of cholesterol and β-sitosterol on oospore formation by P. cactorum. Both compounds did not stimulate oospore formation by P. parasitica even after tlc treatment.

This listing covers the period December 1, 1996 through to December 31, 1996. Citations are arranged in groups which roughly correspond with the British Mycological Society's Special Interest Committees.

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