The production of chloromethane (CH3Cl) by wood rotting fungi of the Hymenochaetaceae is discussed with particular emphasis on emissions by species of Phellinus and Inonotus. Recent work on the metabolic role of CH3Cl as a methyl donor in the biosynthesis of secondary metabolites both in the Hymenochaetaceae and other families of white-rot fungi is reviewed. The parameters affecting the fungal emissions of CH3Cl in forest ecosystems are considered and where possible quantified. The annual global input to the atmosphere from this source is provisionally estimated at 160000 t of which 75% is released from tropical and subtropical forests and 86% is attributable to Phellinus. The possible impact of the contribution from fungi and other biological sources on the atmospheric CH3Cl burden and stratospheric ozone depletion is assessed.

Two new species of Inonotus, I. chihshanyenus sp. nov. and I. formosanus sp. nov. found growing saprotrophically on the decayed stems of Melicope merrillii and Persea zuilhoensis, respectively, in Taiwan are described and illustrated. Their cultural characters are described.

Selenate-resistant (SelR) mutants of Botrytis cinerea were selected by plating conidia or mycelial plugs onto minimal medium amended with selenate and taurine. Ultraviolet irradiation of conidia to give 5% survival increased mutant yield twenty-fold. Mutants could be divided into three classes based on growth in the presence of selenate or chromate and on response to taurine in minimal media. Nitrate non-utilizing (Nit) mutants, generated as spontaneous sectors on minimal media amended with chlorate, behaved as nit1 mutants in growth tests (i.e. putatively defective in nitrate reductase apoenzyme). When nit1 mutants were paired on medium with nitrate as sole nitrogen source some pairings complemented, behaviour attributed to intragenic complementation. Selected crosses of SelR and nit1 mutants with wild-type strains gave 1[ratio ]1 segregation of both phenotypes and no evidence of linkage to either Mbc1 (benzimidazole resistance) or Daf1 (dicarboximide resistance) markers; loose linkage was confirmed between Mbc1 and Daf1. Strains showing the SelR phenotype may result from mutations in different genes; the genotypic symbol Sel 1 is allocated to one of these mutations. Four-point crosses involving the markers at Sel 1, nit1, Mbc1 and Daf1 generated progeny with all 16 genotypes. Both Sel1R and nit1 mutants were stable following subculture and retained pathogenicity in a bean seedling assay. Complementation was demonstrated between SelR and nit1 mutants selected from the same parent.

A new species of Penicillium, Subgenus Biverticillium, was isolated from the root of a wheat seedling during a survey of the ability of rhizosphere fungi to solubilize phosphate. The species, described here as Penicillium radicum, has affinities with P. variabile, P. allahabadense and Talaromyces wortmannii, but can be distinguished by differences in morphology, secondary metabolite profiles and unique DNA banding patterns obtained using RAPD PCR.

Genetic variation in Alternaria brassicae, A. brassicicola, and A. raphani collected from geographically diverse regions of the world was studied with RAPD and RFLP markers. Twenty 10-mer primers of arbitrary nucleotide sequences were tested for amplification of genomic DNA of A. brassicae using PCR. Of these, five primers amplified the genomic DNA from 20 A. brassicae isolates and produced reproducible RAPD profiles. UPGMA analysis of RAPD data showed that isolates collected from geographically distinct regions could be broadly classified into four groups. Intra-regional variation between isolates was less apparent. Variation was, however, higher in A. brassicicola, as based on RAPD analysis. Two isolates (from Canada and France) of A. raphani also showed variability with different RAPD profiles generated by all five primers tested. Five polymorphic, distinct RAPD products were used as hybridization probes for RFLP analysis to detect inter- and intra-specific variation. Variation among A. brassicae, A. brassicicola, and A. raphani was evident. Non-radioactive probes were also used to hybridize with Southern blots of A. brassicae, A. brassicicola, Leptosphaeria maculans, Rhynchosporium secalis and Brassica juncea for the selection of A. brassicae-specific probe(s). Probe AbP3 specifically hybridized with restriction digests of A. brassicae but not with those of A. brassicicola or other tested species. This probe should, therefore, be useful for distinguishing between two important pathogens of crucifers, i.e. A. brassicae and A. brassicicola both in culture and infected tissues.

Over 70% of zygospores of M. piriformis collected from 10 day-old cultures germinated in water and on acidified water agar. Germination originated either through a crack on the zygosporangial wall or through one of the suspensors. The germination percentage was highest when newly matured zygospores were used. Zygospores from cultures older than one month either did not germinate or germinated poorly. The mode of zygospore germination was affected by nutrients and germination condition. Germ-sporangial, germ-sporangial-mycelial and mycelial germination were observed on solid media while germination with an elongated germ-tube was observed in water. Zygospores of M. piriformis germinated under light as well as in darkness. Although low pH is not required for zygospore germination in water, zygospore germination on solid media is favoured by low pH.

Three different proteinase inhibitors purified from crayfish blood, a 23 kDa inhibitor of subtilisin, a 155 kDa trypsin-inhibitor (pacifastin) and an α2-macroglobulin were tested for their inhibitory activities against extracellular proteinases from the specialized crayfish parasite Aphanomyces astaci, the saprotrophic A. laevis and the plant parasitic A. chochlioides and A. euteiches. All three crayfish inhibitors were effective against extracellular proteinases from the different Aphanomyces species when defined peptides were used as substrates for the proteinases. Proteolytic activities from A. astaci against a complex substrate, casein were reduced by any of the three crayfish proteinase inhibitors tested. It is, therefore, possible that these proteinase inhibitors may reduce the proteolytic breakdown exerted by A. astaci proteinases during an infection.

The natural dihydrate form of calcium sulphate, CaSO4.2H2O (gypsum), particularly found in gypsiferous soils and in certain building constructions, was found to be effectively solubilized by both Aspergillus niger and Serpula himantioides. When the fungi were grown on malt extract agar (MEA) medium amended with up to 1% (w/v) of gypsum, solubilization activity was evident by the appearance of a clear zone (haol) around and/or under the growing colonies. The haloes were found subsequently to enclose concentric rings of newly formed crystalline precipitate. The pH profile of the medium underneath the growing mycelium of A. niger was not affected by the presence of gypsum, while the S. himantioides pH profile displayed a slight reduction in pH values when grown on gypsum-containing media compared with the control. Electron microscopy and X-ray microanalysis of the crystals revealed the formation of calcium-containing crystals with the characteristic morphology typical of different forms of calcium oxalate. The complexing activity of fungal-produced organic acids with calcium was suggested to be the prevalent mechanism of solubilization with the production of oxalic acid resulting in precipitation of oxalate. Such activity resulted in the release of available sulphate which increased over the incubation period. The concentrations of sulphate released from 0·5% (w/v) gypsum after growth of A. niger and S. himantioides for 8 d were 14·7±0·7 and 7·4±0·9 μmol cm−3 respectively. These results are discussed in the light of their relevance to land reclamation and plant nutrition, as well as the weathering of building materials containing gypsum.

The effects of temperature and water availability on growth and interactions between fumonisin-producing isolates of Fusarium moniliforme and F. proliferatum and seven other fungi from maize grain were determined in vitro. The type of interaction and index of dominance (ID) between species were markedly influenced by temperature and aw. Generally, F. moniliforme and F. proliferatum were very competitive and dominant against the Penicillium spp. and A. flavus. They were in turn dominated by A. niger, but mutually antagonistic when paired with F. graminearum and A. ochraceus. Under slightly drier conditions (<0·98 aw) A. ochraceus became more competitive and dominant over the fumonisin-producing species. A. flavus was dominant only at 30°C and <0·96 aw. F. moniliforme and F. proliferatum demonstrated dominance against all species over a range of temperatures and 0·994 to 0·96 aw. At lower aw levels they were less competitive. The growth rate of the two fumonisin-producing species was significantly reduced by F. graminearum, regardless of aw. F. moniliforme and F. proliferatum reduced growth of Penicillium and Aspergillus spp., especially at >0·96 aw. At <0·96 aw, growth of these species was unaffected. Using Biolog plates the effect of aw and temperature on utilization patterns of carbon sources in maize were evaluated for the first time. The niche overlap indices relative to F. moniliforme and F. proliferatum were determined and compared with that of each interacting species. NOIs for F. moniliforme and F. proliferatum were >0·90 at >0·96 aw and 25 and 30°, indicative of co-existence with other species. Most of species had NOIs >0·90, except in some cases when paired with F. moniliforme, where NOIs <0·80 suggested the occupation of different niches. Although there was no significant correlation between the ID and NOI methods both suggested that the niche overlap between species was in a state of flux and significantly influenced by both temperature and water availability. This suggests that interpretation of ID, or NOIs carried out under one set of environmental conditions may be misleading when considering interactions between species and also where screening for biocontrol potential is being considered.

A taxonomic and chorologic study of Protophysarum phloiogenum, including light and SEM micrographs is presented. The authors propose the new family Protophysaraceae in the Physarales.

The characterization of type cultures of the S. thermophilum complex remains unclear and morphological features have been relied upon to recognize such isolates. The aim of this study was to compare morphological and thermal methods, in order to identify relationships between cell wall and cultural characteristics. The differences in the proportions of structural and non-structural fractions and the peak decomposition temperatures of the test isolates were significant. The thermograms produced can be grouped into two distinct types, which can be further sub-divided, in agreement with microscopic classification. The relationship between the various morphological parameters including extension rate, sporulation, microscopic type and DTG parameters are discussed briefly.

The occurrence of an undescribed ergot species, Claviceps citrina, on the halophytic chloridoid grass Distichlis spicata, in the Texcoco region of central Mexico, is reported. RAPD and ITS1 sequences of this fungus were compared with other Claviceps species and the morphological uniqueness of the fungus was reinforced. Its sclerotia do not contain any alkaloids of the ergoline type. Germination of sclerotia occurred immediately after placing them on humid sand. After removal of the capitula, the remaining stipe was able to regenerate the capitulum.

PCR was used to amplify ribosomal internal transcribed spacer and 5·8 S DNA from type material of Rhizopogon colossus var. colossus, R. hawkerae, R. parksii, R. reticulatus and R. villosulus plus a number of collections belonging to the same section (Sect. Villosuli). Different restriction enzymes were used to digest these amplified rDNAs to find polymorphisms useful in identification. On the basis of these studies and our previous morphological observations, the conclusion is that the names proposed by Smith & Zeller for collections studied, as well as R. reticulatus, represent only one species, R. villosulus.

Amplification of the internal transcribed spacer (ITS) of ribosomal RNA genes using PCR and subsequent RFLP analysis offers promise for improved species-level identification of ectomycorrhizal fungi. Intrageneric homogeneity and intraspecific heterogeneity of these characters are, however, frequent. A diverse group of ectomycorrhizal fungi with worldwide distribution was characterized by ITS-RFLP analysis. DNA of 64 identified and five unknown ectomycorrhizal fungi was extracted and their ITS regions were selectively amplified with ITS1-F and ITS4 ribosomal RNA gene primers. Each PCR product was digested with seven restriction enzymes. The resulting restriction fragments were compared by distance matrix analysis. Restriction enzyme analysis of amplified fragments was sufficient for distinguishing all but two closely related species. Intraspecific variation was observed in Cenococcum geophilum and Pisolithus arhizus, providing further evidence that these taxa represent species complexes.

Eudarluca caricis, the teleomorph of Sphaerellopsis filum, was found on blackberry rust (Phragmidium violaceum) in south west England and its morphology is described. Cultures derived from ascospores produced pycnidial conidiomata and conidia typical of S. filum, confirming the connection between the meiotic and mitotic stages of the fungus. Microconidia were also found in the cultures derived from ascospores. Conidiomata developed on the majority of uredinial pustules of P. violaceum 10 d after inoculating detached, uredinia-bearing blackberry leaves with the conidia from the cultures derived from ascospores.

The action of high concentrations of benomyl was investigated in the wild-type strain St Lawrence of Neurospora crassa and in mutants displaying various levels of tolerance to the drug. Germ-tube formation by macroconidia, germination pattern (single versus multiple germ-tube emergence) and hyphal tip extension of these strains showed different sensitivities to the microtubule inhibitor, benomyl. The wild-type strain, whose vegetative growth was inhibited at micromolar concentrations, still germinated by multipolar outgrowth at 100 μm. At such a level, germination of the moderately resistant mutant Bml 511(r) was inhibited more than the wild type. Highly resistant mutants capable of hyphal growth at 500 μm were obtained by mutating strain Bml 511(r) using uv. One of these, strain E1-91, showed temporary sensitivity to the microtubule inhibitor and produced multiple germ-tubes. This strain was deficient in the β-tubulin polypeptide during the first hour of germination.

A transformation system is described for the edible mushrooms Pleurotus ostreatus and Volvariella volvacea. The system developed is based on a positive selection strategy using the trp3iar gene from Coprinus cinereus, which confers resistance to the antimetabolite 5-fluoroindole. Transformation frequencies were low in both species. Southern blot analysis confirmed the integration of transforming DNA into the genome of transformants and indicated the presence of tandemly duplicated copies of the plasmid in some of these transformants. The system has potential for introducing beneficial traits such as enhanced substrate bioconversion and faster sporophore development.

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.

Harposporium arcuatum, H. dicorymbum and H. subuliforme were isolated from nematodes and grown in pure culture. All three species produced accessory conidia in culture and two species also produced arthroconidia. A comparative study of spore production within nematophagous members of the genus Harposporium was made.