The taxonomy of several neotropical resupinate Perenniporia is discussed. P. xantha is described as new. It is characterized by a bright yellow resupinate basidiocarp, small pores and small ellipsoid, dextrinoid basidiospores in addition to reduced arboriform skeletal hyphae. Two new combinations are proposed, Perenniporia aurantiaca and P. chromatica. Their relation to other Perenniporia species is briefly discussed.

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.

Genetic variation of the haploid canker pathogen fungus Gremmeniella abietina was investigated by RAPD marker analysis. A total of 126 single pycnidia isolates of G. abietina were sampled from one Pinus contorta plantation in northern Sweden. Average Nei's gene diversity over 32 putative RAPD loci was 0·29. Multilocus genotype analysis revealed 85 different genotypes among the 126 isolates sampled, of which 66 genotypes were detected only once. Nineteen genotypes were detected more than once among 41 isolates, representing 32·5% of clonal fraction of the sampled population. Gametic disequilibrium tests of the sampled population revealed significant associations between 29·6% (147 of 496) of the RAPD loci. When the clonal fraction was removed from the data set, the number of significant pairwise loci combinations decreased from 147 to 73 (14·7%), indicating a high degree of random mating. These results are consistent with previous field observations suggesting that sexual fruiting bodies of G. abietina were common in northern Scandinavia. The high genetic variability detected in the population also suggests that the population was founded by a relatively large number of unrelated genotypes.

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.

Four ericoid mycobionts (two isolates of Hymenoscyphus ericae, and two dark, sterile ericoid mycobionts isolated from metal-contaminated mine sites) were grown on solid agar plates supplemented with zinc phosphate (0.25%) containing different forms of nitrogen (nitrate, ammonium or alanine) and different concentrations of carbon (glucose) and phosphorus (K2HPO4). The influence of nutrient variation on solubilizing ability of the fungi was assessed by measuring the zones of solubilization appearing beneath the growing colonies. All four mycobionts were capable of zinc phosphate solubilization in the presence of all three nitrogen sources and in media containing no nitrogen. No solubilization was observed at 0 mM glucose-C but was observed with increasing glucose concentration from 300 to 600 mM C. Increasing phosphorus concentration (0–5 mM P) had no effect on the solubilizing ability of the isolates. All but one of the mycobionts were capable of solubilizing calcium phosphate (CaHPO4), while no solubilization was observed in media containing aluminium phosphate (AlPO4), iron phosphate (FePO4.4H2O) or copper phosphate (Cu3O8P2.2H2O) under conditions which were found to be optimal for zinc phosphate solubilization. Under conditions of glucose at 300 mM C and alanine as the N source in the zinc phosphate-amended agar medium, one of the mycobionts produced new crystals, which were morphologically distinct from the original zinc phosphate crystals. It is concluded that medium composition influences the metal-phosphate solubilizing ability of ericoid mycobionts. The results are discussed in relation to the possible mechanisms involved in solubilization and the potential benefits of metal-phosphate solubilization to ericoid mycobionts and their host plants.

Co-inoculation of healthy standing rice plants with compatible isolates of Magnaporthe grisea pathogenic to rice resulted in the production of perithecia on the detached portions of leaf sheaths. The isolates had been obtained from the same lesion on a diseased plant collected in Yunnan Province, China. Perithecia were also produced on dead tissue of leaf sheaths and nodes of standing rice plants in a moist chamber. These results strongly suggest that the teleomorph of M. grisea can occur in the upland rice fields in Yunnan.

Cordyceps unilateralis, a fastidious insect pathogenic fungus, was found to produce red naphthoqinones, which possess anti-malarial activity. A method for the isolation and in vitro cultivation of this fungus was, therefore, developed in this study. Ascospores from ant cadavers were used as starting materials, and their secondary spores were allowed to germinate first on PDA for 2 d. Secondary spores were then transferred to Grace's Insect Cell Medium+2 mM glutamine and 10% fetal bovine serum, incubated for 7 d, after which the formation of mycelia was stimulated by transfer to potato dextrose broth. As a result, the growth of C. unilateralis from the steps of secondary spore germination, blastospore formation and mycelial growth was successfully completed for the first time.

Pathways of genetic transfer outside of the normal sexual cycle were examined in Phytophthora infestans. Transformants expressing genes for resistance to G418 or hygromycin were employed to select hybrids or recombinants on double-drug media after in vitro or in planta mixing of zoospores or mycelia. In experiments using pairs of isolates of the same mating type, zoospores fused to form doubly resistant colonies. These were shown to be heterokaryons containing non-recombinant parental nuclei based on the analysis of DNA markers in the hybrids and their single-nuclear derivatives. Mixtures of vegetative hyphae failed to produce hybrids. The application of the drug selection scheme to mating cultures of A1 and A2 strains generally yielded normal progeny, but atypical progeny were also recovered which appeared to be polyploids since all markers from the parents were present.

Coniothyrium minitans was successfully co-transformed with the uidA (β-glucuronidase) and the hygromycin-resistance (hph) genes. Both were under the control of the glyceraldehyde-3-phosphate promoter from Aspergillus nidulans. Hygromycin resistance was used as a selectable marker for transformation. In successive transformation experiments, transformation frequencies of up to 1000 transformants μg−1 of plasmid DNA were obtained for isolate A69. Of the ten monospore hygromycin-resistant cultures tested, nine also expressed the uidA gene. Expression of hph and uidA was stable in all transformants after several months of successive subculturing on non-selective medium, and after passage through a sclerotium of Sclerotinia sclerotiorum. Southern hybridization analyses showed all transformants carried multiple copies of each marker gene. When grown on PDA, the culture morphology of three of the transformants of (T×2, T×3 and T×4) was similar to the wild type. Four of the five transformants (T×3, T×4, T×21 and T×24) grew as well as the wild type on different media, and responded to changes in water potential in a similar manner to the wild type. All five transformants were equally parasitic on sclerotia of S. sclerotiorum compared with the wild type. Transformants T×3 and T×4 were the most similar to the wild type in biological characteristics and will be used in future studies. The results indicate that hph- and uidA-transformed strains of C. minitans will be useful for ecological studies on its survival and dissemination.

The influence exerted by the non-pathogenic binucleate Rhizoctonia (np-BNR) isolate 232-CG in stimulating plant defence reactions in young bean plants inoculated with the root rot fungus Rhizoctonia solani (AG-4) was examined using light and electron microscopy and further investigated by gold cytochemistry. Severe necrotic lesions on hypocotyles of diseased beans were observed, and the pathogen invaded the cortical tissue causing extensive damage including cell disorganization and cell wall degradation. In contrast, these host reactions were not seen in bean plants inoculated with the non-pathogenic BNR or in plants that were inoculated with BNR and subsequently challenge-inoculated with R. solani. Microscopic examination of hypocotyls inoculated with the non-pathogenic BNR, showed a different host reaction typical of plant defence reactions. In these samples, epidermal and outer cortical cells were impregnated with an electron-dense material. Histochemical assays of this material confirmed the substantial presence of phenols, pectic substances and suberin. Electron microscope observations clearly showed that in non-pathogenic BNR-inoculated plants, fungal cells were confined to the epidermal layer which was darkly stained. Gold cytochemistry confirmed the presence of pectic substances in the electron dense material. The possibility that pectic oligogalacturonides released after hydrolysis by the non- pathogenic BNR enzymes may act as elicitors of defence responses is discussed. The present ultrastructural observations corroborate that non-pathogenic BNR isolates may function as potential inducers of plant disease resistance.

The infection process of Alternaria cirsinoxia was studied on Canada thistle (Cirsium arvense) in the controlled environment and in the field. In the controlled environment, germination of conidia began at 2 h and appressoria formation at 4 h after inoculation. Approximately 75% of appressoria formed at the anticlinal wall junctions of the epidermis. Leaf penetration occurred between 6 and 24 h, most commonly in between adjoining anticlinal walls. Penetration through stomata was rare. After penetration, large, intracellular infection hyphae formed and branched within epidermal cells, ramifying throughout the leaf tissues inter- and intracellularly by 24 h. In field conditions, infection coincided with prolonged rainfall and conidia remained viable on the leaf surface for 8–9 days (d) before causing infection on leaves. A host response occurred after penetration, involving deposition of lignin and callose in the infected epidermal and mesophyll cell walls. High levels of silicon were detected in epidermal cells directly below appressoria, often appearing to form entirely silicified infected cells which were resistant to collapse after air-drying. This study shows that A. cirsinoxia has the potential for rapid invasion of the leaf tissues of Canada thistle under good moisture conditions. The implications of the host responses, in terms of defence against infection, are discussed.

In experiments where groundnut plants with sporulating late leaf spot lesions were exposed to increasing ‘gusty’ and ‘steady’ wind speeds, conidia were more effectively removed by gusty winds than by steady winds of the same mean wind speed. Rain drops dislodged conidia more efficiently than wind, with large drops dispersing conidia more effectively than small ones. No conidia were caught in still air. After most of the conidia had been removed by exposure to high wind speeds, rain was found to remove additional conidia. When plants were exposed to continuous wind or rain, most of the conidia were dispersed during the first few minutes, and the concentration of conidia then declined exponentially with time. From field observations on rain-free days, airborne concentrations of conidia tended to increase as the wind speed increased during the day and with a further increase in wind speed, concentrations decreased. On rainy days, the onset of the first shower coincided with a phenomenal increase in the airborne concentrations of conidia.

Anastomoses between hyphae, leading to both successful cell fusions and death of fused cells (vegetative incompatibility) were observed by video microscopy. Anastomosis was seen only to occur between tip cells from side branches, never main runner hyphae, and tip to side fusion was never observed. Perfect hyphal fusion was only observed following pre-contact tropism between the hyphae involved. The time taken for the process of cell wall dissolution and reformation following contact was 15 min.

Ericoid endomycorrhizal fungi (two isolates of Hymenoscyphus ericae obtained from unpolluted heathlands and two H. ericae-type endophytes isolated from Calluna vulgaris growing on Cu-contaminated mine spoil) were grown for 14 d on 10% Rorison's solution containing sodium phytate as the sole P source and either trace (0.16 μM) or elevated (0.25 mM) concentrations of Cu. The elevated levels of Cu in the medium had no effect on the growth of the two H. ericae-type endophytes from mine spoil sites but caused a significant reduction in growth of the two H. ericae isolates from unpolluted sites. Wall, cytoplasmic and extracellular fractions were assayed for phosphomonoesterase (PMEase) and phosphodiesterase (PDEase) activity. Km and Vmax values varied between the different endophytes and both were highest in the wall fractions. Wall-bound phosphatase activity, excluding PDEase of one H. ericae-type endophyte, was generally unaffected after the isolates had been grown on medium containing 0.25 mM Cu. Extracellular PDEase of the two H. ericae-type endophytes from mine spoil sites was stimulated by 0.25 mM Cu in the growth medium. Cu concentrations up to 5.0 mM in the assay medium did not inhibit wall-bound phosphatase activity whereas three of the isolates showed a stimulation of extracellular activity with increasing Cu. The results are discussed in relation to phosphatase activity of ericoid endophytes on Cu-contaminated substrates.

Duddingtonia flagrans was grown in shake flask culture on Sabouraud's dextrose medium with and without the addition of agar (to form a slightly more viscous medium). The addition of agar increased the number of chlamydospores produced in late stationary phase, with 8.6×105 chlamydospores ml−1 being obtained on a medium containing 5 g agar l−1. The pH optimum for growth was between 5.5–7.5 but colonies formed on plate cultures buffered at pH 10.5. When grown in shake flask culture at 25 °C and pH 7 on malt extract–yeast extract–peptone–glucose medium (MYPG), D. flagrans had a specific growth rate of 0.21 h−1 (doubling time 3.3 h) and produced 5.1±0.07 mg biomass ml−1. To increase chlamydospore production in a liquid medium, D. flagrans was also grown in a two phase culture system in which late exponential phase biomass produced in MYPG medium was transferred to Vogel's mineral salts medium containing various nitrogen (mycological peptone, casein) and carbon (sodium acetate, starch and glycerol) sources. The highest chlamydospore concentrations (6.2×105 and 5.6×105 ml−1) were observed when the biomass was transferred to Vogel's medium containing 10 g starch or glycerol l−1, respectively.

Comparisons of the qualitative volatile production patterns between seven species of Agaricus, and between two of Volvariella and Pleurotus and one Coprinus species when grown at 25 °C on agar media for 14 d were made. There was good reproducibility between the volatile production patterns of the same species using an electronic nose unit with a 14 conducting sensor polymer array. Principle Component Analysis (PCA) showed that it was possible to discriminate between five of the seven Agaricus species, but that some overlap occurred between the others. Cluster analysis showed that there was also overlap between some species with the tropical collection of A. bitorquis separating out from the others. The volatile production profile of the commercial A. bisporus was close to that of a wild species, A. campestris. A. bisporus could be readily differentiated from other non-Agaricus species. This study demonstrates the potential for using electronic nose systems to rapidly differentiate mycelial cultures of homobasidiomycete mushrooms.

The discoloration of A. bisporus after infection by Pseudomonas tolaasii, P. gingeri, P. agarici, P. reactans, Verticillium fungicola and Trichoderma harzianum can be distinguished by chromametric measurements. Infection with P. tolaasii caused a specific colour change, independent of the bacterial concentration applied (ΔL = 54.7, Δa = 16.6, Δb = 28.7%). The colour change provoked by P. gingeri had a characteristic profile different from P. tolaasii (ΔL = 36.3, Δa = 14.1, Δb = 49.5%). P. agarici and P. reactans provoked only a slight increase of red colour. Response to T. harzianum was orange, and to V. fungicola brown, similar to P. tolaasii but paler and more yellowish. All pathogens except P. reactans provoked degradation of total tyrosinase to variable extents. Activation of tyrosinase was only observed after infection with P. tolaasii (to almost 7%) and V. fungicola (to 3%).

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 antifungal activity of oxine and copper oxinate was investigated using standardized methods to compare efficacy, discriminate activity patterns, elucidate mechanisms of action and establish attributes of relevance to field use. Both agents were shown to be active against a broad range of physiologically diverse fungi. Species of Aspergillus, Penicillium, Fusarium, Rhizopus, Candida, Rhodotorula and Saccharomyces were significantly more resistant than Pythium, Phytophthora, Sclerotina and Trametes, the difference being greater for oxine than for copper oxinate and in Sabouraud than in Czapek–Dox media. Copper oxinate was generally more active and more broadly and rapidly fungicidal than oxine. Both are fungicidal at low concentrations against significant plant pathogens and relatively active against important spoilage and mycotoxin producing moulds. The MIC (minimum inhibitory concentration) and MFC (minimum fungicidal concentration) for both agents were dependent on method and medium. Neither agent produced changes in morphology, asexual reproduction or differentiation. Oxine and copper oxinate were resistant to inactivation by organic materials, interacted synergistically in vitro and did not elicit resistance on long term exposure. Differences in activity pattern suggest independent modes of action. Oxine is worthy of revisitation as a useful agricultural fungicide and preservative.

Protoplasts were produced by treating the yeast-like cells of O. piceae and O. quercus with high concentrations of Novozym 234 (20 mg ml−1). Transformants with resistance to hygromycin B were obtained by transforming the protoplasts with the plasmids pAN7-1 and pCB1004 containing the hygromycin B phosphotransferase (hph) gene. For all isolates tested, transformation efficiencies ranged between 103 and 105 transformants μg−1 vector DNA. High polyethylene glycol concentration (66 %) increased the transformation efficiency. Integration of the hph gene into the transformant genome was verified by a polymerase chain reaction and dot DNA hybridization analysis. There was no evidence of mitotic instability of hygromycin B resistance in the transformants.