The genetic relatedness of twenty isolates of Paecilomyces farinosus was determined by comparison of the products of polymerase chain reaction amplification of anonymous regions of genomic DNA with single arbitrary sequence oligonucleotide primers (RAPD analysis). Isolates were collected from seven insect species in eastern Canada and they differed greatly in cultural and morphological phenotype. All P. farinosus isolates were clearly distinguished from three other entomopathogenic fungi, including P. fumosoroseus. RAPD banding patterns did not, however, correlate with ecological backgrounds or morphological phenotypes of P. farinosus isolates. These observations support the conclusion that P. farinosus from eastern Canada is not composed of strains which can be separated on the basis of the ecological or morphological criteria selected.

Terminalia ivorensis, a tree of central African origin, is planted in several tropical countries for timber and veneer production. During the course of a recent disease survey, an unknown fungus was found associated with basal cankers on dying T. ivorensis in Ecuador. The fungus has orange fruiting structures and septate, fusoid ascospores, similar to those of Cryphonectria, a well-known genus of canker pathogens. The aim of this study was to identify the fungus and to assess its pathogenicity. Identification was based on morphological characteristics as well as DNA sequence data. DNA sequence data from the ITS regions of the rDNA operon and two regions of the β-tubulin gene, were compared with published sequences of Cryphonectria species and the closely related genera Endothia and Chrysoporthe. Pathogenicity tests were conducted on T. superba saplings. Morphological characterisations revealed that the conidiomata of the fungus from T. ivorensis, differed from those typical of Cryphonectria in being superficial and rostrate. Only Cryphonectria longirostris was similar to the fungus from T. ivorensis, but could be distinguished from it based on conidial size. Phylogenetic analyses showed that the fungus from T. ivorensis grouped closely with species of Cryphonectria, Chrysoporthe and Endothia, yet formed a distinct clade. Pathogenicity tests on T. superba provided evidence that the fungus is able to cause distinct stem cankers. We conclude that the pathogenic fungus from T. ivorensis represents a new genus and new species in the Diaporthales and we provide the name Rostraureum tropicale for it. The genus is typified by R. tropicale. Furthermore, C. longirostris is transferred to Rostraureum.

The broad spectrum fungicide mancozeb was applied to monocultured sugarcane soils affected by the growth constraint known as sugarcane yield decline. The constraint is associated with the long-termmonoculture of sugarcane and has been shown to decrease sugarcane growth by 20% in commercial crops in Queensland. The fungicide was shown to decrease root colonization by soil fungi, particularly dematiaceous sterile fungi. Higher doses of mancozeb (up to 400 mg kg−1) sometimes led to increased populations of Penicillium spp. The fungicide greatly improved plant growth and root health when applied at doses of 100 mg kg−1 and above. Results suggest that the role of dematiaceous sterile fungi in sugarcane yield decline should be further examined.

Dichomitus is re-examined in Africa and six species are accepted. Dichomitus citricremeus and D. kirkii are described as new species. Megasporoporia is reduced to synonymy with Dichomitus, and the new combinations D. carvernulosus, D. delicatulus and D. setulosus, are proposed. An emended description of Dichomitus is provided, to accommodate species with hyphae with a dextrinoid reaction. A key to all accepted species in Dichomitus is given.

Spontaneously-occurring hypovirulence in the tan sclerotial isolate S10 of Sclerotinia sclerotiorum from sunflower in Canada was characterized and compared to another hypovirulent isolate Ep-1PN of S. sclerotiorum from eggplant in China. Hypovirulent isolates derived from S10 were purified by single hyphal tip isolations from colonies of S10 showing abnormal growth on potato dextrose agar (PDA) and tested for pathogenicity on leaves of canola (Brassica napus cv. ‘Westar’). These abnormal isolates differed from the virulent isolate wtS10 derived from a normal colony of S10 by the reduced hyphal growth, induced production of abnormal hyphal branches, enhanced production of brown pigments, reduced sclerotial formation on PDA, reduced oxalic acid accumulation in potato dextrose broth, and reduced pathogenicity on canola. Vegetative transfers revealed that the hypovirulence phenotype of the hypovirulent isolate S10-2A-11 was stable. This preliminary in vitro transmission test indicated that the hypovirulence in the isolate S10-2A-11 was transmissible but at a lower rate than that of the hypovirulent isolate Ep-1PN. Double-stranded ribonucleic acids (dsRNAs) were detected in isolate Ep-1PN, but not in hypovirulent and virulent isolates derived from S10. The existence of dsRNA-free hypovirulence in S10 progenies suggests that another hypovirulence mechanism may exist in S. sclerotiorum.

Three species of fungi endoparasitic in nematodes were obtained in pure culture for the first time. The fungi belong to Harposporium and Verticillium. Morphology of the fungi on corn meal agar was studied and infectivity proving Koch's postulates was achieved for each species. The infection method for Harposporium cycloides was shown to be by spore ingestion. Whilst all species were found to produce infection conidia in pure culture, both species of Harposporium produced accessory conidia and, in H. lilliputanum, arthroconidia were also formed.

Genetic variation within a collection of 25 isolates of Monascus from red rice and sofu was assessed with RAPD markers using genetic distances (1-Jaccard's coefficient) calculated for all combinations of isolates. Cluster analysis based on genetic distance was performed using the Ward's minimum variance method. Five distinct clusters were revealed based on genetic distances between and among clusters. The robustness (reproducibility) of the cluster assignments was tested by resampling (bootstrap) analysis. Cluster distribution was visualized as a three-dimensional graph based on multiple correspondence analysis. A dendrogram, based on the clusters, was constructed to examine the relationships. Three clusters accounted for 21 isolates; the fourth cluster consisted of three isolates which were quite distinct from each other and all other isolates. The fifth cluster, a single isolate from Japan, was very different from all others in RAPD patterns and was used as an outgroup. Resampling analysis indicated that the 25 isolates represented four genetic lineages of red rice fungi, suggesting that a relatively narrow genetic source of Monascus isolates is used in food products in Asia.

A taxonomic review and revision of the dematiaceous hyphomycete genus Acrogenospora is presented. Species in this genus produce acrogenous, solitary, nonseptate conidia from mononematous, simple conidiophores, with multiple percurrent proliferations. Acrogenospora altissima comb. nov. and A. megalospora comb. nov. are proposed for the anamorphic states of two Farlowiella species. A. ovalia and A. subprolata spp. nov. are described from submerged wood in Hong Kong. They differ from other Acrogenospora species in shape, colour, and size of their conidia. A taxonomic key to species in the genus is provided.

The phylogeny of the Dermatocarpon miniatum-complex (Verrucariales, lichenized Ascomycota) was studied using nuclear ITS sequence data by both parsimony and Bayesian inference of phylogeny. The ITS region contains a substantial amount of variation which resolves the relationships of terminal groups, while the more basal clades have low support in the analyses. D. miniatum var. miniatum and var. complicatum are polyphyletic, while var. cirsodes is monophyletic but located within the complex, as are both D. leptophyllum and D. linkolae. The variation within the D. miniatum-complex is significantly greater than that between some transatlantic species such as D. luridum and D. meiophyllizum. The new names D. taminium sp. nov. from the Greater Sonoran area, and D. tenue comb. nov. (syn. D. muehlenbergii var. tenue) are introduced.

The taxonomy of the marine species of Collemopsidium in northwest Europe was investigated using morphological and molecular evidence. 210 specimens were collected from the west coasts of Norway and Ireland, and morphological and ecological variables recorded. ITS1 rDNA sequences were obtained from 24 specimens. A phylogenetic analysis, resulting in a single optimal tree, was performed under the unweighted least squares optimality criterion based on maximum likelihood distances obtained from unaligned sequences. Principal components analysis (PCA) was performed on morphological variables of the sequenced specimens, and classification was carried out by maximizing agreement between the phylogenetic tree and the PCA. Thallus immersion, and perithecial immersion and size, were the most important characters for discriminating between taxa. Apart from substratum, niche separation between taxa was small but statistically significant as shown by a redundancy analysis (RDA). Variance partitioning indicated that genetic variation is vastly more important than ecology for explaining phenotypic variation. Five species of marine Collemopsidium are recognized, including two new combinations: C. foveolatum (syn. Arthopyrenia foveolata) and C. ostrearum (syn. Lecanactis ostrearum) combs. nov.

The ear rot severity of 15 maize hybrids and the accumulation of fumonisin B1 (FB1), fumonisin B2 (FB2), beauvericin (BEA) and fusaproliferin (FP) after artificial inoculation in the field with a toxigenic strain of Fusarium proliferatum has been investigated in Poland during the seasons 1996, 1997 and 1999. The year of inoculation proved a significant influence on ear infection degree and mycotoxin accumulation. Inoculated ears contained 11–71% Fusarium-damaged kernels. Mycotoxins were detected in all hybrids at levels of 18–231.9 μg g−1 for FB1, 0.4–26.5 μg g−1 for FB2, 0.2–19.6 μg g−1 for BEA and 0.3–6.4 μg g−1 for FP. Mycotoxin concentrations were higher in Fusarium-damaged kernels (up to 361.5, 41.1, 44.3 and 10.0 μg g−1 for FB1, FB2, BEA and FP, respectively) than in healthy-looking kernels (up to 26.0, 2.3, 1.9, 0.3 μg g−1 for FB1, FB2, BEA and FP, respectively). All hybrids showed high susceptibility to the fungal infection and high toxin content in kernels during the three years of investigation.

Conidial germination in Neurospora crassa was inhibited by the anticalmodulin (CaM) agents calmidazolium (CaMZ) and trifluoperazine (TFP), indicating the importance of CaM-dependent events during vegetative growth. An increase in intracellular CaM concentration, observed during conidial germination, was associated with enhanced incorporation of [3H]phenylalanine into CaM and increased CaM-dependent protein kinase activity. Phosphorylation of two proteins (71 and 25 kDa) during conidial germination, and of four proteins (71, 47, 38 and 32 kDa) during hyphal elongation was noted to be CaM-dependent since these phosphorylations were inhibited in vitro by CaMZ. The possible regulatory functions of CaM during conidial germination are discussed in relation to phosphorylation of specific proteins during vegetative growth in N. crassa.

Colletotrichum acutatum is the major causative agent of secondary leaf fall disease of rubber. All isolates of the fungus examined secreted polygalacturonase (PG), pectin lyase (PL) and the cellulolytic enzymes, β-glucosidase, and cellobiase in culture. Molecular weight determinations suggest that PG as well as the PL produced by all isolates are similar. PG activity was absent in infected rubber leaves. However, PL activity was detected in infected tissues associated with the enlargement of lesions. β-glucosidase was present in both healthy and infected leaves while cellobiase was detected only in infected leaf tissue.

Compared with other Armillaria species, natural melanized rhizomorphs of A. tabescens are rarely observed. Growing in autoclaved Vitis stem segments, A. tabescens isolates from the Ozark Mountains in the central USA formed fully melanized rhizomorphs, thinner and shorter than those observed for other Armillaria species under field conditions, and only under conditions of both high oxygen availability, [ges ]2 μg cm−2 min−1 and moisture near saturation. Conducive conditions were used to compare the rhizomorph generation capacities of A. tabescens, A. gallica, and A. mellea, which have overlapping host and geographic ranges in central North America. While the rhizomorphs of A. tabescens were significantly shorter than those of the other two species, A. gallica and A. tabescens produced similar numbers of rhizomorph initials. Finally, we demonstrated the ability of melanized A. tabescens rhizomorphs to span woody food bases and thereby establish viable infections by penetration of intact bark of Vitis stem segments. We hypothesize that A. tabescens rhizomorphs form under conditions of periodic saturation which promote rapid water movement through naturally occurring lacunae in the soil. Thus, the role of A. tabescens rhizomorphs in the spread of the fungus should be re-evaluated.

Species belonging to Hypoxylon and related genera are bark pathogens and wood decay agents of angiosperms, sometimes able to live asymptomatically in host tissues. In the present work the ITS regions of the ribosomal DNA from 21 isolates belonging to five species were sequenced and then compared with each other. A phylogenetic parsimony analysis among isolates was carried out. ITS2 appears to be the most informative among the sequenced portions of rDNA. Results are strictly consistent with the latest taxonomic arrangements obtained with classical morphological approaches. The ITS sequence analysis is an efficient and accurate method for discriminating among taxa of Hypoxylon and related genera.

The external morphological changes occurring during initiation and early stages of fruit body development of a Morchella sp., before the development of asci, were examined by scanning electron microscopy. Four stages of primordial development were distinguished. First, disk-shaped knots of 0.5–1.5 mm were observed on the surface of the substrate. Next, the knot inflated and a primordial stem emerged from its centre. Afterward, the stem lengthened, oriented upward, and two types of hyphal elements developed: long, straight and smooth basal hairy hyphae and short stem hyphae, some of which were inflated and projected out of a cohesive layer of tightly packed hyphal elements. Finally, when the stem was 2–3 mm long, pre-apothecia emerged in the apical end, with ridges and pits having distinguished types of paraphyses. Extracelluar mucilage covered the ridge layer and helped give the tissue its shape and rigidity.

The forest pathogen Dothistroma pini, which produces the polyketide toxin, dothistromin, was transformed with the pAN7-1 plasmid containing the Escherichia coli hygromycin B phosphotransferase gene (hph). The frequency of hygromycin resistant transformants was 9–48 μg−1 DNA. Southern blot analysis indicated that a single copy of the vector DNA had integrated into the genome in at least six of the eight transformants tested and that the site of integration was different in each case. All transformants analysed were mitotically stable through several subcultures without selective pressure.

Secretion of a constitutive endopectinase was detected in cultures of Venturia inaequalis grown in complex and defined media. Pectinylase or pectinesterase activity was not present. The attainable level of extracellular pectinase was present after 5–10 d post inoculation, when only about 5–10% of mycelial mass had developed. Time course culture experiments with conidial and mycelial inoculum indicated that enzyme secretion did not depend on physiological effects within or shortly after conidial germination. Cellulosic substrates did not affect pectinase production. Catabolite repression or repression by glucose was not detected and there was no stimulation of enzyme production in media supplemented with pectic substrates. Inhibition of enzyme activity by galacturonic acid was not detected. Nineteen isolates of V. inaequalis were tested, all of which displayed constitutive pectinase production. All isolates were able to grow in the defined media with galacturonic acid or the pectic substrates as the sole carbon source. Mycelial pectinolytic activity was only detectable in substantial quantities when the fungus was grown in media supplemented with 1% pectin. The pectinase preparations displayed a long-term stability at temperatures up to 20°C and within a pH-range of 5–7·5. Activity was very low at 5 and 10° and there was a distinct increase at 15 and 20°. Enzyme activity was highest at pH 4 and decreased with increasing pH. Time course viscometric assays and hplc analyses of liberated galacturonic acid indicated an endo-type degradation of pectin and polygalacturonic acid. Di- and trigalacturonic acid were released from pectin with high enzyme concentration and long incubation. Pectin with a degree of esterification of 93% showed reduced degradability. Pectinase preparations had a macerating activity on solvent extracted apple leaves and caused galacturonic acid release. Isoelectric focusing followed by a zymogram technique revealed a single activity band at pI 10. The pectinase preparations from culture filtrates or mycelia of 19 isolates did not show any differences in characteristics of degradative activity or the activity band detected after isoelectric focusing.

Development of specific DNA probes targeting rDNA internal transcribed spacer (ITS-1 or -2) sequences is described for the detection of strains representing uninucleate and binucleate Rhizoctonia spp. and Suillus bovinus. Discriminatory taxon/species-specific target sequences were identified following full length ITS sequence alignment of the test fungal sequences and those of other root associated pathogenic or mycorrhizal fungi. Both long (124–151 bp) and shorter (20–25 bp) probes were generated for assessment in Southern dot blot and liquid hybridization ITS capture-fragment length polymorphism assays. Fungal genomic DNA was presented as the target in dot blot protocols using the longer DIG (digoxigenin) labelled probes whilst the shorter 3′ biotin-labelled oligonucleotide probes were hybridized to PCR amplified full length ITS (ITS1-5.8S-ITS2) in both dot blot and liquid hybridization assays. The optimal hybridization temperatures for dot blot detection also produced maximal target specific signals in the liquid hybridization protocol. The latter protocol was found to be more discriminatory as target fungi were detected on the basis of combined probe hybridization-ITS capture and 5′ Cy-5 labelled ITS length polymorphism analysis (±5 bp) following denaturing sequencing gel electrophoresis in a ALFexpress DNA sequencer.

The utilization profile of 49 carbohydrates, based on API 50 CH biochemical tests, was used for the identification and the discrimination of 75 isolates of Beauveria and Tolypocladium. The data were used to construct a most parsimonious tree in which Beauveria and Tolypocladium were separated into two main branches. Although the Beauveria isolates could not be separated at the species level, eight different clusters corresponding to the eight Tolypocladium species studied were revealed. The reproducible carbohydrate utilization profiles of B. bassiana, B. brongniartii, T. cylindrosporum, T. niveum, T. geodes and T. tundrense have permitted the construction of an identification key that could serve as a tool to complement the morphological description of selected Beauveria and Tolypocladium isolates for their correct identification at the species level. The API 50 CH method is time-saving and can complement effectively more classical techniques for the discrimination between Beauveria and Tolypocladium and for the taxonomy of Tolypocladium at the species level.