The teleomorph of Phoma medicaginis var. pinodella is reported for the first time. A single isolate, collected from infected plant material in Australia, produced asci and ascospores in culture. The anamorph was identified as Phoma medicaginis var. pinodella on the basis of axenic colony morphology, symptoms on the foliage of a susceptible pea line and characteristic hybridization banding patterns observed during RFLP analysis. The ascospores and asci, although similar in morphology to those produced by Mycosphaerella pinodes, were considerably larger. Therefore, the binomial assignment of the teleomorph remains open to speculation. The potential impact on disease dissemination and effectiveness of control measures against P. medicaginis var. pinodella are discussed.

Although several new techniques for isolating and culturing lichens have been reported in recent years, there is little information available concerning the variability in development of species from different taxonomic groups. A comparison of the early stages of the germination and growth of Xanthoria parietina (Teloschistaceae), Parmelia saxatilis (Parmeliaceae), Physconia distorta and two Diplotomma species (Physciaceae) was performed on two different media: one inorganic, and the other containing 4% glucose (LBM; Lilly-Barnett medium). Different germination and development rates, and isolation success rate (single- and multispore cultures) are reported. The new combination Diplotomma rivasmartinezii (Barreno & A. Crespo) Barreno & A. Crespo is made.

Analysis of 18S rDNA sequence and morphological data indicate that Achlya s. lat. is polyphyletic. Aplanopsis spinosa and Achlya species with subcentric oospores and laterally applied antheridia are transferred to Newbya gen. nov. The relationship of Calyptralegnia and Aplanes androgynus to Newbya is discussed. Molecular data support morphologically based conclusions concerning the relatedness of Pythiopsis and Aplanopsis terrestris. Achlya truncatiformis nom. nov., is provided for material previously identified as Achlya recurva. The following new combinations within Newbya are made: N. pascuicola (type species), N. apiculata, N. braziliensis, N. curvicollis, N. megasperma, N. oblongata, N. oblongata var. gigantica, N. oligacantha, N. polyandra, N. recurva, N. spinosa, and N. stellata combs nov.

The relationship between trichothecene production and pathogenicity was investigated for 29 isolates of Fusarium tumidum, a potential bioherbicide for gorse (Ulex europaeus) and broom (Cytisus scoparius) in New Zealand. All isolates originally derived from broom produced high levels of T-2 tetraol derivatives when grown on ground maize kernels and pearl barley grains, compared with isolates from gorse. Low amounts of scirpentriol derivatives were also produced by both groups of isolates. No nivalenol and deoxynivalenol derivatives were detected in any of the culture extracts. A subset of isolates cultured on gorse and broom tissue produced only small amounts of T-2 tetraol derivatives relative to the amounts produced in grain cultures. Overall, isolates from broom were more aggressive towards both hosts than isolates from gorse, but the pathogenicity of isolates was not correlated with their capacity to produce large amounts of T-2 tetraol derivatives in culture. Two isolates from gorse were highly aggressive towards both weeds. These isolates offer prospects for the development of a safe bioherbicide that could target two major weeds in New Zealand, as trichothecenes were not detected from them at the higher concentrations.

Host specificity of the mycoparasite Hypomyces microspermus to the Xerocomus chrysenteron group has been observed, but primarily from European collections. Our objectives were to test host specificity among Hypomyces spp. associated with boletes in California oak-woodlands, investigate population biology of these parasites, and to initiate studies on host-parasite coevolution. Bolete samples were collected from four locations separated by up to 600 km. Hypomyces isolates were cultured and host tissue samples taken for molecular identification. Based on AFLP analysis, four distinct Hypomyces clades were found with little genotypic diversity within each group. ITS-rDNA regions of selected isolates from each group were sequenced and analyzed along with sequences from a previously published phylogeny. Isolates from two AFLP groups clustered with H. microspermus whereas isolates from the other two AFLP groups clustered with H. chrysospermus. ITS-RFLP followed by sequence analysis identified three bolete hosts: (1) X. dryophilus; (2) a Xerocomus species closely related to X. dryophilus with affinities to X. chrysenteron; and (3) a Xerocomus species related to the X. subtomentosus group, which is not closely related to X. dryophilus and X. chrysenteron. H. microspermus infected X. dryophilus and the species with affinities to X. chrysenteron, whereas H. chrysospermus infected the species with affinities to X. chrysenteron and the species related to the X. subtomentosus group. These results support previous observations that H. microspermus is host-specific to the X. chrysenteron group, and that H. chrysospermus is more of a generalist pathogen. We also conclude that host-parasite coevolution studies within this system will not be possible until a phylogeny of North American boletes is in place.

Aflatoxins (AFs) are secondary metabolites produced mainly by Aspergillus parasiticus and A. flavus. To study AF regulation, previously isolated non-toxigenic A. parasiticus sec− (for secondary metabolism minus) variants were genetically analysed. In parasexual crossing, the sec− strains failed to form heterokaryons and diploids with other sec− strains. Heterokaryon test results suggested that involvement of cytoplasmic elements in the formation of sec− phenotype was unlikely. At the molecular level, the coding sequence of the sec− aflR (the only known positive regulator of AF pathway) was identical to that of their toxigenic sec+ (for secondary metabolism plus) parents. However, the sec− aflR expression was 5- to 10-fold lower compared to that in the sec+ forms. RT–PCR analysis demonstrated that the AF pathway genes were expressed in the sec− forms but in trace amounts and in their unprocessed forms. Combined, these results suggest that aflR is necessary but not sufficient for AF production and that elements involved in fungal development directly or indirectly influence its proper function.

Podosphaera tridactyla (Ascomycota: Erysiphales) is a morphologically variable species occurring on Prunus s. lat. In order to assess the genetic variation within this species, the rDNA ITS region was amplified from 29 specimens from a range of Prunus species collected in Australia, Switzerland, and Korea. RFLP analysis of the PCR products revealed six groups, and a comparison of sequences from representatives of these groups revealed three clades: Clade 1 contained all specimens from Prunus subgen. Prunus; Clade 2 specimens from a variety of Prunus subgenera, except subgen. Prunus, and Podosphaera longiseta was closely allied to this clade; and Clade 3 contained two specimens, from Japan and Korea. Phylogenetic analysis comparing P. tridactyla with of a range of Podosphaera species suggests that P. tridactyla is paraphyletic.

Anaerobic fungi were isolated from both the rumen and faeces of nine sheep and a cow. A reliable and simple method for the isolation of anaerobic fungi using 24 h rumen incubated milled straw as the inoculum source was developed. We also evaluate the use of chitin measurements as an assay of rumen fungal biomass. Chitin levels were determined from various sample sources (milled barley straw used as the fungal culture substrate in vitro; plant particulate digests from the rumen (PLP) and centrifuged strained rumen fluid (CSRF) using both HPLC and colorimetric methods. Both methods were highly correlated and consequently the simpler colorimetric method was adopted for subsequent studies. There was also a high degree of correlation between anaerobic fungal cellulase activities with the assayed chitin content of milled barley straw cultures over 12 d of an in vitro experiment. The colorimetric chitin assay protocol was then used to assess the diurnal variation and abundance of rumen fungi in in vivo assays. We assessed the distribution of chitin (mg g−1 dry matter) in various fractions of the strained rumen fluid (SRF) and PLP samples from the rumen of sheep. Chitin was detected in all fractions of strained rumen fluid but the main source of chitin in the samples may be attributed to the fungal biomass. We did not detect any significant differences in chitin levels over a 24 h sampling period. Finally, an SEM study on subsamples of milled straw and plant particulate matter used in the chitin assays, revealed that the pattern of the fungal development on substrate material differs from the culture medium to the rumen.

Two double-stranded ribonucleic acid (dsRNA) elements were detected in an isolate of the clavicipitaceous grass endophyte Epichloë festucae obtained from an asymptomatic Festuca rubra plant. No dsRNA was detected in three other isolates of E. festucae. The size of the two dsRNA elements isolated from mycelium was of 5·2 and 3·2 kbp. Hybridization experiments with a cDNA probe complementary to the 5·2 kbp dsRNA showed that there was no sequence similarity between the dsRNA elements. Isometric virus-like particles of about 50 nm in diameter were observed by electron microscopy in sucrose-gradient purified virus preparations from the isolate containing dsRNA. The 5·2 kbp dsRNA element was present in the partially purified virus preparations, suggesting that this element is encapsidated. There was no difference with respect to growth rate or colony morphology between the dsRNA containing and dsRNA-free isolates. The presence of dsRNA and virus-like particles suggests the presence of a mycovirus in the Vit5 strain of E. festucae.

Genetic variability among isolates of the ectomycorrhizal fungus genus Pisolithus collected in Brazil, USA and France was examined, based on nucleotide sequence of ITS from rDNA genes and restriction polymorphism of the mitochondrial DNA (mtDNA). Alignment of the ITS sequences showed 97.0% homology among isolates from Brazil, 97.8% homology among isolates from USA and France and 75.7–78.5% among the isolates from Brazil and USA/France. These sequences were aligned with ITS sequences of Australian, Brazilian and Kenyan Pisolithus isolates described in the literature. A consensus tree generated by sequence data of all Pisolithus isolates showed the presence of a number of species among the isolates. The mtDNA analysis was carried out by total DNA restriction analysis with different enzymes (Dra I, EcoR I, EcoR V, Hha I–Xba I, Hind III and Rsa I) and probing with purified mtDNA labelled with fluorescein d-UTP. The size of the mitochondrial genome of isolates Pt 90A, Pt 185R and PF cleaved with EcoR I was estimated to be, approx. 40.5, 47.2 and 47.6 kb, respectively. Cluster analysis based on the mtDNA restriction fragments grouped the isolates into two distinct groups, which coincide with their host specificity and geographical origins. PCR-RFLP analysis of mitochondrial rDNA (mt rDNA) from 12 Pisolithus isolates did not show any polymorphism. These data corroborate previous results obtained in our laboratory with RAPD-PCR and rDNA PCR-RFLP markers and support recent taxonomic studies where a number of Pisolithus species were described.

Nine species of Trametes and five other wood inhabiting basidiomycetes, were collected from the indigenous forests of Zimbabwe and analysed for cellulases, ligninases, extracellular phenolases and wood degrading ability for the first time. Cellulase enzyme activities varied widely among the species. After 15 d growth exo-glucanase activity had increased in the majority of species whilst filter paper activity showed the opposite trend, being greatly reduced in all species on day 15 compared to day 10. Endo-glucanase activity was relatively uniform at both sampling times. The fungi were more active against water soluble cellulose derivatives than filter paper cellulase. In all the fungi tested, cellulose activity on filter paper was significantly less than endo- and exo-glucanase activities. The highest cellulase activity was expressed by Cerrena meyenii (683 U mg−1) Phaeotrametes decipiens, Trametes modesta, and T. pocas also expressed relatively high cellulase activity on all types of cellulose tested. All Trametes species tested positive for extracellular phenol oxidases whilst Fomotopsis spragueii and Irpex stereoides tested negative. All but one of the Trametes species in the study were able to degrade two different lignin preparations in tests for lignin degradation. T. menziesii was unable to degrade both lignin preparations although it had tested positive for production of extracellular oxidase. The species in this study degraded hardwood to a greater extent than softwood. Eight of them caused more than 80% dry weight loss of wood blocks during 70 d incubation. Those fungi that expressed high cellulase activity also caused high weight loss on wood.

Accurate identification of Alternaria spp. is dependent upon the production of diagnostic morphological characters under defined cultural conditions and the proper assessment of character variation. This process is often compromised by variation in laboratory facilities and technical expertise. To assist taxon identification and phylogenetic studies, restriction site information from the intergenic spacer (IGS) region of nuclear rDNA was evaluated. Restriction maps were constructed from 15 species of Alternaria and Stemphylium botryosum (telemorph Pleospora herbarum) for 11 restriction enzymes using a new method for restriction mapping based on differential priming of IGS amplicons. IGS fragment size varied among species from 2.2–3.9 kb. Based upon restriction site homology among closely-related and more distantly related species, the IGS region could be divided into conserved and variable domains. The conserved domain was approximately 0.75 kb in size and was located at the 3′ end of the IGS region. Restriction site homology within this region was very high, especially among closely related taxa. The remainder of the region comprised the variable domain, which encompassed considerable differences in size and restriction sites among taxa. The presence or absence of restriction sites among taxa was analyzed using methods of neighbor-joining. Phylogenetic relationships based on this method were concordant with those previously resolved based upon other methods and other genomic regions.

In an attempt to clarify the relationship between fungi classified as Ophiostoma minus, but of different geographic origins and mating systems, sequencing of the 5.8S and ITS 2 rDNA, and β-tubulin gene was carried out. The β-tubulin gene was highly informative, supporting the sub-division of O. minus into two groups based on geographic origin. Furthermore, isolates previously classified as O. pseudotsugae were confirmed as being clearly distinct from O. minus. However, sequencing did not reveal any polymorphisms between isolates with homothallic as compared to heterothallic mating systems. This was supported by crosses using methylbenzamidazole-2-yl carbamate nuclear markers which showed that hybridisation between isolates of different mating systems was possible. However, we propose that different mating systems may still signal a divergence of isolates of O. minus.

A fossil ascomycete was found attached to the thorax of a stalk eyed fly (Diopsidae: Prosphyracephala succini) in a fragment of Baltic amber. The fungus is assigned to the extant genus Stigmatomyces and described as S. succini sp. nov. This find is the first fossil record of the order Laboulbeniales. At the same time it constitutes the oldest record of a parasitic fungus on an insect. The palaeohabitat is discussed with regard to the find.

Eleven enzymes from 139 specimens of thirteen Italian populations of Tuber magnatum were analysed with multilocus horizontal starch gel electrophoresis. The research was carried out to obtain insight into the genetic variability of this species across its geographic range. All the gene-enzyme systems scored appear to be fixed in homozygosity in accordance with what is hitherto known in the genus Tuber; nine seemed monomorphic, whereas two, that is MDH-1 and ME-2, showed three alleles each. These results indicated a self-reproductive system and the low genetic variability is in agreement with the restricted endemism of the white truffle. The distribution of the electrophoretic types is discussed as a basis for further molecular applications.

The occurrence and relative abundance of Pythium species were quantified by using a cucumber seed baiting assay and P10VP agar medium, and compared among three long-term cropping systems: continuous maize (CC), continuous soybean (SS) and maize soybean rotation (CS) at two Iowa locations. Soil types were different at the two locations. Four Pythium species were isolated, P. ultimum, P. torulosum and P. paroecandrum occurred in soils of all three cropping systems, and P. spinosum occurred in one SS and one CS field. More Pythium isolates were recovered from CS and SS composite soil samples than from CC samples. P. torulosum was isolated most frequently.

The genetic structure of five Fennoscandian populations of the threatened wood-decay fungus Fomitopsis rosea (Basidiomycota) was investigated using codominant PCR–RFLP, allele specific amplification (ASA) markers, inter simple sequence repeat (ISSR) markers and mating studies. Sequence analyses of a subset of single spore isolates revealed sequence variation in four target sequences; internal transcribed spacer (ITS) and intergenic spacer (IGS1) of the nuclear ribosomal DNA, the translation elongation factor 1 alpha (efa) gene and the super oxide dismutase (sod) gene. No sequence variation was found in amplified portions of the mitochondrial large and small rRNA genes. Genotype distributions were mostly (90%) in accordance with Hardy–Weinberg expectations, and the nrDNA markers (ITS/IGS1), efa and sod were in most cases (87%) in linkage equilibrium, indicating an outcrossing reproductive mode, panmictic conditions and large population sizes of the fungus. Mating tests confirmed that F. rosea exhibits an outcrossing bipolar heterothallic mating system. Mating allele richness was high in two investigated populations. Phylogenetic analyses of ITS and IGS1 sequences from the five geographic populations revealed some geographic sub-structuring of the ITS sequences, but no sub-structuring of IGS1. The nrDNA (ITS/IGS1), efa and sod markers gave a low overall FST (0.013). The ISSR markers gave no clustering of the populations in UPGMA, and the between-population variance component was very low in AMOVA (0.4%), indicating a high level of gene flow.

An undescribed species of the heterobasidiomycetous genus Chionosphaera is carried by the bark beetles Dryocoetus autographus, Hylurgops palliatus, Ips acuminatus, Ips sexdentatus, Ips typographus, Orthotomicus laricis, Pityogenes chalcographus, Pityokteines spinidens, and Polygraphus poligraphus infesting conifers in Europe (Abies alba, Larix decidua, Picea abies, and Pinus sylvestris). Chionosphaera cuniculicola sp. nov. differs morphologically from C. apobasidialis in the more slender basidiospores. The segregation of the two species is supported by comparison of partial sequences of the large subunit of the ribosomal gene. Isotype material of Chionosphaera lichenicola was re-examined. In contrast to C. cuniculicola and C. apobasidialis, C. lichenicola exhibits clamps at the septa. Fibulostilbum phylacicola is considered as a clamp-bearing species of Chionosphaera.

Rhizoctonia solani AG-3 causes considerable yield loss in potato fields in eastern Canada and U.S.A. The accurate identification of AG-3 isolates is strategic prior to planting potatoes. To obtain a fast and reliable identification method, RAPD experiments were carried out to obtain specific genetic markers of AG-3 isolates. DNA from various isolates of R. solani was submitted to RAPD amplification using random 10 mers primers. One of the forty primers used yielded a 2·6 kbp fragment present in all isolates of AG-3. The specificity of this fragment was assessed by Southern blot analysis. It was partly sequenced and DNA primers were designed for PCR amplification experiments. A PCR-based restriction mapping method, using one restriction endonuclease, Xho I, was developed for specific detection of AG-3 isolates. Analysis of data showed that AG-3 isolates were distinct to other AGs R. solani. The detection method described here is very specific and reliable; it can be applied on plant tissue and soil infected with R. solani AG-3.