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.

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.

The phylogenetic relationship of 52 specimens representing 30 species of Anthracoidea (Ustilaginales) was investigated by molecular analyses using sequence data from the large subunit (LSU) of nuclear rDNA. Phylogenetic trees were inferred with neighbour-joining (NJ), maximum parsimony (MP), and Bayesian Markov chain Monte Carlo (MCMC) methods. The results are discussed with respect to the species concept and the subdivision of the genus into subgenera and sections. Collections from different hosts and localities were compared. Our analyses can neither support nor significantly reject the hypothesis of the bipartition of the genus Anthracoidea. Thus, the representatives of the subgenus Proceres appeared in the NJ analysis as a moderately supported monophylum, whereas MCMC analysis revealed a polyphyletic topology for this group. Paraphyly of the subgenus Anthracoidea was supported by all methods used. Sections Echinosporae and Leiosporae were each represented by two species in our analyses which grouped together with high support. Section Anthracoidea should be restricted to a highly supported group with extremely irregular to angular teliospore shape. However, these three sections do not cover the whole diversity of the subgenus Anthracoidea. Molecular data largely supported the traditional circumscription of species, and species delimitations are discussed.

Four new taxa are described, each having multiseptate ascospores with hyaline end cells; Savoryella limnetica, Ascotaiwania wulai, A. hsilio and A. sawada. Savoryella and Ascotaiwania are evaluated and separated by the following characters: Savoryella has broad, up to 8 μm paraphyses (sparse) that are septate and rounded at their ends, and smaller asci with an apical thickening containing a plugged pore and 3-septate ascospores; Ascotaiwania has narrow, filiform, septate paraphyses up to 2 μm wide, but these deliquesce early and are rarely observed in mature ascomata. Ascotaiwania also has asci with a well-developed apical ring and plugged pore and ascospores generally with more than 3 septa. Ultrastructural studies of A. lignicola showed that the ascopores are covered by a thin mucilaginous sheath and unitunicate asci with the wall comprising an outer, 30–40 nm electron-dense layer and an inner, 420–450 nm, thick, electron-transparent layer. Asci have a well-developed apical apparatus consisting of an electron-dense apical ring with a plug. The plug deliquesces prior to ascospore release. The ascospore wall comprises an electron-dense episporium and a less electron-dense mesosporium. External to the episporium is a fibro-granular sheath.

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 genetic variation of Duddingtonia flagrans, which has become a promising biocontrol agent of animal parasitic nematodes, was investigated in a worldwide collection of 22 isolates. We analysed the sequence variation in four nuclear genes, tubA (β-tubulin), CMD1 (calmodulin), EF1α (translation elongation factor 1α), and PII (extracellular serine protease). 1428 aligned base pairs (bp) were analysed from the four genes, including 709 bp of introns. In addition, the variations in three anonymous genomic regions comprising 1155 bp were examined. Three single nucleotide polymorphisms (SNPs) were detected in the seven loci, none of them in the protein encoding genes. The genetic variation was significantly higher in the nematode-trapping fungus Arthrobotrys oligospora, the closest evolutionary relative to D. flagrans. Analysis of 12 isolates of A. oligospora revealed 30 SNPs in tubA, CMD1, EF1α and PII. The genetic variation in the isolates of D. flagrans was further examined using AFLP analysis. Five primer combinations were used to detect 159 bands, of which 94 (59.1%) were polymorphic. A neighbour-joining tree based on the AFLP data showed no clear association between genotype and geographical origin. Furthermore, the AFLP data suggest that D. flagrans is mainly clonal and no recombination could be detected, not even within the same country. The low genetic variation in D. flagrans suggests that this fungus has recently diverged from a single progenitor. Based on estimations of mutation rates, it was calculated that this most recent common ancestor lived about 16000–23000 years ago.

Selected isolates of Phytophthora infestans from around England and Wales were fingerprinted using both RG57, a multi-locus RFLP probe, and Amplified Fragment Length Polymorphisms (AFLPs). The larger number of polymorphisms detectable with the AFLP method allowed resolution of several similar AFLP genotypes among isolates with identical RG57 fingerprints. However, some isolates with the same RG57 genotype had remarkably dissimilar AFLP genotypes, suggesting that there has been convergent evolution of some RG57 fingerprints. Also, some isolates with dissimilar RG57 fingerprints had similar or identical AFLP fingerprints. Both techniques distinguished isolates of mitochondrial DNA haplotype Ia from those of haplotype IIa. However, with AFLPs only, most of the isolates of A2 mating type were very similar and were distinguished from those of A1 mating type, suggesting that gene flow between A1 and A2 genotypes is limited and that sexual recombination is rare.

A synopsis of the subgenus of lichenicolous fungi Lichenogramma is presented. It comprises eight species of Lichenostigma with oval to elongate ascomata connected to superficial strands of vegetative hyphae. Five of them are described here as new: Lichenostigma diploiciae (on Diploicia subcanescens); L. epipolina (on Diplotomma epipolium); L. gracilis (on Acarospora fuscata); L. rouxii (on Squamarina spp.); and L. subradians (on Acarospora spp., mainly subgen. Acarospora). The concept of the genus Lichenostigma is enlarged to accommodate also species with submuriform ascospores. A key to all the species of the subgenus is provided.

DNA polymorphisms among Magnaporthe grisea isolates from rice and from finger millet were examined using restriction analysis of genomic DNA. The rice-infecting isolates produced 50–70 resolvable EcoRI fragments with the rice blast-derived repetitive sequence probe MGR586, while isolates infecting finger millet showed only one prominent band. Probes derived from a repetitive sequence (grasshopper) from a finger millet also distinguished the two pathogenic forms; grh pES 3–3 (35–70 EcoRI RFLPs) and grh pKE 2–2 (2–12 EcoRI RFLPs) hybridized exclusively with isolates infecting finger millet. Probes of two avirulence genes derived from rice blast genomes hybridised exclusively with rice blasts. These distinctions in Indian blast populations matched those observed elsewhere in Asia and in the Americas. No genomes were observed in the field that shared RFLPs from rice-infecting and finger millet-infecting isolates, even among isolates from a Himalayan area where the two forms have coexisted for centuries. Pathogenicity tests showed that the blast fungus from the two hosts did not cross-infect, nor did the two forms cross in the laboratory. The results confirm that the rice and millet-infecting M. grisea populations in India are distinct.

Several fungi associated with leaf spots and stem cankers of Proteaceae are reported. The new species Kabatiella proteae, Phloeosporella protearum, Septoria grandicipis, Stilbospora proteae and Trimmatostroma elginensis are described. Several new teleomorph-anamorph connections are reported, including Mycosphaerella stromatosa and Pseudocercospora stromatosa, Teratosphaeria microsporum and Trimmatostroma microsporum, and Lembosia proteae and Clasterosporium proteae. Additional species described are Lophiostoma fuckelii and Verrucisporota proteacearum which are also newly recorded associated with leaf spots of Proteaceae in South Africa.

Interactions between springtails (Onychiurus armatus, O. tuberculatus, Folsomia candida) and plant pathogenic fungi (Gaeumannomyces graminis var. tritici, Fusarium culmorum, Bipolaris sorokiniana and Rhizoctonia cerealis) living in the same soil layer were investigated under laboratory conditions. The fungi are responsible for the foot and root disease complex of winter cereals and can cause serious reduction in yield. Since these species coexist in agricultural soils, feeding preference tests were performed in such a way that the springtails were allowed to interact simultaneously with all the tested fungi. O. armatus, O. tuberculatus and F. candida fed on the mycelia of G. graminis var. tritici, F. culmorum and R. cerealis: in the first hours of the trials individuals of all springtail species distributed themselves among the colonies, though moving from one to the other. Subsequently F. culmorum mycelium became the preferred food of all species tested; however, the other two fungi continued to be consumed. Mycelia of G. graminis var. tritici, F. culmorum and R. cerealis were shown to be an adequate food source for reproduction of Folsomia candida. Bipolaris sorokiniana mycelium had both repellent and lethal effects on F. candida and O. armatus, whereas this fungus was lethal, although not repellent, for O. tuberculatus. Long-term experiments on F. candida indicate that conidia of B. sorokiniana were eaten and proved to be a sufficient diet for reproduction.

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.

The abilities of 12 ericoid mycorrhizal endophytes isolated from Woollsia pungens (Epacridaceae) and three Hymenoscyphus spp. isolates to grow on a range of amino acids as sole nitrogen sources were investigated in axenic liquid culture. The majority of endophytes grew to some extent on all amino acids tested, with most isolates from W. pungens showing a significant preference for histidine and/or alanine. Poorest growth of the endophytes from W. pungens was observed on lysine. In contrast, the Hymenoscyphus spp. isolates showed either no preference or a preference for lysine over histidine. Although some isolates produced some growth on the sulphur-containing amino acid cysteine, biomass production on this substrate by all isolates was significantly enhanced in the absence of inorganic sulphur.

The teleomorphic state of the ericoid mycorrhizal Hymenoscyphus ericae is known only from the type deposition. The production of both the teleomorph and anamorph by an isolate recovered from Ledum groenlandicum collected in an acidic peatland in Alberta, Canada, provided an opportunity to describe and illustrate the holomorph for a North American collection as a new record and as a supplement to the original diagnosis. It also provided further evidence that Hymenoscyphus ericae and Scytalidium vaccinii represent states of a single species, a hypothesis that previously had been tested using nuclear ribosomal DNA analysis. Appropriate cultural conditions and the use of molecular markers are advocated in order to facilitate the identification of mycorrhizal isolates which often remain sterile in pure culture.

A pair of primers specific for Neonectria galligena were designed from comparisons of the internal transcribed spacer (ITS) regions 1 and 2 of 32 isolates of diverse origins with sequences from 7 other nectriaceous species: ‘Nectria’ ditissima, N. coccinea, N. coccinea var. faginata, N. punicea, N. fuckeliana, N. cinnabarina, and N. radicicola. Comparisons were also made with sequences from several commonly encountered fungal endophyte species of apple wood, in particular Fusarium lateritium. Under stringent PCR conditions, primers Ch1 and Ch2 amplify a 412 bp fragment from N. galligena DNA nectriaceous but not from other nectriaceous species, fungal apple endophyte species, rosaceous, or beech host tissues. The identity of PCR products from total DNA extracts from woody tissues was confirmed by Southern hybridization. A 500 bp heterologous internal standard incorporating identical primer recognition sites was generated for use as an internal positive control for individual PCR assays to identify false negatives due to the presence of high levels of co-precipitated PCR inhibitory compounds. Further adaptation of this approach allowed for semi-quantitative competitive PCR enabling the determination of target fungal levels in infected lignified tissues.

This study aims to clarify taxonomic relationships within the current concept of Xanthoria parietina in northern Europe. For comparison, X. calcicola was also included in the study. Morphological as well as molecular data were utilized. Morphology indicated the presence of three species, Xanthoria parietina, X. calcicola, and X. aureola, the latter of which is resurrected here from synonymy. The most important separating characters involve colour and thickness of the thallus, lobe width, morphology of laminar structures, and the texture of the upper surface. X. aureola, as recognized here, mostly occurs on seashore rocks. Part of the IGS region as well as the complete ITS were sequenced in 70 individual thalli representing ten geographical regions in Europe. In total, 19 different IGS haplotypes and 20 different ITS haplotypes were present in the data set. Owing to indications of possible recombination between the IGS and the ITS, the two data sets were analyzed separately. Haplotype networks were estimated, both of which indicate that X. parietina is distinct from X. aureola and X. calcicola. In our sample, the two latter do not share haplotypes, but are only separated by a few mutational steps.

Double-stranded (ds) RNA of various types was detected by electrophoresis in 23 of 25 isolates of Helicobasidium mompa. These dsRNAs varied in size from ca. 2 kbp to more than 10 kbp. dsRNAs from an isolate V1 had two distinct nucleotide sequences for putative RNA-dependent RNA polymerase (RDRP). Their complete sequences revealed that V1 dsRNA1 was 2247 bp in length, with a single ORF that encoded a 706-amino acid residue polypeptide with a predicted molecular mass of 82.6 kDa, and that V1 dsRNA3 was 1776 bp in length, with a single ORF that encoded a 538-amino acid residue polypeptide with a predicted molecular mass of 62.6 kDa. RDRP-conserved motifs were identified in both predicted amino acid sequences. Phylogenetic analysis indicated that V1 dsRNA1 was most closely related to Fusarium poae virus 1, while V1 dsRNA3 was most closely related to Helicobasidium mompa 70 virus. These results indicate coinfection of isolate V1 by two distinct partitiviruses.

Micropeltopsis cannabis sp. nov. and Orbilia luteola (Roum.) comb. nov. are proposed. New Cannabis host associations include binucleate Rhizoctonia spp., Curvularia cymbopogonis, Sphaerotheca macularis, Glomus mosseae, and Pestalotiopsis sp. The geographic ranges of Pseudoperonspora cannabina, Septoria neocannabina and Fusarium graminearum are expanded.

275 isolates of Ophiostoma novo-ulmi, sampled across the southern Great Lakes region of North America from Wisconsin to Ohio in 1996, were analysed for vegetative compatibility (vc) types. Over 60% of the sample was a clonal vc component, comprising only two vc types (the AMSG and EUSG); the remainder of the sample was highly heterogeneous for vc types. Vc diversity was highest in Indiana and Michigan; close to where NAN O. novo-ulmi probably first appeared in North America. Each vc clone exhibited a uniform RAPD haplotype and a lower frequency of the A compared with the B mating type. This is consistent with the clones being mainly asexually spread, but with a potential for inbreeding, an unusual feature in a ‘genetic clone’. The heterogeneous component, however, exhibited diverse RAPD haplotypes and a near 1[ratio ]1 ratio of A[ratio ]B mating types, indicating that the mainly novel vc types of this component arise via sexual recombination. In Europe, dominant vc clones have been quickly replaced by novel vc types. In the Great Lakes region, however, vc clones appear to have survived for over 50 years despite a high potential for emergence of new vc types via sexual recombination. No differences were found between the clonal and heterogeneous components with regard to growth rate and pathogenicity, two important fitness parameters. Two other factors, a low level of selection imposed by deleterious d-factor viruses and a density dependent effect associated with vegetative incompatibility, may have favoured prolonged survival of the clones in North America.

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.