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.

The relative abilities of the multilayer perceptron, radial basis function, asymmetric radial basis function and learning vector quantization artificial neural networks (ANNs) and two non-neural methods to identify fungal spores were compared. ANNs were trained on morphometric data from spores of Pestalotiopsis spp. and a few species in the related Truncatella and Monochaetia. The optimized neural and statistical classifiers had similar identification success on an unseen data set – between 76·0 and 78·8% of a 16-species group and between 63·0 and 67·7% of a 19-species group. The relative merits of each classifier are discussed, as is the potential of ANNs in mycology.

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.

Rubukia splendida sp. nov. from Mauritius is described, illustrated and compared to the only other species in the genus, R. samsonii from Honduras.

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.

Hyphal growth of the white button mushroom Agaricus bisporus on spawn grains and compost is typically vegetative. Hyphae are loosely arranged, in contrast to the organized texture in tissues, and needle-like calcium oxalate crystals are frequently present on the surface of vegetative hyphae. The mycelial cord is the first well-organized tissue of the fruiting mycelium; it is surrounded by fluffy white hyphae that grow vegetatively. The hyphae of the cord are held together through a semi-fluid medium, the extracellular matrix, which aids in creating a three-dimensional pseudoparenchymatous structure. The matrix material seems to be secreted into the extracellular environment by specifically differentiated cells, but the vegetatively growing hyphae of A. bisporus initially exploit a different mechanism in the production of matrix which involves a type of cell death different from cell necrosis. This primary matrix production leads to the formation of minute cord tissues in which oxalate crystals are no longer present. Once the hyphal cells of A. bisporus pass the threshold from a vegetative form into organized structures, they become differentiated and self-maintaining in the production of the extracellular matrix material. Morphogenetic cell death has been observed before in A. bisporus development and here we show that it occurs in various species of macrofungi: a mucoid zone of the pileipellis typically found in developing fruit bodies of Psilocybe and Panaeolus spp. contains numerous, dying or dead hyphal cells which show ultrastructural features comparable to those observed during the mycelial cord formation of A. bisporus. Studies performed using specimens of Stropharia rugoso-annulata, Coprinus domesticus, Psathyrella candolleana, Tremella mesenterica, Otidea onotica and Peziza ostracoderma in representative growth stages revealed supporting evidence for the view that morphogenetic cell death plays a key role at different stages during the development of fungal fruit bodies. This phenomenon may be related to the programmed cell death occurring in developing plants and animals.

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.

Fifty-five strains of Phanerochaete chrysosporium were isolated in South Africa, and screened for indicators of ligninolytic activity: lignin peroxidase (LiP), manganese peroxidase (MnP) and glyoxal oxidase (GLOX). MnP-production as a function of time was followed in all strains. Nine strains were selected for quantification of MnP, LiP and GLOX activities. Statistically significant variation in MnP and GLOX activities existed among the different strains. Under low nitrogen, LiP activity of selected strains showed no significant variation, whereas strain PP25 had significantly increased LiP levels under high nitrogen conditions. Probing genomic DNA with the genes encoding lignin peroxidase (lipD and lipI1), manganese peroxidase (mnp2), and glyoxal oxidase (glox) showed significant genetic diversity with lignin peroxidase and manganese peroxidase probes, but not with the glyoxal oxidase probe.

The cyclic tetrapeptide, HC-toxin, is a host-selective virulence determinant produced by the foliar pathogen of maize, Cochliobolus carbonum race 1. HC-toxin is synthesized by a multifunctional peptide synthetase (HTS) encoded by the HTS1 gene. Analyses of culture filtrates identified low toxin-producing and high toxin-producing strains among field isolates of the pathogen. These strains were analyzed by reverse transcription PCR to determine whether synthesis of the toxin is directly influenced by HTS1 transcript levels. The results indicated that expression of HTS1 was up-regulated and reached maximal levels several days before the toxin was detected in the culture medium and that HTS1 transcript levels were not correlated with toxigenicity. These observations suggest that genes in addition to HTS1 are involved in regulation of HC-toxin biosynthesis. The toxin-producing ability of low toxin-producing isolates was enhanced following inoculation and reisolation from leaves of susceptible maize genotypes, suggesting that additional factors within the host environment influence toxin production during pathogenesis.

Recent studies suggest that the antifungal agents itraconazole, bifonazole, and ketoconazole affect calcium-mediated signal transduction in Trichophyton rubrum. We have now examined the effects of azole-antifungal agents on cell membrane function in T. rubrum, by analysing the effects of itraconazole, bifonazole, ketoconazole, and lanoconazole on ionomycin-induced changes in intracellular calcium concentration ([Ca2+]i). Addition of 1 μm ionomycin to the culture medium produced a persistent increase in [Ca2+]i. While treatment with 1·5–15 nM of lanoconazole or bifonazole for 24 h did not affect this ionomycin-induced increase in [Ca2+]i, 30 nM of these agents resulted in a transient increase in [Ca2+]i rather than the usual sustained increase in [Ca2+]i. This transient ionomycin-induced increase in [Ca2+]i was also observed after treatment with only 1·5 and 3 nM of ketoconazole or itraconazole. Incubation in the presence of lanoconazole or bifonazole at [ges ]150 nM, and ketoconazole or itraconazole at [ges ]15 nM inhibited both the persistent and transient ionomycin-induced increase in [Ca2+]i. On the basis of these findings, it is suggested that azole antifungal agents disturb membrane function in T. rubrum, and that one manifestation of this effect is the disruption of the ionomycin-induced increase in [Ca2+]i. We report that the ionomycin-induced increase in [Ca2+]i is more sensitive to low concentrations of ketoconazole and itraconazole compared to bifonazole and lanoconazole.

Genotypic variation among 62 strains of Aphanomyces euteiches, four of A. cochlioides, and a Saprolegnia sp. was investigated using RAPD analysis. Pathogenicity assays on pea, bean, alfalfa, red clover, and sugarbeet were used to determine host preference among the strains of A. euteiches and A. cochlioides. Pathogenicity tests revealed six pathotypes of A. euteiches with host preferences for bean, alfalfa, pea, pea and alfalfa, red clover and alfalfa, and bean and alfalfa. Another group of strains was non-pathogenic on the five plant species. The host of origin tended to be the host on which each strain incited the highest disease severity. A. euteiches did not incite root rot symptoms on sugarbeet, and A. cochlioides was pathogenic only to sugarbeet. RAPD analyses provided a measure of genetic diversity in Aphanomyces. Fifty random decanucleotide primers were screened with five test strains from four hosts representing different pathotypes, and 32 primers amplified DNA fragments from all five strains. Eight primers were chosen for most of this study based on number and polymorphic nature of the bands generated. RAPD assays of 62 strains of A. euteiches with the eight primers yielded 159 polymorphic and no monomorphic, strongly amplified bands. Cluster analyses of RAPD data revealed genotypic differences among three groups of A. euteiches which corresponded to their host of origin and host preference for bean, alfalfa, and red clover/alfalfa. Strains nonpathogenic on all plants tested formed another genotypic group, corroborating results from the pathogenicity assays that indicated this is a discrete group. The bean and non-pathogenic groups were the most distinct. The A. cochlioides and Saprolegnia strains were genotypically distinct from the pathogenic, but not the non-pathogenic strains of A. euteiches. Reproducibility of RAPD assays was confirmed by replicated amplifications and DNA hybridization analysis. Results indicated that A. euteiches is composed of distinct subspecific groups based on genotype and host preference.

Species of Gloniella, Glonium and Gloniopsis from southern South America were studied. A new fungus Glonium colihuae sp. nov., with hysterothecia is described from Argentina, Patagonia; Glonium chusqueae is synonymized with Gloniella typhae; Gloniopsis argentinensis and Glonium costesi are validated, and some comments on the taxonomy and occurrence of Gloniopsis araucana, G. praelonga, Glonium abbreviatum and G. cumingii are presented.

Heterothallism was confirmed in Mortierella umbellata from Japan. Anisogamic zygospore formation is described and illustrated with time-lapse light micrographs. The anisogamic behaviour of the species is discussed with reference to previous studies on anisogamic zygospore and azygospore formation in Zygomycetes.

This is the first report demonstrating Amorphotheca resinae to be a natural member of the soil mycobiota in Germany. The fungus was detected at 19 out of 68 collection sites and was most frequently isolated from soil under or in the vicinity of yew trees (Taxus baccata). This finding is in contrast to reports from other countries, where no correlation was found between the presence of the fungus and the kind of soil or vegetation. A. resinae could not be re-isolated by standard methods like the soil dilution technique or the soil plate method, unless the fungus was present in high numbers of colony forming units. By a modification of the creosoted matchstick method it was possible to detect the fungus when as few as 11 viable spores were present in a plate with 20 g of soil.

Arctic and temperate strains of Hebeloma spp. were grown in axenic culture on glutamic acid, alanine, lysine and NH4+ as sole sources of nitrogen (N), with excess carbon (C) or deficient C (supplied as glucose). Their ability to utilize seed protein as a natural N source was also assessed. All strains tested had the capacity to assimilate amino acids and generally utilized alanine and glutamic acid more readily than NH4+. Some strains were able to utilize amino C when starved of glucose C, and could mineralize amino-N to NH3-N. Arctic strains, in particular, appeared to be pre-adapted to the utilization of seed protein N and glutamic acid N, which is often liberated in high concentrations after soil freezing. The results are discussed in relation to their possible ecological importance.

Spore proteins of different species and isolates of arbuscular mycorrhizal (AM) fungi were compared by PAGE. Reproducibility of protein patterns was assessed by using cultures of the same species either grown on different host plants, or produced during successive propagation cycles and stored up to 5 years. The results consistently showed that host species, different generations and storage, did not affect protein profiles, thus validating the accuracy of the method. Comparison among different geographical isolates of the same species revealed consistent protein patterns. The stability and diversity of spore protein profiles suggested that PAGE could be used to discriminate and identify AM fungal species and isolates. By contrast, the physiological state of spores affected the quality and quantity of bands, with germinating spores showing marked profile changes, as compared to quiescent spores, both in denaturating and native analytical conditions. The disappearance of some polypeptides in germinated spores might be related to the occurrence of storage proteins in AM fungi.

Ancorasporella mexicana gen. et sp. nov., collected on the dead leaf stalk of an unidentified fern in a cloud forest in the state of Veracruz, México, is described and illustrated. This singular hyphomycete is distinguished from known genera by its euseptate, triangular or fusiform conidia which are attached at 90° to the long axis of the cicatrized conidiogenous cell.

Hebeloma strains of arctic and temperature origin, grown at 22° or 6°, were assayed for wall-bound and extracellular acid phosphomonoesterase (pNPPase) across a temperature range 2–37°. Only when grown at 6° was a cold active extracellular pNPPase induced in all the arctic strains and most of the temperature strains tested. Such enzymes are suggested to be an adaptation to low soil temperatures, and are discussed in the context of ectomycorrhizal access to soil PO4− monoesters at low temperature.

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.

Six new species of Puccinia on Baccharis are described: Puccinia basirostrata, P. ecuadorientalis, P. lentapiculata, P. otavalensis and P. quitensis from Ecuador, and P. vulcanicola from Costa Rica. Beside features of telio-, uredinio- and aeciospores, basidiospore morphology yielded important characters for species delimitation.