Collybia fusipes is a common root rot fungus in mature pedunculate oak forest, that causes drastic destruction of the tree root systems, especially in dry or mildly waterlogged soils. We wanted to check, under controlled conditions or in forest ecosystems, whether reduced O2 during saturation of the soil by water could interact with disease evolution. Susceptibility of waterlogged oak seedlings to C. fusipes was tested in a greenhouse and the survival of the pathogen in woody substrates was assessed in hydromorphic soils in a forest. A direct and detrimental effect of soil waterlogging on C. fusipes survival was evidenced both under controlled conditions and in forest stands. Growth of C. fusipes mycelium on agar media was monitored under low O2 mole fraction and compared to that of Armillaria mellea and Heterobasidion annosum. A drastic reduction in mycelial growth was evidenced in C. fusipes and H. annosum but not in A. mellea.

To compare genetic variation among four geographically distant populations of the fungus species Melampsora epitea causing willow rust, a two-primer combination was used for ALFP fingerprinting of 24 isolates from Sweden, along with 10 from France, 24 from Northern Ireland, and 35 from Chile. The banding patterns of all 93 isolates were easily distinguished and revealed polymorphism among individuals within and between the four M. epitea populations. No clustering on the dendrogram could be attributed to country of origin, or almost equivalently, country of origin correlated poorly with genetic distance, suggesting that the geographically distant populations developed collectively as a metapopulation, instead of separately.

Oxine and copper oxinate have a long history of use as fungicides. Ability to chelate and lipophilicity have been regarded as essential to the action of oxine. The most widely held hypothesis on the mechanism of action of oxine holds that oxine is only active when it can form saturated chelates with metals in the medium which enter the cell and dissociate to liberate a toxic half-chelate. Metals, chelating molecules and pH were investigated for their effect on the fungitoxicity of oxine and copper oxinate. Oxine fungitoxicity increased with increase in medium pH, inhibitory activity corresponding most closely with the concentration of the neutral species. Chelation of oxine with metals in the medium was found not to be a requirement for oxine fungitoxicity. Potentiation of the action of oxine by metals is explained by the formation of more fungitoxic and soluble metal oxinates and antagonism by the formation of less soluble or less active metal oxinates. Chelating amino acids, nucleic acid bases and EDTA did not antagonize oxine fungitoxicity. Antagonism by riboflavin and folic acid suggests interaction of oxine with specific cellular functions in fungi. The fungitoxicity of copper oxinate was generally not affected by metals, chelating molecules or changes in medium pH. It is proposed that the data support the inherent fungitoxicity of oxine, the role of metal oxinates as co-toxicants and independent mechanisms of action for oxine and copper oxinate.

Amphipathic glucose derivatives 3-O-octyl- and 3-O-decyl-D-glucose were synthesized, and the ability to induce fruit bodies on Pleurotus ostreatus was examined. Surfactants such as CHAPS, CHAPSO, MEGA-8, MEGA-9, and MEGA-10 were also assayed. The result was that both glucose derivatives could stimulate fruiting on P. ostreatus, while none of the surfactants assayed in this study stimulated the fruiting of P. ostreatus. These results suggest that sugar moiety is necessary for amphipathic compounds to work as a fruiting signal for P. ostreatus.

We try to explain the large differences observed in the proportion of needles colonized by fungal species in coniferous litter by spore dispersal properties. We constructed a population dynamics model, assuming that litter is a resource that is fragmented into ephemeral units, periodically produced. Spore dispersion on needles on a small spatial scale was assumed to follow a Poisson distribution. The model was compared with an experimental system using Thysanophora penicillioides on Abies alba needles and its relevance to field conditions is discussed.

The production of cellulases on minimal medium in the edible mushroom Agaricus bisporus is regulated by the carbon source: induced by cellulose and repressed by glucose. In order to isolate cellulose-growth specific sequences, a cDNA library from A. bisporus using suppression subtractive hybridization (SSH) was constructed. Northern blot analysis indicated that a high level of enrichment was achieved; 183 clones were isolated. A preliminary screen with cellulose-specific genes of A. bisporus (cel1, cel2, cel3 and cel4) using Southern hybridization resulted in 28 clones to be cel3, and 5 clones were cel2. The remaining 144 clones were sequenced. Partial sequences of the following genes were found: a β-glucosidase homologue of the blvk gene of Kluyveromyces marxianus; a cellulase homologue of an endoglucanase (avicellase III) of Aspergillus aculeatus, four different xylanases homologue of the xyn genes of different fungi, and one hexose transporter homologue to the hxtA gene of Aspergillus parasiticus. The apparent full-length of two hydrophobins homologue to the abh3 gene of A. bisporus and one histone homologue to the h2a gene of Aspergillus niger were also found. The remaining sequences did not have homology to any known genes.

Two new aeroaquatic fungi, Ramicephala sphaerospora gen. sp. nov. and Beverwykella clathrata sp. nov., are described and illustrated from tropical and subtropical latitudes. B. clathrata, a species similar to B. cerebriformis, deviates from the latter in having a clathrate outermost cell layer instead of tightly appressed cells, a feature unique in Beverwykella. The second species, Ramicephala sphaerospora gen. sp. nov., has a unique combination of features concerning conidial ontogeny and morphology, and is therefore placed in a new genus. The genus most similar to Ramicephala is Beverwykella, from which it differs in having: (1) globose, non-flattened conidia; (2) a large central globose cell giving rise to centrifugally branching, tightly packed chains of cells; and (3) a compact peripheral cell layer, the cells of which are tightly interlocked in a zipper-like form. Similarities of R. sphaerospora to species of Pseudaegerita, Candelabrum and Cristulariella are discussed. Illustrations of and a key to all described species of Ramicephala and Beverwykella are provided.

Three British rust fungi reported to form aecia on daisy (Bellis perennis) are compared. A recently discovered species, possibly introduced from Australia, is identified as Puccinia distincta. It is a short-cycled -opsis form lacking uredinia, with aecia and telia confined to Bellis and its aeciospores capable of reinfecting the same host. This rust is compared with a macrocyclic heteroecious eu-form, P. obscura, which produces pycnia and aecia on Bellis and uredinia and telia on Luzula. Puccinia distincta is probably derived from and correlated with P. obscura because both species have the same aecial host, and because their teliospores are closely similar in morphology and dimensions. Comparison is extended to P. lagenophorae, a common rust with aecia and telia on Senecio spp., which has been reported to form aecia on Bellis following inoculation with aeciospores from Senecio. The repeated failure of our own reciprocal inoculation experiments using aeciospores from the two different hosts and differences in teliospore morphology between P. distincta and P. lagenophorae lead us to conclude that the current rust epidemic on daisies is caused by P. distincta which is distinct from P. lagenophorae.

A key to six taxa of Hygrocybe, subgenus Hygrocybe, sections Chlorophanae and Hygrocybe is provided. One species is new and four species are reported for the first time from the Greater Antilles. The new species is H. chimaeroderma (section Chlorophanae). Hygrocybe acutoconica, H. calyptriformis and H. incolor (section Hygrocybe) are reported for the first time, and two new varieties, H. konradii var. antillana and H. calyptriformis var. domingensis (section Hygrocybe) are described. Three new combinations are made: H. acutoconica var. microspora, H. conica var. brevispora and H. luteistipes (section Hygrocybe).

The structure of rhizomorphs of Armillaria luteobubalina grown on agar and in liquid culture has been compared using light and scanning electron microscopy. They differed in the extent of their peripheral hyphae, amount of surface mucilage, degree of pigmentation, growth rate, and structure of their inner cortex. Otherwise their internal structure was similar. At maturity four distinct radial zones could be recognised: (1) surface layer of peripheral hyphae from which hyphae extended radially; (2) outer cortex; (3) inner cortex; and (4) central medulla. The A. luteobubalina rhizomorph can be interpreted as a relatively strong ‘tube' of hyphae with a variously developed surface, surrounding a medulla of gas space containing wefts of fluffy fine hyphae. Submerged rhizomorphs grew at much faster rates than aerial rhizomorphs. The central gas-filled cavity most likely facilitates diffusion of oxygen along the rhizomorph, allowing growth through anaerobic environments. There was no evidence for specialised translocatory hyphae such as vessel hyphae. A zone of swollen hyphae interspersed with narrow hyphae developed at the interface between the inner cortex and medulla in submerged rhizomorphs. These were alive and septate and gave the tissue a resemblance to vascular plant aerenchyma, rather than specialised translocatory tissue. Peripheral hyphae took up and hydrolysed the fluorescent probe carboxy-DFFDA (Oregon Green) and accumulated the hydrolysis product in the vacuoles, suggesting that they are permeable. In contrast penetration of the cortex by the probe was limited. These data support the view that in moist conditions these rhizomorphs can function as organs of absorption and play a role in nutrient uptake.

Pycnodallia dupla gen. sp. nov. and Hymenopsis chlorothrix sp. nov. are described from saltmarsh Juncus roemerianus in North Carolina. Conidiomata of P. dupla develop on senescent inflorescences and involucral leaves, between 40 and 60 cm above the rhizome, therefore, the species can be considered as facultative marine. Conidiomata of H. chlorothrix are found on dead culms, 16–43 cm above the rhizome. This species is classified as obligately marine. Dwayaangam junci, the anamorph of Orbilia junci, has been found for the first time in nature. Conidia develop on the medulla of leaves, in lesions caused by grasshoppers.

We compared the degradative enzymology of fusaria in a small clade of closely related species as determined by phylogenetic analysis of nuclear 28S rDNA sequences. The clade includes entomogenous species and at least one recently discovered lichenicolous species. The lichenicolous Fusarium sp. and three entomogenous species were tested for the ability to degrade lichen tissue in both the presence and the absence of antibiotic secondary compounds. Only the undescribed lichenicolous Fusarium sp. showed degradative ability irrespective of lichen secondary chemistry and this was correlated with its ability to hydrolyse enzymatically the antibiotic depside, lecanoric acid. Similarly, the lichenicolous Fusarium sp. exhibited the greatest capacity for degrading lichen cell walls and the highest levels of cell wall-degrading polysaccharidases. These results correlate the ability to exploit lichen substrates with the production of specific enzyme activities able to overcome the chemical and physical barriers that characterize lichen hosts.

Various substrates and temperatures were evaluated for their effect on the sporulation and virulence of F. avenaceum, a potential biological control agent for marsh reed grass (Calamagrostis canadensis). Prior to assessing sporulation, growth was optimal on potato dextrose agar (PDA) between 15°–28°C, and minimal on malt extract agar (MEA). Temperature predisposed sporulation of 15 d old cultures, with refrigeration of PDA stock cultures of 4° causing a nearly ten-fold decrease in sporulation. Sporulation increased when PDA was juxtaposed with MEA or vice versa. In juxtaposed media, inoculation with MEA stock cultures significantly reduced macroconidial production. Although juxtaposition of MEA with PDA enhanced conidial production, there was no clear relationship between maltose-based substrates and conidial abundance. In 30 d old cultures, sporulation levels were higher when daytime temperatures were 30° versus 20°. The high daytime temperature also caused a greater proportion of macroconidia to form, and lowered the abundance of mesoconidia. In comparisons of bag cultures incubated at 20°, inoculum produced on puffed wheat was twice as virulent as that produced on marsh reed grass straw amended with malt extract. Mesoconidial production was maximal (2·6×108 mesoconidia g−1) using a 1:1 mixture of puffed wheat and wheat straw with malt extract. Straw cultures without malt extract produced the most virulent inoculum. Straw cultures generally produced a higher proportion of macroconidia but virulence was not a directly related to conidial morphology. While conditions favouring abundant sporulation did not favour virulence, bag cultures were a suitable method for production of F. avenaceum conidia.

Morphologically different thalli of Laboulbenia richardiana sp. nov. (Laboulbeniales, Ascomycota) were found on various parts of the body of the South American fly Richardia teevani. These thalli lack a separate cell IV and have similar appendages and perithecial apices. They are interpreted here as ‘growth forms’ of a single biological species. Spore characteristics and insect behavior support this view, rather than the hypothesis of several different species displaying position specificity.

Evidence that chemical changes in litter exposed to elevated CO2 might alter the composition and function of fungal communities in soil is presented. Some potential effects of elevated atmospheric CO2 on the decomposition of Fraxinus excelsior leaf litter and the interactions of the colonizing fungi, growing singly or in simple associations in microcosms, were investigated. Fungal colonization was monitored by analysis of the ergosterol content of litter and specific PCR-amplified ribosomal DNA spacer products. After < 42 d, fungal colonization was less on litter with a higher C[ratio ]N ratio when obtained from seedlings grown in elevated CO2 (600 ppm). After triple-species inoculation percentage α-cellulose and, in some combinations, nitrogen content was reduced on litter from seedlings grown in elevated CO2.

Venturia populina, first described on European Populus nigra, has been thought to be the only species of Venturia in Europe and North America to cause leaf and shoot blight of balsam poplars and cottonwoods in Populus sects. Tacamahaca and Aigeiros. The species of Venturia occurring on introduced P. nigra and native P. trichocarpa in the Pacific northwest were examined. Venturia populina was consistently found on P. nigra (i.e. the widespread P. nigra cv. ‘italica’) in the region, but V. inopina sp. nov. was present on native P. trichocarpa and its hybrids. There were neither examples of V. populina on P. trichocarpa and its hybrids nor of V. inopina on P. nigra cv. ‘italica’ (27 collections from 16 sites in Oregon, Washington, and Vancouver Island were made during 1995–2002). In an inoculation study, host-range separation was confirmed in that V. inopina caused sporulating leaf lesions on P. trichocarpa and its hybrids, but only non-sporulating lesions on P. nigra cv. ‘italica’. These two species of Venturia can readily be distinguished by conidial septation; V. populina is primarily 2-septate, whereas V. inopina is primarily 1-septate. Growth rates on PDA at 15 °C, and ITS sequences (2.3% divergence) were also distinct in isolates of these congeners. Conidial shape was of more value in discriminant analysis than conidial length. Venturia inopina is homothallic, given the sexual fertility of cultures of single ascospores that were overwintered under ambient conditions. Its geographic range appears to be restricted even within the Pacific northwest, leaving open the possibility that still other undescribed, native species of Venturia occur elsewhere in North America on sects. Tacamahaca and Aigeiros.

We studied the occurrence of genotypes of Gnomonia setacea by RAPD-PCR analysis at two natural sites in SW Finland to study site-, tree- and leaf-level genetic diversity. The analysis was performed with two primers by using 40 isolates from a total of 250 colonies isolated from two trees from each of two sites. Genetic diversity of G. setacea was found to be very high: every isolate studied was a unique genotype, even within the same leaf. This is probably due to sexual reproduction and the horizontal transmission system of airborne spores. Genotype distribution exhibited site-level similarity, indicating limited spore deposition and the ability to form local populations.

During a survey of 375 strains of the Xylariales, one isolate (F127076) was observed to have an ITS1 size of 833 bp. This size exceeds the average ITS1 size in the Xylariales (mean=209±57 bp). Comparison of the DNA sequence with GenBank and with a proprietary DNA database revealed low homology with Xylaria hypoxylon ATCC 42768, and with one undescribed Xylaria species. When the ITS2 sequence was compared, these isolates were 96–98% homologous. Sequences of other variable genes confirmed the relatedness among these strains. A closer observation of the ITS sequence of this isolate revealed the presence of three repeated domains of 250 bp plus one truncated domain, showing 52–75% homology. Sequence similarity suggests that the repeated domain is derived from the fusion of the ITS1 with a DNA fragment derived from the γ-glutamyltranspeptidase gene. This example suggests that the rate of evolution of ITS1 can be independent of the rate of evolution of other genes, even when this variability is not a result of slipped strand misspairing events like in other Xylariales. This observation also indicates that recombination with other nuclear genes could participate in the evolution of the internal transcribed spacer.

Spatial distributions and species diversity of ectomycorrhizal fungi were studied. Epigeous fungal fruit bodies and mycorrhizas were investigated in a reforested stand of Pinus densiflora aged 45 yr. Forty species of fruit bodies, including the dominant genera, Russula and Inocybe, were recorded throughout the three-year investigation. A species–area curve of the fruit bodies indicated that mean species number in 1.5 m2 was ca 1.0. Pine ectomycorrhiza, which were randomly sampled throughout the same investigation period, were assigned to 51 morphotypes microscopically. Although the dominant morphotypes were not manifested due to the sampling method used, a species–area curve of the mycorrhizas indicated the mean species number in 1.5 m2 was ca 25. Thus, spatial distributions among fruit bodies and mycorrhizas were quite different, and the mycorrhizas showed more complex distributions than fruit bodies. Several species abundance and diversity coefficients changed in relation to both the calculation method and fungal material used, which suggested the necessity for a uniform method of characterizing ectomycorrhizal fungal community structure.

Torrentispora fibrosa gen. sp. nov. (Ascomycota, Annulatascaceae) is described based on specimens from submerged wood collected from streams in Tai Po Kau Forest Reserve, Hong Kong. T. fibrosa is characterized by immersed to superficial ascomata with a peridium of black cells arranged in irregular rows, wide septate paraphyses, long cylindrical asci with a relatively massive refractive apical ring, and unicellular ascospores with a fibrillar sheath. Illustrations from light and scanning electron microscopy are provided. It is compared with species in the genus Annulatascus, from which it differs in ascoma peridium and ascospore sheath morphology, and with other aquatic ascomycetes possessing ascospores with a similar fibrillar sheath structure.