Nia globospora sp. nov., a marine basidiomycete, provisionally put in the Melanogastrales, producing fruit bodies on dead culms of Spartina maritima is described. The species grew on baits that were submerged for a period of 6 months in the Mira River estuary, Portugal. Comparisons with other species of Nia are made.

Morphogenesis is not simply a matter of playing out a predefined genetic programme. Expression of developmentally important genes is epigenetic and place- and time-dependent relying on previously-formed tissue structures. Most differentiated hyphal cells require reinforcement of their differentiation ‘instructions’. This reinforcement is part of the context (chemical, electrical and structural/mechanical environment) within which they normally develop. Key words at each stage of development in fungi are: competence, induction and change. Fungal morphogenesis is compartmentalized into a collection of ‘sub-routines’ which are distinct genetically and physiologically. Flexibility in expression of developmental sub-routines illustrates that tolerance of imprecision is an important attribute of fungal morphogenesis.

Peridermium harknessii, cause of western gall rust of pines, comprises two populations of multilocus electrophoretic types (zymodemes) in the western United States. When stained with a DNA-specific fluorochrome, mature, ungerminated aeciospores from zymodeme I were found to be predominantly binucleate (70%), as were those of the related macrocyclic species, Cronartium quercuum (74%), whereas aeciospores from zymodeme II were predominantly uninucleate (93%). Within each zymodeme, aeciospores with two nuclei had significantly (P=0·01) more DNA than spores with one nucleus, and numbers of nuclei in germlings increased arithmetically over time. These data suggest that aeciospore nuclei in both zymodemes I and II divide mitotically, not meiotically, as is consistent with an asexual life cycle.

Photometric measurements also indicated that the amount of DNA in one nucleus of a uninucleate zymodeme II aeciospore was similar to the total amount of DNA in a binucleate zymodeme I aeciospore. These data, coupled with recent isozyme studies, suggest either that zymodeme II evolved after karyogamy of zymodeme I and an unidentified zymodeme, or that zymodeme I evolved after haploidization of zymodeme II.

Discolouration due to senescence differs from blotch-related discolouration, which might indicate differential mechanisms being operational. In samples infected with bacteria or with a partially purified toxin extract, a higher degradation of total tyrosinase than in senescening mushrooms was found. Simultaneously, the active tyrosinase was increasing resulting in an increase in percentage of active tyrosinase. Phenolic substrates of the active tyrosinase were being oxidized, proportionally to the damage detectable on the mushroom cap. γ-Glutaminyl-3,4-dihydroxybenzene was degraded first, followed by γ-glutaminyl-4-hydroxybenzene and later tyrosine. The amount of melanin that was synthesized was larger than the sum of oxidation of the phenols measured. Principal Component Analysis explained 84% of the variance in symptoms, and it demonstrated the phenol oxidation and active tyrosinase level as the most important parameters for the browning induced by bacteria or a tolaasin preparation treatment.

Three polypeptides with manganese superoxide dismutase (MnSOD) activity were found in mycelium, zoospores and germinated cysts of Phytophthora nicotianae. Their relative molecular weights in non-denaturing gels were approximately 34.5, 36 and 50 kDa. No evidence for the presence of either iron or copper/zinc SODs was detected at any of the developmental stages examined. The level of activity of the MnSOD polypeptides was similar in mycelia and spores. Degenerate PCR was used to amplify partial genes of two different MnSODs, designated PnMnSOD1 and PnMnSOD2, from P. nicotianae. Southern blot analysis indicated that there are two PnMnSOD1 genes in the P. nicotianae genome. Full length sequence was obtained for one of these genes, PnMnSOD1a, from a P. nicotianae bacterial artificial chromosome (BAC) library. RNA blots probed with PnMnSOD1 showed similar levels of expression in vegetative and sporulating hyphae, lower levels in germinated cysts and no detectable expression in zoospores. PnMnSOD1a had 96%, 97% and 99% amino acid identity with homologous genes from P. ramorum, P. infestans and P. sojae, respectively. The second gene cloned from P. nicotianae, PnMnSOD2, had only 38% amino acid identity with PnMnSOD1a and was homologous to MnSODs that possessed an N-terminal mitochondrial targeting sequence in Phytophthora species and other eukaryotes. Southern blots indicated that there is one copy of PnMnSOD2 in the P. nicotianae genome. PnMnSOD2 was expressed at similar levels in mycelia and germinated cysts but PnMnSOD2 transcripts were not detectable in zoospores.

The new species Umbelopsis dimorpha sp. nov. was isolated from a soil sample in the Red Hills area of Mt Richmond Forest Park, in the northern part of the South Island of New Zealand. It has two kinds of pale pinkish sporangia: (1) single-spored, indistinguishable from those of U. versiformis; and (2) multi-spored, similar to those of U. vinacea. ITS sequences place the species in the immediate vicinity of the former species.

Linear mycelial aggregates (rhizomorphs) produced by the squamulose lichens Toninia opuntioides, Squamarina cartilaginea, Lecanora rhizinata, and Acarospora scotica were examined by transmission electron microscopy (TEM). Cytological features typical of lichenized mycobionts were present, including concentric bodies and plasmalemma invaginations. Some septa in rhizomorphs of S. cartilaginea and A. scotica appeared to be multipored. Septal pores were usually plugged by an electron-dense structure. Intrahyphal hyphae were common to abundant in the rhizomorphs of all four species examined. The wall of the invasive hypha was continuous with inner wall layers of the cell of origin. Contacts between adjacent hyphae involved wall dissolution and formation of new wall layers, leading to anastomosis and/or possibly to intrahyphal invasion. Differentiation of an outer layer of collapsed cells in rhizomorphs of Squamarina cartilaginea and of extremely thick-walled cells Lecanora rhizinata was evident, but no anatomical specialization comparable to the ‘vessel hyphae’ of non-lichen linear mycelial organs was observed. Enlarged spheroid or ovoid cells with dense cytoplasm, numerous mitochondria and lipid reserves occurred in short chains in rhizomorphs of Acarospora scotica; infrequently, similar cells were observed singly in those of Squamarina cartilaginea. These cells were reminiscent in shape of certain types of oil hyphae found in endolithic lichens, although often the lipid content of the enlarged cells was not particularly pronounced.

Leptographium species are common inhabitants of fresh conifer logs and lumber that are known for their ability to cause blue-stain and, in some cases, their association with disease. L. procerum has been associated with a root disease although controversy surrounds its role in tree death. During the course of the past two decades, a relatively large number of isolates tentatively identified as L. procerum have been collected in various parts of the world. Some of these display morphological characters unlike those of L. procerum s. str. and this has prompted us to re-examine them. Four groups of morphologically distinct isolates were identified, of which L. procerum s. str. represented one. The remaining isolates of Leptographium are newly described as L. alethinum, L. pityophilum and L. euphyes spp. nov.

The genetic relatedness among 29 collections belonging to 20 of the most common species of genus Amanita in the Iberian Peninsula have been studied by means of restriction analysis of the amplified ITS1-5.8S-ITS2 region of rDNA. Sixty restriction fragments were considered for the analysis. The main conclusion is that this technique could be useful to identify and characterize isolates from Amanita species. Although ARDRA did not show an appropriate level of discrimination to unambiguously infer phylogenetic relationships at or below the section level, some general trends could be outlined when the different haplotypes generated were compared by means of neighbour joining analysis. Thus, members from the same sections were frequently grouped together.

Single-strain biocontrol agents often look promising when tested against single-strain pathogens. When confronted with a biodiverse field population, however, biocontrol is inconsistent. This study implies that biodiversity of the crown rot pathogen Colletotrichum musae leads to strain discrimination by antagonists which results in variable biocontrol of the disease. Broad host-range mycoparasites of fungi of the crown rot disease complex of banana (C. musae, Fusarium moniliforme and Botryodiplodia theobromae) which attacked at least two of the pathogen genera, exhibited significant differences in aggression against different strains of C. musae, the main pathogen. Antagonists acted via several different mechanisms, i.e. parasitism, antibiosis or competition, simultaneously. The relative importance of each mechanism differed with the individual mycoparasites. Strain discrimination was correlated to differential susceptibility to one or more minor mechanism(s). When as many as four antagonists were combined into one inoculum, they complemented rather than antagonised each other. Biocontrol efficiency increased with the number of antagonist strains combined. Therefore, strain mixtures should be sought to control the crown rot disease complex of banana.

A new species of Ascobotryozyma, A. cognata sp. nov. (anamorph Botryozyma cognata), was isolated from beetle galleries in Idaho, USA. A. cognata was found on the surface of free-living nematodes, Panagrellus dubius, collected from galleries created by the long-horned beetle Saperda calcarata in Populus (aspen), and the weevil Cryptorhynchus lapathi in Salix (willow). A. cognata isolates were collected from similar habits and in relatively close proximity to those of A. americana, the only species described from North America. The recognition of A. cognata as a distinct species was supported by morphological and molecular data. Thallus cells of A. cognata were significantly shorter than those of A. americana. Low DNA reassociation values, notably different randomly amplified polymorphic DNA (RAPD), inter-sequence simple repeat (ISSR), and amplified fragment-length polymorphic (AFLP) fingerprints, and sequence divergence in both the D1/D2 domain of the nuc-LSU rDNA and an additional unidentified region were all consistent with the recognition of a new species.

Two main taxa of Phomopsis associated with Phomopsis cane and leaf spot disease of grapevine have been recognized in Australian vineyards. The present investigation identifies Diaporthe viticola, recorded for the first time since 1867 on grapevines, as the teleomorph of Taxon 1. Perithecia of D. viticola were found on 1 and 2 year old canes of cvs Chardonnay, Shiraz, Riesling, Cabernet and Pinot Noir in many vineyards in southern Australia. The teleomorph was induced in vitro on oatmeal agar and on sterilised segments of grapevine cane inoculated with isolates of Phomopsis Taxon 1.

DsRNAs were detected in 36 of 49 Monilinia fructicola isolates from stone fruit orchards in New Zealand. The dsRNA profiles were highly variable, even between isolates from a single tree. Comparison of pathogenicity on detached fruit, in vitro growth rate, and sporulation of 14 isolates showed no obvious correlation with presence of dsRNAs. Partially purified extracts from four isolates were examined for the presence of virus-like particles by transmission electron microscopy. One isolate contained 45 nm isometric particles similar in appearance to totiviruses and partitiviruses. A second isolate contained 200–250×25 nm rigid rods similar in appearance to the plant pathogenic tobraviruses and furoviruses. This is the first report of the presence of viral-like agents in the brown rot fungus Monilinia fructicola.

To understand the mechanism of wood discolouration employed by the staining fungus Ophiostoma floccosum, a gene involved in dihydroxynaphthalene (DHN) melanin biosynthesis was cloned from this organism and its function was examined. Degenerate oligonucleotide primers were designed according to conserved regions of hydroxynaphthalene (HN) reductases and used to PCR-amplify a 380 bp fragment from genomic DNA of O. floccosum. The amplified product was used as a probe to screen an O. floccosum genomic phage library. A genomic clone containing a full-length HN reductase gene was retrieved and a total of 1681 bp of its nucleotide sequence was determined. The determined sequence contained 673 bp of 5′ untranslated sequence, 807 bp of putative open reading frame (ORF) encoding a protein of 269 amino acids and 197 bp 3′ untranslated sequence. The ORF contained a 76-bp intron. Based on the similarity of the inferred amino acid sequence to other known fungal HN reductases, the cloned O. floccosum gene was considered an HN reductase gene. Disruption of the O. floccosum reductase gene was unsuccessful due to integration anomalies during homologous recombination. As an alternative, we complemented an HN reductase deficient buf mutant of the rice blast fungus Magnaporthe grisea by introducing the cloned O. floccosum reductase gene using hygromycin B resistance plasmid pCB1004. The complemented M. grisea buf mutants produced a black pigment like a wild type strain, indicating that the O. floccosum reductase is functionally homologous to other fungal HN reductases. These results suggest that O. floccosum uses the DHN pathway for pigmentation.

Helicodendron fuscum is described and compared with the similar species H. cumbriense and H. pinicola. Helicondron websteri, formerly confused with H. fuscum, is described as a new species. The anamorph of Tyrannosorus pinicola, Helicodendron pinicola, which has not been validly published is validated. A key for identification and illustrations are provided for all species treated.

Linocarpon smilacis sp. nov., Nitschkia phaeospora sp. nov., Ophiodothella cyclobalanopsidis sp. nov., Physalospora palmicola sp. nov., Physalospora smilacis sp. nov. and Tubeufia miscanthi sp. nov. from Taiwan are described and illustrated by microphotographs. Each is compared with related taxa.

Stipe elongation in fruit bodies of Coprinopsis cinerea (syn. Coprinus cinereus) was examined from a biomechanical perspective. Two strains were studied: the self-compatible Amut Bmut homokaryon that produces normal fruit bodies with relatively short stipes, and mutant B1918 that produces abnormally elongated stipes. Measurements of the pressure exerted by developing mushrooms were made using strain gauges, and these data were compared with measurements of the pressures exerted by vegetative hyphae of the same strains. The experiments demonstrate that AmutBmut hyphae elongating within stipe tissue push with the same pressure (approx. 0.5 atmosphere) as vegetative hyphae growing through their food sources. In purely biomechanical terms, the fruit body may therefore be viewed as a relatively uncomplicated sum of its parts. Analysis of the mutant strain B1918 demonstrated that hyperelongation of the stipe is not associated with any difference in the pressure exerted by the fruit body. The fault in the mechanism of stipe extension in B1918 may be reflected in the increased fluidity of the cell wall of vegetative hyphae of this strain, but further work is necessary to resolve this.

Species of Leptographium are well-known inhabitants of conifers in the Northern Hemisphere, in which they cause a blue-stain. They are also known to be associated with insects, especially bark beetles (Coleoptera: Scolytidae). Surveys of dying stands of Siberian fir (Abies sibirica) have resulted in the consistent isolation of an unknown Leptographium from the galleries of the fir sawyer beetle, Monochamus urussovi (Coleoptera: Cerambycidae). This fungus is responsible for the blue-stain in living trees. Comparison with known species of Leptographium led to the conclusion that it had not been previously described, and the name Leptographium sibiricum sp. nov. is introduced here.

The new genus Lichenopyrenis is described for L. galligena, a cecidiogenous species parasitic on the lichen Leptochidium albociliatum. This genus is characterized by perithecioid ascomata with a cellular wall, formed by relatively large, somewhat compressed cells, fissitunicate, I- asci, wide hamathecium filaments, and 1-septate, pale orange brown ascospores with distoseptate thickenings which at maturity are seemingly bulging out of the exospore wall at the septum and apices. The conidia have a rhexolytic type of secession, and are attached to the conidiogenous cells by a separating cell. Lichenopyrenis is referred tentatively to the family Pleomassariaceae.

A new species of Boerlagiomyces is described from submerged wood collected from a freshwater river in the Philippines. Boerlagiomyces grandisporus is compared with previously described species in the genus and is shown to possess greatest similarity with B. websteri. Selected ultrastructural characteristics of the ascospores of B. grandisporus are illustrated and discussed in relation to other fungi. The taxonomic relationship of the genera Boerlagiomyces and Garethjonesia are reassessed and shown to be congeneric; the new combination B. lacunosispora is accordingly validated.