This paper describes the use of a monoclonal antibody-based ELISA for the quantification of the effects of Trichoderma harzianum on the saprotrophic growth dynamics of Rhizoctonia solani in unsterile compost-based microcosms. Quantification of R. solani was based on the immunological detection of a constitutive, extracellular, water soluble glycoprotein antigen (the copper-containing enzyme catechol oxidase) which is secreted by actively growing mycelium of the fungus only. Extracts derived from lyophilized mycelium (FDM) were used as a quantifiable and repeatable source of the antigen in order to prepare calibration curves that accounted for incomplete extraction of the antigen from compost samples. These curves were used to convert the absorbance values of extracts in ELISA to FDM biomass equivalents, which allowed comparisons of the saprotrophic growth dynamics of R. solani to be made in the presence and absence of T. harzianum. The high pH (9·6) of the buffer used to extract the antigen from microcosm samples also resulted in the extraction of humic components of the compost which interfered with the sensitivity of the assay. A protocol, based on the determination of optimal ELISA absorbance[ratio ]extract dilution ratios, was used in order to reduce the interference and improve the sensitivity of the quantitative assay.

Accumulation and transformation of tellurite (TeO32−) by a species of Fusarium and Penicillium citrinum was examined using both solid and liquid Czapek Dox medium. In liquid medium, tellurite partitioned into soluble and insoluble species, and in tellurite-containing (1 mM) liquid medium at pH 6, approx. 60% of added tellurite precipitated after 48 h. Experiments showed that in liquid medium containing 1 mM sodium tellurite, the Fusarium sp. accumulated a maximum of ∼0·6 μmol Te (mg D.W.)−1 after 48 h. P. citrinum accumulated a much lower amount of tellurium, ∼0·07 μmol (mg D.W.)−1 falling to <0·02 μmol (mg D.W.)−1 after 48 h. Both organisms showed marked differences in the pattern of pH change of the medium, with the pH increasing during growth of the Fusarium sp. in 1 mM tellurite to ∼pH 6·7 after 2 wk. In contrast, the pH decreased during growth of P. citrinum in 1 mM tellurite, to a level of ∼pH 2·7 after 2 wk. On agar medium, test fungi exhibited tolerance to high levels of tellurite (up to 100 mM Na2TeO3) and this was associated with blackening of the growing colonies as well as the surrounding agar. TEM revealed the deposition of large black granules, apparently in vacuoles, which corresponded with the reduction of tellurite to amorphous elemental tellurium. Precipitation of amorphous tellurium on and around the biomass was also observed and confirmed by energy-dispersive X-ray microprobe analysis. In addition to the reductive transformation of tellurite, Fusarium sp. also displayed transformation of tellurite into a volatile form. The production of volatile tellurium by Fusarium sp. occurred over the whole growth period and amounted to an average value of 7·8 μmol Te (∼0·16%) from 51 growth medium with an initial concentration of 1 mM Na2TeO3. Although P. citrinum also transformed tellurite to elemental tellurium, volatilization of tellurium was not detected. It is concluded that different mechanisms of tellurium transformation are species-dependent and can be influenced by physico-chemical changes in the medium, e.g. pH, which can affect tellurium speciation into soluble and insoluble forms and bioaccumulation. In view of the extremely small amounts of Te volatilized by the Fusarium sp., this process cannot be considered to be an important detoxification mechanism.

A new Claviceps species that causes ergot in sorghum and Sudan grass in Japan is described. The new species is distinct from C. sorghi and C. africana, from India and Africa, respectively, in the colour and texture of sclerotia, colour and morphology of stromata arising from the sclerotia, and size of ascospores and conidia. The pathogen infected only Sorghum in inoculation tests using 11 gramineous plants. Hyphal growth of C. sorghicola was 1 mm d−1 on PDA at 25 °C. Production of a different ergoline alkaloid in the sclerotia was suggested.

Plating of individual soil particles onto an agar medium, poured into Petri dishes, is a method of studying fungal distribution between microhabitats in soil. The substitution of Petri dishes with well plates reduced both the required amount of agar medium and labour. A microshovel prepared from an injection needle facilitated the handling of individual, small size, soil particles (0·25–0·50 mm). The described method was evaluated in a study of the distribution of Fusarium within two wheat field soils from Ås, Norway, and from Østermarie, Denmark. Four types of organic particles were distinguished: light coloured root pieces, dark coloured root pieces, straw pieces, and miscellaneous organic pieces. The dominating species were F. culmorum, F. oxysporum and F. avenaceum. Aspects on the value of the method with regard to fungal substrate preference are discussed.

Isolates of Verticillium lecanii, from insects and other substrates, were tested for vegetative compatibility by observing heterokaryon formation among complementary nitrate-nonutilizing (nit) mutants, Among 33 V. lecanii isolates, 17 were self-incompatible. The 16 self-compatible isolates were divided into 13 vegetative compatibility groups (VCGs). Eleven VCGs were single-member VCGs, and the remaining two included two or three isolates each. Self-incompatibility occurred more frequently among isolates with abundant aerial mycelium, whereas most of the isolates with short or reduced aerial mycelium were self-compatible. Virulence to larvae of Bemisia tabaci ranged from 0 (four isolates) to 83% mortality 4 d after treatment with conidial suspensions. There was no correlation between the capacity of isolates to anastomose and their virulence to larvae of Bemisia tabaci: highly virulent isolates were found at similar frequencies among self-compatible and self-incompatible isolates. Those with abundant aerial mycelium were collectively more virulent (28·5% mortality) than those with reduced mycelium (10·7% mortality). Three isolates belong to VCG VL-11 were all highly virulent.

Fifty-five Phytophthora sojae isolates were collected from soil samples and diseased soybean plants from Illinois, Indiana, Iowa, and Minnesota in 1994 and 1995. Races for the isolates were determined. DNA of P. sojae isolates was amplified with 16 Operon decanucleotide primers. Twenty-three of 75 amplified fragments were polymorphic. Based on the 23 RAPD markers, a dendrogram depicting the relatedness of the isolates was constructed using UPGMA. The P. sojae isolates clustered into four distinct groups. The isolates of races 3, 4 and 25 clustered into group I. The isolates of races 1, 8 and 13 clustered into group II. The isolates of race 5 clustered into group III, and the isolates of race 7 clustered into group IV. Genetic diversity was detected among isolates of races 1, 3, 4, 5, 7 and 25 but not among isolates of races 8 and 13.

The biotrophic species of Phyllachoraceae associated with the angiosperm family Erythroxylaceae are examined, and five new species and one new subspecies proposed. Five species of Phyllachora are accepted, including the four undescribed taxa P. occultans from Mexico, P. usteriana subsp. piliformis and P. reticulata from Brazil, and P. tanensis from Madagascar. The new genus Fremitomyces is introduced for two undescribed species from East Africa and the Seychelles, which have initially brightly coloured stromata.

Ascospore progenies from two crosses between a wild single-ascospore strain and two mutants of Phaeosphaeria nodorum were obtained in vitro. Cultural characters, sensitivity to carbendazim (MBC), nitrate utilization, mating type, esterase zymograms and aggressiveness of these progenies and parents were compared and differences were detected between the ascospores. The single-ascospore strains from each single ascus could always be grouped into four pairs using a combination of markers. Recombinations were observed between nitrate non-utilizing phenotype and mating type or esterase patterns for one cross. For the other cross, recombinations between MBC resistance and esterase patterns were detected. The values of aggressiveness in each progeny were distributed along a wide range confirming the polygenic character of aggressiveness in P. nodorum. No close relationship was observed between in vitro conidiogenesis, the intensity of leaf necrosis and the fertile pycnidia production on leaf lesions.

Since secondary metabolites are involved in fungal-host interactions, those of endophytes and their hosts were studied to try to understand why endophytic infections remain symptomless. A screening of fungal isolates for biologically active secondary metabolites (antibacterial, antifungal, herbicidal) showed that the proportion of endophytic isolates that produced herbicidally active substances was three times that of the soil isolates and twice that of the phytopathogenic fungi. As markers for the plant defence reaction, the concentrations of certain phenolic metabolites were chosen. Those that differed in concentration were higher in the roots of plants infected with an endophyte than in those infected with a pathogen. The results presented here were regarded together with previous studies on other aspects of the plant defence response using dual cultures of plant host calli and endophytes, and of cell suspension cultures following endophytic as compared to pathogenic elicitation. The following hypothesis was developed: both the pathogen-host and the endophyte-host interactions involve constant mutual antagonisms at least in part based on the secondary metabolites the partners produce. Whereas the pathogen-host interaction is imbalanced and results in disease, that of the endophyte and its host is a balanced antagonism.

Metarhizium anisopliae has potential as a biological control agent. Included among its hosts are certain insect pests of brassica crops. Brassica species produce isothiocyanates, some of which are known to be fungitoxic. In our study, isothiocyanates inhibited both germination and subsequent growth by M. anisopliae in vitro and its ability to infect insects. Conidia were more sensitive than the mycelium to these compounds, the most fungistatic of which were phenylethyl-, 2-chlorophenyl- and allyl-isothiocyanates. Appressorium production in vitro was suppressed by all isothiocyanates except allyl- and propyl-isothiocyanates, which appeared to stimulate appressorium formation. Phenylethyl- and 3-butenyl isothiocyanates, which are present in several of the plant hosts of Phaedon cochleariae, reduced the pathogenicity of M. anisopliae when inoculated insects were exposed to their vapours. These findings have implications for the efficacy of biocontrol of brassica pests by this fungus.

Eleven new intertidal fungi Aniptodera intermedia, Anthostomella nypae, Anthostomella nypensis, Anthostomella nypicola, Helicorhoidion nypicola, Herpotrichia nypicola, Leptosphaeria nypicola, Lignincola nypae, Phomatospora nypicola, Trichocladium nypae, and Vibrissea nypicola spp. nov., are described from Nypa fruticans. These new species are compared with existing species in the genera and illustrated with interference light micrographs.

Healthy-looking needles were randomly collected from Pinus mugo ssp. uncinata at two sites in the montane zone with different edaphic and microclimatic conditions and examined for the diversity of endophytic fungi. One site is on a mountain ridge, the other in a peat bog. On average, about 35–40% of the needles were colonized at both sites. Eleven species of fungi were isolated. Cenangium ferruginosum and Cyclaneusma minus dominated the endophytic mycobiota of the tree stand along the mountain ridge. C. ferruginosum and Lophodermium pinastri were the dominant species in the needles of the trees in the peat bog. C. ferruginosum and L. pinastri occurred mainly in the needle tip; C. minus occurred most frequently in the middle segment of the needles. The needle base was rarely colonized by these fungi. Endophyte colonization of trees along the mountain ridge increased significantly from the uppermost trees to the ones further down the ridge. No clear pattern of colonization was observed for trees in the peat bog except for the colonisation by L. pinastri, which showed a tendency to form infection centres. Species composition was constant within sites, but the frequency of colonization by C. minus and L. pinastri varied greatly among trees.

The taxonomy of several neotropical resupinate Perenniporia is discussed. P. xantha is described as new. It is characterized by a bright yellow resupinate basidiocarp, small pores and small ellipsoid, dextrinoid basidiospores in addition to reduced arboriform skeletal hyphae. Two new combinations are proposed, Perenniporia aurantiaca and P. chromatica. Their relation to other Perenniporia species is briefly discussed.

Isolates of Pisolithus and Scleroderma species from different northern temperate and tropical geographical regions were subjected to analyses of pure culture morphology, colony growth rates, isozyme (allozyme) variation and ribosomal DNA (rDNA) restriction fragment length polymorphisms (RFLPs). Cultural characteristics enabled clear species separation of isolates and together with growth rates suggested geographically-linked intraspecific variability in the Pisolithus populations. Combined or method-specific hierarchical cluster analyses of allozyme polymorphisms and RFLPs of the fungal internal transcribed spacer (ITS) and intergenic spacer (IGS) sequences confirmed the Scleroderma species groupings and considerable geographical and host-linked variation in the Pisolithus population. Isolates of Pisolithus from the Philippines were genetically very homogeneous and distinct from less related isolates from Europe, Scandinavia and North America. Based on the ITS–RFLP and isozyme polymorphism data, the isolates investigated probably represent four different ‘species groupings’ which supports similar findings from recent taxonomic and genetic studies of Australian Pisolithus species.

Five lignicolous mangrove fungi (Hypoxlon oceanicum, Julella avicenniae, Lignincola laevis, Savoryella lignicola and Trematosphaeria mangrovei) produced extracellular endoglucanase, cellobiohydrolase and β-glucosidase when cultivated under static conditions in a defined liquid growth medium. Agitation of cultures completely repressed enzyme production. Cellulase production by H. oceanicum was 2–5 fold higher compared to other strains. Increasing salinity generally resulted in reduced enzyme production although responses varied, but J. avicenniae appeared relatively unaffected by salinity within the range 0–3·4%.

Progress in understanding the biology of arbuscular mycorrhizal fungi is hampered by the limited number of species that can be successfully propagated and studied in vitro. We report the establishment of monoxenic cultures of Glomus etunicatum in association with excised Ri T-DNA transformed carrot roots. The fungus can be propagated in vitro using monoxenically formed resting spores and/or colonized root fragments. Modified White's medium buffered with 10 mM MES (pH 6) or MOPSO (pH 6·5) was most optimal for the host root growth as well as for G. etunicatum spore germination and mycorrhiza formation. The number of resting spores formed in vitro correlated positively with the length of roots occupied by arbuscular mycorrhizal structures, including arbuscules and vesicles. Spores first appeared in dual cultures within two weeks of root inoculation. Sporulation was asynchronous and continued until root senescence. Under applied culture conditions, spores achieved mature appearance within 5–7 d after their initiation. Approximately 6% of monoxenic spores were aborted at different stages of their development. Although G. etunicatum spores formed in vitro exhibited general morphological and anatomical similarity to soil-borne inoculum, they were significantly smaller and had thicker spore walls than their soil-borne counterparts. Caution should, therefore, be exercised in utilizing the in vitro system as a model of growth and development of glomalean fungi in soil.

Mass mortality among pond cultured red drum (Sciaenops ocellatus) was observed in Hong Kong. Affected fish were lethargic and lost their appetite but no lesions on the body surface were apparent. Patches of white to brownish cottony growth on the gills of affected fish were observed and microscopic examination revealed mats of hyaline mycelia with mature zoosporangia and oogonia which were identified as Saprolegnia diclina. During induced sporulation, production of primary and secondary zoospores, oogonia, and antheridia were observed. A physiological study of the growth and sporulation of a representative isolate determined its optimum growth requirements. The isolate can grow from pH 4 to 10, in distilled water, at salinities of 5–30‰, and temperatures of 4–30°. Maximum growth was observed at pH 5 and 8–10, at salinities of 5–10‰, and 25–30°. Production of zoosporangia only occurred in distilled water, 5 and 10‰ salinities, with zoospores released in distilled water and 5‰ salinity. Zoospore release was also observed from 4 to 30° with greater abundance at 25 and 30°, while oogonia and antheridia were produced in distilled water and from 5 to 30‰ salinities and at 20–30°.

Recent field work on smut fungi in Cuba yielded one new species and, among many new records, several poorly known species which are described and illustrated. The new species, Cintractia cubensis on Rhynchospora microcephala, is characterized by rather large, dark, and finely foveolate teliospores which can germinate with basidia of only two basidial cells. The poorly known C. samanensis was found on the new host Rhynchospora fascicularis ssp. fascicularis. Entyloma guaraniticum on Bidens pilosa differs from E. bidentis on the same host by thick-walled teliospores embedded in the mesophyll of leaves deforming them. Spores of E. bidentis are smaller and do not deform the leaf. Sphacelotheca everhartii on Andropogon virginicus, S. microspora on Paspalum notatum, and S. panici-leucophaei on Trichachne insularis are transferred into Sporisorium.

Phellinus formosanus sp. nov. and P. prunicola sp. nov. found growing saprotrophically on decayed stems of Schima superba and Prunus mume, respectively, in Taiwan, are described and illustrated. Cultural characters are described.

Medusoides gen. nov. is described from North Carolina, U.S.A. The fungus reproduces sexually, with oogonia and antheridia, but no asexual stage has yet been found. The fungus has not yet been obtained in culture. The vegetative growth is mycelial but the hyphae are very narrow (<3 μm) with vesiculate nodes. The oospores are strictly plerotic. Oogonial and oospore walls are distinctive with unique ultrastructure. The peronosporomycete is a typical aero-aquatic fungus, having markedly buoyant propagules, due to the possession of long, recurved, oogonial outgrowths covering the oogonium sufficiently densely so as to retain air between them and the oogonial surface after exposure and reimmersion. Its habitat, in the lower layers of submerged deciduous leaf litter, suggests survival in an anaerobic environment and a fermentative capacity. An affinity with Pythiogeton is proposed, and Pythiogeton is made the type genus of a new family, the Pythiogetonaceae.