Arbuscular mycorrhizal (AM) fungi are obligate biotrophic organisms. Root organ culture (ROC) can be used to grow these fungi under in vitro conditions. The ROC technique was used with Gigaspora margarita and Ri T-DNA transformed carrot roots to examine the fungal growth and physiology under long-term axenic symbiosis. The fungus formed spores inside the host roots under in vitro conditions. Sporulation was a temporal phenomenon found in dual cultures more than 18–20 mo old. The spores were formed singly or in rare cases clusters of two or three. No preferential zone of formation was found. The spores formed intraradically were 10–15% of the total spores formed in a single culture. These intraradical spores were analysed for their morphology and DNA polymorphism pattern with spores which had formed conventionally in the medium. Both analyses showed no detectable variation. This is the first report of spore formation by Gigaspora inside the roots of a host.

Contour-clamped homogeneous electric field has been applied to analyse genome size and organisation of two important pathogens of barley, Pyrenophora graminea and P. teres.

Electrophoretic karyotypes of four P. graminea isolates resolved 6–8 chromosomal bands, depending on the isolate, while the one P. teres isolate analysed contained six chromosomal bands. Chromosome length polymorphism was observed among P. graminea isolates. For both fungi the chromosomes ranged from 1.6 to more than 6 Mb, with chromosomes larger than 6 Mb migrating as a single band within the compression zone of the gel.

Alkali-extractable and water-soluble cell-wall polysaccharides were purified from cell walls of some species of Fusarium and Gibberella. Their structures were determined by chemical analysis and NMR. The polysaccharides consisted of a main chain of β-(1 → 6)-linked galactofuranose units almost fully branched at positions O-2 by single residues of glucopyranose or acidic chains containing glucuronic acid and mannose. Individual differences were found, concerning the proportion of neutral and acidic side chains. These polysaccharides showed major differences from those of Microdochium nivale, Plectosphaerella cucumerina, Fusarium ciliatum, F. aquaeductuum and F. cavispermum. Highly specific polyclonal antibodies were raised against this structure, which were used in immunocompetence and immunofluorescence experiments.

Oxalate decarboxylase activity was present in liquid culture medium and mycelium of Agaricus bisporus. Enzyme activity in the mycelium peaked at two-weekly intervals after primary growth phase and into secondary metabolism, with activity peaks in the medium occurring 7 d later than in the mycelium. The enzyme was partially purified and had two isozymes with pIs 3.0 and 3.4. Characterization of the protein by SDS–PAGE and Western blotting against a polyclonal antibody raised to oxalate decarboxylase from Collybia velutipes showed a major protein band of 64 kDa. Oxalate decarboxylase was also detected in the fruit body up to the cup stage of development. The pH optimum for the enzyme was 3.6 and temperature optimum was 35 °C.

Five local oak species, Quercus boissieri, Q. calliprinus, Q. cerris, Q. ithaburensis and Q. libani were identified as hosts of Tuber melanosporum, the black truffle of Perigord, following inoculation of roots. Q. cerris and Q. libani developed abundant mycorrhizal roots, similar to the amount found in roots of Q. pubescens, the traditional host of this mycorrhizal fungus. Roots of Q. ilex, Q. hartwissiana and Q. pedunculiflora, introduced species in Israel, were also heavily colonized by the mycorrhizal fungus. Mycorrhized hazel (Corylus avellana) roots, were also obtained by the same inoculation procedure. Recovery of T. melanosporum from roots of inoculated oak was improved when chloramphenicol was added to the isolation medium. Recovery varied between 14 and 54% for C. avellana and Q. calliprinus, respectively. Recovery was highest for the two local species, Q. calliprinus (54%) and Q. boissieri (50%), followed by Q. pubescens (44%) and Q. ilex (41%). Identification of the isolated fungi was conducted using arbitrarily-primed PCR. Identical band patterns were observed among AP-PCR-amplified DNA extracted from an authentic culture of the fungus, ascocarps (truffles) and cultures isolated from roots. In addition, AP-PCR was reliable for differentiating between representative isolates of T. melanosporum, T. magnatum, T. borchii, T. maculatum, T. dryophilum, T. macrosporum and T. uncinatum.

Many intimate associations between different species of ectomycorrhizal fungi are inferred on the basis of the consistent co-occurrence of their fruit bodies. Suillus bovinus and Gomphidius roseus, where the latter never occurs without the former, is one example. This association was examined with PCR identification and light microscopy. S. bovinus and G. roseus were unambiguously separated on the basis of RFLPs of the PCR-amplified ITS region of ribosomal DNA. Tuberculate mycorrhizas of Pinus sylvestris sampled under fruit bodies of G. roseus and S. bovinus were investigated and the majority were identified as mixed associations involving both G. roseus and S. bovinus. Tuberculate mycorrhizas, which macroscopically resemble the ones of Suillus species, contained typical chlamydospores of G. roseus and they had haustoria where G. roseus hyphae penetrated the cortical root cells. Pine seedlings collected near the fruit bodies of the two species were mainly colonised by S. bovinus. Mycelial rhizomorphs collected under the fruit bodies of G. roseus were identified as S. bovinus, while both fungal species were present at the base of G. roseus fruit bodies. The significance of these observations and the possibility that G. roseus acts as a parasite are discussed.

Individual tall fescue (Festuca arundinacea) plants infected with both Neotyphodium coenophialum and N. lolii endophytes, and individual perennial ryegrass (Lolium perenne) plants infected with both N. lolii and Neotyphodium LpTG-2, were obtained following inoculation of naturally infected seedlings with the second endophyte. Differences in the ability of the endophytes to produce conidia, together with colony characteristics, enabled the endophytes in plants to be identified following incubation of excised leaf tissue on potato dextrose agar. Most tillers of dually infected plants were infected with just a single endophyte, but tillers infected with two endophytes were identified in three tall fescue plants. In these tillers one endophyte was always present at a much higher concentration than the other. Over time the incidence of dually infected tillers decreased and no tillers with both N. coenophialum and N. lolii were present 5 months after the associations were established. No evidence was obtained of exchange of nuclei between different endophytes present in dually infected tillers giving rise to heterokaryons or interspecific hybrids.

Extraradical hyphae of Glomus intraradices or G. claroideum were extracted from root free sand of two-compartment pot cultures and used to determine fungal phosphatase activity [p-nitrophenyl phosphate (p-NPP) hydrolysis]. Enzyme activity was assayed with respect to pH, temperature and different fractions of the hyphae (external soluble, wall-bound and internal phosphatases). The results showed an overall maximum enzyme activity at pH 5·2–5·6 for both fungi, with a possible secondary maximum at pH [ges ]8·8 for G. claroideum. Of the two fungi tested, G. intraradices had the highest external phosphatase activity in two experiments and the same activity in one experiment, reaching 184 μmol p-NPP hydrolysed mg−1D.W. h−1. Phosphatase activity at pH 5·2 decreased sharply with temperature, with 4·5 and 10·5% of the enzyme activity remaining at 5 °C relative to that at 37° for G. intraradices and G. claroideum, respectively. Separation of the phosphatase activity into external soluble, wall-bound and internal fractions revealed that up to 70% of the measured activity was associated with the hyphal wall, and the rest with internal structures. Exuded phosphatases were not found in measurable amounts. The implications of these results on possible hyphal utilization of organic P in soil are discussed.

At one sampling site an entomopathogenic fungus, tentatively identified as Tolypocladium cylindrosporum, was found to severely reduce populations of hibernating turnip moth larvae (Agrotis segetum) in consecutive winters, while it was never recorded from other collection sites. It produced cylindrical conidia (5·5×2 μm) and smaller, ellipsoidal conidia (3·8×2·8 μm) in slimy heads from flask-shaped phialides with thin necks, which occasionally were bent. Phialides were scarce and never occurred in true verticils. Colonies were pale yellow, cottony on artificial medium, with a characteristic mouldy smell. The infectivity of the fungus was tested in a semi-field trial, where suspensions of conidia were applied to hibernating turnip moth larvae in plastic buckets. The experiment also included buckets with larvae and/or soil from the infested site in order to study the natural fungal-induced mortality. The experiment was started in mid-October and buckets were collected four times from January until May. The fungus had caused high mortality by January, when almost 70% of the treated larvae were infected and by March more than 94% of the larvae had been killed. For larvae from the naturally infested site the prevalence was 21% in mid-October and by March it had reached 93%. The ability of the fungus to infect insects at low temperatures may be related to a relatively low optimum temperature for growth of 21 °C, which is lower than for the majority of entomopathogenic hyphomycetes. Host range studies with 10 insect species indicated that the fungus is probably specific to hibernating cutworms.

The genus Tricholosporum is characterised by cruciate spores. The formation of these basidiospores and their subsequent growth until release from the sterigmata, is described from a sequence of SEM photographs. The spores on a basidium form either a diad, a triad or a tetrad during their development. The outer cell wall layer of the basidiospore enlarges, resulting in the cruciate shape of the spores and the ultimate calyptrate appearance after release when desiccated. The spores are seceded sequentially.

The ultrastructure of the septal pore cap (SPC) of Asterodon, Asterostroma and Coltricia were examined to establish the taxonomic position of these genera. Asterostroma has dolipores with perforate SPCs and is classified in the Lachnocladiaceae. In contrast, Asterodon and Coltricia have dolipores with imperforate SPCs and belong to the Hymenochaetaceae. Other selected species of genera belonging to the Hymenochaetaceae like Hydnochaete, Coltriciella, Inonotus, Onnia, and Cyclomyces also contained imperforate SPCs. Coltriciella, Inonotus and Cyclomyces moreover presented a lamella of endoplasmic reticulum above the imperforate SPC after chemical fixation. Such a lamella could rarely be observed in Coltricia only after high-pressure freezing and freeze substitution. Cryofixed fungal cells of Cyclomyces and Coltricia showed differences in the architecture of the matrix of the SPC. Coltricia showed a more layered matrix structure than the SPC of Cyclomyces. In addition, transmission- and scanning electron microscopy revealed an indent in the centre of the imperforate SPC of Cyclomyces, indicating a reduced thickness, and resulting into a tented profile in cross-sections.

Two species of Melanochaeta and three species of Sporoschisma are reported from Thailand. Two connections of Sporoschisma and Melanochaeta are confirmed. Melanochaeta hemipsila has Sporoschisma saccardoi as its anamorph with a Chalara synanamorph in culture. Melanochaeta garethjonesii is described as a new species and linked with S. uniseptatum. S. nigroseptatum was recorded but no evidence of a Melanochaeta teleomorph state could be found.

The discoloration of A. bisporus after infection by Pseudomonas tolaasii, P. gingeri, P. agarici, P. reactans, Verticillium fungicola and Trichoderma harzianum can be distinguished by chromametric measurements. Infection with P. tolaasii caused a specific colour change, independent of the bacterial concentration applied (ΔL = 54.7, Δa = 16.6, Δb = 28.7%). The colour change provoked by P. gingeri had a characteristic profile different from P. tolaasii (ΔL = 36.3, Δa = 14.1, Δb = 49.5%). P. agarici and P. reactans provoked only a slight increase of red colour. Response to T. harzianum was orange, and to V. fungicola brown, similar to P. tolaasii but paler and more yellowish. All pathogens except P. reactans provoked degradation of total tyrosinase to variable extents. Activation of tyrosinase was only observed after infection with P. tolaasii (to almost 7%) and V. fungicola (to 3%).

A panel of monoclonal antibodies (MAbs) was raised to Botrytis cinerea using four different immunogens. Co-immunization with cross-reactive monoclonal antibodies helped to increase the percentage of specific hybridoma cell lines produced. The abilities of the MAbs to detect fungal antigens in extracts from infected tissue was correlated with their taxonomic specificities and with the localization of the antigens on the surfaces of the hyphae and conidia. Four distinct groups were identified: taxonomically unrelated, near-genus-, genus- and near-isolate-specific. Genus-specific antibodies gave the highest absorbance values in ELISAs with extracts from infected plant tissues. MAbs from this group all recognized heat-stable epitopes on antigens expressed along the length of the extracellular matrix of the hyphae and surface of the conidia. Antibodies from this group were all IgG1 antibodies.

The fatty acid composition of pea roots with and without the root pathogen Aphanomyces euteiches was studied using whole cell fatty acids (WCFA), phospholipid fatty acids (PLFA) and neutral lipid fatty acids (NLFA). Initial screening for A. euteiches markers using WCFA analysis showed that the fatty acids 14[ratio ]1ω9, 14[ratio ]0, 20[ratio ]4 and 20[ratio ]5 were specific to roots infected with A. euteiches. The amounts of these fatty acids correlated positively with the percentage of the root system containing A. euteiches oospores, suggesting that they could be useful indicators of A. euteiches root-infection levels. Analysis of the composition of phospholipid fatty acids (PLFA) and neutral lipid fatty acids (NLFA) of pea roots with and without A. euteiches showed similar specificity as found with WCFA analysis. PLFAs and NLFAs specific to roots inoculated with A. euteiches were also present in mycelium from pure culture of A. euteiches. The PLFAs 14[ratio ]0, 20[ratio ]4 and 20[ratio ]5 were used to estimate biomass of A. euteiches and the NLFAs 14[ratio ]1ω9, 14[ratio ]0, 20[ratio ]4 and 20[ratio ]5 were used as indicators of energy reserves of the pathogen. The possible use of specific fatty acids to study growth and development of A. euteiches in pea roots is discussed.

We isolated ascospores and conidia of fungi associated with leaf spots common in birch leaves, and prepared mycelial cultures from them. The taxonomic positions of the fungi were determined by analysing morphological characteristics with photomicroscopy. The relationship between the teleomorph and anamorph was tested using random amplified microsatellite fingerprints, in which the variation was not explained by the origin of isolates (e.g. ascospores or conidia). This suggested that the ascospores and conidia would have been produced by the same biological species. In pathogenicity tests birch leaves inoculated with mycelia derived from ascospores developed spots showing that the fungus could be the cause of the leaf spots. The anamorph was isolated from the developing spots. Based on these results and on review of the literature we concluded that the causative agent of the leaf spot disease of birch in Finland is Pyrenopeziza betulicola, the anamorph of which belongs to Cylindrosporium.

Catalase and ascorbate peroxidase enzymatic activities were examined during the interaction between Nicotiana tabacum and the arbuscular mycorrhizal Glomus mosseae. Transient enhancements of both enzymatic activities were detected in the inoculated plant roots coinciding in time with the stage of appressoria formation in the root surface. The analysis of free salicylic acid content in roots revealed that the increases in enzymatic activities were coincident in time with the accumulation of SA in inoculated roots. These data indicate that the first reaction of the root cells to the invasion of arbuscular mycorrhizal fungi is a defence response.

Sclerotinia nivalis causing lettuce drop was found in central China. It was identified on the basis of comparisons of morphological features, cultural characteristics and sclerotial proteins with those of S. sclerotiorum, S. trifoliorum, S. minor and S. nivalis. This is the first report of S. nivalis in China and lettuce is a new host for this pathogen.

About 35 Trichoderma species are currently recognised on the basis of morphological and molecular characters. Besides the role of a few of these species in biotechnology, several seem to play prominent roles in soil ecosystems. With a goal of investigating global biodiversity in Trichoderma, we report on the occurrence of Trichoderma spp. in Russia (Moscow and Ural areas), Siberia (Krasnoyarsk area) and the Himalayan mountains – areas from which no Trichoderma isolates are so far available. The ITS 1 and 2 sequence of the rDNA cluster of the 75 isolates obtained was compared with that of ex-type strains and taxonomically established isolates of Trichoderma. Thirty-nine isolates were positively identified as T. atroviride, T. virens, T. hamatum, T. asperellum, T. koningii and T. oblongisporum. A further 26 isolates yielded six closely related ITS1/2 sequence types, which are highly similar yet different from the ex-(neo)type strains of T. harzianum and T. inhamatum. Some of these genotypes (i.e. 1 and 2a) occurred only in Russia/Siberia, whereas others (2b, 3, 4 and 5) were found only in the Himalayas. RAPD analysis was consistent with these genotypes, and revealed genetic homogeneity even between strains from widely separated areas. Parsimony analysis placed these five genotypes, together with T. harzianum, T. inhamatum and the mushroom-aggressive T. harzianum ‘biotype 2’ in a large, unresolved ‘harzianum’ clade. Ten isolates were not safely alignable within known species, and five of them may be undescribed taxa: one isolate from 2700 m elevation in the Himalayas, which clustered in parsimony analysis at a basal position in section Longibrachiatum; and four isolates, displaying two closely related sequence types, forming a separate clade with T. stromaticum. The five remaining isolates also exhibited three unique ITS1 and 2 sequence patterns, but parsimony analysis placed them into the unresolved ‘harzianum’ clade, and their relationship to T. harzianum is thus unclear. The study shows that molecular screening of uninvestigated geographic areas can lead to the identification of isolates with new ITS1 and ITS2 sequence patterns, some of which may be new taxa. It also reveals that T. harzianum is at present the genetically most diverse member of the genus.

The development and selection of a morphological variant were systematically observed during continuous cultures of Aspergillus oryzae A1560 carried out at a dilution rate of 0.1 h−1. The selection was monitored by following the changes in the population morphology and in the α-amylase production during these experiments. A mathematical model for the selection was proposed assuming that the inoculum consisted of a mixed population. Growth, glucose uptake and α-amylase production for the selected morphological variant were further investigated in glucose-limited continuous cultures carried out at dilution rates ranging from 0.06 to 0.2 h−1. The selected variant was distinguished from the parental strain in three main aspects: (1) a higher capacity of α-amylase production at all dilution rates investigated; (2) a 36% higher maximum specific growth rate; and (3) a more sparsely branched mycelium, with fewer aerial hyphae and loss of sporulation ability on solid media.