In this investigation, we have determined the life span of the fruit bodies of Agaricus bisporus grown in a protected cultivation environment as 36 d. We describe the morphological changes occurring in ageing mushrooms and find that signs of senescence become visible around day 18; they steadily increase in amplitude towards the end of the fruit bodies' life. Cytologically, karyolysis and focal cytoplasmolysis were the first signs followed by indications of an increased permeability of the cytoplasmic membranes and by structural changes of the cell wall. These changes result in extracellular aggregations of the lytic cell remains encapsulating or bridging the hyphal cells. Cells of the stipe tissues were transformed to empty cylinders or had irregularly collapsed. Most basidia and subhymenial cells remained alive even on day 36. When the mushrooms were cultivated according to our usual growth procedures, about 50% of the fruit bodies were infected by Trichoderma harzianum and/or Pseudomonas tolaasii on day 18; all fruit bodies died on day 24 due to diffuse bacterial and mycotic infections manifesting themselves by tissue necrosis and discoloration of the caps and stipes. When none of the fruit bodies was harvested at the time of the first flush they soon formed a canopy of pilei and their growth ceased. On day 14, all these fruit bodies showed widespread mixed infections followed by a diffuse liquefaction necrosis of all tissues including the hymenium. Post-harvest fruit bodies kept at ambient temperature or at 2 °C at low r.h., or at 20° at high r.h. revealed a diffuse cell wall destruction which was followed by cytoplasmic degeneration in due course. Fruit bodies kept refrigerated had the least gross and cell structural changes during our observation period of 7 d. We conclude that the morphological changes occurring in post-harvest and in senescent fruit bodies of Agaricus bisporus are different.

DNA was extracted from dried specimens of nine taxa of the Cantharellaceae. Approximately 325 bases near the 5′ end of the nuclear 28S ribosomal gene were sequenced, and the sequences were compared. Sequence analyses demonstrated that Cantharellus and Craterellus should be treated as distinct genera. The phylogeny generated using parsimony suggests that Cantharellus tubaeformis and Pseudocraterellus sinuosus should be considered species of Craterellus. As a result of this study, we recognize the first placement of these two species in Craterellus by Fries and Quélet. A reassessment of the morphological characters used to separate Cantharellus and Craterellus is indicated.

The two forms of acid phosphatase secreted by Botrytis cinerea were purified, characterized and found to possess fundamentally different properties. The phosphate-repressible acid phosphatase was a monomer of clearly defined molecular weight (55–56 kDa), with a polypeptide component of 43 kDa. The enzyme was secreted through the hyphal apex and accumulated in the culture fluid. Its high affinity for a wide range of substrates rendered it suitable for a putative role as an extracellular phosphate-scavenging enzyme. Secretion of a constitutive acid phosphatase occurred at low levels in phosphate-enriched culture; at phosphate starvation, the activity of this enzyme was enhanced ten-fold in the culture fluid and two-fold in the cell wall. The constitutive enzyme had strikingly different properties from those of the repressible form. It consisted of a 93 kDa polypeptide which was heavily glycosylated such that the secreted protein displayed size heterogeneity of 140–200 kDa by SDS–polyacrylamide gel electrophoresis and 320–450 kDa by native Sephacryl S-300 chromatography. Irrespective of the phosphate status, most of the secreted constitutive enzyme activity was retained by the cell wall. These results were consistent with ultrastructural histochemical observations which suggested that this enzyme form was secreted by a novel pathway via the fusion of vacuoles with the plasma membrane in mature hyphal segments.

An assay based on the competitive polymerase chain reaction (PCR) was developed to quantify Glomus mosseae, an arbuscular mycorrhizal (AM) fungus, within plant roots. Using previously designed G. mosseae specific primers, a heterologous internal standard was constructed by amplifying Pseudomonas DNA under low stringency annealing conditions. Co-amplification of G. mosseae and internal standard DNA within leek root extracts provided accurate quantification of target DNA. Colonization of leek roots by G. mosseae was monitored in a comparative study by competitive PCR and microscopy, a conventional method of quantification. These two methods gave closely parallel data for G. mosseae colonization from three different inoculum levels over a 6 week period. Results indicate that competitive PCR is a sensitive and accurate method of quantification. The major advantage of competitive PCR over microscopy is that it can quantify specific AM fungi.

To imbibe and germinate urediniospores require free water or near saturated atmospheres in which both adsorption of water is maximal and capillary condensation pads form. The rate of spore germination is influenced by the amount of free water available. During imbibition, spores swell and capillary pads form beneath spores in contact with the substratum. These pads greatly increase the area of contact with the substratum. Pad area fluctuates and may depend on the balance between the rate of capillary condensation and the rate of uptake of fluid by spores. When spores, on leaves or cellulose acetate, are misted with water they imbibe rapidly and germinate. Adhesion pads which form under fully imbibed, germinating spores are morphologically similar to capillary pads but they differ in composition. On synthetic surfaces, during imbibition of spores and under microscopic glass beads, pads are composed principally of volatile capillary condensation and are removed when samples are freeze-dried. On host surfaces, when spores are fully imbibed and germinating, pads contain non-volatile soluble materials derived from both pathogen and host. These substances are not removed by extended freeze-drying.

Elicitins, holoproteins which act as inducers of hypersensitivity on tobacco, were considered as a characteristic of Phytophthora. They are also produced, along with glycosylated isoforms, by three species belonging to the related genus Pythium, Py. vexans, Py. oedochilum and Py. marsipium, while other Pythium species do not possess such proteins. Various elicitin-like sequences were determined, bringing novel features to the elicitin family, such as an histidine residue and C-terminal extensions on the deduced peptide sequences. As the unique elicitin content of these species supports a distinct location among Pythiaceae, we suggest the separation of vexans, Py. oedochilum and Py. marsipium from Pythium and consider them as linking species between Phytophthora and Pythium.

The temperature optima for germination, radial hyphal extension rate and sporulation were determined for two isolates of Metarhizium flavoviride from acridoid hosts. I91-609 exhibited lower temperature optima for hyphal extension (25·5 °C) and sporulation (24°) than IMI 330189 (27° and 25°, respectively), although temperature optima for germination were similar (ca 30°). The temperature optimum for sporulation was lower than that for hyphal extension.

Further studies were carried out on I91-609 to investigate the effect of temperature and dose on the infection mortality rate of the grasshopper pest, Zonocerus variegatus. Increasing dose resulted in a decrease in mean survival time regardless of incubation temperature. Dose and temperature were shown to interact, with the effects of dose increasing at temperatures either side of the optimum. Furthermore, for each dose, the optimum temperature for infection was estimated to be ca 5° higher than the optimum for growth, and no significant relationship was identified between hyphal extension rate in vitro and host survival time. The implications of these results are discussed with regard to the selection of isolates for use in biological control.

A mathematical model is presented which qualitatively describes the growth kinetics of the aphid-pathogenic Erynia neoaphidis in liquid culture. An essential feature of the model is that it allows for the presence of a toxic component within the growth medium which may be broken down by an extracellular enzyme released by the biomass. In this investigation, the toxin was oleic acid which had previously been shown to be essential for the growth of E. neoaphidis, but only at low concentration.

The model reproduces a number of unusual features of the kinetics of growth of E. neoaphidis in liquid culture. These include: the requirement for a high inoculum concentration to successfully initiate growth in liquid culture; failure to grow in continuous culture under conditions similar to those supporting successful batch culture; a reduced growth yield in continuous culture compared to batch culture; a depressed apparent specific growth rate in continuous culture compared to batch culture and, deviation from the usual exponential decrease of biomass concentration during washout. Through the development of the model, and the application of predictions derived from it to the laboratory situation, continuous culture of E. neoaphidis was achieved for the first time.

Conidial germination in Neurospora crassa was inhibited by the anticalmodulin (CaM) agents calmidazolium (CaMZ) and trifluoperazine (TFP), indicating the importance of CaM-dependent events during vegetative growth. An increase in intracellular CaM concentration, observed during conidial germination, was associated with enhanced incorporation of [3H]phenylalanine into CaM and increased CaM-dependent protein kinase activity. Phosphorylation of two proteins (71 and 25 kDa) during conidial germination, and of four proteins (71, 47, 38 and 32 kDa) during hyphal elongation was noted to be CaM-dependent since these phosphorylations were inhibited in vitro by CaMZ. The possible regulatory functions of CaM during conidial germination are discussed in relation to phosphorylation of specific proteins during vegetative growth in N. crassa.

‘Casa Lis’ is the most characteristic building in Salamanca, Spain, belonging to the modernist trend. It was built with Villamayor sandstone from nearby Salamanca, which has high porosity providing an easy medium for water absorption and capillarity. During a restoration process on the southern wall, near an underground water flow, two well defined, naturally developed layers were observed on the sandstone surface: an outer, hard crust with greyish shades and whitish salt patches resulting from rising damp, and an inner, green layer with organic material linking the sandstone to the inorganic crust. The microbiological study of this biofilm showed an ecologically obligate, stable mutualism between a dematiaceous mitosporic fungus (Septonema tormes sp. nov.), a coccoid cyanobacterium (Cyanothece-group) and a green alga (Gloeocystis rupestris), with the accumulation of different metabolites excreted by these microorganisms. The case reported here is one of the few studies where a microbial mat, in association with the external crust, avoids a further weathering of the stone because of an unforeseen biopreservation effect due to the maintenance of humidity at constant levels under the crust avoids changes in clay swelling and subsequent surface arenization of the sandstone. The lichenized complex of a mitosporic mycobiont and two photobionts, in this case, has not been reported before as a stable association on this kind of substrate.

Mycovellosiella malloti-repandi, M. nerii-indici and M. solanacearum, occurring on Mallotus repandus (Euphorbiaceae), Nerium indicum (Apocynaceae) and Solanum verbascifolium (Solanaceae), respectively, are described and illustrated. The first was collected from the North-Eastern Terai region of India and the other two from Nepal.

In response to the need for a faster, more reliable method for identifying Phytophthora cinnamomi in cork oak soils in Portugal, a simple, fast, sensitive molecular identification method is described. It is based on a colorimetric assay which involves an oligonucleotide capture probe covalently immobilised on microtitration wells, a multi-biotinylated oligonucleotide detection probe and the PCR-amplified target DNA. The target DNA is a 349 bp DNA fragment partially covering the 3′-translated and 3′-untranslated regions of the cinnamomin gene. When the specificity of the PCR reaction was evaluated in vitro using isolates of P. cinnamomi and eight other Phytophthora species, including the related P. cambivora, it was specific to P. cinnamomi. When 30 isolates of P. cinnamomi from oak roots in southern Portugal were assayed, 26 gave a strong positive response. The assay has a sensitivity of about 2–5 genome equivalents of P. cinnamomi. The reason for the negative response of four isolates remains unclear.

Didymium subreticulosporum, a rare species from Valencia, is described and illustrated by SEM and LM photographs, and compared to related species.

In Melanospora zamiae a total of five nuclear divisions took place during ascosporogenesis. The first and second divisions were meiotic in which the single diploid nucleus divided into four haploid nuclei. The mitosis that followed gave rise to eight nuclei which characteristically assumed a 1[ratio ]4[ratio ]3 (apical[ratio ]middle[ratio ]basal) spacing in the clavate ascus. After ascospore delimitation, each nucleus in the young ascospore underwent two successive mitoses producing four haploid nuclei in each spore. Equatorial arrangement of these nuclei was observed in the mature ascospores.

Coccodothis sphaeroidea var. mexicana var. nov., a fungus parasitic on Juniperus flaccida, is described and compared with typical C. sphaeroidea.

Chaetopsina hongkongensis sp. nov. from decaying palm rachids, and Kionochaeta australiensis sp. nov. from decaying wood submerged in a freshwater stream, are described and illustrated. Both species produced setose conidiophores and phialidic conidiogenous cells. The former is distinct in having polyblastic conidiogenous cells with multiple denticulate loci, and is compared with C. polyblastia. In Kionochaeta australiensis conidiophores have accessory setiform lateral branches, and it is compared with K. keniensis, K. pughii, and K. ramifera. The delimitation of these two genera is discussed with additional information provided from an SEM study of conidiogenous characters in C. hongkongensis.

Samples from the intertidal zone of mooring posts of oak standing in Svanemøllen Harbour and samples from fallen oak trees lying in the waterline at Strandegaard Dyrehave were examined for the occurrence of marine lignicolous fungi. Buxetroldia bisaccata gen. et sp. nov., belonging to the Halosphaeriaceae, was encountered and is described from light microscope (LM) and SEM studies. The taxonomic position of B. bisaccata is discussed especially in relation to Tunicatispora australiensis; the main difference between the two species is found in the structure of the ascospore appendages.

Gyrothrix flagelliramosa, a new species of hyphomycete, found in litter floating in hydrocarbon-polluted water in the Santiago River, Argentina, is described and illustrated.

Two new coelomycetes with appendaged conidia collected on branches of Eucalyptus species in Tasmania are described, illustrated and compared with closely related taxa. They are Ciliosporella tuberculiformis sp. nov. on E. regnans and Neoplaconema cymbiforme sp. nov. on E. nitens.

Dictyocaulus viviparus and Pilobolus coexist in individual elk of the Yellowstone National Park's northern herd. It is suggested that Pilobolus transfers infective larvae to forage grasses, so spreading the lungworm disease.