Perhaps like many other mycologists, my initial encounters with fungi filled me with a desire to engage with mysteries: mysteries embedded in the diversity of form and function in fungi and how this diversity might be related to the life of the forest in which so many of these organisms appear to find their homes. In all good mysteries, the resolution of underlying causes at one level of comprehension only serves to reveal deeper levels for exploration.This can open the way into a cascade that nourishes a growing empathy with fellow beings and so assuages that most fundamental need to have a sense of belonging – to be as one; to be at peace; secure in the knowledge of idiosyncrasies embraced in the fondness of others. I dreamt that fungi would somehow eventually lead me and my fellow travellers down that cascade. I still do.

The occurrence and relative abundance of Pythium species were quantified by using a cucumber seed baiting assay and P10VP agar medium, and compared among three long-term cropping systems: continuous maize (CC), continuous soybean (SS) and maize soybean rotation (CS) at two Iowa locations. Soil types were different at the two locations. Four Pythium species were isolated, P. ultimum, P. torulosum and P. paroecandrum occurred in soils of all three cropping systems, and P. spinosum occurred in one SS and one CS field. More Pythium isolates were recovered from CS and SS composite soil samples than from CC samples. P. torulosum was isolated most frequently.

A total of 34 isolates of Cylindrobasidium evolvens were obtained from wounded Picea abies in five sample plots in Sweden and Lithuania. Population structure and genetic variation within the species were assessed by somatic incompatibility and arbitrary primed DNA (AP-DNA) analysis, using the M13 core sequence as a primer. All somatic incompatibility pairings between different C. evolvens isolates resulted in weak mycelial antagonism. The AP-DNA profiles indicate genetic variation was high in the species with no differentiation among isolates being found either on a large (more than 700 km) (R2=0·108) or a fine scale (200 m) (R2=0·024). In a plot, genetic similarity was significantly higher (P<0·02) among isolates from wounds infected during the previous 2 years than among the rest of the same population.

Agaricus bisporus browning is a common and economically detrimental phenomenon, in which melanogenic phenols are enzymically processed into quinones, which evolve eventually to melanins. This review deals with the two fundamental sides of this process, enzyme(s) and phenolic substrates. Mushroom tyrosinase, the main polyphenol oxidase encountered in the A. bisporus sporophore, is treated in the first part. Its overall molecular architecture, isoforms, primary sequence and genetic background are considered. The presentation of tyrosinase catalytic features, including enzyme assays, kinetic properties, substrates and inhibitors, is followed by a comprehensive description of the active site and reaction mechanisms. Because of their relevance for studies of mushroom browning during development and post-harvest storage, the occurrence and properties of latent enzyme forms, as well as the location of tyrosinase and variations of its activity during the A. bisporus life cycle, are also reviewed. The second part deals with the substrates, particularly γ-L-glutaminyl-4-hydroxybenzene (GHB) and its derivatives. Main data concerning the nature, obtention (by extraction or synthesis), spectrometric and chromatographic characteristics, chemical stabilities and biological properties of these typical Agaricaceae compounds are presented. Their distribution and levels according to the strains and flushes are described, as well as their variations during storage. Thirdly, the relationship between browning and the natural or pathogenic discolouration intensity is developed.

Dicellomyces calami sp. nov. was collected on rotang palm in southern India. It is the first Dicellomyces species on palms. A key to the known Dicellomyces species is presented and possible relationships of the genus are discussed.

Four rare microfungi, Dactylaria appendiculata, Exserohilum novae-zelandiae, Monacrosporium psychrophilum and Pleurocatena acicularis, were found when root pieces taken from wheat crops were incubated on low nutrient agar (SNA).

The saprotrophic fungus Fusarium culmorum, Penicillium hordei, Rhizoctonia solani and Trichoderma harzianum and the arbuscular mycorrhizal fungus Glomus intraradices were examined for content of phospholipid fatty acids (PLFA) and neutral lipid fatty acids (NLFA). The AM fungus differed from the saprotrophic fungi especially by its content of the fatty acid 16[ratio ]1ω5 which was absent in the saprotrophs. The fatty acid 18[ratio ]2ω6,9 was the dominant fatty acid of the saprotrophic fungi while it was negligible in mycelium of G. intraradices. Specificity in content of fatty acids made it possible to quantify G. intraradices and F. culmorum simultaneously in soil. Furthermore, a compartmented growth system made it possible to study mycelial interactions in the absence of roots. We measured hyphal spread of both fungi, hyphal 33P transport of G. intraradices and sporulation of F. culmorum. The two fungi did not interact according to the parameters used in this study. We conclude that fatty acid signatures may be a valuable tool when studying interactions between AM fungi and other fungi in root-free soil.

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.

Larix kaempferi seedlings, in the process of becoming established during the revegetation process following a volcanic eruption, were assessed for the types, occurrence patterns and diversity of their ectomycorrhizas along an elevation gradient. On the basis of macro- and microscopic characteristics, 12 types of ectomycorrhizas were classified. In general, ectomycorrhizal types differed more by site than by seedling age. The majority of root systems of seedlings with an age ranging from 1 to 5 years were colonized by 1 or 2 types of mycorrhizal fungi at low and intermediate elevations, 2 or 3 types at a higher elevation. Under the more stressed environments of high and intermediate elevations, the mean d.w. of 1 yr old seedlings, 40% of which were colonized by 3 or 4 mycorrhizal fungi, was double the weight of the same aged seedlings at lower elevation sites, only 10% of which were colonized by 3 or 4 mycorrhizal fungi. The correspondence between the type and frequency of mycorrhizas, the elevation gradient and litter accumulation suggests that change in litter accumulation along gradient may influence not only mycorrhizal types and their occurrence, but also the diversity of mycorrhizas on one seedling. Diversity of mycorrhizas on the same seedling is assumed to be critical for the establishment of seedlings from the very beginning on stressed sites, and may also be influenced by the availability of nutrients. The more intensive competition between mycorrhizas that occurs due to a reduction in the food source (tip roots) shared by the mycorrhizal fungi with similar resource requirements, results in frequent co-occurrence of mycorrhizas in the same root system or even the same root tip. As a result, the diversity of mycorrhizal types seems to become simplified as the seedlings age.

Prosthemium betulinum and Pleomassaria siparia are found in the same sites on birch branches. Single spore cultures of P. siparia produced conidia similar to those of P. betulinum. Restriction analysis of 18S rDNA did not differentiate between P. betulinum and P. siparia. Random amplified microsatellite fingerprints showed a high amount of variation, which was not explained by the origin of cultures. We conclude that P. betulinum is the anamorphic state of P. siparia.

Germlings of Uromyces appendiculatus respond to topographical stimuli and develop appressoria. During this period several genes are expressed, one of which is Inf24. Germlings were microinjected with a sense and antisense fragment of the ORF of Inf24. Sense (Inf24-S), 5′-ATG AGT GCT TCA TCG CAG CAG CAG-3′ fragment did not affect germling response to the topographical stimuli and the developed appressoria. Microinjection of antisense (Inf24-RC), 5′-CTG CTG CTG CGA TGA AGC ACT CAT-3′ blocked gene transcription and appressoria were rarely formed. Injection of Inf24-RC into already formed appressoria did not inhibit continued development of subsequent infection structures, e.g. penetration peg, sub-stomatal vesicle.

The thiophene 5-(4-hydroxy-1-butinyl)2,2′-bithienyl (BBTOH) strongly inhibited in vitro eight different dermatophytes. Epidermophyton floccosum proved most sensitive to all doses of BBTOH when applied in conjunction with uv-A irradiation. BBTOH also proved quite active against Nannizia cajetani, the only dermatophyte which was also strongly inhibited when treated (50 μg ml−1) and kept in the dark. For this reason, N. cajetani was chosen as the test organism for TEM and SEM aimed at determining what treatment-induced ultrastructural and morphological modifications had occurred. TEM revealed that the photoactive mechanism of BBTOH was similar to that of 2,2′[ratio ]5′,2″-terthienyl (α-T). SEM, on the other hand, showed that early culture aging resulted from treatment.

Arctic and temperate strains of Hebeloma spp. were grown in axenic culture on glutamic acid, alanine, lysine and NH4+ as sole sources of nitrogen (N), with excess carbon (C) or deficient C (supplied as glucose). Their ability to utilize seed protein as a natural N source was also assessed. All strains tested had the capacity to assimilate amino acids and generally utilized alanine and glutamic acid more readily than NH4+. Some strains were able to utilize amino C when starved of glucose C, and could mineralize amino-N to NH3-N. Arctic strains, in particular, appeared to be pre-adapted to the utilization of seed protein N and glutamic acid N, which is often liberated in high concentrations after soil freezing. The results are discussed in relation to their possible ecological importance.

Hebeloma strains of arctic and temperature origin, grown at 22° or 6°, were assayed for wall-bound and extracellular acid phosphomonoesterase (pNPPase) across a temperature range 2–37°. Only when grown at 6° was a cold active extracellular pNPPase induced in all the arctic strains and most of the temperature strains tested. Such enzymes are suggested to be an adaptation to low soil temperatures, and are discussed in the context of ectomycorrhizal access to soil PO4− monoesters at low temperature.

In situ gene amplification (in situ PCR) is a recent, powerful molecular technique which allows the localization of low abundance nucleic acids targets directly within tissue sections. The work presented here is, to our knowledge, the first report of successful direct detection of in situ PCR amplification with fluorescently-labelled primers, and the first successful in situ PCR performed on arbuscular mycorrhizal (AM) fungi. Ribosomal SSU genes within AM fungal spore sections were amplified by using fluorescent, glomalean-specific primers, then directly detected by means of epifluorescence microscopy. Different controls confirmed the successfulness of the in situ amplification. These results open new avenues in the study of arbuscular mycorrhizas, where genetic processes seem to be transient and very localized.

Colletotrichum gloeosporioides f. sp. malvae (C. g. malvae) is effective in controlling round-leaved mallow (Malva pusilla), a common weed in the Canadian prairies. To confirm host range experiments, the latent period and penetration of C. g. malvae was determined under controlled environmental conditions on field crops (wheat, flax, lentil, mustard, rape seed, sugar beet, sunflower, safflower) and on crops in the Malvaceae (okra and cotton) as well as on round-leaved mallow, from which C. g. malvae was originally isolated. In non-target crop plants, very little germination, appressoria formation, or penetration of C. g. malvae were observed compared with the infection occurring on round-leaved mallow. Of the non-target species tested, most penetration was observed on safflower, with only 5·1% penetration form the total appressoria formed compared with 17% on round-leaved mallow. C. g. malvae was re-isolated from all crop cvs tested, but only from inoculated stems and leaves. The recovery of C. g. malvae significantly decreased with time of isolation of plant material for most cvs. Of the millions of conidia applied to non-target crops, only a few were present after 72 h, few appressoria were produced, and only minimal penetration occurred. The behaviour of C. g. malvae conidia on the surface of leaf material of non-target plants supports the visual disease ratings observed in the experiments of crop tolerance under controlled and field condition and host-range tests.

Chlorophenols have been commonly used as disinfectants and preservatives but their recalcitrant nature, persistence and toxicities make them priority pollutants for treatment. The ability of various fungi (Armillaria gallica, A. mellea, Ganoderma lucidum, Lentinula edodes, Phanerochaete chrysosporium, Pleurotus pulmonarius, a Polyporus sp., Coprinus cinereus and Volvariella volvacea), and the spent mushroom substrate of P. pulmonarius (SMS) to remove pentachlorophenol (PCP) was compared using a batch cultivation system. The PCP content was monitored by reversed phase HPLC, and the breakdown products were determined by GC-MS. Possession of ligninolytic ability was determined by ability to decolourize the dye Poly-R478 at two N levels. Not all the fungi tested decolourized the dye, and for those that did, not all showed N-modulation response on dye decolourization. All these fungi showed active breakdown in addition to biosorption as their PCP removal mechanisms. The tolerance level of the fungus towards PCP did not correlate with its degradative capacity, nor to its ability to decolourize Poly-R478. The A. mellea strain showed the highest degradative capacity (13 mg PCP g−1 mycelium; D.W.) while the Polyporus possessed the greatest biosorption capacity (31 mg PCP−1 mycelium, d.w.). In comparison, Pleurotus SMS harbouring both bacteria and fungi functioned over a wide range of initial PCP concentrations and reached a higher degradative capacity (19 mg PCP g−1) in only 3 d. GC-MS chromatograms revealed only residual PCP peaks in SMS extracts, a contrast with the mycelial incubations in which a variety of breakdown products were detectable. Use of SMS for bioremediation of biocide-contaminated sites seems promising.

Syncephalastrum racemosum RR 96, MTCC 2774, synthesized extra-cellular β-amylase (EC 3.2.1.2) when cultivated with starch as sole carbon source. The strain showed maximum β-amylolytic activity on the fourth day of cultivation, and the partly purified enzyme showed highest activity at 60° and pH 5. About 60% of the activity was found to be retained within the range pH 4–7. The enzyme activity was not increased in presence of exogenous thiols and remained unaffected in presence of heavy metals and the thiol inhibitor p-chloromercuribenzoate, indicating the absence of thiols at the active site of the enzyme. Absence of substrate cross specificity and ability to hydrolyse waste starches made the enzyme competent for industrial application.

This listing covers the period July 1, 1997 through to August 31, 1997. Citations are arranged in groups which roughly correspond with the British Mycological Society's Special Interest Committees. All correspondence about this item should be addressed to the Executive Editor. Reprints of this feature will not be available.