Genetic characterization of 15 aggressive weed mould strains that were identified morphologically as Trichoderma harzianum (sensu Rifai) from mushroom compost in commercial units in North America (designated T. harzianum group 4) was undertaken using various molecular techniques. RFLP analysis of rDNA revealed homogeneity among these strains; a low level of polymorphism was detected in mitochondrial DNA. RAPD analysis also indicated a very high degree of homogeneity among the T. harzianum group 4 strains. Nucleotide sequence determination of the rDNA internal transcribed spacer (ITS) 1 revealed five base pair differences between T. harzianum groups 4 and 2. Comparison of molecular data on T. harzianum group 4 with that of T. harzianum group 2, which caused green mould epidemics in the mushroom industries of the British Isles, indicated that T. harzianum group 4 is not the same as group 2.

The morphology of infection structure development of Puccinia recondita f. sp. tritici on and in susceptible and resistant wheat lines inoculated with urediospores was examined by SEM. The germ-tube extends over the leaf surface and elongates perpendicularly to the long axis of the leaf. When the germ-tube encounters the stomatal lip, an appressorium forms over the stoma and the pore is entered by an infection peg produced on the surface of the appressorium in contact with the host leaf. At 6 h post-inoculation (hpi), infection pegs develop terminally substomatal vesicles (SSVs) in the substomatal chambers of all wheat lines. A septum separates each SSV from its interconnective tube. A primary infection hypha forms terminally from the elongated SSV either parallel to the long axis of the stomatal slit or perpendicular to the leaf surface. When a primary infection hypha attaches to a host cell, a septum forms cutting off the tip of the hypha, delimiting a terminal haustorium mother cell (HMC) by 12 hpi. Secondary infection hyphae arise from a position proximal to, and in the proximity of, the HMC septum. Additional HMCs are formed when a secondary hypha or a tertiary hypha adheres to a plant cell. Infection sites with HMCs were observed at 24 hpi and at subsequent sampling stages. There were no significant differences between the infection processes on the three wheat lines examined in this study.

Antrodia lalashana sp. nov. and Antrodiella formosana sp. nov. found growing saprotrophically on the decayed stems of Persea zuilhoensis and Abies kawakamii, respectively, in Taiwan, are described and illustrated. Cultural characters are described for the two species.

This paper reports the first biochemical characterisation of Tuber borchii mycelial strain ATCC 96540, grown in liquid media containing either glucose, fructose or sucrose. A new biochemical method, based on the estimation of total protein content, was developed for determining the amount of mycelium growth. This method is more sensitive than other methods, allowing growth to be monitored in the lag phase and when small amounts of mycelium are grown on a solid medium. Mycelium of T. borchii utilizes glucose and fructose as carbohydrate sources but grows poorly if at all on sucrose. In these experiments the functional state of the mycelium was evaluated by determining the activity of enzymes of the glycolytic and pentose phosphate pathways which are involved in producing energy and in supplying reducing power through the formation of reduced pyridine coenzymes. The biochemical data on mycelium growth were supported by observations on ultrastructural morphology which revealed the different steps in hyphal depletion during ageing. In addition, the monitoring of alanine content of the liquid media during mycelial growth indicated that there was an increasing loss of alanine from their cytoplasm as hyphae aged. The development of this procedure makes it possible to identify the conditions under which T. borchii is able to synthesize a mycorrhiza with a compatible host.

Candelabrum desmidiaceum sp. nov. and C. clathrosphaeroides sp. nov. are illustrated and described. Morphologically, they represent a new type of conidium development previously unknown in Candelabrum: the formation of a basal plate by dicho- or trichotomous branching of the conidial body in combination with branches growing upwards at the outer margin of the basal plate which are distinctly verrucose outside, forming a hollow sphere enclosing an air bubble in the centre. In Austria, both species were found mainly on submerged beech leaves, but in the U.S.A., C. clathrosphaeroides was isolated from submerged leaves of many different deciduous species, indicating a wider host range. Both species are aero-aquatic fungi, and C. clathrosphaeroides, at least, is widely distributed in temperate climates. A key to the species of Candelabrum is provided.

One hundred and thirty four dikaryotic isolates of Ganoderma, morphologically determined as G. adspersum, G. annulare, G. applanatum, G. brownii, G. lobatoideum, G. lobatum, G. lucidum, G. oerstedii, G. resinaceum, and G. tornatum, were examined by horizontal PAGE for eight enzymatic activities. A total of 94 bands were analysed. The objective was to evaluate the relatedness among the specific taxa by analysing numerically the isoenzymic patterns. To discern fungal individuals somatic incompatibility tests were used. Within each enzyme system several allozyme phenotypes could be observed. The enzymic systems analysed failed to yield diagnostic bands for each morphologically defined group, except the AKP system for G. resinaceum. Some bands were shared by all the isolates studied. On the other hand, diagnostic bands at the species complex level were encountered.

The ectomycorrhizal Laccaria bicolor, cultivated axenically in modified Pachlewski's medium, can use a broad spectrum of nitrogen and carbon sources. The fungus exhibited greater growth in the presence of ammonium or nitrate than with ammonium nitrate. With the latter salt, the drop in pH of the culture medium indicated that ammonium was taken up preferentially to nitrate. L. bicolor grew more poorly on amino acids such as glycine, alanine, aspartate and glutamate, the latter three being very poor carbon sources. By contrast, glycine was used as nitrogen and carbon sources. Glucose and maltose in mixture, with a 20[ratio ]5 ratio, were the most effective carbohydrates for promoting growth, followed by starch, dextrins, maltose, glucose and sorbitol. L. bicolor failed to grow in the presence of sucrose and galactose.

Isocitrate dehydrogenase (IDH), a key enzyme linking carbon and nitrogen metabolism, is present in L. bicolor as NAD- and NADP-dependent proteins. Both enzymes were stimulated in response to nitrogen starvation and appeared to operate in close association with the glutamine synthetase and NADP-dependent glutamate dehydrogenase of the fungus, indicating that 2-oxoglutarate produced by IDHs is probably utilized in the assimilation of inorganic nitrogen. The highest specific activities of NAD and NADP-IDH coincided in most cases with the rapid growth periods of the fungus, although in slow growing conditions obtained by addition of glycine or sorbitol to the culture media, only NADP-IDH activity increased in conjunction with growth. In addition, activity of the NADP-IDH was constantly higher than that of NAD-IDH. These results are indicative that the NADP-dependent enzyme plays a substantial biosynthetic role, possibly by an additional production of reduced nucleotides.

Gilmaniella bambusae sp. nov., from senescent culms of Bambusa tuldoides in Hong Kong, is described and illustrated. It differs from other species of Gilmaniella in having small conidia and conidiogenous cells with a verrucose wall. A key to and a synopsis of the known species of Gilmaniella is provided.

Schizochytrium limacinum sp. nov, a thraustochytrid, is described from sea water from a mangrove area of the Yap Islands in the west Pacific Ocean. It is closest to S. aggregatum, and differs from other Schizochytrium spp. in its limaciform amoeboid cells, the size of zoospores, released without an amoeboid stage, and the assimilation profile of carbon sources.

Pleurotus pulmonarius is a species of the oyster mushroom which has become the second most popularly cultivated mushroom in the world. In this study, we show that renewed fruiting from excised stipes can be used as a simple and rapid in vitro bioassay system to detect fruiting modulators. We used this and conventional cultivation techniques to examine the effects of cadmium, a potential contaminant from industrial sources, calcium, which is an ingredient in mushroom compost, and manganese, which has been claimed to improve the yield of P. ostreatus. All the three metallic salts did not affect sporulation. Calcium chloride addition shortened the time taken for the mushroom to fully cover the cultivation compost and improved yield. Insoluble calcium salts at higher concentrations had a similar though less pronounced effect. The calcium and total amino acid contents of fruit bodies also increased. Compost supplementation with calcium is desirable for cultivation of the oyster mushroom but not indispensable since the straw-based cultivation substrate is itself able to provide the required minerals. By contrast, manganese chloride retarded mycelial growth and decreased yield but increased the total amino acid content in the stipe whilst manganese sulphate did not enhance accumulation of manganese into fruit bodies. Excess manganese induced browning of vegetative tissues. Cadmium ions did not kill the oyster mushroom at 4·5 mM but reduced yield by 50%. At this concentration cadmium decreased the total amino acid content and affected the amino acid profile but did not affect the form and shape of the fruit bodies. Pleurotus pulmonarius concentrated cadmium to such an extent that consumption of as little as 20 g (D.W.) of the most contaminated samples would exceed the weekly limit tolerated by humans and thus pose a health hazard. Monitoring the heavy metal contents of mushrooms marketed for food is, therefore, advised as the source of the substrate for cultivation is usually not known.

The presence of the xylariaceous genus Entonaema in Thailand is confirmed. One collection from Chiang Mai Province, E. siamensis, is described as new.

Pestalotiopsis microspora is an endophyte associated with many plants including Taxus wallachiana. Isolates commonly produce taxol in liquid culture. Defining culture amendments to optimize taxol production by P. microspora is a critical step toward the realization of fungal taxol for treating human cancers. The lowering of phosphate and the addition of sodium benzoate in the medium increased taxol production. Sterol biosynthesis inhibitors, such as tebuconazole and triadimefon, dramatically increased taxol yields.

Genotypic variation among 62 strains of Aphanomyces euteiches, four of A. cochlioides, and a Saprolegnia sp. was investigated using RAPD analysis. Pathogenicity assays on pea, bean, alfalfa, red clover, and sugarbeet were used to determine host preference among the strains of A. euteiches and A. cochlioides. Pathogenicity tests revealed six pathotypes of A. euteiches with host preferences for bean, alfalfa, pea, pea and alfalfa, red clover and alfalfa, and bean and alfalfa. Another group of strains was non-pathogenic on the five plant species. The host of origin tended to be the host on which each strain incited the highest disease severity. A. euteiches did not incite root rot symptoms on sugarbeet, and A. cochlioides was pathogenic only to sugarbeet. RAPD analyses provided a measure of genetic diversity in Aphanomyces. Fifty random decanucleotide primers were screened with five test strains from four hosts representing different pathotypes, and 32 primers amplified DNA fragments from all five strains. Eight primers were chosen for most of this study based on number and polymorphic nature of the bands generated. RAPD assays of 62 strains of A. euteiches with the eight primers yielded 159 polymorphic and no monomorphic, strongly amplified bands. Cluster analyses of RAPD data revealed genotypic differences among three groups of A. euteiches which corresponded to their host of origin and host preference for bean, alfalfa, and red clover/alfalfa. Strains nonpathogenic on all plants tested formed another genotypic group, corroborating results from the pathogenicity assays that indicated this is a discrete group. The bean and non-pathogenic groups were the most distinct. The A. cochlioides and Saprolegnia strains were genotypically distinct from the pathogenic, but not the non-pathogenic strains of A. euteiches. Reproducibility of RAPD assays was confirmed by replicated amplifications and DNA hybridization analysis. Results indicated that A. euteiches is composed of distinct subspecific groups based on genotype and host preference.

Gloeocantharellus lateritius and Lentinellus pseudobarbatus, previously known only from their type specimens, are described, illustrated and discussed based on fresh collections made in southern India.

Inocybe inexpectata sp. nov., from Spain, is described and illustrated. It is characterized by its small size, brown–argillaceous tinges, strongly decurrent gills, absence of metuloid cystidia, cylindrical to suballantoid spores and a well-developed trichoderm.

Myriogenospora atramentosa produces partial to complete sterility of host grasses. Geographical and host species distributions were assessed and updated. It is reported only from the New World and appears to be limited to the highly evolved grass tribes Andropogoneae and Paniceae. Included in these tribes are the previously unreported host species Panicum scoparium, Paspalum urvillei, Erianthus brevibarbis, E. contortus, E. giganteus, and hybrids from crosses with Erianthus spp. Additionally, M. atramentosa is reported for the first time growing on Paspalum notatum (bahiagrass), and Panicum hemitomon in South Carolina, U.S.A. Sequence data (ITS regions 1 and 2 and 5·8S rDNA) from several isolates indicated that there is a significant level of DNA sequence differentiation between isolates of M. atramentosa, which suggests that there are at least two distinct sequence groups, or cryptic species, within the currently defined morphological species.

The green fluorescent protein (GFP) has been widely used as an extremely useful vital marker in a large number of organisms, but good expression in filamentous ascomycetes has not been reported. To facilitate the research of fungal development and fungal-plant interaction, we constructed two plasmid vectors for the expression of the synthetic SGFP-TYG gene in ascomycete species, and used these vectors for transformation of the maize pathogen Cochliobolus heterostrophus. High level expression of GFP was obtained, as detected by anti-GFP antibodies and by fluorescence microscopy. The intense fluorescence was used as a highly efficient vital marker to detect cytoplasmic and developmental changes that occur in the fungus, and to follow phytopathogenic development of the fungus on and inside maize leaves. The hyphae within the leaf form a unique parallel growth pattern, closely associated with, and apparently determined by, the anatomy of the leaf. Fluorescence intensity was quantified by digital analysis of the green fluorescence image and was highly correlated with the amount of mycelium and levels of disease. Expression of GFP was obtained in additional ascomycetes that were transformed with the new constructs, indicating that SGFP-TYG can be used as a highly effective vital marker in ascomycetes.

Arbuscular mycorrhizal fungi (AMF) are obligate symbionts which can only be propagated in association with intact plants or root explants. Molecular study of these fungi has been hampered by the inability to grow them in vitro and to obtain protoplasts. With the advent of advanced gene transformation systems, the opportunity has arisen to use biolistic technology to introduce foreign DNA linked to molecular markers into these fungi. The biolistic transformation system chosen for the AMF was GUS-based as this system was shown to work effectively for ectomycorrhiza. In this study the plasmid pNOM102 was used for transformation of Gigaspora rosea and transient GUS gene expression was detected in 40–50% of spores by colorimetric and immunological based methodologies.

Lindtneria hydnoidea sp. nov. is described, characterized by a hydnoid hymenophore and a total lack of clamp-connections on the generative hyphae. A key is given to all currently accepted Lindtneria species.

A stalked, cyphelloid basidiomycete from Kenya described as Stipitocyphella keniensis gen. et sp. nov. is illustrated. Possible relationships of this species with other basidiomycetes are discussed. Phylogenetic processes during gill and basidioma formation are proposed.