Two fruitbodies each of Russula messapica and Macowanites messapicoides, identified by morphological characters, were screened for polymorphism in the ITS and the IGS of their ribosomal DNA, as well as in mitochondrial rDNA by RFLP analysis of PCR-products. The two species were monomorphic for all markers with the exception of the IGS. This limited genetic differentiation indicates a close relationship between these two species. The overall correspondence of the RFLPs between R. messapica and M. messapicoides adds molecular evidence to the relatedness of Russula and Macowanites, and suggests the possibility that M. messapicoides is recently derived from R. messapica.

Massarina proprietunicata sp. nov., is described and illustrated based on a specimen occurring on submerged wood in the Lam Tsuen River, Hong Kong. It is characterized by verrucose ornamented ascospores bearing a narrow mucilaginous sheath, which is drawn out at the poles to form tapering appendages, with thickened and arrowhead-like tips. Massarina proprietunicata is compared with other aquatic Massarina species having ascospores bearing a narrow mucilaginous sheath or polar appendages. Details of morphology are illustrated with interference and scanning electron micrographs.

The growth characteristics and uptake capacities for NO3− and NH4+, as well as activities of nitrogen assimilating-enzymes have been determined in Scleroderma verrucosum. Biomass, grown on agar or liquid MMN media, was higher on nitrate. When S. verrucosum was grown in the presence of equal amounts of ammonium and nitrate, uptake rate for NH4+ was considerably higher than that of NO3−. In addition, it was found that a limitation in ammonium concentration was a prerequisite for nitrate uptake. Nitrate reductase was stimulated when the fungus was transferred from ammonium to nitrate containing media, indicating that the enzyme was inducible by nitrate and repressed by ammonium. Glutamine synthetase and NAD-glutamate synthase activities were clearly detected in S. verrucosum, while the NADP-glutamate dehydrogenase was almost undetectable. This is consistent with the view that ammonium assimilation occurs through the GS/GOGAT cycle in S. verrucosum.

Isolates of Verticillium nigrescens and V. tricorpus were obtained from potato, cotton, eggplant, weeds and field soil in Israel. Chlorate- resistant nitrate-nonutilizing (nit) mutants were generated from each isolate and used in complementation (heterokaryon) tests. Eleven vegetative-compatibility groups (VCGs) were found among 19 V. nigrescens isolates from nine sites, and nine VCGs among 26 isolates of V. tricorpus from eight sites. Optimal growth temperature was 24–27°C for V. nigrescens and 24° for V. tricorpus. None of the isolates caused leaf symptoms or stunting in inoculated eggplant and cotton seedlings, while severe symptoms were caused by V. dahliae. Colonization of inoculated seedlings by V. nigrescens and V. tricorpus occurred primarily in roots and hypocotyls, while V. dahliae heavily colonized upper stems as well.

The effect of the environment on the germination, survival and infection of sorghum by conidia of Peronosclerospora sorghi is unknown in Africa. Dew point temperature, and the effect of conidium age was characterized for an isolate of P. sorghi from Zimbabwe. Germination and germ tube growth took place in the range 10–34°C (optimal at 10–34 and 20–33°, respectively). Infection was optimal at 14–30°. Incidence of infection at different temperatures was correlated with germ tube growth (r=0·8, P<0·001). Germination and germ tube growth occurred from 5 h after commencing incubation of infected leaf material, although immature conidia harvested at 3 h caused a low incidence of infection. Plant age also affected the incidence of infection. Container grown sorghum plants older than 20 d, and maize plants older than 15 d were resistant to systemic infection by conidia. The results indicate that germination, germ tube growth and infection take place over a wide temperature range, and that some limited biotypic variation may exist when these data are compared to other reports of the environmental requirements of P. sorghi from the U.S.A. and India.

The likelihood of development of penconazole resistance in Venturia inaequalis was demonstrated using chemical mutagenesis of a wild isolate of the pathogen not previously exposed to penconazole. Mutant strains displayed a high degree of resistance which was stable. There was significant variation in the rate of total lipid and ergosterol biosyntheses between the resistant and sensitive strains. Low uptake of penconazole due to energy-dependent efflux was found to be the mechanism underlying penconazole resistance in the mutant strains, which also exhibited negatively correlated cross-resistance to mancozeb.

Puccinia recondita f. sp. tritici pathotype (pt) 64-(6),(7),(10),11 was first detected in Australia in northern New South Wales in 1990. Greenhouse tests of pathogenicity on wheat and triticale genotypes indicated that this pathotype was similar to two closely related pathotypes, but differed from them in at least three pathogenic features indicating that it had not arisen by a simple mutational event. Pathotype 64-(6),(7),(10),11 combined several pathogenic and isozymic features which, prior to its detection, were known only in two different groups of pathotypes, strongly suggesting that it had arisen via somatic hybridisation between isolates from each group. This hypothesis was supported by the RAPD phenotypes of isolates representing pathotypes present in Australia at the time pt 64-(6),(7),(10),11 was first detected. The hybrid pathotype combined virulence for Lr1 with partial virulence for gene Lr13 and was fully virulent in greenhouse adult plant tests on two hybrid wheats heterozygous for these genes. This is the first case where compelling evidence has been obtained for somatic hybridization in Prt and only the second of inter pathotype somatic hybridization in a wheat rust under field conditions.

Sarcodon imbricatus has long been used to extract blue and greenish pigments for wool dyeing. We found that fruit bodies growing with Pinus sylvestris seemed to be superior for dyeing compared to fruit bodies growing with Picea abies, and macroscopical differences between the forms indicated that they are different taxa. By studying sequences of rDNA ITS and macroscopical characters, two species were recognized. Sarcodon imbricatus grows in association with Picea, and S. squamosus with Pinus. The latter species, described by Schaeffer in 1774, has been lumped with S. imbricatus during the past 50 years, creating great confusion among wool dyers.

The ability of six fungi to solubilize natural-occurring gypsum was tested in vitro. The solubilization process was monitored by the production of a clear zone (halo) around or underneath the growing colony on Czapek–Dox agar containing 0·5% (w/v) gypsum (CaSO4.2H2O). Aspergillus niger, Penicillium bilaii, P. simplicissimum and Paxillus involutus displayed differential solubilization activities depending on the supplemented nitrogen source. Colonies grown on nitrate-containing medium showed the ability to solubilize gypsum, but when ammonium (at equivalent nitrogen) was used there was a significant reduction in solubilization. It was found that liquid cultures of nitrate-grown fungi produced substantial amounts of oxalic acid, whereas in ammonium-containing medium oxalic acid was only detected in small amounts. The production of citric and gluconic acid under these experimental conditions was low in both media, although the involvement of citric acid in gypsum solubilization is possible. Coriolus versicolor and Phanaerochaete chrysosporium did not exhibit any solubilization activity in nitrate- or ammonium-containing medium. Additionally these two fungi excreted small quantities of oxalic acid in both media with no citric acid being produced in liquid medium. Concomitant with the solubilization process and inside the clear solubilized zone, A. niger, Pax. involutus and P. bilaii produced crystals of differing shapes and abundance depending on the fungal strain. No crystals were produced by P. simplicissimum. These crystals were identified as calcium oxalate based on HPLC analysis and energy-dispersive X-ray microanalysis. Abundance of these crystals was found to be correlated with both oxalic acid production and the acidity of the medium. It is concluded that gypsum solubilization was predominantly achieved by both oxalic acid, which was accompanied by formation of calcium oxalate crystals, and citric acid production rather than the acidity of the medium. The results are discussed in relation to the significance of such an activity in agricultural applications, e.g. land reclamation, as well as the possible roles played by these fungi in mineral cycling.

Thirty-five isolates of Gaeumannomyces graminis were tested for ability to infect wheat, rye and oats, and for DNA polymorphisms using nuclear ribosomal DNA (rDNA) RFLP patterns and RAPD analysis. In general, the cereal-attacking isolates could be readily assigned to the rye-attacking (R) or non-rye-attacking (N) subgroups of var. tritici, or to var. avenae, on the basis of either of these molecular approaches. A small number of isolates gave anomalous rDNA RFLP patterns, but could nevertheless be assigned to one of the three groups by RAPD analysis. Two related G. graminis var. tritici isolates (T1–1 and T1–2) clearly grouped with the N rather than the R var. tritici subgroup on the basis of molecular analysis but were pathogenic to rye, indicating that the ability to infect this host may have arisen more than once. An earlier phylogenetic study of Gaeumannomyces involving DNA sequence analysis of the internal transcribed spacers of the rDNA indicated that several oat-infecting isolates originally classified as G. graminis var. tritici could be grouped with var. avenae isolates. From the rDNA RFLP and RAPD analysis described here, however, these isolates appear to be intermediate between var. avenae and var. tritici, although it is not clear whether they represent evidence of inter-varietal sexual hybridization.

The present study treats several fungi associated with leaf spots of Proteaceae from Africa, Australia and India. Leptosphaeria leucadendri (anamorph: Sclerostagonospora leucadendri) is described from Leucadendron leaves from Australia, while three previously described African taxa from Protea leaves are transferred to Phaeophleospora as P. abyssinicae, P. congestum and P. protearum. Trimmatostroma protearum and a Phyllosticta sp. are described from Protea leaves collected in South Africa and Australia, respectively. Cercospora agharkarii, which occurs on Grevillea, is redisposed to Pseudocercospora, while a new genus Pseudohendersonia, is proposed for P. proteae occurring on Protea leaves in South Africa.

Antrodia taxa sp. nov. and Perenniporia celtis sp. nov. found growing saprotrophically on the decayed stems of Taxus mairei and Celtis sinensis, respectively, in Taiwan, are described and illustrated. A. taxa is distinguished by effused-reflexed to pileate basidiomes and small oblong ellipsoid basidiospores 4×2·5 μm. P. celtis is characterized by large, subglobose to tear-shaped, non-truncate basidiospores 8·5–10×5–7 μm and encrusted cystidia. Cultural characteristics are described for the two species.

The responses of a number of wood-rotting fungi to culture filtrates of Phellinus contiguus strain GWR, which contained a factor active in self-induction of precocious fruiting, were tested by means of a bioassay. Fruiting of a second isolate of P. contiguus was stimulated by active filtrate and the responses of single basidiospore progeny of GWR ranged from nothing to full fruiting. In similar bioassays culture filtrates from 13 out of 16 single spore progeny stimulated fruiting in GWR but production of active filtrate did not correlate with capacity to respond. Other wood-rotting fungi (two other strains of P. contiguus, P. occidentalis, P. ferruginosus, P. igniarius and P. pini, Phylloporia ribis and Trametes versicolor) produced filtrates capable of inducing fruiting in P. contiguus strain GWR. P. pomaceus, lacked inducing activity and the inactive filtrate of Coniophora puteana was also inhibitory to mycelial growth. It is concluded that production of the factor inducing fruiting in P. contiguus is not species specific.

Melanospora pascuensis sp. nov., isolated from soil of Easter Island, is described and illustrated. The ITS1, ITS2 and 5·8 S rRNA gene sequences are also provided. The fungus can be recognized by the setose perithecial ascomata and the peculiar ring-like structure surrounding the ascospore germ pores. It is compared with other species of Melanospora and related genera.

The morphology of the extracellular mucilaginous material (ECM) produced by Coniophora puteana and Coriolus versicolor during colonization of Scots pine and beech was studied using SEM. Wood specimens were examined in the frozen hydrated (FH) condition using low-temperature SEM, and in the freeze-dried (FD) and critical point dried (CPD) state, using conventional SEM. All techniques produced artifacts but the ECM was best preserved when examined in the FH state. Very little difference was observed between FH and FD preparations, but critical point drying damaged the ECM extensively. Copious amounts of ECM were produced by both fungi. It was found to line much of the lumen surface, establishing contact between the mycelium and the wood substratum. Most aerial hyphae were coated with ECM, appearing glued together in a bundle-like fashion. The ECM thickness varied within the same wood cell and from one cell to another. A peculiar granular pattern, in which the ECM was definitely involved, was seen on occasion to encircle the infecting hyphae where they contacted the wood surface. Other morphological patterns of ECM distribution were also observed. Calcium oxalate crystals of varying shapes and sizes were often seen associated with the mycelia and mucilage of the two fungi in beech but not in Scots pine. The probable roles played by the ECM in wood decay mechanisms are discussed.

Ultrastructure of the marine, bitunicate, ascomycete Julella avicenniae is presented and compared with the marine Pleospora gaudefroyi. Asci of J. avicenniae possess an ocular chamber, a thick endoascus, and a thinner ectoascus. Pseudoparaphyses are enveloped by mucilage (hyphal sheath) which stains with ruthenium red. The mucilage appears to be an extension of the pseudoparaphysis cell wall and internally these cells contain an array of vesicles. Muriform ascospores are surrounded by an exosporial sheath, an electron-dense episporium and a bilamellate mesosporium. Optimum conditions for growth are 25–30°C in 100% artificial seawater glucose- yeast extract-tryptone media, but the fungus also is able to grow at 35° and at higher salinities. The ability of the fungus to withstand extremes of environmental conditions is discussed.

Twenty-seven Fusarium oxysporum isolates were studied by RAPD-PCR and isozyme analyses. Thirteen isolates were from barley and the rest from different hosts, most of which were dicotyledonous plants. All isolates could be distinguished from each other by RAPD-PCR analysis, and clustered into seven groups in NJ and parsimony consensus trees. Isozyme analysis detected polymorphism in five of the six enzymes and the isolates could be divided into 26 different electrophoretic groups. Five groups were supported by high branch support and bootstrap values in the approximate support tree of combined RAPD-PCR and isozyme data. These five groups were found also in NJ and parsimony consensus trees. The matrices from RAPD-PCR and isozyme data proved to be incongruent, but they did not totally disprove each other. Some correlation was found between geographical origin and phylogenetic relationships of isolates collected from barley. Representatives of the main clades of phylogenetic trees, were further studied by rDNA RFLP and rDNA sequence analyses, together with isolates of other Fusarium species. Isolates of F. oxysporum and F. avenaceum formed distinct groups in the phylogenetic analyses, except for two isolates of F. oxysporum which were grouped with isolates of F. redolens.

The succession of microfungal communities on Myrtus communis leaf litter was monitored from Jan. 1993 to Nov. 1994 using the litter bag method. Three main groups of fungal colonizers were identified, whose presence is correlated with the successive decomposition stages of the substrate and with seasonal variations.

Protoplasts were produced by treating the yeast-like cells of O. piceae and O. quercus with high concentrations of Novozym 234 (20 mg ml−1). Transformants with resistance to hygromycin B were obtained by transforming the protoplasts with the plasmids pAN7-1 and pCB1004 containing the hygromycin B phosphotransferase (hph) gene. For all isolates tested, transformation efficiencies ranged between 103 and 105 transformants μg−1 vector DNA. High polyethylene glycol concentration (66 %) increased the transformation efficiency. Integration of the hph gene into the transformant genome was verified by a polymerase chain reaction and dot DNA hybridization analysis. There was no evidence of mitotic instability of hygromycin B resistance in the transformants.

The ability of three Australian Pisolithus species, discriminated on the basis of ITS sequence data, to utilize a range of inorganic and organic nitrogen sources was assessed in liquid axenic culture. Both intra-, and putative interspecific, variation in nitrogen source utilization was observed. Most isolates demonstrated a preference for NH4+ over NO3−, although some showed no significant preference for either inorganic source. All isolates utilized a range of amino acids. Species I isolates demonstrated a preference for acidic and/or neutral amino acids over basic acids, while species II and III isolates generally utilized amino acids poorly relative to species I. Although most isolates utilized BSA poorly, two species I isolates that had been maintained in axenic culture for > 10 y grew well on this substrate, suggesting possible changes in nitrogen utilization with extended storage in axenic culture.