Rhizoctonia solani AG-3 causes considerable yield loss in potato fields in eastern Canada and U.S.A. The accurate identification of AG-3 isolates is strategic prior to planting potatoes. To obtain a fast and reliable identification method, RAPD experiments were carried out to obtain specific genetic markers of AG-3 isolates. DNA from various isolates of R. solani was submitted to RAPD amplification using random 10 mers primers. One of the forty primers used yielded a 2·6 kbp fragment present in all isolates of AG-3. The specificity of this fragment was assessed by Southern blot analysis. It was partly sequenced and DNA primers were designed for PCR amplification experiments. A PCR-based restriction mapping method, using one restriction endonuclease, Xho I, was developed for specific detection of AG-3 isolates. Analysis of data showed that AG-3 isolates were distinct to other AGs R. solani. The detection method described here is very specific and reliable; it can be applied on plant tissue and soil infected with R. solani AG-3.

In September 1990, 74 sporocarps of Battarrea stevenii were observed on the floodplain of the ephemeral Kuiseb River in western Namibia. Herein we report subsequent studies of the distribution, abundance, nutritional role, phenology, and sporocarp development of this fungus in the hyper-arid Namib Desert. Included are full descriptions of developing and mature sporocarps. B. stevenii is a common associate of riparian forests on silty floodplain terraces, but does not form mycorrhizal associations with the dominant woody species, Faidherbia albida or Tamarix usneoides. Rather, clamped mycelium extends throughout floodplain soils decomposing coarse and fine particulate organic material (4–7% of soil dry weight). Sporocarp production occurs 4·5–12 mo post-flooding in response to soil desiccation at depths of 20–35 cm. The extensive mycelium, duration of vegetative growth post-flooding, and large size and abundance of B. stevenii sporocarps suggest that it is an important component of the subsurface decomposer community in the Namib's ephemeral rivers. Given that the fungus has also been recorded from floodplain soils of Angola, Hungary, and New Mexico (U.S.A.), and is known to have a world-wide distribution, we predict that further biogeographical studies will reveal that B. stevenii is a characteristic element of the riparian biota in dryland rivers, which drain approximately one-third of the earth's land surface.

Germinating spore-balls of Urocystis hypoxis produce both unicellular basidia, crowned with 4–6 basidiospores, and what appear to be transversely septate, 3-celled, prostrate basidia with conjugation, through a conjugation tube, between top and bottom cells. This most unusual situation is discussed in relation to the taxonomy of smut fungi.

Phomopsis cucurbitae is a latent infection fungus which causes muskmelon fruit decay only after harvest. It can cause severe losses during fruit storage and marketing in the U.S.A., Japan and some Central American countries. Previous studies showed that P. cucurbitae produced polygalacturonase (PG) in both culture and muskmelon fruit tissue. In this study, a prominent PG isozyme (PG1) produced by P. cucurbitae in decayed fruit was purified to homogeneity by a procedure of extraction, ultrafiltration, preparative isoelectric focusing, anion exchange, and gel filtration chromatography. The isozyme had a primary endo-activity, a relative molecular weight of 54 kD according to SDS-PAGE, and a pI of 4·2 based on IEF-PAGE. The isozyme was active in a low pH range from 2 to 6, and was optimum at pH 5. Optimum temperature for the activity of PG1 was 40–45°C. The Km and Vmax on polygalacturonic acid were 44·7 μg ml−1 and 0·14 U μg−1 enzyme, respectively. The purified PG1 effectively macerated mature fruit tissue, suggesting that the isozyme may be involved in the pathogenesis of Phomopsis fruit rot of muskmelon.

A new species of Crocicreas is reported on overwintered stems of Epifagus virginianus in New York State in apparently non-organic association with sclerotia of Sclerotium orobanches, itself a rarely reported fungus. The changing concepts of the generic names Crocicreas and Cyathicula are discussed in regard to placement of the new taxon.

The elemental composition of vacuolar granules in different ectomycorrhizal fungi, Suillus bovinus, Paxillus involutus, Pisolithus tinctorius and Laccaria laccata was analysed by energy dispersive X-ray spectroscopy (EDXS) either after chemical preparation or cryofixation, freeze-drying and pressure infiltration. Vacuolar inclusions were present in living hyphae and were not an artifact of specimen preparation, and they can be referred to as polyphosphate granules. These granules were localized in fungal vacuoles and the main counter-ions were K and Mg. The postulated association of these granules with the divalent cation Ca has to be interpreted as an artifact of the specimen preparation and was caused by the chemical preparation of former EDXS studies. The incorporation of cations, such as K, Na and Zn, depended on the external supply and emphasized the importance of these granules for the intracellular homeostasis of fungal cells. EDXS studies of polyphosphate granules in ectomycorrhizal associations of Pinus sylvestris showed that the elemental composition of granules differed between the sheath and the Hartig net. In polyphosphate granules of the Hartig net a higher content of K was detectable, whereas the incorporation of Mg was reduced. These results indicated a possible role of K in the transfer of short chained, mobile polyphosphates through the hyphae to the Hartig net. The concentration of potassium and phosphate in the fungal vacuole and the cytoplasm was closely correlated, which can be explained by a possible linkage between the phosphate and K uptake, which would maintain the charge balance and the pH of the fungal cell. The estimation of different phosphate pools in axenic cultures and mycorrhizal roots revealed that the fungal metabolism was changed by the association with an ectomycorrhizal host plant. In a mycorrhizal association higher proportions of absorbed phosphate were translocated into the metabolically inactive polyphosphate pool, which demonstrates the importance of this pool for the nutrition of the ectomycorrhizal host plant.

A study of the holotype and several collections of Cercospora zeyrae on leaves of Zeyheria digitalis from the Brazilian cerrado showed that it is actually a Pseudocercospora species with amphigenous fruit structures, here designated as P. zeyheriae (Henn.) comb. nov.

Ascospore progenies from two crosses between a wild single-ascospore strain and two mutants of Phaeosphaeria nodorum were obtained in vitro. Cultural characters, sensitivity to carbendazim (MBC), nitrate utilization, mating type, esterase zymograms and aggressiveness of these progenies and parents were compared and differences were detected between the ascospores. The single-ascospore strains from each single ascus could always be grouped into four pairs using a combination of markers. Recombinations were observed between nitrate non-utilizing phenotype and mating type or esterase patterns for one cross. For the other cross, recombinations between MBC resistance and esterase patterns were detected. The values of aggressiveness in each progeny were distributed along a wide range confirming the polygenic character of aggressiveness in P. nodorum. No close relationship was observed between in vitro conidiogenesis, the intensity of leaf necrosis and the fertile pycnidia production on leaf lesions.

Phellinus formosanus sp. nov. and P. prunicola sp. nov. found growing saprotrophically on decayed stems of Schima superba and Prunus mume, respectively, in Taiwan, are described and illustrated. Cultural characters are described.

The Amphisphaeriaceae (sensu lato) presently includes 36 genera and 23 synonyms and is a heterogeneous assemblage of ascomycetes. In this paper molecular and morphological data and teleomorph–anamorph connections are examined and confirm that the Amphisphaeriaceae (sensu stricto) should be confined to ten teleomorphic genera and their Pestalotia-like anamorphs. These include Amphisphaeria, Broomella, Discostroma, Ellurema, Griphosphaerioma and Neobroomella which are described and illustrated; and Blogiascospora, Lepteutypa, Paracainiella and Pestalosphaeria which are discussed.

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.

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.

A new freshwater ascomycete genus Proboscispora is introduced to accommodate P. aquatica collected on wood submerged in streams in Australia and the Philippines. Proboscispora is characterized by having immersed, ellipsoidal, papillate ascomata, septate tapering paraphyses, cylindrical unitunicate asci with a refractive apical ring, and 3-septate, hyaline ascospores provided with coiled or proboscis-like bipolar filamentous appendages. Proboscispora aquatica is illustrated at the electron microscope level and is compared with Annulatascus, Ceratosphaeria, Ceriospora, Ceratostomella and Rivulicola, with which it shares some common characters.

An agar plate test is described to determine the growth inhibition of dermatophytes by fungicides applied to fabrics. Trichophyton rubrum and Epidermophyton floccosum, two major causative agents of tinea pedis (athlete's foot), were used as test organisms. The assay was capable of distinguishing between direct contact effects and diffusion of fungicide into the agar medium, and could be used semi-quantitatively. The method included an essential sterilization stage to prevent interference by micro-organisms contaminating the test materials. Loss of fungicide efficacy due to the sterilization procedure required careful control.

A detailed examination of the rediscovered type of Tulostoma volvulatum leads to the conclusion that it represents an earlier name for T. giovanellae. The former name will be proposed for rejection and the latter for conservation. Tulostoma volvulatum s. auct. becomes T. obesum.

Gaeumannomyces graminis var. graminis produces 1,8-dihydroxynaphthalene (DHN) melanin in its hyphal and hyphopodial cell walls. We isolated G. graminis mutants that were affected in their melanin biosynthesis. One was unable to synthesize DHN-melanin and, because it accumulated 2-hydroxyjuglone, a DHN melanin pathway shunt product, it is most likely to be defective in the reductase that catalyzes the conversion of 1,3,8-trihydroxynaphthalene to vermelone, the penultimate reaction in DHN synthesis. Genetic crosses with our wild-type strain indicated that this trihydroxynaphthalene reductase deficiency was the result of a single mutation. Another mutant constitutively synthesized DHN melanin and genetic crosses with our wild-type strain suggested that this heavily melanized mutant had a single mutation responsible for its phenotype. This mutant produced more melanin than the wild-type strain as measured by Azure A binding to melanin. The wild type and constitutively melanized mutant hyphae were more hydrophobic and more resistant to lytic enzymes, benomyl, restrictive temperature, and uv light than the non-melanized mutant, which also autolysed more readily. The non-melanized mutant was not more sensitive to heavy metal than the melanized strains. In addition, the non-melanized mutant was unaltered in pathogenicity to rice, whereas the constitutively melanized mutant was less pathogenic. The constitutively melanized mutant produced less extracellular lytic enzymes than the wild-type and the non-melanized mutant, which may explain its reduced virulence.

In vitro, antibiotic effects of the culture filtrates of 29 species of aquatic hyphomycetes against Gram-negative and Gram-positive bacteria, yeasts and hyphomycetes were studied. The culture filtrates of 38% of isolates were active in at least one of our tests for biological activity. Fifteen species inhibited growth of bacteria and four demonstrated antifungal activity. Filtrates of 35% of the isolates were antibacterial. About 50% of the isolates, those with the largest in vitro inhibitory activities (Dimorphosphora foliicola, Flagellospora sp. and Mycocentrospora sp.) were obtained from wood. Filtrates of Articulospora tetracladia were not only active against Gram −ve bacteria, but were also antiviral against bacteriophage T4 and influenza virus.

This listing covers the period September 1, 1997 through to October 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.