Four inhibitors of the lysine biosynthetic enzyme dihydrodipicolinate synthase (DHDPS) were examined for their effects on the late blight fungus Phytophthora infestans. One of these compounds, dipicolinic acid, reduced mycelial growth of P. infestans by 61% and completely controlled blight infection of leaf discs when used at 1 mM. The other inhibitors, chelidamic acid, chelidonic acid and dimethyl cis-piperidine-2,6-dicarboxylate, were less effective against P. infestans in vitro and in vivo. The effects of dipicolinic acid and chelidonic acid on mycelial growth were partly overcome by the addition of lysine to the growth medium. Both of these compounds reduced DHDPS activity and lysine concentrations in P. infestans, although they had no effect on activities of aspartate kinase and diaminopimelic acid decarboxylase. Both dipicolinic acid and chelidonic acid reduced in vitro activity of DHDPS from P. infestans.

Pycnothryria of Tubakia dryina on naturally infected sweet gum (Liquidamber styraciflua) leaves were examined using transmission electron microscopy. The conidioma was attached to mycelium within the leaf tissue by a multicellular columella. Columellar cells were multinucleate. The surface layer of the pycnothyrium, the scutellum, was composed of thick walled prosenchymatous hyphae. Numerous conidiogenous cells were associated with the ventral surface of the scutellum and the columella. Conidia were produced enteroblastically from conidiogenous cells exhibiting a prominent collarette at their apex.

Ascospore germlings of Monosporascus cannonballus attached to melon roots were examined with the scanning electron microscope. Results showed that ascospores germinated with one to three germ tubes. Sixty percent of the ascospores germinated with two germ tubes. No germ pores were observed. Instead, germ tubes emerged from a single linear fissure on each ascospore. The largest fissure measured 25 μm in length and 6 μm at its greatest width. Germ tubes of ascospore germlings were firmly anchored to melon roots. However, no structures resembling appressoria were observed. Rather, the tips of germ tubes, upon contact with the epidermis, appeared to have penetrated the epidermis directly. When the germ tube at the point of attachment was dislodged, no infection peg was present at the germ tube tip.

Immunoblotting combined with computer imaging and a simple, non-linear mathematical model were used to demonstrate the potential of a technique for non-destructive visualisation and analysis of fungal growth of Rhizoctonia solani over the surface of non-sterile sand. Immunoblotting detected actively growing regions of mycelium enabling visualisation of individual hyphae at the colony edge. A zone of active growth was detected expanding radially over time. Active growth did not continue in the centre of the fungal colony leading to the development of a ring of mycelium surrounding the inoculum. Change in the density of actively growing mycelium with distance from the inoculum unit was summarised for each colony at each time by a Gaussian function, describing a wave of actively growing mycelium, symmetrical in density about its centre but differing amongst replicate colonies. The effectiveness of the immunoblotting technique to detect differences in colony growth was tested by comparing the growth of replicate colonies for two contrasting isolates of R. solani. When both isolates of R. solani were grown at 23 °C the amplitude of the wave increased to a maximum and then decayed over time, the location of the centre of the wave moved outwards at a constant rate, whilst the width of the wave increased. Increasing the temperature to 28 °, accelerated this intrinsic growth process for one isolate, but retarded growth of the other.

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.

Recently we cloned and characterized three laccase genes from Gaeumannomyces graminis var. tritici, an important pathogen of wheat. Here we report cloning and characterization of two laccase genes from G. graminis var. graminis, a weak pathogen of rice and turf grasses. LAC1 and LAC2 genes were present in both varieties of the fungus. The genes were 94–95% identical, and intron positions were conserved between the two varieties. Our data demonstrated that laccases might be useful for phylogenetic studies to detect fine differences between G. graminis subspecies, varieties, or strains of the fungus that cannot be detected by traditional sequencing of 18S rRNA genes or ITS regions. We previously characterized two G. graminis var. graminis melanin mutants with altered lytic enzyme secretion patterns. Here we demonstrate altered transcription patterns of laccase genes between the two varieties and between the wild type and melanin mutants of G. graminis var. graminis. Transcription of LAC2 was downregulated in the over-melanized mutant as compared to wild-type G.graminis var. graminis and the unmelanized mutant, whereas transcription of LAC1 in planta was up-regulated in the over-melanized mutant, as compared to the wild type and the unmelanized mutant. In the unmelanized mutant transcription of both genes was similar to that observed in the wild type.

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.

Four strains of Tuber borchii were grown in liquid medium containing glucose. Evaluation of growth patterns revealed a trend of exponential growth for only one strain. Subsequently, enzyme levels were assayed and polypeptide and mRNA electrophoretic profiles were analyzed. Although the four strains were found to have many properties in common such as the growth behaviours for three strains and the levels of some glycolytic enzymes, the polypeptide and mRNA electrophoretic patterns highlighted intraspecific variability.

A new anamorph genus, Acarocybiopsis, with A. cubitaensis as type species, is described. It is characterized by an unusual combination of indeterminate synnemata having two kinds of hyphae and terminal head composed of a single conidium.

Corallocytostroma ornicopreoides sp. nov. is described and illustrated from large (up to 3 cm diam.) conidiomata and sclerotia found on the living stems of four perennial grasses, Astrebla elymoides, A. pectinata, A. squarrosa and Dichanthium fecundum, in northern Western Australia and the Northern Territory. It is compared with Corallocytostroma oryzae, the only other species in the genus.

The polygalacturonase (PG)-encoding gene (rpg1) of Rhizopus oryzae, the causal pathogen of rhizopus rot of mulberry, was cloned and sequenced. PGs were partially purified from incubation mixture of 2% pectin medium and their N-terminal amino acid sequences were determined by a gas-phase protein sequencer. RT-PCR was performed using degenerate primers designed from the amino acid sequences, which resulted in part of a PG-encoding gene being obtained. By 3′-RACE and TAIL-PCR analyses, the entire region of the PG-encoding gene was cloned and sequenced. The structural gene comprised 1199 bp coding for 383 amino acids with a putative signal peptide of 26 amino acids, and the open reading frame was interrupted by single intron of 47 bp. Phylogenetic analysis using the deduced amino acid sequence revealed that R. oryzae RPG1 belonged to a clade consisting of exo-PGs of ascomycete fungi.

A study of the macroscopic and microscopic characters of type material of Tulostoma leiosporum, T. exitum, T. operculatum and T. puncticulosum showed their heterogeneity. An attempt was made to resolve the taxonomic problems involved in the selection of lectotypes, and new synonymies are proposed. SEM photographs of spore ornamentation are provided.

Lepteutypa hexagonalis sp. nov. is described from a dead trunk of Pinanga sp. (Palmae) collected in an Ecuadorean rainforest. Ascomata are deeply immersed with a distinct ostiolum, asci are cylindrical with a J+ subapical ring, and ascospores are brown, 4-celled, and hexagonal or heptagonal in transverse section.

The toxic naphthoquinone juglone (5-hydroxy-1,4-naphthoquinone) is efficiently degraded by the ligninolytic fungus Pleurotus sajor-caju, as demonstrated by the total bleaching within 9 d of a conventional liquid culture medium supplemented with 0.6 mM juglone. The oxidative degradation involves the production of hydrogen peroxide arising from both enzymic and non-enzymic oxidation reactions, promoted by the fungus. Juglone is not directly attacked by the oxidative enzymes of the ligninolytic machinery of P. sajor-caju, such as laccase, manganese peroxidase and arylalcohol oxidase. On the other hand, this naphthoquinone is a good substrate for a reductase, which triggers an auto-oxidative process producing reactive oxygen species and leading to juglone degradation. The degradation process continues to completion by means of a direct, presumably non-catalysed reaction with hydrogen peroxide.

Melanospora collipora sp. nov. is described from soil. The most noteworthy feature is the presence of a hyaline rim around the germ pores. Relationships of the new species to other members of Ceratostomataceae and Chaetomiaceae are discussed.

Batcheloromyces spp. are dematiaceous hyphomycetes which cause leaf spots on members of the Proteaceae in South Africa. The leaf spots are non-necrotic and composed of numerous sporodochial conidiomata. Conidiogenesis is holoblastic with percurrent, enteroblastic proliferation producing conidiogenous cells with ragged and irregular annellations. Brown, verrucose, aseptate and multiseptate conidia are produced. Conidia produced percurrently, can remain adhered to each other in fragile chains, disarticulating to produce aseptate conidia or, in some cases, they remain as multiseptate conidia where further schizolytic cleavage, at the delimiting septa, may or may not occur. This paper compares Batcheloromyces with the morphologically similar Stigmina, discusses the current members of Batcheloromyces and introduces the new species B. leucospermi.

The cell wall alkali-extractable water-soluble polysaccharide (F1SS) purified from the three species of Cephalotheca has been characterized. Two different structures have been deduced by chemical and structural analyses. The structure of the polysaccharide F1SS from C. purpurea and C. reniformis is similar, and composed of 3,6-di-O-substituted mannopyranose with terminal residues of rhamnopyranose. The polysaccharide F1SS from C. sulfurea contains 2,6-di-O-substituted mannopyranose and terminal residues of galactofuranose. Our results confirm the relatedness of C. purpurea and C. reniformis with Ophiostomatales and of C. sulfurea with Sordariales.

Polygalacturonase (PG) secretion was analysed from five independent isolates of Botrytis cinerea grown in minimal liquid media enriched with pectin as the only carbon source. To acquire information about the biochemical characteristics of the PGs secreted in vitro, we combined enzyme-activity assays with Western blot analysis and isoelectro-focusing (IEF). All isolates secreted at least four PGs isozymes with a similar electrophoretic patterns, easily distinguishable by western blots. IEF enabled the isoelectric point of the PGs for each isolate to be determined. Wide variability in isoelectric point was observed between the PGs of each isolate, ranging from above pH 9.0 to below pH 5.0. For one of the isolates, each PG secreted in vitro was further purified by chromatofocusing and analysed for endo/eso-polygalacturonase activity by thin layer chromatography. This combination of analytical techniques and enzyme assays provided a view of the pool of PGs produced by B. cinerea and defined the biochemical features of each isozyme.

Cercospora beticola strains with laboratory induced resistance to tetraconazole were compared with their parental WT sensitive strains to evaluate the effects of resistance on fitness and assess whether any change in the sterol biosynthetic pathway was associated to the reduced fungicide sensitivity. In vitro growth rate on agar media and pathogenicity were found to be negatively affected by resistance. The main functional sterols in C. beticola WT strains under investigation were ergosterol, brassicasterol and ergosta-7,22-dienol. Resistant strains showed the same qualitative sterol composition, ruling it out as, per se, a cause for resistance. On the basis of the sterols detected both in sensitive and resistant strains, a possible biosynthetic pathway to the three functional sterols is proposed. Tetraconazole treatment caused, in all sensitive strains, the immediate accumulation of 14α-methylated sterols, which, for inhibitor concentrations up to EC50 values, were, in order of abundance, 14α-methylergosta-8,24(28)-dien-3β,6α-diol, eburicol and obtusifoliol. However the data do not support a critical role of the 14-methyl-3,6-diol derivative in the growth arrest of C. beticola. As main difference between sensitive and resistant strains, the formers were found to accumulate higher amounts of 14α-methylated sterols. Although the data do not allow to establish a specific mechanism for resistance, some molecular mechanisms such as target site alterations and sterol biosynthetic pathway can be ruled out as a possible cause for reduced sensitivity.