In the coastal cliff landscape of southern Scandinavia dense populations of the saxicolous, lichen-forming fungus Lasallia pustulata are subject to disturbances creating small or larger gaps; one or several thalli are removed by strong winds, icing, rock slides, log-falls, branch sweeping or trampling. New patches for colonization are also created when mats of bryophytes, fruticose lichens or pine needles are removed by the same forces. The disturbance gaps are major sites of recruitment in the populations and the age structure of a population is spatially structured by the pattern of gap formation. The revegetation of experimentally created gaps were monitored over a four year period, at the end of which the gaps were filled with new, 1–9 mm sized thalli, unevenly scattered, on average 6500 individuals m−2, covering less than 1% of the substrate. In addition there were clusters of small thalli sprouting from the former attachment site of some of the large thalli that had been removed. The growth of individual thalli in natural gaps and mature populations was also monitored for four years. The largest annual increment in thallus diameter was 15 mm, the average 5·5 mm. Some thalli did not increase in size at all, some became slightly smaller, and some were completely eliminated, apparently by self-thinning. There was no correlation between initial thallus size and annual growth; and age and size are not correlated. The individual variations in growth rate seem to reflect the degree of initial crowding, subsequent competitive success, and local supply of nutrients. The average growth and initial size of individuals plus their density and dispersion are used to model the speed of gap-closure, estimated to be 10–15 years.

Plant pathogenesis by fungi is known to be dependent on the host genotype, the virulence of the pathogen and certain environmental conditions influencing fungal establishment. Previously, it has been shown that Chaetomium globosum, a fungus well-characterized for its biocontrol potential, causes necrosis on barley roots grown in Murashige and Skoog (MS)-agar. Using MS-agar and aeroponic culture as axenic plant growth systems, C. globosum pathogenesis was analyzed with serological and histological methods. Irrespective of the growth system, C. globosum infected the root epidermis. Roots grown in MS-agar were extensively colonized intercellularly and intracellularly up to the inner cortex and the tissue underwent necrosis. In contrast, roots grown in aeroponic culture were not colonized beyond the epidermis and the roots appeared healthy. Histochemical analyses revealed that hypodermal suberization stopped fungal invasion. In root tips known to lack suberization, epidermal papilla formation reduced overall infection frequency. The results indicate that specific environmental conditions are important for infection and disease expression in barley roots. Infection is restricted by two spatial and temporal distinct defence mechanisms: (1) papillae in root tips retarding fungal invasion; and (2) suberization of hypodermal cells blocking fungal radial growth.

Experimental preparations (alginate granules and mycelial mats) of the entomopathogenic Erynia neoaphidis were assessed for their capacity to cause infections in populations of Macrosiphum euphorbiae on pepper plants, in a greenhouse trial performed over 14 d. The dried preparations contained hyphal cells, which upon rehydration produced conidiophores and ejected ballistospores. Applications of alginate granules and mycelial mats on soil were more rapid in causing infections in the host population compared with foliar applications. On the last sample date, infection rates of 10–14% were obtained with foliar applications of E. neoaphidis as alginate granules and mycelial mats, respectively. With soil applications of E. neoaphidis granules and mats, infections were 23–36% after 14 d. From all sample dates, 183 cadavers were found on pepper plants treated with E. neoaphidis and 37 (= 20%) exhibited external sporulation after overnight incubation.

Comparisons were also made with single foliar sprays of Beauveria bassiana (Mycotrol WP®) and the systemic insecticide pymetrozine (Chess WP®), the latter being the only treatment to significantly reduce aphid numbers during the trial period. Treatment with B. bassiana resulted in good initial infection rates (50–60%) which declined over the period and reached the same infection level as E. neoaphidis treatments at the end of the trial. With B. bassiana, a total of 81 cadavers were found, of which 62 (= 77%) sporulated.

Trichoderma harzianum (CCM F-470) was found to produce large amounts of extracellular mutanase (0·33 U ml−1, 1·85 U mg protein−1) when grown aerobically on the optimized mutan medium in fermenter culture with an automatic pH control. The mutanase from this source was purified to homogeneity by a rapid procedure, using ion-exchange chromatography, hydrophobic interaction chromatography and chromatofocusing. The enzyme was recovered with a 94-fold increase in specific activity and a yield of 73%. The molecular weight of the purified enzyme proved to be 67 kDa, as estimated by SDS–PAGE, and to be 274 kDa, as determined by size-exclusion HPLC. These results indicate that the native mutanase is probably a tetramer protein. The isoelectric point was at 7·11, and the carbohydrate content in the purified enzyme was 4·42%. The pH and temperature optima were 5·5 and 40 °C, respectively. The enzyme remained stable over a pH range of 4·5–6·0 and up to 35 ° for 1 h. The values of Km and Vmax under standard assay conditions were 1·2×10−3 g ml−1 and 8·48×10−2 U mg−1, respectively.

Two nematode-parasitic isolates of Harposporium are reported to form synanamorphs attributable to the Hirsutella. One is attributedto Harposporium anguillulae, the second is described as a new species, H. cerberi. H. cerberi also produced an arthroconidial synanamorph. In infection studies of nematodes, conidia typical of Harposporium proved to be capable of killing bacterial feeding nematodes (Rhabditis sp.) when ingested. Infective conidia of H. cerberi were located posterior to the oesophageal bulb, while those of H. anguillulae lodged above it. Hirsutella conidia were not observed to be infective or adhesive, and none of the spore forms was capable of infecting either of two species of stylet-bearing nematodes (Aphelenchus sp. and Meloidogyne hapla).

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.

Random amplified polymorphic DNA polymerase chain reaction (RAPD–PCR) was used to assess the genetic diversity in twelve populations (a total of 144 isolates) of the Pleurotus eryngii complex, sampled in Israel. Our results show a higher level of diversity of RAPD polymorphism in the populations, especially in the drier, stressful climates. Twelve primers used in this study amplified 164 scorable RAPD loci, of which 163 (99.4%) were polymorphic and only 1 monomorphic. Out of the 164 loci, 123 (75%) varied significantly (P < 0.05) in allele frequencies among populations. This total proportion (75%) of significant polymorphic loci far exceeds the 5% level expected by chance (binomial test, P < 0.000001). The levels of polymorphism and gene diversity appeared to be highly significantly different between the populations. Sixty-eight per cent of the RAPD diversity was within populations and 32% was between populations. Inter-population genetic distances showed positive association with geographic distance, which was confirmed with spatial autocorrelation analysis of RAPD frequencies. Spearman rank correlation revealed a strong positive association between high polymorphism and the aridity index. In multiple regression, the coefficient of determination of polymorphism and gene diversity was explained by climatic variables linked to temperature and humidity. Our findings further demonstrate the validity of the ‘environmental theory of genetic diversity' hypothesis within P. eryngii populations in Israel. We suggest that natural selection develops a high level of RAPD polymorphism as adaptation to cope with stressful and temporally heterogeneous environments.

Twenty-six isolates representing six morphologically similar taxa of Tilletia occurring in the western U.S.A. were compared using randomly amplified polymorphic DNA (RAPD) markers and restriction fragment length polymorphisms (RFLP) of the 5·8 s rDNA and flanking ITS regions. Two distinct clusters were separated in the dendrogram based on the RAPD analysis. One cluster contained isolates of T. controversa, Apera interrupta-infecting isolates of a potentially new species of Tilletia, and isolates of the Bromus-infecting varieties bromi-tectorum and guyotiana of the T. fusca (=T. bromi) complex. The second cluster contained Vulpia-infecting isolates of T. fusca var. fusca. The separation of the Bromus-infecting varieties from the Vulpia-infecting variety of T. fusca was supported by distinct restriction digest phenotypes. The RAPD analysis was more sensitive than the RFLP analysis, and allowed separation of the Bromus-infecting varieties bromi-tectorum and guyotiana corresponding to host specificity shown in previous studies. The presence of genetically distinct populations of T. fusca var. fusca occurring on V. microstachys and V. octoflora is indicated by RAPD and RFLP analyses. Species status of T. togwatii, a bunt infecting Poa reflexa that was previously removed from the T. fusca complex, is also supported by RAPD and RFLP analyses.

Two rapid, independent molecular assays have been developed for discriminating between the closely related rusts of hard pines, Cronartium flaccidum and Peridermium pini. A portion of the ITS region and a portion of the IGS region from the ribosomal RNA operon of the two organisms were amplified with the PCR. Amplifications were made using DNA extracted from aeciospores collected from unopened aecia, taking a small number of spores as a source of template DNA. Amplified fragments were subjected to RFLP or to SSCP analysis. Digests of the amplified products from the IGS1 region were electrophoresed on polyacrylamide gel and stained with ethidium bromide. Hinf I digestion of these fragments created polymorphic restriction profiles which allowed differentiation of the autoecious P. pini from the heteroecious C. flaccidum. Similar-sized DNA fragments representing the ITS2 region of the two rusts were denatured, subjected to electrophoresis as single strands on polyacrylamide gel under non-denaturing conditions and ‘silver stained’. The different mobility displayed by these short fragments revealed sequence polymorphism in the examined portion of the ITS region. This technique therefore represents an accurate and sensitive method for detection of base changes in given sequences of genomic DNA. A high level of homology was found between the two biotroph organisms in the loci screened. Results obtained in this trial indicate that PCR-RFLP and PCR-SSCP can be used as simple, speedy taxonomic tools for elucidating relationships among related organisms.

Techniques to rapidly identify the basidiomycete fungal partner of ectomycorrhizal associations would be a major advantage for ecological, fungal population dynamics and life history studies of epigeous and hypogeous forms in plantations, forests, wild lands and other native or natural vegetation. PCR–RFLP (Polymerase Chain Reaction–Restriction Fragment Length Polymorphism) identification of DNA regions is an available technique; however, primers which have a high probability of amplifying only the basidiomycete DNA are needed. Here we have assessed the specificity, sensitivity and discrimination of six different primer pairs, three targeting nuclear and three mitochondrial regions, for use in identification of Australian basidiomycete fungi from Eucalyptus forests by matching PCR–RFLP patterns to morphologically defined species. Two sets of primers, one newly designed and targeting the nuclear ribosomal DNA internal transcribed spacers (ITS) and the other amplifying a fragment of mitochondrial large subunit ribosomal DNA met the requirements of high specificity and sensitivity, amplifying DNA from a broad range of larger basidiomycetes, with no amplification of plant, bacterial or ascomycete DNA. The specificity of the ITS primer pair was compared with that of ITS1-F/ITS4-B. PCR–RFLP of the two regions discriminated fungi to species level for 91 fungal species from 28 families. Hence these two DNA regions and the specific primers are a potential practical PCR–RFLP tool for identifying basidiomycetes associated with plants from field samples.

The saprobic microfungi associated with endemic plants of Mauritius have been studied. Over 200 taxa were identified of which approximately 90% are new records for Mauritius including one genus and 38 new species. The mycobiota encountered on the monocotyledonous genus Pandanus is more distinct than that on three dicotyledonous hosts Sideroxylon, Cordemoya and Olea. Arguments are presented to support the inclusion of microfungi in in situ conservation management policies.

Analysis of quality-related parameters at the green leaf-stage and in orthodox-made tea revealed marked quality deterioration with increasing blister blight severity. Total phenols, catechin(s), total nitrogen, amino acids, and chlorophylls, as well as polyphenol oxidase activity, declined in tea shoots with increasing disease severity. Depending on disease intensity, orthodox tea made from infected shoots showed loss in leaf-style. Likewise, theaflavins, thearubigins, caffeine, and high polymerized substances as well as total liquor colour, brightness and briskness also exhibited marked progressive decline in tea made from shoots with increasing disease severity. Aroma components, particularly hexene-1-ol, phenyl acetaldehyde, linalool, methyl salicylate, geraniol, indole, β-ionone, nerolidol, and several unassigned components were also lower in disease affected teas. The magnitude of decline in various aroma constituents corresponded to disease intensity.

RAPD amplifications of 119 Mexican Colletotrichum gloeosporioides isolates from wild native Stylosanthes plants, of two Australian (internal reference isolates of type A and type B) and of two African (previously demonstrated as different from the A and B types) allowed the generation of four polymorphic clusters. The RAPD cluster I contained the Australian type A and 103 Mexican isolates from other species than S. guianensis. The cluster II contained the Australian type B isolate and 14 Mexican isolates from S. guianensis. The clusters III and IV contained one African and one Mexican isolate each.

A phylogenetic study was performed using the ITS1 sequences from 32 representative Mexican isolates selected in the four RAPD clusters, from the two Australian and the two African used as references, from 13 C. gloeosporioides from various hosts and origins available in the EMBL databank and from three phylogenetically related species of Colletotrichum. Two clusters (S and VHO) were generated. Cluster S contained the 30 isolates clustered in RAPD I and II, and the type A and B isolates from Stylosanthes selected in EMBL. Cluster VHO contained the two isolates belonging to RAPD clusters III and IV as well as the remaining Colletotrichum spp. and C. gloeosporioides isolates from various hosts and origins selected in EMBL.

Severe type A lesions were observed on several Stylosanthes species, including S. guianensis, after inoculation with the 26 Mexican isolates selected in RAPD cluster I. The four Mexican isolates selected in RAPD cluster II induced extensive type B lesions only on S. guianensis genotypes. The virulence spectra of the isolates was not linked to variations in their ITS1 region sequence. A wide range of anthracnose lesions was induced by the Mexican isolates in interactions with the various Stylosanthes genotypes.

On the basis of results obtained from the molecular and pathogenic experiments in the present study, of morphological and molecular data from previous work, as well as from other authors, a taxonomic infraspecific differentiation was proposed, as C. gloeosporioides f. stylosanthis f. sp. stylosanthis and f. sp. guianensis.

Byssosphaeria, Chaetosphaeria and Niesslia are discussed and illustrated in relation to their occurrence on palms. New collections of B. schiedermayeriana are reported including Chaetosphaeria exima, which is a new synonym. Chaetosphaeria arecacensis, C. hongkongensis and C. palmicola spp. nov. are described and new collections of C. callimorpha are reported. Cryptophiale is reported as a new anamorph connection for Chaetosphaeria. Niesslia palmicola sp. nov. is described and new collections of N. exosporioides are recorded. Ornatispora gen. nov. is introduced to accommodate several Chaetosphaeria-like species from palms. In Ornatispora, ascomata are superficial, black, papillate, smooth-walled or covered in setae and paraphyses are filiform, non-septate and deliquesce in dried material. Asci are 8-spored, clavate, and lack an apical apparatus and deliquesce at maturity, while ascospores are ellipsoidal, 1-septate, hyaline, verrucose and surrounded by a mucilaginous sheath. One species is closely associated with Didymostilbe aurantiospora, which is considered to be the anamorph. Three new species of Ornatispora, and one new combination are described and illustrated. Ornatispora is compared with Bertia, Chaetosphaeria, Peethambara and Niesslia.

Comparative morphology, mating compatibility and extracellular laccase approaches were used to provide information on infraspecific variation within geographically separated collections of Marasmius androsaceus. Collections/cultures from North America and Europe were used for these analyses. While all utilized collections belonged to one morphological species, mating compatibility crosses revealed three intersterility groups. Extracellular laccase banding patterns confirmed genetic isolation of intersterility groups I and II.

Four day/night temperature regimes (11/6, 14/9, 17/12, 20/15 °C), three photoperiods (0, 12, 24 h d−1), and four continuous temperature regimes (10, 13, 16, 19 °) were evaluated for their effects on growth, sporulation, and conidia discharge of two isolates of Valdensinia heterodoxa, a foliar pathogen of salal (Gaultheria shallon). All temperature regimes supported mycelial growth; however, growth rates were faster at higher temperatures. Sporulation and conidia discharge in both isolates was generally highest at 17/12 ° (day/night) or 16 ° constant compared with other temperature regimes. Photoperiods of 12 and 24 h d−1 resulted in faster growth and significantly greater sporulation and discharge compared with a continuous dark treatment. The study shows that temperature and light conditions have a moderate effect on mycelial growth but are crucial for sporulation of V. heterodoxa. Possible implications for the use of V. heterodoxa as a potential biological control agent for salal are discussed.

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.

Pseudohelicomyces albus gen. et sp. nov. is described. It is characterised by the presence of hyaline, cylindrical arthroconidia originating from either spiral vegetative hyphae or from spiral, branched conidiophores. The hyphae and conidiophores may or may not possess clamp connections. The characteristics of the basidiocarps formed in culture were identical to material collected from nature. P. albus is the anamorphic stage of Psilocybe merdaria and shows similarities to Helicomyces.

Two new thermotolerant species of Thielavia were isolated from Easter Island and India, after treating soil samples with 65% (v/v) ethyl alcohol: T. intermedia sp. nov. characterized by large, obovate, dark brown ascospores with a terminal germ pore; and T. arxii sp. nov. distinguished by the large, ellipsoidal to fusiform, brown ascospores with a prominent, lateral to medial germ pore. A phylogenetic study of the ITS-5.8S rDNA sequences of 18 species of Thielavia and Melanocarpus thermophilus was performed. This analysis revealed that T. intermedia could be the ancestor of the remaining species and that all the species tested were genetically closely related.

More than 90 species are accepted in the xylariaceous genus Rosellinia. Thorough morphological characterisation of all known species will provide a taxonomic hypothesis that can be later tested by DNA sequence analysis. Exploratory analyses of ascospore morphology, shape of ascus apical structure, and anamorph genus suggest six morphological groups in the genus.