‘Casa Lis’ is the most characteristic building in Salamanca, Spain, belonging to the modernist trend. It was built with Villamayor sandstone from nearby Salamanca, which has high porosity providing an easy medium for water absorption and capillarity. During a restoration process on the southern wall, near an underground water flow, two well defined, naturally developed layers were observed on the sandstone surface: an outer, hard crust with greyish shades and whitish salt patches resulting from rising damp, and an inner, green layer with organic material linking the sandstone to the inorganic crust. The microbiological study of this biofilm showed an ecologically obligate, stable mutualism between a dematiaceous mitosporic fungus (Septonema tormes sp. nov.), a coccoid cyanobacterium (Cyanothece-group) and a green alga (Gloeocystis rupestris), with the accumulation of different metabolites excreted by these microorganisms. The case reported here is one of the few studies where a microbial mat, in association with the external crust, avoids a further weathering of the stone because of an unforeseen biopreservation effect due to the maintenance of humidity at constant levels under the crust avoids changes in clay swelling and subsequent surface arenization of the sandstone. The lichenized complex of a mitosporic mycobiont and two photobionts, in this case, has not been reported before as a stable association on this kind of substrate.

The genetic variation of Armillaria mellea sensu stricto was studied within and among non-heterothallic populations from Japan and Africa, and heterothallic populations from Europe and North America, using somatic incompatibility tests and RAPD analysis. Non-heterothallic isolates from Japan and Africa were divided into four somatic compatibility (SI) groups (A, B, C and D). SI group A contained half of all Japanese isolates and all African isolates. SI groups B and C each contained four Japanese isolates and D contained one isolate. All European and North American isolates were clearly separated from each other by somatic incompatibility tests. From the RAPD analysis, three distinct groups were separated (non-heterothallic, European and North American groups). The non-heterothallic group was divided into three subgroups (Ia, Ib and Ic). Subgroup Ia and Ib corresponded to SI groups A and B, however, Ic contained SI groups C and D. Subgroup Ia, in which 12 of 14 isolates had the same haplotype, showed a little variation. Non-heterothallic populations were less variable than heterothallic populations. The distribution of the isolates belonging to each SI group overlapped within Japan.

Non-pathogenic binucleate Rhizoctonia species (BNR) belonging to the anastomosis group AG-G are commonly associated with members of the Rhizoctonia solani complex. They provide effective protection to young bean seedlings against root rot caused by R. solani AG-4. Both fungi are morphologically similar and it is difficult to differentiate between them without using laborious conventional techniques. RAPD assays were carried out on a large range of isolates of binucleate Rhizoctonia species to identify markers common to all AG-G isolates. Two fragments of 1368 bp and 882 bp were isolated, cloned and used to probe Southern blots of DNA from: AG-G isolates; isolates from other AGs of binucleate and multinucleate Rhizoctonia species; various heterogeneous pathogens known to infect bean plants; and co-inoculated bean plants with BNR AG-G and R. solani AG-4. The fragments hybridized only to DNA from AG-G isolates. Both fragments were nucleotide sequenced and two pairs of SCAR (sequence characterized amplified region) primers (BR1a F/R and BR1b F/R) were generated for use in PCR. Two fragments of anticipated size were generated following PCR of all isolates of AG-G and not from any range of other fungal species associated with root and leaf diseases of beans. The SCAR primers were also used to detect AG-G isolates in DNA extracted from bean and soil samples co-inoculated with binucleate and multinucleate Rhizoctonia species. The assays were capable of detecting as little as 2·6 pg of fungal DNA in extracts of soil samples. This system offers the potential to determine the presence of AG-G isolates in infected soil and plant samples.

The effects of varying carbon (glucose), nitrogen ((NH4)2SO4, KNO3) and phosphate (KH2PO4) source on solubilization of insoluble Co3(PO4)2.8H2O, Zn3(PO4)2.2H2O and ZnO by the soil fungus Aspergillus niger were assessed. Solubilization activity was quantified by measuring the clear zones produced around colonies of A. niger growing on solidified mineral salts medium amended with the insoluble metal compounds. Effects of nutrient variation on solubilizing properties were compared using ratios of colony growth rate on the metal compounds (Rm) to control growth rate (Rc) and the rate of extension of the zone of solubilization (Rs) compared to the colony growth rate on the metal compound (Rm), i.e. Rm[ratio ]Rc and Rs[ratio ]Rm. Ratios of solubilization rate to growth rate (Rs[ratio ]Rm) on all the compounds decreased with decreasing glucose concentration; there was no solubilization of ZnO below 60 mm glucose and no solubilization of the metal phosphates below 6 mm glucose. Reducing the concentration of ammonium sulphate in the growth medium decreased Rs[ratio ]Rm but these values were increased when the nitrogen source was nitrate. Reducing the phosphate concentration increased solubilization of Co3(PO4)2 but reduced solubilization of Zn3(PO4)2. These findings demonstrate that manipulation of carbon, nitrogen and phosphate sources in the growth medium, and variation of the form of the nutrient source, can be used to alter the solubilizing ability of A. niger. Whilst, in the natural environment, this response to different nutrient sources allows optimal exploitation of resources, the potential to manipulate nutrients for maximum solubilizing ability may prove beneficial for the optimization of the solubilization of metal compounds with respect to the bioremediation of metal-contaminated wastes and polluted ecosystems. It could also prove useful in other biotechnological applications such as metal recycling and extraction of metals from low-grade ores.

Anamika gen. nov. is described from southern India with one species, A. indica sp. nov. The genus is characterized by spores with a strongly cavernous ornamentation due to cavernae in the epitunica (perispore), and the possession of cheilo-, pleuro-, and caulocystidia. It seems to be associated with Hopea species (Dipterocarpaceae). Molecular data suggest a close relationship to Hebeloma and Naucoria, but indicate that it represents an independent line of evolution.

Coniothyrium canker, caused by Coniothyrium zuluense, is a serious stem canker disease of Eucalyptus in subtropical parts of South Africa. A Coniothyrium associated with similar symptoms to those in South Africa was observed on E. camaldulensis in 1996 in Thailand. It was previously thought that C. zuluense was restricted to South Africa. This study compares South African isolates of C. zuluense with isolates of the Coniothyrium from Thailand. Results of morphological comparisons indicate that the South African and Thailand isolates are the same. This was further confirmed when all Coniothyrium isolates associated with stem cankers on Eucalyptus spp. grouped together in a single major clade for both rDNA sequence data and AFLP analysis. This clade was distant from isolates of other Coniothyrium spp. included for comparative purposes. Although the Coniothyrium isolates from South Africa and Thailand resided in two separate clades, these were closely related and, we believe that the isolates from Thailand represent C. zuluense. This is the first record of the important Eucalyptus stem canker pathogen outside South Africa.

To imbibe and germinate urediniospores require free water or near saturated atmospheres in which both adsorption of water is maximal and capillary condensation pads form. The rate of spore germination is influenced by the amount of free water available. During imbibition, spores swell and capillary pads form beneath spores in contact with the substratum. These pads greatly increase the area of contact with the substratum. Pad area fluctuates and may depend on the balance between the rate of capillary condensation and the rate of uptake of fluid by spores. When spores, on leaves or cellulose acetate, are misted with water they imbibe rapidly and germinate. Adhesion pads which form under fully imbibed, germinating spores are morphologically similar to capillary pads but they differ in composition. On synthetic surfaces, during imbibition of spores and under microscopic glass beads, pads are composed principally of volatile capillary condensation and are removed when samples are freeze-dried. On host surfaces, when spores are fully imbibed and germinating, pads contain non-volatile soluble materials derived from both pathogen and host. These substances are not removed by extended freeze-drying.

The relative abilities of the multilayer perceptron, radial basis function, asymmetric radial basis function and learning vector quantization artificial neural networks (ANNs) and two non-neural methods to identify fungal spores were compared. ANNs were trained on morphometric data from spores of Pestalotiopsis spp. and a few species in the related Truncatella and Monochaetia. The optimized neural and statistical classifiers had similar identification success on an unseen data set – between 76·0 and 78·8% of a 16-species group and between 63·0 and 67·7% of a 19-species group. The relative merits of each classifier are discussed, as is the potential of ANNs in mycology.

Ophiostoma europhioides and O. huntii are two very similar fungi known to cause blue-stain of timber. Both species have been isolated from pine and spruce in Canada and are characterized by Leptographium anamorphs and hat-shaped ascospores. The aim of this study was to compare isolates of O. huntii and O. europhioides from various parts of the world. These isolates were compared morphologically using light and scanning electron microscopy. Sexual compatibility was determined using mating studies. O. huntii isolates from the different geographical areas were similar to each other but distinct from O. europhioides. A new Ophiostoma species, O. aenigmaticum, is described for the Japanese isolates; Leptographium aenigmaticum, its anamorph, is described as a new species.

Orphella catalaunica and O. helicospora spp. nov. both from the hindgut of stonefly (Leuctra) nymphs from Spain, are described and illustrated. They are compared with the other species of the genus. Orphella haysii is reported for the first time in Europe. The generic description of Orphella is emended to accommodate the new characters described for the new species. A dichotomous key for separating the species is provided.

Sclerotinia nivalis causing lettuce drop was found in central China. It was identified on the basis of comparisons of morphological features, cultural characteristics and sclerotial proteins with those of S. sclerotiorum, S. trifoliorum, S. minor and S. nivalis. This is the first report of S. nivalis in China and lettuce is a new host for this pathogen.

Macro- and micromorphology of 124 specimens and 11 holotypes of South American taxa of subgenus Elfvingia (= G. applanatum complex) were examined, and were compared with isoenzymic data previously obtained. Two major dermis types were defined and illustrated. Spore ornamentation was inspected under SEM. Sixty-four per cent of the specimens had an anamixodermis, 80% had spores with longitudinal furrows under SEM and 83% had a context layer without streaks of melanoid deposits. Some of our South American collections could be ascribed to G. lipsiense, G. tornatum, G. testaceum and G. lobatum. Other taxa are critically discussed. The position adopted in this work was to join under synonymy closely related taxa on the grounds of morphology and geographical distribution. In general, correlation between morphological features and isoenzymic patterns could not be established. In this group, phenotypic plasticity appears to be great.

From 1991 to 1996, Phellinus noxius was collected on 60 host plant species at 136 different sites in Taiwan, and two host plant species at two different sites on Kinmen Island. It was collected mostly on hosts growing in the low elevation plains and hills of western, eastern and southern Taiwan, while it was found on only a few hosts in northern Taiwan and was absent from the high mountain areas. P. noxius was observed on and isolated from 57 woody species, and three annual herbaceous plants. In the field, basidiomes of P. noxius have only been observed on Casuarina equisetifolia, Delonix regia and Ficus microcarpa. A dark brown mycelial mat on the surface of the roots and up the base of stems was used reliably for the field identification of P. noxius. Although P. noxius did not favour a particular soil pH, it was not found in extreme pH conditions. It was found in soils from pH 4 to 9 and most frequently in soil from pH 5 to 8. P. noxius occurred mostly in soils with sand, loamy sand and sandy loam textures.

The taxonomy of several neotropical resupinate Perenniporia is discussed. P. xantha is described as new. It is characterized by a bright yellow resupinate basidiocarp, small pores and small ellipsoid, dextrinoid basidiospores in addition to reduced arboriform skeletal hyphae. Two new combinations are proposed, Perenniporia aurantiaca and P. chromatica. Their relation to other Perenniporia species is briefly discussed.

Genetic variation of the haploid canker pathogen fungus Gremmeniella abietina was investigated by RAPD marker analysis. A total of 126 single pycnidia isolates of G. abietina were sampled from one Pinus contorta plantation in northern Sweden. Average Nei's gene diversity over 32 putative RAPD loci was 0·29. Multilocus genotype analysis revealed 85 different genotypes among the 126 isolates sampled, of which 66 genotypes were detected only once. Nineteen genotypes were detected more than once among 41 isolates, representing 32·5% of clonal fraction of the sampled population. Gametic disequilibrium tests of the sampled population revealed significant associations between 29·6% (147 of 496) of the RAPD loci. When the clonal fraction was removed from the data set, the number of significant pairwise loci combinations decreased from 147 to 73 (14·7%), indicating a high degree of random mating. These results are consistent with previous field observations suggesting that sexual fruiting bodies of G. abietina were common in northern Scandinavia. The high genetic variability detected in the population also suggests that the population was founded by a relatively large number of unrelated genotypes.

Banksia brownii plants treated with a range of potassium phosphonate solutions were examined histologically to determine the mechanism of resistance to invasion by Phytophthora cinnamomi. Reaction zones in plants treated with the chemical compartmentalized P. cinnamomi in both bark and woody tissues, similar to acquired host resistance. Compartmentalization corresponded with the CODIT model of decay in trees. Reaction zones analogous to walls 2 and 3 of CODIT were actively rather than passively formed, and were associated with the ray and axial parenchyma, respectively. While the anatomical evidence of resistance in Australian native flora to this pathogen has been reported previously, this is the first report of enhanced compartmentalization responses of a susceptible native species after treatment with phosphonate.

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.

DNA fingerprinting with a set of synthetic oligonucleotides complementary to simple repetitive sequences was used to develop molecular markers for Ascochyta rabiei, the most important fungal pathogen of chickpea (Cicer arietinum). Two compatible mating type isolates (MatI and MatII) from the U.S. Pacific Northwest with the same low level of aggressivity were compared to highly virulent isolates from the Mediterranean region and Pakistan to find suitable mating partners for the production of a mapping population. After Hinf I or Taq I restriction, electrophoresis and in-gel hybridization with ten different simple repetitive oligonucleotides, all tested single-spored isolates exhibited unique fingerprint patterns. The analysis revealed that the two U.S. mating types share a considerable amount of genetic variability. A total of 77 polymorphic marker bands were detected. A higher number of polymorphic bands (up to 104) was observed between these isolates and those from different geographical regions. The isolates from the Mediterranean region and Pakistan shared a lower degree (between 80 and 90 bands) of detectable genetic diversity. These data permit selection of highly virulent crossing partners for the different mating types with a high degree of detectable polymorphism.

A sexual cross was performed to prove the Mendelian segregation of fingerprint bands for future linkage analysis. Additionally, the fingerprint data based on 268 informative characters combined with phenetic and phylogenetic algorithms allow determination of the genetic identity, relatedness and diversity of the different isolates. To confirm the phylogenetic data, two outgroupers Ascochyta fabae and Ascochyta pisi, were included. Results indicate that A. pisi is more closely related to A. rabiei than A. fabae.

Cordyceps unilateralis, a fastidious insect pathogenic fungus, was found to produce red naphthoqinones, which possess anti-malarial activity. A method for the isolation and in vitro cultivation of this fungus was, therefore, developed in this study. Ascospores from ant cadavers were used as starting materials, and their secondary spores were allowed to germinate first on PDA for 2 d. Secondary spores were then transferred to Grace's Insect Cell Medium+2 mM glutamine and 10% fetal bovine serum, incubated for 7 d, after which the formation of mycelia was stimulated by transfer to potato dextrose broth. As a result, the growth of C. unilateralis from the steps of secondary spore germination, blastospore formation and mycelial growth was successfully completed for the first time.

Larix kaempferi seedlings, in the process of becoming established during the revegetation process following a volcanic eruption, were assessed for the types, occurrence patterns and diversity of their ectomycorrhizas along an elevation gradient. On the basis of macro- and microscopic characteristics, 12 types of ectomycorrhizas were classified. In general, ectomycorrhizal types differed more by site than by seedling age. The majority of root systems of seedlings with an age ranging from 1 to 5 years were colonized by 1 or 2 types of mycorrhizal fungi at low and intermediate elevations, 2 or 3 types at a higher elevation. Under the more stressed environments of high and intermediate elevations, the mean d.w. of 1 yr old seedlings, 40% of which were colonized by 3 or 4 mycorrhizal fungi, was double the weight of the same aged seedlings at lower elevation sites, only 10% of which were colonized by 3 or 4 mycorrhizal fungi. The correspondence between the type and frequency of mycorrhizas, the elevation gradient and litter accumulation suggests that change in litter accumulation along gradient may influence not only mycorrhizal types and their occurrence, but also the diversity of mycorrhizas on one seedling. Diversity of mycorrhizas on the same seedling is assumed to be critical for the establishment of seedlings from the very beginning on stressed sites, and may also be influenced by the availability of nutrients. The more intensive competition between mycorrhizas that occurs due to a reduction in the food source (tip roots) shared by the mycorrhizal fungi with similar resource requirements, results in frequent co-occurrence of mycorrhizas in the same root system or even the same root tip. As a result, the diversity of mycorrhizal types seems to become simplified as the seedlings age.