In an attempt to clarify the relationship between fungi classified as Ophiostoma minus, but of different geographic origins and mating systems, sequencing of the 5.8S and ITS 2 rDNA, and β-tubulin gene was carried out. The β-tubulin gene was highly informative, supporting the sub-division of O. minus into two groups based on geographic origin. Furthermore, isolates previously classified as O. pseudotsugae were confirmed as being clearly distinct from O. minus. However, sequencing did not reveal any polymorphisms between isolates with homothallic as compared to heterothallic mating systems. This was supported by crosses using methylbenzamidazole-2-yl carbamate nuclear markers which showed that hybridisation between isolates of different mating systems was possible. However, we propose that different mating systems may still signal a divergence of isolates of O. minus.

The phylogeny of 116 species and varieties of Pythium was studied using parsimony and phenetic analysis of the ITS region of the nuclear ribosomal DNA. The D1, D2 and D3 regions of the adjacent large subunit nuclear ribosomal DNA of half the Pythium strains were also sequenced and gave a phylogeny congruent with the ITS data. All the 40 presently available ex-type strains were included in this study, as well as 20 sequences of recently described species from GenBank. Species for which no ex-type strains were available were represented by either authentic strains (6), strains used in the 1981 monograph of the genus by van der Plaats-Niterink (33), or strains selected on morphological criteria (17). Parsimony analysis generated two major clades representing the Pythium species with filamentous or globose sporangia. A small clade of species with contiguous sporangia was found in between the two main clades. A total number of 11 smaller clades was recognized, which often correlated with host-type or substrate and in several cases with a subset of morphological characters. Many characters used in species descriptions, such as antheridium position, did not correlate with phylogeny. A comparison of the ex-type and representative strains with all ITS sequences of Pythium in GenBank revealed limited infraspecific variation with the exception of P. rostratum, P. irregulare, P. heterothallicum, and P. ultimum. The total number of species examined was 116 (including 60 ex-type strains). Twenty-six species had ITS sequences identical or nearly identical to formerly described species, suggesting possible conspecificity. The importance of comparing ITS sequences of putative new species to the now available ITS database in order to avoid unwarranted new species names being introduced.

Within the basidiomycetes, the vast majority of known mycorrhizal species are homobasidiomycetes. It was therefore surprising when molecular and ultrastructural studies revealed a broad diversity of mycorrhizal associations involving members of the heterobasidiomycetous Sebacinaceae, fungi which, due to their inconspicuous basidiomes, have been often overlooked. To investigate the phylogenetic position of the Sebacinaceae within the basidiomycetes and to infer phylogenetic relationships within the Sebacinaceae, we made molecular phylogenetic analyses based on nuclear rDNA. We present a well-resolved phylogeny of the main lineages of basidiomycetes which suggests that the Sebacinaceae is the most basal group with known mycorrhizal members. Since more basal taxa of basidiomycetes consist of predominantly mycoparasitic and phytoparasitic fungi, it seems possible that a mycorrhizal life strategy, which was transformed into a saprotrophic strategy several times convergently, is an apomorphic character for the Hymenomycetidae. Mycorrhizal taxa of Sebacinaceae, including mycobionts of ectomycorrhizas, orchid mycorrhizas, ericoid mycorrhizas, and jungermannioid mycorrhizas, are distributed over two subgroups. One group contains species with macroscopically visible basidiomes, whereas members of the other group probably lack basidiomes. Sebacina appears to be polyphyletic; current species concepts in Sebacinaceae are questionable. Sebacina vermifera sensu Warcup & Talbot consists of a broad complex of species possibly including mycobionts of jungermannioid and ericoid mycorrhizas.

This wide spectrum of mycorrhizal types in one fungal family is unique. Extrapolating from the known rDNA sequences in Sebacinaceae, it is evident that there is a cosm of mycorrhizal biodiversity yet to be discovered in this group. Taxonomically, we recognise the Sebacinaceae as constituting a new order, the Sebacinales.

This paper continues a revision of generic concepts in the parmelioid lichens using molecular data in order to reach a consensus among lichenologists over which segregates proposed over the last two decades should be accepted. Here we employ data from three gene portions to provide a basis for a revised generic concept of the brown parmelioid lichens hitherto classified in Melanelia. The phylogeny was studied using a Bayesian analysis of a combined data set of nuclear ITS, LSU rDNA and mitochondrial SSU rDNA sequences. 173 new sequences were obtained from 38 specimens of 15 Melanelia species, 37 related parmelioid species, and eight non-parmelioid species. The results indicate that Melanelia is not monophyletic but falls into four different clades. The genus Melanelia is restricted here to a small group of saxicolous lichens related to the type species M. stygia, and with bifusiform conidia, while the remaining species, most of which are primarily corticolous and have mainly cylindrical to filiform conidia, belong to two other clades recognised as two new genera: Melanelixia and Melanohalea, to accommodate the M. exasperata and M. glabra groups, respectively. 27 new combinations are made. The epicortex of Melanelixia species have pores or special structures termed here ‘fenestrations’, while most Melanohalea species are pseudocyphellate. Pleurosticta links to the Melanohalea clade but without strong support, and the phylogenetic position of M. disjuncta and its related species remains uncertain, linking with the Xanthoparmelia (syn. Neofuscelia) clade but also without strong support.

The genetic structure within and between USA and European populations of the emerging phytopathogen Phytophthora ramorum was examined. Four primer combinations were used for amplified fragment length polymorphism (AFLP) fingerprinting of 67 USA isolates from California and Oregon, and 18 European isolates from Belgium, Germany, The Netherlands, Spain and the UK. In addition, three DNA regions (ITS, cox II, and nad 5) of additional Phytophthora species were amplified by polymerase chain reaction, sequenced, and analysed to provide better phylogenetic understanding of P. ramorum within the genus Phytophthora. AFLP banding patterns indicate that the 85 isolates form two distinct lineages within a monophyletic group, distinct from the closely related outgroup species P. lateralis. With the exception of two isolates from an Oregon nursery, European and USA isolates clustered separately within individual clades. The AFLP profiles also indicate that a single clonal lineage dominates the North American population, while the European population consists of an array of mainly unique, closely related AFLP types. Sequences from the three DNA regions were identical among all P. ramorum isolates, and phylogenetic analysis indicates that P. ramorum is closely related to P. lateralis and P. hibernalis.

Genetic variability among sterile cultured single ascospore isolates of Xanthoria parietina, X. calcicola, X. ectaneoides, X. capensis, X. polycarpa and X. resendei was investigated with RAPD-PCR. If available five out of eight ascospores per ascus were analysed. In some samples multispore and mycelial isolates from ascomata were included in the analysis. Ascospore germination rates and phenotypic features such as growth rate, pigmentation and secondary metabolites were uniform in X. parietina sporelings of the same ascus, but varied among the progeny of meiosis in all other species. Phenotypic features correlated with genetic variability. X. parietina revealed polymorphisms among specimens from different worldwide locations. In contrast nine out of ten sets of sibling spores were genetically uniform, with only 2% polymorphism in the remaining set, indicating that X. parietina might be homothallic. X. calcicola, X. ectaneoides, X. capensis, X. polycarpa and X. resendei revealed 9–66% polymorphic loci and therefore are considered heterothallic.

Mycoëmilia scoparia gen. sp. nov. is described as a new member of Kickxellales. It is characterized by lageniform sporocladia produced acrogenously in mass and bears wet and fusiform spores on the sporocladia. Ramicandelaber brevisporus sp. nov. is distinguished from the type species of the genus, R. longisporus, by producing much shorter asexual spores, (3–)8(–13) long fertile branches arising from a globose body, and lateral branches.

Daldinia macaronesica (from the Canary Islands and Madeira), D. palmensis (from the Canary Islands), D. martinii and D. raimundi (from Sicily), and D. vanderguchtiae (from Jersey, Channel Islands) spp. nov., are described, based on new combinations of teleomorphic and anamorphic characters. They all resemble the pantropical D. eschscholzii and/or the European D. concentrica with regard to teleomorphic characters and secondary metabolite profiles generated by analytical HPLC. The status of the newly described taxa was established by SEM of ascospores and microscopic studies of their anamorphs in comparison with various materials of the aforementioned known species. HPLC and SEM studies on the holotype of D. bakeri confirmed its relationships to D. fissa and D. loculata. Yellowish pigments contained in the type specimen of D. bakeri are probably artificial.

Entoleuca mammata (syn. Hypoxylon mammatum) is a damaging pathogen of Populus tremuloides and P. grandidentata in North America and P. tremula in Europe, where the fungus occurs only sporadically in alpine regions and Scandinavia. It has been hypothesized that E. mammata was introduced to Europe from North America. In this study, E. mammata isolates collected from Europe and North America were compared by a sequence analysis of two DNA markers derived from DNA fingerprints. The objective of the study was to elucidate the relationship between North American and European E. mammata populations by testing two hypotheses: (1) North American and European isolates are conspecific; and (2) the fungus was introduced between continents causing both a founder effect and a genetic bottleneck. North American populations were found to be more polymorphic, but no major phylogenetic differences between fungal isolates collected from different continents were found. This result combined with the historical observations of the disease in Europe implies that E. mammata was introduced to Europe several centuries ago.

A prerequisite for symbiotic phosphate transfer in an ectomycorrhizal (ECM) association is hypothesized to be conditions in the interface between both symbiotic partners, that either promote the release of inorganic phosphate (P) from the Hartig net into the interfacial apoplast and/or decrease the fungal reabsorption from this location. To get more information about conditions, which might be involved in the regulation of P efflux or P reabsorption, the effect of various external conditions on 33P-orthophosphate (33P) uptake or efflux by axenic cultures of the ECM basidiomycetes Hebeloma crustuliniforme, Amanita muscaria and Laccaria laccata was analysed. In short-time experiments the following external conditions were analysed: an external supply of (1) P in the preculture, (2) cations (0.1–100 mM K, 0.1–50 mM Na, Mg and Ca), and (3) carbohydrates (0.5–50 mM glucose, fructose or sucrose).

The P absorption was generally reduced in cultures previously supplied with an abundant P supply and with increased P concentrations in their tissues. The P uptake was also affected by an external supply of cations, whereas carbohydrates had only a slight effect. Compared to Na, Mg and Ca, the P absorption by H. crustuliniforme and L. laccata was increased by 0.1 mM K in the labelling solution but decreased after a supply of 100 mM K and then did not differ from the other cation treatments. Compared to other cations, an addition of 50 mM Ca led to a decrease of P absorption by A. muscaria, whereas 50 mM Mg increased the P uptake by H. crustuliniforme.

The P efflux from the fungi was affected by both the cation and carbohydrate concentration of the bathing solution. High concentrations of the monovalent cations K and Na (5 mM or 50 mM) in the bathing solution increased the P efflux by H. crustuliniforme (only Na) and L. laccata (K and Na), but had little effects on A. muscaria. By contrast, the same concentrations of the divalent cation Mg reduced the P efflux from all fungal basidiomycetes. The P efflux from hyphae of H. crustuliniforme and A. muscaria was also affected by the carbohydrate concentration in the bathing solution. Compared to the hexoses, glucose and fructose, the P efflux by both basidiomycetes was stimulated even by low concentrations of sucrose (0.5 mM) in the bathing solution. The effect of carbohydrates on P efflux especially from hyphae of H. crustuliniforme was clearly concentration-dependent and the maximal efflux rates were observed after a supply of 2.5 mM sucrose or fructose or 5 mM glucose in the bathing solution. A further rise of the carbohydrate concentration led to a progressive decrease of P efflux from hyphae of H. crustuliniforme. The results are discussed with respect to the transfer processes between both symbiotic partners in a mycorrhizal association and a possible regulation of these exchange processes.

Mycobiont isolation experiments were performed on six species of Ramalina from Brazil: R. celastri, R. complanata, R. dendriscoides, R. gracilis, R. peruviana and R. sprengelii. This study aimed to optimize the culture conditions and nutrient requirements of the selected mycobionts. The aposymbiotic R. complanta was successfully isolated from ascospores, while aposymbiotic R. peruviana was obtained from thallus fragments. In R. peruviana the production of secondary metabolites was investigated under aposymbiotical growth conditions using HPLC. When cultivated on solid medium, this mycobiont produced the typical chemosyndrome (sekikaic acid and satellite compounds), found in the voucher lichen thallus. When cultivated in liquid medium (immersed in malt yeast medium in the absence of agar), only one, the major lichen substance, sekikaic acid, was synthesized by the fungus. In addition, atranorin was formed, but was not detected in any of the voucher specimens. Red pigments were found in solid and liquid cultures. These were separated into two compounds, but could not be fully identified. R. celastri spores germinated, but did not form mycelia. R. dendriscoides, R. gracilis and R. sprengelii were not successfully cultivated in aposymbiotic conditions, although eight different culture media were tested.

Mycology is changing as an era of extensive genome sequencing comes of age and provides vital information that enables questions to be addressed about fungi in all the major taxonomic groups. As technology transfer facilitates what was once only possible for a very small number of model species, it becomes possible to explore the biology and biodiversity of fungi as a whole. The availability of genome sequence information and reverse genetic technologies allows hypotheses that emerge from biological observations to be tested. Genomic and post-genomic technologies will underline the importance of fungi as excellent models for the study of fundamental biological phenomena. Two enduring areas of research in my own laboratory are described that are now being extended using post-genomic approaches. These projects relate to how fungal hyphae extend and guide their tips and secondly how plant pathogenic oomycete zoospores are guided on their journey to the plant surface.

The molecular phylogeny and biogeography of two widely distributed Amanita species, A. muscaria and A. pantherina, were studied based on specimens from diverse localities. Analyses of both a partial sequence of the ITS region of nuclear DNA and a partial sequence of the β-tubulin gene were able to resolve specimens of each species. Analyses revealed a greater divergence of the β-tubulin region than the ITS region. Based on molecular phylogeny of the combination of the ITS and β-tubulin regions, A. muscaria could be separated into at least three groups (Eurasian, Eurasian subalpine, and North American), and A. pantherina could be separated into at least two groups (North American and Eurasian). We hypothesize that the speciation of A. muscaria occurred in Eurasia with subsequent migration to North America via land bridges. However, it is impossible to determine whether A. pantherina moved from Eurasia to North America or vice versa. For both A. muscaria and A. pantherina, the intracontinental relationships of both Eurasia and North America were closer than the relationships between eastern Asia and eastern North America.

Bayesian and maximum parsimony phylogenetic analyses of 92 collections of the genera Basidiophora, Bremia, Paraperonospora, Phytophthora and Plasmopara were performed using nuclear large subunit ribosomal DNA sequences containing the D1 and D2 regions. In the Bayesian tree, two main clades were apparent: one clade containing Plasmopara pygmaea s. lat., Pl. sphaerosperma, Basidiophora, Bremia and Paraperonospora, and a clade containing all other Plasmopara species. Plasmopara is shown to be polyphyletic, and Pl. sphaerosperma is transferred to a new genus, Protobremia, for which also the oospore characteristics are described. Within the core Plasmopara clade, all collections originating from the same host family except from Asteraceae and Geraniaceae formed monophyletic clades; however, higher-level phylogenetic relationships lack significant branch support. A sister group relationship of Pl. sphaerosperma with Bremia lactucae is highly supported. Within Bremia lactucaes. l., three distinct clades are evident, which only partly conform to the published host specificity groups. All species of the genera Basidiophora, Bremia, Paraperonospora and Plasmopara included in the present study were investigated for haustorial morphology, and all had ellipsoid to pyriform haustoria, which are regarded as a diagnostic synapomorphy of the whole clade. Aspects of coevolution and cospeciation within the downy mildew pathogens with ellipsoid to pyriform haustoria are briefly discussed.