Partial sequences of the mtLSU rDNA were obtained from the arbuscular mycorrhizal (AM) fungi Glomus proliferum (isolate DAOM 226389) and G. intraradices (isolates JJ291 and BEG75). The exon sequences of the two species showed regions of strong divergence. There was no evidence of intra-isolate sequence heterogeneity as it is found in variable regions of nuclear ribosomal genes of Glomeromycota. In G. intraradices JJ291, two introns were found in the partial LSU sequence. One of the introns contained an ORF for a putative site-specific homing endonuclease of the LAGLIDADG family. In G. intraradices BEG75, one of the introns was missing and the other had a DNA sequence distinct from JJ291. G. proliferum had no introns in the region sequenced. A PCR primer was designed to amplify the fragment of the mtLSU of a different, distinguishable G. intraradices genotype from colonized roots of a field sample. These mitochondrial gene sequences are the first reported from the phylum Glomeromycota. Our findings indicate that the intra-individual sequence heterogeneity of the Glomeromycota may be a peculiar feature of the nuclear genes. Therefore, mtLSU and its introns have the potential to be highly sensitive genetic markers for these fungi in the future.

In the southeastern USA, Armillaria root rot disease on peach (Prunus persica) is caused by Armillaria tabescens, and to a lesser degree by A. mellea. Recent attempts to genetically characterize A. tabescens isolates using rDNA indicated the existence of heterozygosity in diploid isolates. In order to clarify this heterozygosity, DNA from stipe and single spore cultures of A. tabescens isolate SC.MF-1.01 was characterized using RFLP and sequence analysis. Direct sequencing of rDNA amplicons from diploid stipe tissue indicated heterozygosity in the IGS1 and ITS2 regions. IGS1 copies A and B, and ITS copies A and B segregated in a 1[ratio ]1 ratio in single spore progeny, whereby IGS1 copy A always segregated with ITS copy A and IGS1 copy B always segregated with ITS copy B. The results indicate the existence of divergent haplotypes in the two nuclei of SC.MF-1.01 diploid mycelium and a single locus for rDNA tandem repeats. Additional IGS1 copies, designated IGS1 copy C, D, and E, with variable AluI restriction sites were cloned from SC.MF-1.01 diploid mycelium indicating polymorphism within ribosomal tandem repeats in A. tabescens. IGS1 copies C, D, and E were found once each in 100 clones analyzed, and therefore seemed to be rare compared to copies A (44 clones) and B (53 clones). RFLP and sequence analysis of the ribosomal IGS1 and ITS1 regions in North American A. tabescens isolates indicated that heterozygosity is common in A. tabescens diploid mycelium. A PCR-based molecular technique was developed to distinguish A. tabescens from many other North American Armillaria species, including A. mellea.

All hypocrealean species of the genus Geosmithia are anamorphic fungi with connections to bark beetles. G. fassatiae, G. langdonii and G. obscura are described as new sympatric species associated with Scolytus carpini, S. intricatus and S. rugulosus in Central Europe. The species represent a complex of three sister taxa with affinities to G. flava that may be distinguished by differences in morphology, unique RAPD patterns and by sequences of ITS region rDNA. Intraspecific variability and habitat specificity of new species is described and discussed. The high morphological, genetic and ecological uniformity suggest that these Geosmithia spp. are recently derived. A key to all accepted hypocrealean species of the genus is provided.

In spite of the term ‘endophyte’ being employed for all organisms that inhabit plants, mycologists have come to use the term ‘fungal endophyte’ for fungi that inhabit plants without causing visible disease symptoms. The term refers only to fungi at the moment of detection without regard for the future status of the interaction. This paper is a review of literature on non-balansiaceous fungi involved in asymptomatic colonisations of plants. These fungal endophytes represent a continuum of fungi with respect to physiological status, infection modus, colonisation pattern, secondary metabolism, life-history strategy, and developmental and evolutionary stages, but also with respect to the fungal and host taxa involved in the symbioses.

We hypothesize that there are no neutral interactions, but rather that endophyte-host interactions involve a balance of antagonisms, irrespective of the plant organ infected. There is always at least a degree of virulence on the part of the fungus enabling infection, whereas defence of the plant host limits development of fungal invaders and disease. It is also hypothesized that the endophytes, in contrast to known pathogens, generally have far greater phenotypic plasticity and thus more options than pathogens: infection, local but also extensive colonisation, latency, virulence, pathogenity and (or) saprophytism. This phenotypic plasticity is a motor of evolution.

The diversity of the family Trichocomaceae, which includes the major anamorph genera Aspergillus and Penicillium, was studied in the Katandra Nature Reserve, Central Coast, NSW, Australia. Soil, living leaves, leaf litter and detritus were examined by both direct and dilution plating techniques. Fungi were isolated on dichloran Rose Bengal chloramphenicol agar, and dichloran 18% glycerol agar, media suitable for cultivation of many species within this family. Species of Trichocomaceae were isolated from all sites and all substrates examined. A high diversity was found, with more than 50 known species identified, and an equal number of undescribed species detected. More species of Penicillium were recovered than other genera, with Aspergillus species the next most common. Most of the species recovered were anamorphs, though 16 known and unknown ascosporic species were also isolated from heated and unheated soil. Soils, leaf litter, a scat from a native herbivore and leaves of living native plants yielded higher diversity than insects, worms or introduced plants. More species belonging to the family were isolated from soil in dry sclerophyll forest than in rainforest. Conversely, native rainforest plants harboured more diversity than the dry sclerophyll forest plants examined.

Fusarium graminearum and F. pseudograminearum are important plant pathogens in New Zealand and around the world. Headblight and crown rot diseases of cereals caused by these species are responsible for large economic losses due to reduction in seed quality and contamination of grain with tricothecene mycotoxins. In the current study we have used two different molecular phylogenetic approaches, AFLPs and gene genealogies, to gain insight into the evolutionary relationships between F. graminearum, and F. pseudograminearum in New Zealand. The worldwide genetic diversity of F. graminearum clade is represented by at least eight biogeographically distinct species (previously designated as lineages of F. graminearum). Our analysis demonstrated that this clade is represented by F. graminearum (=F. graminearum Lineage 7) and F. cortaderiae (=F. graminearum Lineage 8) in New Zealand. Through our analysis we also confirm the presence of F. pseudograminearum in New Zealand as a first record for this organism. Information on species is necessary for preventing the inadvertent intercontinental introduction of genetically unique foreign pathogens associated with world trade. The ability to place species information into a worldwide context enabled postulation that the New Zealand representatives of F. graminearum clade originated from at least two regions, and probably on at least two hosts. Correlation of species descriptions with biogeographical and host information revealed evidence for co-localisation of F. graminearum clade species with potential for genetic outcrossing in the field. Mycotoxin analysis showed F. graminearum (=lineage 7) isolates produce either nivalenol (NIV) or deoxnivalenol (DON). In contrast, F. cortaderiae isolates produced only NIV. These findings support earlier observations that mycotoxin production in the F. graminearum clade is not species specific, but suggest maintenance of chemotype diversity through speciation may have been restricted to a subset of species.

A personal perspective of John Webster, with an emphasis of studies of aero-aquatic hyphomycetes and the techniques pioneered to enable them to be studied, illustrated by examples particularly from the genera with helicoid conidia, Helicodendron and Helicoon, showing flotation devices.

A new Phytophthora pathogen of trees and shrubs, previously informally designated Phytophthora taxon C, is formally named here as P. kernoviae. P. kernoviae was discovered in late 2003 during surveys of woodlands in Cornwall, south-west England, for the presence of another invasive pathogen, P. ramorum. P. kernoviae is self-fertile (homothallic), having plerotic oogonia, often with distinctly tapered stalks and amphigynous antheridia. It produces papillate sporangia, sometimes markedly asymmetric with medium length pedicels. Its optimum temperature for growth is ca 18 °C and upper limit ca 26 °. Currently, P. kernoviae is especially noted for causing bleeding stem lesions on mature Fagus sylvatica and foliar and stem necrosis of Rhododendron ponticum. P. kernoviae is the latest of several invasive tree Phytophthoras recently identified in the UK. Its geographical origins and the possible plant health risk it poses are discussed.

We isolated over 650 yeasts over a three year period from the gut of a variety of beetles and characterized them on the basis of LSU rDNA sequences and morphological and metabolic traits. Of these, at least 200 were undescribed taxa, a number equivalent to almost 30% of all currently recognized yeast species. A Bayesian analysis of species discovery rates predicts further sampling of previously sampled habitats could easily produce another 100 species. The sampled habitat is, thereby, estimated to contain well over half as many more species as are currently known worldwide. The beetle gut yeasts occur in 45 independent lineages scattered across the yeast phylogenetic tree, often in clusters. The distribution suggests that the some of the yeasts diversified by a process of horizontal transmission in the habitats and subsequent specialization in association with insect hosts. Evidence of specialization comes from consistent associations over time and broad geographical ranges of certain yeast and beetle species. The discovery of high yeast diversity in a previously unexplored habitat is a first step toward investigating the basis of the interactions and their impact in relation to ecology and evolution.