This issue of Mycological Research News features: Sudden oak death: Phytophthora ramorum exhibits transatlantic differences; and Cordyceps sinensis and Ganoderma lucidum amongst top ‘herbal’ medicines. An obituary of John Calhoun (1913–2002) is also included.

Papers in this part report on fungicide-resistant genes in Beaveria bassiana, and the transformation of Coniothyrium minitans. Molecular phlylogenetic studies reveal additional species in the Phytophthora gonapodyides–P. megasperma complex, establish the identities of Armillaria species in Zimbabwe, and analyze Didymella bryoniae isolates worldwide. Conditions affecting indole-3-acetic acid production in Lentinus sojar-caju have also been explored.

Endophytes reduce the density of rust pustules of Puccinia recondita f. sp. tritici in wheat. Thinning of Scots pine stands is shown to have little effect on the ectomycorrhizal species fruiting over 16 yr, and the strategies adopted by two Armillaria species in Norway spruce stump colonization have been compared.

Molecular data justifies the recognition of a new family and previously little-known generic name in Mucorales for the Mortierella isabellina group. Several new species of Mycosphaerella are reported on from Eucalyptus in Australia, and of Anthostomella on fynbos vegetation in South Africa. A new Lewia with an Alternaria anamorph on wheat in Norway has also been found.

The following new scientific names are introduced in this part: Umbelopsidaceae fam. nov.; Anthostomella brabeji, A. cynaroides, A. leucosperma, A. proteae, Lewia avenicola, Mycosphaerella ambiphylla, and M. aurantia spp. nov.; Umbelopsis autotrophica (syn. Mortierella ramanniana var. autotrophica), U. isabellina (syn. Mortierella isabellina), and U. ramanniana (syn. Mucor ramannianus) combs. nov.

This issue of Mycological Research News features: Vagaries in interest in natural products by drug discovery companies.

The first paper in this issue describes the application of topological analysis to hyphal branching patterns in fungal colonies for the first time. Molecular phylogenetic papers concern the relationships of genera and species of Peronosporaceae, South American Cortinarius species, Amanita spp. genotypes in Australian sclerophyll vegetation, new cryptic species of Albatrellus, Cantharellus and Ophiostoma, and the occurrence of group I introns in Beauveria bassiana.

The sterols of field and fungicide resistant Cercospora beticola have been studied, and three novel illudins are described from Coprinopsis episcopalis. An innovative seed-baiting technique to detect different orchid mycorrhizas at the same time has also been devised, and local site variations in fungi on pine needles is documented.

The following new scientific names are introduced in this part: Albatrellus citrinus, Cantharellus cascadensis, and Ophiostoma kryptum spp. nov.; and O. crenulatum (syn. Ceratocystiopsis crenulata) comb. nov.

An α-L-arabinofuranosidase gene (abf1) from Penicillium purpurogenum was identified and sequenced. abf1 has an open reading frame of 1518 bp, does not contain introns and codes for a protein of 506 amino acids. The deduced mature protein has a molecular mass of 49.6 KDa, and its sequence is homologous to arabinofuranosidases of glycosyl hydrolase family 54. Southern blots suggest that abf1 is a single copy gene. Putative sequences for the binding of the transcriptional regulators XlnR, CreA, PacC, AlcR and AreA are present in the promoter. Northern-blot analysis shows that abf1 is expressed at neutral but not at alkaline or acidic pH values. The presence of binding sites for regulatory elements in the promoter region has been compared to the genes of other fungal enzymes belonging to the same family. This is the first characterization of an abf gene from a Penicillium species.

Topology provides a novel means to describe branching patterns and has not been applied to fungal colonies previously. For any branched structure, various topologies are possible, and these lie between two extremes, a herringbone pattern (main axis with primary laterals) and a dichotomous pattern (highly branched system). We applied topological methods to colonies of Peronospora viciae 48 h after inoculation of Pisum sativum leaves. The methods are based on two simulations, one developed for channel networks such as found in river systems and another for biological systems. Although not a true herringbone form, the Peronospora viciae colonies have a strong herringbone element within their growth pattern. All 25 colonies analysed fell into the random distribution according to the confidence limits calculated from simulations for biological systems. These confidence limits, however, represent the percentile distribution of all simulated networks, and only those structures with a perfect herringbone or dichotomous topology fall outside the range. The tendency of P. viciae colonies towards herringbone growth is reflected by the topological indices for altitude and external pathlength (a(obs)/E(a) and pe(obs)/E(pe), where a=altitude, pe=external pathlength, obs=observed for the P. viciae colonies and E=expected values for random growth), and the slope of the regression analysis for a(obs) and pe(obs). We consider this trend as significant because it was consistent for all but one of the colonies, and implies that growth can be envisaged as an intermediate between random and herringbone topology. It is proposed that initial herringbone growth may reflect a strategy that is aimed at overcoming host resistance, achieving rapid colonisation of infected tissue and maximising the potential for nutrient acquisition. This topology would also increase the likelihood of finding a compatible mating type for reproduction between heterothallic isolates.

Sudden oak death has been an emerging disease problem in coastal California and has caused significant losses in forest ecosystems in some regions of the state. The causal agent of this disease has been described as Phytophthora ramorum with two other less aggressive species, P. nemorosa and P. pseudosyringae, recovered from some symptomatic plants. The phylogenetic relationship of these species with other members of the genus was examined by sequence alignment of 667 bp of the mitochondrially-encoded cytochrome oxidase II gene and the nuclear encoded rDNA internal transcribed spacer region. P. ramorum was most closely related to P. hibernalis and P. lateralis in trees from both regions, although the specific relationship among species differed depending on the tree. In the cox II tree these species were on a single clade with P. lateralis basal to a group containing P. ramorum and P. hibernalis. On the maximum parsimony ITS tree P. ramorum was most closely affiliated with P. lateralis and in the same clade as P. hibernalis, but with maximum likelihood analysis P. ramorum was basal to a grouping of P. hibernalis and P. lateralis. While bootstrap support was strong for the grouping of these species together, it was not for determining the relationship among them. In contrast to the cox II tree, the clade containing these three species grouped with P. cryptogea, P. drechsleri, P. erythroseptica, and P. syringae in the ITS tree. Since the same isolates of these species were used for both the cox II and ITS sequence analysis, this difference in species grouping suggests either a differential rate of evolutionary divergence for these two regions, incorrect assumptions about alignment of ITS sequences, or different evolutionary histories of the regions under study. Analysis of combined cox II and ITS data sets gave trees where the relationships among these species were the same as for the ITS tree alone, although the results of the partition homogeneity test (P=0.072) suggest caution should be used in interpretation of this data. All analyses supported a close relationship between P. ilicis, P. nemorosa and P. pseudosyringae, although the analysis did not clarify the evolutionary relationships among these three species. Interestingly, these three species had a unique 6 bp deletion in the cox II gene just before the termination codon. While there was some similarity in phylogenetic grouping of these species and morphological characteristics, this was not consistent across all comparisons in the genus. Data would suggest that P. ramorum, P. nemorosa and P. pseudosyringae are phylogenetically distinct new species and not the result of interspecific hybridization.

The entomopathogenic Beauveria bassiana is a potential biopesticide. Fungicide-tolerant isolates of this fungus would have an added advantage of being compatible with the conventional chemical methods of pest control. Therefore, 30 isolates of the fungus were screened for tolerance to bavistin a commonly used benzimidazole fungicide containing methyl benzimidazol-2-yl carbamate (MBC). Germination and growth bioassays in the presence of 0.05% bavistin were conducted for screening. Three tolerant isolates were identified, showing tolerance up to 2% bavistin. Mutation in the β-tubulin gene is known to confer tolerance to MBC; the nine known mutation sites in the gene involved were sequenced in the tolerant strains. The β-tubulin gene from codons 1–405 was amplified using two pairs of degenerate primers, designed for the conserved region of the β-tubulin gene and sequenced. From the sequence suitable primers were designed for the regions flanking the nine known sites involved in mutations conferring MBC tolerance. The amplified products with these primers from the MBC-tolerant isolates were sequenced and in two (ARSEF 1315 and ARSEF 1316) a mutation was detected in the 198 codon resulting in replacement of glutamic acid with lysine. In the third tolerant isolate (ITCC 913) no mutation could be detected in any of the nine known sites conferring tolerance to MBC. To complete the sequencing of the β-tubulin gene, the remaining part (from codon 405 onwards) of the gene was isolated by a three-prime gene walk. The gene sequence showed a close homology to fungal β-tubulin genes with four introns.

Nuclear ribosomal DNA sequences characteristic of Sebacinaceae were detected by direct amplification of DNA from field collected ectomycorrhizal samples. A study was undertaken to confirm the formation of ectomycorrhizas by Sebacinaceae and to characterise representative samples genetically, morphologically and ultrastructurally. The investigated sebacinoid mycorrhizas were sufficiently characteristic to be identified morphologically. They are distinguished by a characteristic, clampless, hydrophilic extramatrical mycelium, which is very variable in diameter and in wall thickness, and by the presence of distinctive, y-shaped, inflated multibranchings. Differences in the mantle structure clearly discriminate the two investigated sebacinoid mycorrhizal types. Comparison of the D1/D2 domains of the nuclear large subunit pseudogene and the ITS1 and ITS2 regions identifies the fungal partner of one of the mycorrhizal samples as Sebacina incrustans. Ultrastructural investigations of the ectomycorrhizas show a doliporus/parenthesome architecture consistent with that of the Sebacinaceae. Recently published sequence data obtained from sebacinoid mycorrhizas are compared to our sequences and the complex trophic relationships in the Sebacinaceae are discussed. Observations on ectomycorrhizas and basidiomes suggest that species of Sebacinaceae are fairly common mycobionts in various ectomycorrhizal plant communities.