This issue of Mycological Research News features: Standardized data on 474 fungal metabolites; Doubt over the identity of soma; Additional evidence for recombination in Candida albicans; Unexpectedly high diversity in leaf decomposition in water and Synthesys: the world's largest network of natural history institutions.

Original research papers in this part examine phosphate transfer in ectomycorrhizal fungi, phosphate efflux in arbuscular mycorrhizal (AM) fungi, and the diversity of AM fungi associated with aquatic plants.

The frequencies of dsRNA elements in Helicobasidium mompa and Rosellinia necatrix have been assessed, and that in H. mompa has been characterized. The separation of H. mompa from H. brebissonii is also examined.

A PCR-based detection method for Rhizoctonia solani on rice, and a genetic transformation system for use in Pochonia chlamydosporia, have been developed. Endophytic Phoma medicaginis can produce brefeldin A which inhibits some phylloplane fungi.

Molecular phylogenetic studies included an examination of Mycosphaerella species on Eucalyptus in South Africa, Aphanomyces species, ophiostomatoid fungi on pine beetles, and report a novel Leptographium. A new family and genus are described in the Glomeromycota for two species formerly referred to Glomus.

The following new scientific names are introduced in this part: Gerdemanniaceae fam. nov.; Gerdemmania gen. nov.; Letographium bistatum, Mycosphaerella fori, and Ophiostoma pulvinisporum spp. nov.; and G. chimonobambusae (syn. Glomus chimonobambusae) and G. scintillans (syn. Glomus scintillans) combs. nov.

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.

We developed a method for separating physiologically active intraradical hyphae of arbuscular mycorrhizal (AM) fungi from mycorrhizal roots, allowing the hyphae to be used for physiological and biochemical experiments. In the present study, the phosphate efflux from the intraradical hyphae in vitro was examined in relation to hyphal phosphatase activity. Onion seedlings (Allium cepa) were planted in the soil inoculated with Gigaspora margarita. Six weeks after transplanting, the intraradical hyphae were isolated from the mycorrhizal roots using plant cell-wall digestion enzymes. The hyphae were incubated briefly at 25 °C in a buffer solution (50 mM Tris/HCl, pH 7.4), then incubated for 2 h and gently shaken with various inhibitors. Phosphate efflux, the amount of phosphate released to the buffer, was analysed by EnzChek phosphate assay kit. Hyphal phosphatase activity was stained histochemically and the proportion of phosphatase-active arbuscules was examined for each inhibitor. Phosphate effluxes were to some degree reduced by all inhibitors used, while the phosphatase inhibitor, BeSO4, greatly reduced the efflux. The degree of inhibition in the arbuscular phosphatase by each chemical was closely correlated to the decrease in the phosphate efflux. These results suggest that hyphal phosphatase may be partially involved in the phosphate efflux process from intraradical hyphae.

The colonisation intensity and composition of the mycorrhizal community in the aquatic plants Lobelia dortmanna and Littorella uniflora were studied. The mycorrhizal fungi were characterised by fungal specific nested PCR and sequencing using the 5′-end of the LSU rDNA as target. For this, primers for the clade of Acaulospora, the clade including Glomus mosseae and G. intraradices and the clade containing G. etunicatum and G. claroideum were used.

The nested PCR products were screened for different sequence types using single stranded conformation polymorphism (SSCP) and representatives for each type were sequenced. A phylogenetic analysis of the sequences showed two phylotypes of Acaulospora, one phylotype within the clade of G. etunicatum/G. claroideum and five within the G. mosseae/G. intraradices clade. The colonisation intensity was comparable to that seen in typical grassland vegetation. The neutral lipid fatty acid 16[ratio ]1ω5 was seen to be indicative of mycorrhizal colonisation with concentrations up to 35 nmol mg−1 root DW, which indicates that the fungi are active.

The diversity and vertical transmission of double-stranded (ds) RNA in Helicobasidium mompa and Rosellinia necatrix was examined by electrophoresis and Northern hybridization. These two fungi share the similar niche as root rot pathogens of trees in forests and orchards, and had diverse dsRNAs. The detection frequency of dsRNA in both fungi was different; in H. mompa, 68.4% (132 out of 193 MCGs; mycelial compatibility groups) had dsRNA, whereas 20.9% (53 out of 254 MCGs) in R. necatrix. dsRNA banding patterns and Northern blot analyses revealed the presence of various dsRNA elements in both fungi. Hyphal tip isolation was mostly unsuccessful to remove dsRNA with some exceptions. Sexual reproduction functioned to remove dsRNA in both fungi since dsRNA was not detected from single sexual spore cultures. Possible explanations for the difference in the detection frequency of dsRNA are discussed in terms of the differences in their sexual reproduction and other factors.

Double-stranded (ds) RNA of various types was detected by electrophoresis in 23 of 25 isolates of Helicobasidium mompa. These dsRNAs varied in size from ca. 2 kbp to more than 10 kbp. dsRNAs from an isolate V1 had two distinct nucleotide sequences for putative RNA-dependent RNA polymerase (RDRP). Their complete sequences revealed that V1 dsRNA1 was 2247 bp in length, with a single ORF that encoded a 706-amino acid residue polypeptide with a predicted molecular mass of 82.6 kDa, and that V1 dsRNA3 was 1776 bp in length, with a single ORF that encoded a 538-amino acid residue polypeptide with a predicted molecular mass of 62.6 kDa. RDRP-conserved motifs were identified in both predicted amino acid sequences. Phylogenetic analysis indicated that V1 dsRNA1 was most closely related to Fusarium poae virus 1, while V1 dsRNA3 was most closely related to Helicobasidium mompa 70 virus. These results indicate coinfection of isolate V1 by two distinct partitiviruses.

A violet root rot fungus recently found in Japan was identified as Helicobasidium brebissonii. The fungus was compared with another violet root rot fungus, H. mompa, which is distributed throughout Japan, in terms of morphological characteristics of the basidiospores and the conidial state, sequences of rDNA ITS regions, and pathogenicity on carrot, sweet potato and apple rootstock. The two species were clearly discriminated by these features and the taxonomic status of both species is discussed.

Rhizoctonia solani is a destructive fungal pathogen of many economically important plants all over the world and the causative organism of sheath blight of rice in many tropical countries including Sri Lanka. A repetitive sequence from the genome of R. solani was cloned and characterized with a view to develop a DNA probe and a PCR diagnostic assay for detection of the fungus. The cloned sequence was 1550 bp long and appeared to be interspersed throughout the genome. The cloned sequence hybridized only to R. solani DNA and was sensitive enough to detect 100 pg of R. solani genomic DNA. PCR primers were designed from the cloned sequence and it was possible to develop a PCR assay for the specific detection of the fungal DNA with 10 pg sensitivity.

The nematophagous fungus Pochonia chlamydosporia is a potential biocontrol agent against root knot and cyst nematodes. Genetic transformation of the fungus to introduce visual marker genes, novel traits, or changes in expression levels of endogenous genes, would greatly enhance understanding of its behaviour on nematode-infested roots and of its interactions with other soil and rhizosphere microorganisms. A transformation system for the introduction of novel genes into P. chlamydosporia has been developed. Methods to generate protoplasts, introduce DNA and regenerate transformed viable fungal mycelium have been optimised, using plasmids carrying the green fluorescent protein marker gene gfp and the hygromycin resistance gene hph. Cultures of P. chlamydosporia were resistant to high levels of a range of fungal inhibitors, including hygromycin, that are commonly used with dominant selectable marker genes in the transformation of other fungi. However, regenerating protoplasts transformed with hph could be selected by their ability to grow through an agar overlay containing 1 mg ml−1 hygromycin. Green fluorescence was observed in protoplasts and regenerating mycelium after transformation with gfp, but the GFP phenotype was lost on subculture. Maintenance of introduced genes was not stable, and during subculture, PCR assays indicated that the transformants lost both hph and gfp. When these genes were introduced on the same plasmid, segregation of hph and gfp was observed prior to their loss. It was unclear whether the introduced plasmids were able to replicate autonomously in P. chlamydosporia, or if they integrated transiently into the fungal genome. Possible reasons for the instability of the transformants are discussed.

Phoma medicaginis was isolated as the dominant endophyte from surface-sterilized shoots of Medicago sativa and M. lupulina growing outdoors. Plants were either symptomless or showed signs of infection in the shape of limited lesions which sometimes contained melanized pycnidial initials. Rapid colonization of host tissue and sporulation were observed within 9 d on dead plant material upon incubation in a moist chamber. Such colonized material, but not freshly harvested living tissue, contained brefeldin A (1.7 μg g−1D.W.). This toxin was also produced in pure culture (20 mg l−1) and in artificially inoculated autoclaved M. sativa stems (3 mg g−1D.W.=920 μg ml−1). The latter concentration of brefeldin A should be similar to that produced within a fruiting lesion of P. medicaginis and suppressed spore germination and growth of nine of 11 common phylloplane fungi tested. This metabolite may thus have a function in substrate defence after the switch from the endophytic to the saprotrophic period in the life-cycle of P. medicaginis following the death of infected host tissue.

Commercial Eucalyptus plantations provide an important source of hardwood for forestry industries, worldwide. Several species of Mycosphaerella are associated with a destructive Eucalyptus leaf disease known as Mycosphaerella Leaf Blotch (MLB). During 2000, a survey was undertaken in several commercial Eucalyptus growing areas of South Africa to determine the identity of the Mycosphaerella spp. contributing to outbreaks of MLB. Symptomatic leaf samples were collected from three major Eucalyptus growing areas and the Mycosphaerella spp. were isolated. Isolates were identified using morphology, ascospore germination patterns and sequence data from the ribosomal DNA operon. Six species, namely M. ellipsoidea, M. irregulariramosa, M. juvenis, M. lateralis, M. marksii, M. nubilosa, as well as a new species, described here as M. fori sp. nov., were recognized. Mycosphaerella nubilosa was the most common species isolated from commercial plantations, particularly on E. nitens, and appears to be the dominant species contributing to MLB. Data obtained in this study show that MLB is caused by a complex of species contributing to disease outbreaks in South Africa.

The identification of plant-associated isolates of Aphanomyces spp. has been mainly based on morphological characters. These types of features, however, can be unreliable due to their high variation and degree of overlap between different taxa. In this work, strains of Aphanomyces, with plant pathogenic and non-pathogenic characteristics, derived mainly from the roots of several leguminous crops in Sweden, as well as a number of reference strains of A. euteiches, A. cladogamus and A. cochlioides were compared by morphology, AT-rich DNA RFLPs and sequence analysis of the total ITS/5.8S rRNA gene region. Parsimony analysis of the sequence data of the total ITS region of 21 strains separated the taxa at the specific level, while two intra-specific groups were also detected within A. euteiches. One comprised all pathogenic isolates of A. euteiches from Sweden, together with two isolates from France and the USA. These isolates formed a homogenous group with identical ITS regions and a single AT-rich DNA RFLP banding pattern. The second ITS subspecific group included reference strains of A. euteiches with preferential pathogenicity to bean and alfalfa, all of which originated from the USA. The bean and alfalfa pathotypes were further distinguished by their different AT-rich DNA RFLPs. The non-pathogenic isolates of Aphanomyces from Sweden associated with the roots of several legumes, formed a genotypically uniform group with an identical ITS sequence and a single AT-rich DNA RFLP pattern. The ITS sequence of this group was identical to that of reference strains of A. cladogamus, suggesting that the non-pathogenic isolates belonged to this species. Intra-specific AT-rich DNA banding profiles were also obtained for isolates of A. cladogamus and these patterns corresponded well to the original hosts.

Bark beetles (Coleoptera: Scolytidae) are common vectors of Ophiostoma species. These fungi include primary tree pathogens and important sapstain agents. In Mexico, Ips calligraphus and Dendroctonus mexicanus occur on many species of pine. Pinus maximinoi and P. pseudostrobus are the hosts of both species of insects. Little research has been done on ophiostomatoid fungi associated with pine bark beetles in Mexico. We recently obtained specimens of these bark beetles and their galleries from Mexico. The aim of the study was to isolate and identify Ophiostoma species associated with the two beetle species. In total, six ophiostomatoid species were found to be associated with them. These included Ceratocystiopsis minuta, Ophiostoma pluriannulatum, an O. galeiformis-like species, two unidentified Sporothrix spp., as well as a new species similar to O. adjuncti, O. ips, and O. montium, that we name as O. pulvinisporum sp. nov.

Radiata pine (Pinus radiata) lumber from Australia, Chile, and New Zealand is imported into Korea where it represents one of the most important sources of timber. Blue stain of this timber is a serious problem for which an integrated control strategy is being developed. One of the fungi that has been isolated from stained radiata pine sapwood in Korea is a Leptographium sp. that has a distinct Sporothrix synanamorph. The aim of this study was to classify this fungus. Morphological comparisons showed that this fungus is distinct from all other species of Leptographium and especially L. elegans and L. francke-grosmanniae that also have Sporothrix synanamorphs. Comparisons of sequence data for the ITS2 and part of the 28S rDNA genes as well as the β-tubulin gene also confirmed that this fungus represents an undescribed taxon, described here as Leptographium bistatum sp. nov.

Molecular, morphological, and cytological evidence show that the arbuscular mycorrhizal fungus Glomus scintillans is more closely related to the genera Gigaspora and Scutellospora (Gigasporaceae) than it is to Glomus s. str., and consequently it contributes to the non-monophyly of the genus Glomus. We transfer the species to Gerdemannia gen. nov., with consequent autonymy of an appropriate family, Gerdemanniaceae fam. nov. Small subunit (SSU) rDNA analysis places Gerdemannia in a clade sharing common ancestry with the Gigasporaceae, and therefore within the Diversisporales (Glomeromycota). Glomus dominikii is considered to be conspecific with G. scintillans, and these species are synonymised. Glomus chimonobambusae is also transferred to the new genus as Gerdemannia chimonobambusae comb. nov.