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Abstract: The ascomycete Cadophora finlandica, which can form mycorrhizas with ectomycorrhizal and ericoid hosts, is commonly found in heavy metal polluted soils. To understand the selective advantage of this organism at contaminated sites heavy metal regulated genes from C. finlandica were investigated. For gene identification a strategy based on a genomic microarray was chosen, which allows a rapid, genome-wide screening in genetically poorly characterized organisms. In a preliminary screen eleven plasmids covering eight distinct genomic regions and encoding a total of ten Cd-regulated genes were identified. Northern analyses with RNA from C. finlandica grown in the presence of either Cd, Pb or Zn revealed different transcription patterns in response to the heavy metals present in the growth medium. The Cd-regulated genes are predicted to encode several extracellular proteins with unknown functions, transporters, a centaurin-type regulator of intracellular membrane trafficking, a GNAT-family acetyltransferase and a B-type cyclin. [Copyright &y& Elsevier]

Abstract: Fully subterranean Rhizanthella gardneri (Orchidaceae) is obligately mycoheterotrophic meaning it is nutritionally dependent on the fungus it forms mycorrhizas with. Furthermore, R. gardneri purportedly participates in a nutrient sharing tripartite relationship where its mycorrhizal fungus simultaneously forms ectomycorrhizas with species of Melaleuca uncinata s.l. Although the mycorrhizal fungus of R. gardneri has been morphologically identified as Thanatephorus gardneri (from a single isolate), this identification has been recently questioned. We sought to clarify the identification of the mycorrhizal fungus of R. gardneri, using molecular methods, and to identify how specific its mycorrhizal relationship is. Fungal isolates taken from all sites where R. gardneri is known to occur shared almost identical ribosomal DNA (rDNA) sequences. The fungal isolate rDNA most closely matched that of other Ceratobasidiales species, particularly within the Ceratobasidium genus. However, interpretation of results was difficult as we found two distinct ITS sequences within all mycorrhizal fungal isolates of R. gardneri that we assessed. All mycorrhizal fungal isolates of R. gardneri readily formed ectomycorrhizas with a range of M. uncinata s.l. species. Consequently, it is likely that R. gardneri can form a nutrient sharing tripartite relationship where R. gardneri is connected to autotrophic M. uncinata s.l. by a common mycorrhizal fungus. These findings have implications for better understanding R. gardneri distribution, evolution and the ecological significance of its mycorrhizal fungus, particularly in relation to nutrient acquisition. [Copyright &y& Elsevier]

Abstract: The fungal community associated with the terrestrial photosynthetic orchid Gymnadenia conopsea was characterized through PCR-amplification directly from root extracted DNA and cloning of the PCR products. Six populations in two geographically distinct regions in Germany were investigated. New ITS-primers amplifying a wide taxonomic range including Basidiomycetes and Ascomycetes revealed a high taxonomic and ecological diversity of fungal associates, including typical orchid mycorrhizas of the Tulasnellaceae and Ceratobasidiaceae as well as several ectomycorrhizal taxa of the Pezizales. The wide spectrum of potential mycorrhizal partners may contribute to this orchid''s ability to colonize different habitat types with their characteristic microbial communities. The fungal community of G. conopsea showed a clear spatial structure. With 43 % shared taxa the species composition of the two regions showed only little overlap. Regardless of regions, populations were highly variable concerning taxon richness, varying between 5 and 14 taxa per population. The spatial structure and the continuous presence of mycorrhizal taxa on the one hand and the low specificity towards certain fungal taxa on the other hand suggest that the fungal community associated with G. conopsea is determined by multiple factors. In this context, germination as well as pronounced morphological and genetic differentiation within G. conopsea deserve attention as potential factors affecting the composition of the fungal community. [Copyright &y& Elsevier]

Abstract: While it is established that increasing atmospheric inorganic nitrogen (N) deposition reduces ectomycorrhizal fungal biomass and shifts the relative abundances of fungal species, little is known about effects of organic N deposition. The effects of organic and inorganic N deposition on ectomycorrhizal fungi may differ because responses to inorganic N deposition may reflect C-limitation. To compare the effects of organic and inorganic N additions on ectomycorrhizal fungi, and to assess whether host species may influence the response of ectomycorrhizal fungi to N additions, we conducted an N addition experiment at a field site in the New Jersey pine barrens. Seedlings of two host species, Quercus velutina (black oak) and Pinus rigida (pitch pine), were planted at the base of randomly-selected mature pitch pine trees. Nitrogen was added as glutamic acid, ammonium, or nitrate at a rate equivalent to 227.5 kg ha−1 y−1 for eight weeks, to achieve a total application of 35 kg ha−1 during the 10-week study period. Organic and inorganic N additions differed in their effects on total ectomycorrhizal root tip abundance across hosts, and these effects differed for individual morphotypes between oak and pine seedlings. Mycorrhizal root tip abundance across hosts was 90 % higher on seedlings receiving organic N compared to seedlings in the control treatment, while abundances were similar among seedlings receiving the inorganic N treatments and seedlings in the control. On oak , 33–83 % of the most-common morphotypes exhibited increased root tip abundances in response to the three forms of N, relative to the control. On pine , 33–66 % of the most-common morphotypes exhibited decreased root tip abundance in response to inorganic N, while responses to organic N were mixed. Plant chemistry and regression analyses suggested that, on oak seedlings, mycorrhizal colonization increased in response to N limitation. In contrast, pine root and shoot N and C contents did not vary in response to any form of N added, and mycorrhizal root tip abundance was not associated with seedling N or C status, indicating that pine received sufficient N. These results suggest that in situ organic and inorganic N additions differentially affect ectomycorrhizal root tip abundance and that ectomycorrhizal fungal responses to N addition may be mediated by host tree species. [Copyright &y& Elsevier]

Abstract: Examining the fine-scale spatial structure of fungal populations can tell us much about how individual species reproduce and disperse throughout natural landscapes. Here we study the fine-scale genetic structure of Tricholoma matsutake, a prized edible and medicinal mushroom, by systematic sampling of mycorrhizas within fairy rings in 50-y-old and old-growth forests in two villages. Using single nucleotide polymorphism DNA markers we show that mycorrhizas in both forest age classes in both villages showed high levels of genotypic diversity, consistent with a reproductive life history predominated by outcrossing via basidiospore dispersal. Both the percentage of polymorphic loci within fairy rings, as well as genotype diversity were higher in old-growth compared to 50-y-old forests. Fifty-year-old forests showed significant spatial autocorrelation between pairs of mycorrhizas up to 42m, and a pattern consistent isolation-by-distance structure. Spatial patterns in old-growth forests were random. Furthermore, AMOVA analysis indicates that 11% of molecular variance in 50-y-old forests is partitioned between villages, whereas no significant variance is partitioned between villages in old-growth forests. We conclude that populations of T. matsutake in 50-y-old forests are the result of a founder effect maintained by local inoculation sources. This pattern attenuates as forests age and accumulate inocula from more distance sources. We speculate on how genetic mosaicism within T. matsutake fairy rings may structure populations within a chronosequence. Finally, we discuss how population spatial dynamics and dispersal strategy in T. matsutake contrast with other ectomycorrhizal species. [Copyright &y& Elsevier]

Abstract: The present study was undertaken to investigate whether the behaviour in vitro of Lunularia cruciata grown with Glomus intraradices and G. proliferum, on SRV medium with 29.2mm sucrose satisfies the requirements of Koch'' postulates for mutualistic symbiosis. Hyphae emerging from mycothallus were able to grow over a two-compartment Petri dish barrier and capture and translocate phosphorus into the host liverwort. Thus, there were increases in plant dry weight, higher AM fungi spore production, and higher plant total phosphorus content. Moreover, this colonization of L. cruciata reproduces typical symptoms generally associated with mycorrhizae. These results showed that mycothalli of L. cruciata have available functionalities generally associated with mycorrhizal symbiosis in higher plants; however, the energy/photosynthetic carbon requirements to maintain a mutualistic symbiosis may be a limiting factor in vivo. Features here discussed indicate that, at least in tested experimental conditions, the endophytic association of L. cruciata with both G. intraradices and G. proliferum is a parasitic/opportunistic partnership rather than a mutualistic symbiosis. [Copyright &y& Elsevier]

Abstract: European aspen is one of the most widely distributed trees in Central Europe and is a typical early colonizer of poor and disturbed soils. However, little is known about ectomycorrhizal (ECM) fungi in these ecosystems. We examined the ECM community of European aspen growing on a heavily contaminated site in southern Austria by analysing ECM roots, sorting them into morphotypes, subjecting them to DNA extraction, PCR, and DNA sequencing. ECM root symbionts were sampled two times in 2004. During this time, the below-ground community structure was relatively stable; we found no evidence of taxa adapted to summer or autumn conditions and only two species varied widely in occurrence between soil horizons. The ECM fungal community was diverse (54 species), rich in Basidiomycota (43 species), and dominated by Cenococcum geophilum and fungi with corticoid basidiomes (e.g. Thelephoraceae). [Copyright &y& Elsevier]

Abstract: Paxillus involutus (basidiomycetes, Boletales) is a common ectomycorrhizal fungus in the Northern Hemisphere. The fungus displays significant variation in phenotypic characters related to morphology, physiology, and ecology. Previous studies have shown that P. involutus contains several intersterility groups and morphological species. In this study, we have used concordance of multiple gene genealogies to identify genetically isolated species of P. involutus. Fragments from five protein coding genes in 50 isolates of P. involutus collected from different hosts and environments in Europe and one location in Canada were analysed using phylogenetic methods. Concordance of the five gene genealogies showed that P. involutus comprises at least four distinct phylogenetic lineages: phylogenetic species I (with nine isolates), II (33 isolates), III (three isolates), and IV (five isolates). The branches separating the four species were long and well supported compared with the species internodes. A low level of shared polymorphisms was observed among the four lineages indicating a long time since the genetic isolation began. Three of the phylospecies corresponded to earlier identified morphological species: I to P. obscurosporus, II to P. involutus s. str., and III to P. validus. The phylogenetic species had an overlapping geographical distribution. Species I and II differed partly in habitat and host preferences. [Copyright &y& Elsevier]

Abstract: To understand the biogeography of truffle-like fungi, DNA sequences were analysed from representative taxa of Hysterangiales. Multigene phylogenies and the results of ancestral area reconstructions are consistent with the hypothesis of an Australian, or eastern Gondwanan, origin of Hysterangiales with subsequent range expansions to the Northern Hemisphere. However, neither Northern Hemisphere nor Southern Hemisphere taxa formed a monophyletic group, which is in conflict with a strictly vicariant scenario. Therefore, the occurrence and importance of long-distance dispersal could not be rejected. Although a pre-Gondwanan origin of Hysterangiales remains as a possibility, this hypothesis requires that Hysterangiales exist prior to the origin of the currently recognized ectomycorrhizal plants, as well as the arrival of mycophagous animals in Australia. This also requires that a basal paraphyletic assemblage represents parallel evolution of the ectomycorrhizal symbiosis, or that Hysterangiales was mycorrhizal with members of the extinct flora of Gondwana. Regardless, models for both ancient and more recent origins of Hysterangiales are consistent with truffle-like fungi being capable of transoceanic dispersal. [Copyright &y& Elsevier]

Abstract: Soil salinization has become a severe global problem and salinity is one of the most severe abiotic stresses inhibiting growth and survival of mycorrhizal fungi and their host plants. Salinity tolerance of ectomycorrhizal fungi and survival of ectomycorrhizal inocula is essential to reforestation and ecosystem restoration in saline areas. Proteomic changes of an ectomycorrhizal fungus, Boletus edulis, when exposed to salt stress conditions (4% NaCl, w/v) were determined using two-dimensional electrophoresis (2DE) and mass spectrometry (MS) techniques. Twenty-two protein spots, 14 upregulated and 8 downregulated, were found changed under salt stress conditions. Sixteen changed protein spots were identified by nanospray ESI Q-TOF MS/MS and liquid chromatography MS/MS. These proteins were involved in biosynthesis of methionine and S-adenosylmethionine, glycolysis, DNA repair, cell cycle control, and general stress tolerance, and their possible functions in salinity adaptation of Boletus edulis were discussed. [Copyright &y& Elsevier]

Abstract: Hygromycin B resistance was transferred to the sterile mycelia of Cadophora finlandia and Phialocephala fortinii by co-cultivation with Agrobacterium tumefaciens. Constitutively expressed green fluorescent protein (GFP) was also introduced using the same vector. Confocal laser scanning microscopy (CLSM) revealed strong fluorescence of transformants. Both traits were mitotically stable during one year of subculturing on non-selective growth medium. Southern blot analysis showed that the majority of the transformants contained single-copy integrations at random sites in the genome. [Copyright &y& Elsevier]

Abstract: There are very few studies on Tuber melanosporum associated with Cistus populations. In central Spain, we confirm that C. laurifolius shows carpophore production of Tuber melanosporum. This study demonstrates a correlation between T. melanosporum production and the size of the 41 burns, with burn size explaining 26% of the variability in carpophore production. However, statistical analysis of the results indicates that average production of 21 burns with Cistus laurifolius is 73% lower than the production of 20 burns associated with Quercus/Corylus without Cistus laurifolius in this zone, respectively. C. laurifolius develops small burns, which has an impact on their carpophore production, and their soils have 92% less active carbonate than the burns associated with Quercus/Corylus in this zone, respectively. The low levels of active carbonate allow Cistus laurifolius to grow, but impair Tuber melanosporum production. We thus provide a mechanism, based on the inability of Cistus laurifolius to grow in highly carbonated soils, which contradicts the well-known fact that C. laurifolius might act as a transmitter of Tuber melanosporum mycorrhizae. These results indicate that this rockrose can not be considered a useful species for truffle culture. We thus recommend that particular attention should be given to the concentration of active carbonate present in the soil in future studies on the relationship between Cistus species and truffles. [Copyright &y& Elsevier]

Abstract: The diversity of mycorrhizal fungi associated with an introduced weed-like South African orchid (Disa bracteata) and a disturbance-intolerant, widespread, native West Australian orchid (Pyrorchis nigricans) were compared by molecular identification of the fungi isolated from single pelotons. Molecular identification revealed both orchids were associated with fungi from diverse groups in the Rhizoctonia complex with worldwide distribution. Symbiotic germination assays confirmed the majority of fungi isolated from pelotons were mycorrhizal and a factorial experiment uncovered complex webs of compatibility between six terrestrial orchids and 12 fungi from Australia and South Africa. Two weed-like (disturbance-tolerant rapidly spreading) orchids —D. bracteata and the indigenous Australian Microtis media, had the broadest webs of mycorrhizal fungi. In contrast, other native orchids had relatively small webs of fungi (Diuris magnifica and Thelymitra crinita), or germinated exclusively with their own fungus (Caladenia falcata and Pterostylis sanguinea). Orchids, such as D. bracteata and M. media, which form relationships with diverse webs of fungi, had apparent specificity that decreased with time, as some fungi had brief encounters with orchids that supported protocorm formation but not subsequent seedling growth. The interactions between orchid mycorrhizal fungi and their hosts are discussed. [Copyright &y& Elsevier]

Abstract: The study of the role that fungi have played and are playing in fundamental geological processes can be termed ‘geomycology’ and this article seeks to emphasize the fundamental importance of fungi in several key areas. These include organic and inorganic transformations and element cycling, rock and mineral transformations, bioweathering, mycogenic mineral formation, fungal–clay interactions, metal–fungal interactions, and the significance of such processes in the environment and their relevance to areas of environmental biotechnology such as bioremediation. Fungi are intimately involved in biogeochemical transformations at local and global scales, and although such transformations occur in both aquatic and terrestrial habitats, it is the latter environment where fungi probably have the greatest influence. Within terrestrial aerobic ecosystems, fungi may exert an especially profound influence on biogeochemical processes, particularly when considering soil, rock and mineral surfaces, and the plant root–soil interface. The geochemical transformations that take place can influence plant productivity and the mobility of toxic elements and substances, and are therefore of considerable socio-economic relevance, including human health. Of special significance are the mutualistic symbioses, lichens and mycorrhizas. Some of the fungal transformations discussed have beneficial applications in environmental biotechnology, e.g. in metal leaching, recovery and detoxification, and xenobiotic and organic pollutant degradation. They may also result in adverse effects when these processes are associated with the degradation of foodstuffs, natural products, and building materials, including wood, stone and concrete. It is clear that a multidisciplinary approach is essential to understand fully all the phenomena encompassed within geomycology, and it is hoped that this review will serve to catalyse further research, as well as stimulate interest in an area of mycology of global significance. [Copyright &y& Elsevier]

Abstract: Fruit bodies of hypogeous fungi are an important food source for many small mammals and are consumed by larger mammals as well. A controversial hypothesis that prescribed burning increases fruiting of certain hypogeous fungi based on observations in Tasmania was tested in the Australian Capital Territory to determine if it applied in a quite different habitat. Ten pairs of plots, burnt and nonburnt, were established at each of two sites prescribe-burnt in May 1999. When sampled in early July, after autumn rains had initiated the fungal fruiting season, species richness and numbers of fruit bodies on the burnt plots were extremely low: most plots produced none at all. Both species richness and fruit body numbers were simultaneously high on nonburnt plots. One of the sites was resampled a year after the initial sampling. At that time species richness and fruit body abundance were still significantly less on burnt plots than on nonburnt, but a strong trend towards fungal recovery on the burnt plots was evident. This was particularly so when numbers of fruit bodies of one species, the hypogeous agaric Dermocybe globuliformis, were removed from the analysis. This species strongly dominated the nonburnt plots but was absent from burnt plots in both years. The trend towards recovery of fruit body abundance in the burnt plots one year after the burn was much more pronounced with exclusion of the Dermocybe data. The Tasmanian-based hypothesis was based mostly on the fruiting of two fire-adapted species in the Mesophelliaceae. Neither species occurred on our plots. Accordingly, the results and conclusions of the Tasmanian study cannot be extrapolated to other habitats without extensive additional study. Implications for management of habitat for fungi and the animals that rely on the fungi as a food source are discussed. [Copyright &y& Elsevier]

Abstract: The mycorrhizal state of epiphytic orchids has been controversially discussed, and the state and mycobionts of the pleurothallid orchids, occurring abundantly and with a high number of species on stems of trees in the Andean cloud forest, were unknown. Root samples of 77 adult individuals of the epiphytic orchids Stelis hallii, S. superbiens, S. concinna and Pleurothallis lilijae were collected in a tropical mountain rainforest of southern Ecuador. Ultrastructural evidence of symbiotic interaction was combined with molecular sequencing of fungi directly from the mycorrhizas and isolation of mycobionts. Ultrastructural analyses displayed vital orchid mycorrhizas formed by fungi with an imperforate parenthesome and cell wall slime bodies typical for the genus Tulasnella. Three different Tulasnella isolates were obtained in pure culture. Phylogenetic analysis of nuclear rDNA sequences from coding regions of the ribosomal large subunit (nucLSU) and the 5.8S subunit, including parts of the internal transcribed spacers, obtained directly from the roots and from the fungal isolates, yielded seven distinct Tulasnella clades. Tulasnella mycobionts in Stelis concinna were restricted to two Tulasnella sequence types while the other orchids were associated with up to six Tulasnella sequence types. All Tulasnella sequences are new to science and distinct from known sequences of mycobionts of terrestrial orchids. The results indicate that tulasnelloid fungi, adapted to the conditions on tree stems, might be important for orchid growth and maintenance in the Andean cloud forest. [Copyright &y& Elsevier]

Abstract: The aim of this study was to reassess the use of autofluorescence for evaluating AM colonization in mycorrhizal roots in the light of criticisms of this method that affirmed that only metabolically inactive arbuscules autofluoresce. It was also investigated whether other mycorrhizal structures, such as hyphae, vesicles and spores, could be detected by autofluorescence, and whether the autofluorescence pattern of AM fungal structures could be exploited methodologically, for example, in the detection and sorting of spores by flow cytometry. Mycorrhizal roots of the palm species Brahea armata, Chamaerops humilis, Phoenix canariensis and Phoenix dactylifera were sectioned and observed by means of fluorescence microscopy. In addition, fungal structures isolated from mycorrhizal roots of P. dactylifera were examined. The same root sections and isolated fungal structures were subjected to vital staining with nitro blue tetrazolium to determine their metabolic state (active or inactive). Moreover, spores of Glomus intraradices, and Glomus clarum were studied by epifluorescence and flow cytometry. Mycorrhizal whole roots of Medicago sativa were also assessed by autofluorescence detection. In contrast to previous reports, the results presented in this paper clearly demonstrate that all fungal structures, both intra- and extraradical, autofluoresced under blue light excitation, regardless of their state (dead or alive). Some arbuscules isolated from roots and mature spores showed further autofluorescence under green light excitation. The source of the autofluorescence was localized in the fungal cell wall. It was shown that AM spores can be detected by flow cytometry. The results support the use of autofluorescence for the evaluation of AM colonization, at least in palm species, and refute previous criticisms of the method. [Copyright &y& Elsevier]

Abstract: Two new ectocarpic arbuscular mycorrhizal fungal species, Glomus drummondii and G. walkeri (Glomeromycota), found in maritime sand dunes of northern Poland and those adjacent to the Mediterranean Sea are described and illustrated. Mature spores of G. drummondii are pastel yellow to maize yellow, globose to subglobose, (58–)71(–85)μmdiam, or ovoid, 50–80×63–98μm. Their wall consists of three layers: an evanescent, hyaline, short-lived outermost layer, a laminate, smooth, pastel yellow to maize yellow middle layer, and a flexible, smooth, hyaline innermost layer. Spores of G. walkeri are white to pale yellow, globose to subglobose, (55–)81(–95)μmdiam, or ovoid, 60–90×75–115μm, and have a spore wall composed of three layers: a semi-permanent, hyaline outermost layer, a laminate, smooth, white to pale yellow middle layer, and a flexible, smooth, hyaline innermost layer. In Melzer''s reagent, only the inner- and outermost layers stain reddish white to greyish rose in G. drummondii and G. walkeri, respectively. Both species form vesicular–arbuscular mycorrhizae in one-species cultures with Plantago lanceolata as the host plant. Phylogenetic analyses of the ITS and parts of the LSU of the nrDNA of spores placed both species in Glomus Group B sensu Schüßler et al. [Schüßler A, Schwarzott D, Walker C, 2001. A new fungal phylum, the Glomeromycota: phylogeny and evolution. Mycolological Research 105: 1413-1421.] [Copyright &y& Elsevier]

Ericoid mycorrhizal endophytes and other root-associated fungi from Epacris pulchella (Ericaceae) in an eastern Australian sclerophyll forest, along with Hymenoscyphus ericae, were tested for their abilities to produce extracellular chitinolytic activities during growth in axenic culture. Two root-associated fungi produced activities that were active against only a monomeric 4-methylumbelliferyl (4-MU) glycoside of N-acetylglucosamine, suggesting exo-acting β-N-acetylhexosaminidase (EC 3.2.1.52) activity. All ericoid mycorrhizal fungi and two root-associated fungi produced activities against dimeric and trimeric 4-MU glycosides of N-acetylglucosamine, suggesting production of chitobiosidase and endo-acting chitinase (EC 3.2.1.14) respectively in addition to β-N-acetylhexosaminidase. Specific activities for all ericoid mycorrhizal fungi, including H. ericae, were of the same order of magnitude, suggesting that their chitinolytic potential is broadly similar. Chitinase activities were only produced by an ericoid mycorrhizal fungus when chitin was included in the medium, however, no activity was produced if glucose was also present in the medium. [Copyright &y& Elsevier]

Abstract: Simple sequence repeat (SSR) markers were developed from SSR-enriched genome libraries for the ectomycorrhizal basidiomycete Laccaria bicolor. Seven markers were single-locus and amplified unambiguously in L. bicolor. The seven SSR markers were further characterized using an array of 15 L. bicolor strains representative of diverse origins worldwide. The observed number of alleles per locus varied from 5–9 and the values of observed heterozygosity from 0.167 to 0.667. The seven SSR loci could be amplified from DNA extracted from root tips of L. bicolor inoculated pine seedlings. All the L. bicolor ectomycorrhizas analysed exhibited the same SSR multi-locus profile as that detected for the UAMH8232 inoculant strain. The set of markers described represents a potent tool for the monitoring of introduced strains of L. bicolor and for molecular ecology applications. [Copyright &y& Elsevier]

Abstract: A rapid procedure was developed to amplify ITS fragments directly from Tuber ectomycorrhizas either synthesized in a greenhouse or collected from the field. The addition of Bovine Serum Albumin (BSA) to the reaction mixtures overcame the presence of reaction inhibitors present in fungal and root cells, and enabled the amplification of the ITS regions directly from ectomycorrhizal tissues. This method is cheaper and less time-consuming than conventional procedures, and reduces the time required from 1-4h to a few minutes. It is also much more sensitive, allowing the identification of just a small fragment of a mycorrhizal root tip. Because of this it is possible to select only the target fungal tissue and hence minimise the risk of contamination by saprobic or other mycorrhizal species. The method also avoids the use of toxic or hazardous substances. This method could have a wider application in other areas of applied mycology. [Copyright &y& Elsevier]

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. [ABSTRACT FROM AUTHOR]

All available publications providing descriptions of ectomycorrhizas (ECM) were reviewed in order to build a database containing details on fungus forming the ECM, host tree, country where the material for description was collected, and habitat of the ECM. Other secondary data were also recorded. In all 1244 descriptions of ECM published since 1961 in 479 papers were reviewed. The number of different ECM morphotypes described was 814. Most ECM described were collected in Europe and North America. Gymnosperms were the most common tree associates, and boreal and temperate forests the most studied ecosystems. Fungal symbionts were mostly Basidiomycota, epigeous, and with mushroom-like morphology. The paper also addresses the gaps in ECM knowledge that mycorrhizologists should address in future studies. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Unlike previous reports that have shown that water soluble and volatile compounds from roots or root exudates play an important role in precolonization events during arbuscular mycorrhizal (AM) fungus-host root interactions (Bécard & Piché 1989, Giovannetti et al. 1993), the results shown here deal with particulate and viscous fractions isolated from host roots. Root caps and a slow sedimenting particulate fraction (SSPF) were rapidly isolated and separated from Ri T-DNA transformed carrot roots (D. carota) grown in liquid culture. In addition, border cells (BC) and mucilage were isolated from aseptically grown corn seedlings (Zea mays). Root caps, SSPF (composed mainly of small root cap fragments and some BCs), BCs, and mucilage all had an associated AM fungus hyphal branching stimulator. Root caps stored for 5 d at 4 °C appeared to either synthesize or slowly release the branching stimulator. Also, isolated root caps from roots grown in the absence of P contained more branch stimulating activity than those isolated from roots grown in the presence of P. Although the branching stimulation activity in particulate fractions was low compared to that of the exudate, the particulate fractions can stick to the root surface at considerable distances from the root tip. This may be significant during the infection and colonization of host roots at sites far removed from the primary location of exudation. [ABSTRACT FROM AUTHOR]

Mycorrhizal associations, including ericoid, arbuscular and ecto-mycorrhizas, are found colonising highly metal contaminated soils. How do mycorrhizal fungi achieve metal resistance, and does this metal resistance confer enhanced metal resistance to plant symbionts? These are the questions explored in this review by considering the mechanistic basis of mycorrhizal adaptation to metal cations. Recent molecular and physiological studies are discussed. The review reappraises what constitutes metal resistance in the context of mycorrhizal associations and sets out the constitutive and adaptive mechanisms available for mycorrhizas to adapt to contaminated sites. The only direct evidence of mycorrhizal adaptation to metal cation pollutants is the exudation of organic acids to alter pollutant availability in the rhizosphere. This is not to say that other mechanism of adaptation do not exist, but conclusive evidence of adaptive mechanisms of tolerance are lacking. For constitutive mechanisms of resistance, there is much more evidence, and mycorrhizas possess the same constitutive mechanisms for dealing with metal contaminants as other organisms. Rhizosphere chemistry is critical to understanding the interactions of mycorrhizas with polluted soils. Soil pH, mineral weathering, pollutant precipitation with plant excreted organic acids all may have a key role in constitutive and adaptive tolerance of mycorrhizal associations present on contaminated sites. The responses of mycorrhizal fungi to toxic metal cations are diverse. This, linked to the fact that mycorrhizal diversity is normally high, even on highly contaminated sites, suggests that this diversity may have a significant role in colonisation of contaminated sites by mycorrhizas. That is, the environment selects for the fungal community that can best cope with the environment, so having diverse physiological attributes will enable colonisation of a wide range of metal contaminated micro-habitats. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

This issue of Mycological Research News features: Kelo trees: a vanishing fungal habitat; Polarized growth in fission yeast; Comparative genomics and functional elements in the yeast genome; When physics meets biology: high-resolution laser-based techiques to study plant–microbe interactions; and an Acknowledgement. The largest molecular phylogenetic fungal tree yet to have been published is presented, based on 1551 sequences; this will be of interest to all concerned with fungal relationships, especially at family and higher levels. Hepatic mycorrhizas are described ultrastructurally and molecularly, and the relationships of the mycobionts determined. The cytology and behaviour of nuclei in tri- and tetraradiate conidia in coelomycetes is examined, and micronuclei are documented for the first time. Confocal laser scanning electron microscopy examines nuclei and ascospore formation using a methodology likely to have wide utility. The conditions affecting the production of the siderophore rhodotorulic acid by Rhodotorula mucilaginosa have been investigated. The poisonous Clitocybe lactea produces phallatoxins, previously only known from Amanita spp., and its relationships are explored by molecular methods. Swainsonine, the cause of locoism in cattle etc. in the USA, is produced by endophytic fungi inside the plants consumed. The enyzmes produced by the lignin-degrading Mycena galopus and responsible for this activity have been investigated and identified. The following new scientific names are introduced in this part: Cornutispora intermedia, C. pittii, and Furcaspora abieticola spp. nov. [ABSTRACT FROM AUTHOR]