Parvodontia relampaga sp. nov.: A Cystostereaceae fungal pathogen that is the causal agent of relampago blight of woody plants in Florida, USA.

Starting in the fall of 2019, mortality, blight symptoms, and signs of white fungal mycelia were observed on external host tissues of non-native landscape trees as well as numerous native trees, understory shrubs, and vines throughout northern and central Florida, USA. We determined that the fungus is an undescribed species of Basidiomycota based on morphological characteristics and DNA sequence analysis. Phylogenetic analyses of the internal transcribed spacer (ITS), large subunit (LSU), and translation elongation factor 1-alpha (tef1) regions revealed that this novel plant pathogen is an undescribed taxon of the genus Parvodontia (Cystostereaceae, Agaricales). We propose the name Parvodontia relampaga sp. nov. which describes its unique morphological features and phylogenetic placement. We confirmed the pathogenicity of P. relampaga in greenhouse inoculations on host plants from which strains of this novel pathogen were isolated, including the non-native gymnosperm Afrocarpus falcatus, the non-native and commercially important Ligustrum japonicum, and the native tree Quercus hemisphaerica. P. relampaga was also detected on a total of 27 different species of woody host plants, including such economically and ecologically important hosts as Fraxinus, Ilex, Magnolia, Persea, Prunus, Salix, Vitis, and Vaccinium. For this new plant disease, we propose the name "relampago blight," which refers to the lightning-like rhizomorph growth (relámpago means 'lightning' in Spanish). This study presents a newly discovered fungal taxon with a wide host range on both angiosperms and gymnosperms that may be an emerging pathogen of concern in Florida and the Gulf Coast region.

The fungal Clitocybe nebularis lectin binds distinct cell surface glycoprotein receptors to induce cell death selectively in Jurkat cells.

Clitocybe nebularis lectin (CNL) is a GalNAcß1-4GlcNAc-binding lectin that exhibits an antiproliferative effect exclusively on the Jurkat leukemic T cell line by provoking homotypic aggregation and dose-dependent cell death. Cell death of Jurkat cells exhibited typical features of early apoptosis, but lacked the activation of initiating and executing caspases. None of the features of CNL-induced cell death were effectively blocked with the pan-caspase inhibitor or different cysteine peptidase inhibitors. Furthermore, CNL binding induced Jurkat cells to release the endogenous damage-associated molecular pattern molecule high-mobility group box 1 (HMGB1). A plant lectin with similar glycan-binding specificity, Wisteria floribunda agglutinin (WFA) showed less selective toxicity and induced cell death in Jurkat, Tall-104, and Hut-87 cell lines. HMGB1 release was also detected when Jurkat cells were treated with WFA. We identified the CD45 and CD43 cell surface glycoproteins on Jurkat cells as the main targets for CNL binding. However, the blockade of CD45 phosphatase activity failed to block either CNL-induced homotypic agglutination or cell death. Overall, our results indicate that CNL triggers atypical cell death selectively on Jurkat cells, suggesting the potential applicability of CNL in novel strategies for treating and/or detecting acute T cell leukemia.

The ability of Listeria monocytogenes to form biofilm on surfaces relevant to the mushroom production environment.

Due to its ubiquitous nature, Listeria monocytogenes is a threat to all fresh fruits and vegetables, including mushrooms, which are Ireland's largest horticultural crop. Although fresh cultivated mushrooms (Agaricus bisporus) have not been previously linked with listeriosis outbreaks, the pathogen still poses a threat to the industry, particularly due to its ability to form biofilms. This threat is highlighted by the multiple recalls of mushroom products caused by L. monocytogenes contamination and by previous studies demonstrating that L. monocytogenes is present in the mushroom production environment. In this study, the biofilm formation potential of L. monocytogenes strains isolated from the mushroom production environment was investigated on materials and at temperatures relevant to mushroom production. A preliminary assessment of biofilm formation of 73 mushroom industry isolates was undertaken using a crystal violet assay on polystyrene microtitre plates. The biofilm formation of a subset (n = 7) of these strains was then assessed on twelve different materials, including materials that are representative of the materials commonly found in the mushroom production environments, using the CDC biofilm reactor. Vertical scanning interferometry was used to determine the surface roughness of the chosen materials. All the strains tested using the CDC biofilm reactor were able to form biofilms on the different surfaces tested but material type was found to be a key determining factor on the levels of biofilm formed. Stainless steel, aluminium, rubber, polypropylene and polycarbonate were all able to support biofilm levels in the range of 4-4.9 log10 CFU/cm2, for seven different L. monocytogenes strains. Mushroom industry-specific materials, including growing nets and tarpaulins, were found to support biofilms levels between 4.7 and 6.7 log10 CFU/cm2. Concrete was found to be of concern as it supported 7.7 log10 CFU/cm2 of biofilm for the same strains; however, sealing the concrete resulted in an approximately 2-log reduction in biofilm levels. The surface roughness of the materials varied greatly between the materials (0.7-3.5 log10 Ra) and was found to have a positive correlation with biofilm formation (rs = 0.573) although marginally significant (P = 0.051). The results of this study indicate that L. monocytogenes can readily form biofilms on mushroom industry relevant surfaces, and additionally identifies surfaces of specific concern, where rigorous cleaning and disinfection is required.

Antiproliferative Activity and Cytotoxicity of Some Medicinal Wood-Destroying Mushrooms from Russia.

We analyzed the antiproliferative activity of 6 medicinal wood-destroying mushrooms (Fomes fomentarius, Fomitopsis pinicola, Trametes versicolor, Trichaptum biforme, Inonotus obliquus, and Coniophora puteana) that are common in deciduous and mixed coniferous forests in Central Russia. Morphological identification of strains collected from the wild was confirmed based on ribosomal DNA internal transcribed spacer phylogenetic analysis. We observed cytotoxic and cell growth-inhibitory effects of hot water extracts from mycelial biomass of 5 species-T. versicolor, C. puteana, F. fomentarius, F. pinicola, and I. obliquus-on leukemia cell lines (Jukart, K562, and THP-1); the effective extract concentrations were mostly less than 50 µg · mL-1. However, we observed no antiproliferative activity of dry biomass from methanol-chloroform (1:1) extracts of C. puteana and F. fomentarius. A chemosensitivity assay showed that the most effective polypore mushroom extract was the methanol extract of T. versicolor (strain It-1), which inhibited the growth of 6 various solid tumors (A-549 and SWi573 [lung], HBL-100 and T-47D [breast], HeLa [cervix], and WiDr [colon]) at concentrations below 45 µg · mL-1, with a concentration as low as 0.7-3.6 µg · mL-1 causing 50% reduction in the proliferation of cancer cells in lung and cervix tumors. Methanol extracts of F. pinicola and I. obliquus were less effective, with proliferation-inhibiting capacities at concentrations below 70 and 200 µg · mL-1, respectively. Thus, T. versicolor is a prospective candidate in the search for and production of new antiproliferative chemical compounds.

A review on the nucleic acid constituents in mushrooms: nucleobases, nucleosides and nucleotides.

Mushrooms have become increasingly important as a reliable food source. They have also been recognized as an important source of bioactive compounds of high nutritional and medicinal values. The nucleobases, nucleosides and nucleotides found in mushrooms play important roles in the regulation of various physiological processes in the human body via the purinergic and/or pyrimidine receptors. Cordycepin, a 3'-deoxyadenosine found in Cordyceps sinensis has received much attention as it possesses many medicinal values including anticancer properties. In this review, we provide a broad overview of the distribution of purine nucleobases (adenine and guanine); pyrimidine nucleobases (cytosine, uracil, and thymine); nucleosides (uridine, guanosine, adenosine and cytidine); as well as novel nucleosides/tides in edible and nonedible mushrooms. This review also discusses the latest research focusing on the successes, challenges, and future perspectives of the analytical methods used to determine nucleic acid constituents in mushrooms. Besides, the exotic taste and flavor of edible mushrooms are attributed to several nonvolatile and water-soluble substances, including the 5'-nucleotides. Therefore, we also discuss the total flavor 5'-nucleotides: 5'-guanosine monophosphate (5'-GMP), 5'-inosine monophosphate (5'-IMP), and 5'-xanthosine monophosphate (5'-XMP) in edible mushrooms.

Nuclear populations of the multinucleate fungus of leafcutter ants can be dekaryotized and recombined to manipulate growth of nutritive hyphal nodules harvested by the ants.

We dekaryotized the multinucleate fungus Leucocoprinus gongylophorus, a symbiotic fungus cultivated vegetatively by leafcutter ants as their food. To track genetic changes resulting from dekaryotization (elimination of some nuclei from the multinuclear population), we developed two multiplex microsatellite fingerprinting panels (15 loci total), then characterized the allele profiles of 129 accessions generated by dekaryotization treatment. Genotype profiles of the 129 accessions confirmed allele loss expected by dekaryotization of the multinucleate fungus. We found no evidence for haploid and single-nucleus strains among the 129 accessions. Microscopy of fluorescently stained dekaryotized accessions revealed great variation in nuclei number between cells of the same vegetative mycelium, with cells containing typically between 3 and 15 nuclei/cell (average = 9.4 nuclei/cell; mode = 8). We distinguish four mycelial morphotypes among the dekaryotized accessions; some of these morphotypes had lost the full competence to produce gongylidia (nutritive hyphal-tip swellings consumed by leafcutter ants as food). In mycelial growth confrontations between different gongylidia-incompetent accessions, allele profiles suggest exchange of nuclei between dekaryotized accessions, restoring full gongylidia competence in some of these strains. The restoration of gongylidia competence after genetic exchange between dekaryotized strains suggests the hypothesis that complementary nuclei interact, or nuclear and cytoplasmic factors interact, to promote or enable gongylidia competence.

Characterization of the legumains encoded by the genome of Theobroma cacao L.

Legumains are cysteine proteases related to plant development, protein degradation, programmed cell death, and defense against pathogens. In this study, we have identified and characterized three legumains encoded by Theobroma cacao genome through in silico analyses, three-dimensional modeling, genetic expression pattern in different tissues and as a response to the inoculation of Moniliophthora perniciosa fungus. The three proteins were named TcLEG3, TcLEG6, and TcLEG9. Histidine and cysteine residue which are part of the catalytic site were conserved among the proteins, and they remained parallel in the loop region in the 3D modeling. Three-dimensional modeling showed that the propeptide, which is located in the terminal C region of legumains blocks the catalytic cleft. Comparing dendrogram data with the relative expression analysis, indicated that TcLEG3 is related to the seed legumain group, TcLEG6 is related with the group of embryogenesis activities, and protein TcLEG9, with processes regarding the vegetative group. Furthermore, the expression analyses proposes a significant role for the three legumains during the development of Theobroma cacao and in its interaction with M. perniciosa.

The activity of TcCYS4 modified by variations in pH and temperature can affect symptoms of witches' broom disease of cocoa, caused by the fungus Moniliophthora perniciosa.

The phytocystatins regulate various physiological processes in plants, including responses to biotic and abiotic stresses, mainly because they act as inhibitors of cysteine proteases. In this study, we have analyzed four cystatins from Theobroma cacao L. previously identified in ESTs libraries of the interaction with the fungus Moniliophthora perniciosa and named TcCYS1, TcCYS2, TcCYS3 and TcCYS4. The recombinant cystatins were purified and subjected to the heat treatment, at different temperatures, and their thermostabilities were monitored using their ability to inhibit papain protease. TcCYS1 was sensitive to temperatures above 50°C, while TcCYS2, TcCYS3, and TcCYS4 were thermostable. TcCYS4 presented a decrease of inhibitory activity when it was treated at temperatures between 60 and 70°C, with the greater decrease occurring at 65°C. Analyses by native gel electrophoresis and size-exclusion chromatography showed that TcCYS4 forms oligomers at temperatures between 60 and 70°C, condition where reduction of inhibitory activity was observed. TcCYS4 oligomers remain stable for up to 20 days after heat treatment and are undone after treatment at 80°C. TcCYS4 presented approximately 90% of inhibitory activity at pH values between 5 and 9. This protein treated at temperatures above 45°C and pH 5 presented reduced inhibitory activity against papain, suggesting that the pH 5 enhances the formation of TcCYS4 oligomers. A variation in the titratable acidity was observed in tissues of T. cacao during the symptoms of witches' broom disease. Our findings suggest that the oligomerization of TcCYS4, favored by variations in pH, is an endergonic process. We speculate that this process can be involved in the development of the symptoms of witches' broom disease in cocoa.

The pathogenesis-related protein PR-4b from Theobroma cacao presents RNase activity, Ca(2+) and Mg(2+) dependent-DNase activity and antifungal action on Moniliophthora perniciosa.

BACKGROUND: The production and accumulation of pathogenesis-related proteins (PR proteins) in plants in response to biotic or abiotic stresses is well known and is considered as a crucial mechanism for plant defense. A pathogenesis-related protein 4 cDNA was identified from a cacao-Moniliophthora perniciosa interaction cDNA library and named TcPR-4b. RESULTS: TcPR-4b presents a Barwin domain with six conserved cysteine residues, but lacks the chitin-binding site. Molecular modeling of TcPR-4b confirmed the importance of the cysteine residues to maintain the protein structure, and of several conserved amino acids for the catalytic activity. In the cacao genome, TcPR-4b belonged to a small multigene family organized mainly on chromosome 5. TcPR-4b RT-qPCR analysis in resistant and susceptible cacao plants infected by M. perniciosa showed an increase of expression at 48 hours after infection (hai) in both cacao genotypes. After the initial stage (24-72 hai), the TcPR-4b expression was observed at all times in the resistant genotypes, while in the susceptible one the expression was concentrated at the final stages of infection (45-90 days after infection). The recombinant TcPR-4b protein showed RNase, and bivalent ions dependent-DNase activity, but no chitinase activity. Moreover, TcPR-4b presented antifungal action against M. perniciosa, and the reduction of M. perniciosa survival was related to ROS production in fungal hyphae. CONCLUSION: To our knowledge, this is the first report of a PR-4 showing simultaneously RNase, DNase and antifungal properties, but no chitinase activity. Moreover, we showed that the antifungal activity of TcPR-4b is directly related to RNase function. In cacao, TcPR-4b nuclease activities may be related to the establishment and maintenance of resistance, and to the PCD mechanism, in resistant and susceptible cacao genotypes, respectively.

Nep1-like protein from Moniliophthora perniciosa induces a rapid proteome and metabolome reprogramming in cells of Nicotiana benthamiana.

NEP1 (necrosis- and ethylene-inducing peptide 1)-like proteins (NLPs) have been identified in a variety of taxonomically unrelated plant pathogens and share a common characteristic of inducing responses of plant defense and cell death in dicotyledonous plants. Even though some aspects of NLP action have been well characterized, nothing is known about the global range of modifications in proteome and metabolome of NLP-treated plant cells. Here, using both proteomic and metabolomic approaches we were able to identify the global molecular and biochemical changes in cells of Nicotiana benthamiana elicited by short-term treatment with MpNEP2, a NLP of Moniliophthora perniciosa, the basidiomycete responsible for the witches' broom disease on cocoa (Theobroma cacao L.). Approximately 100 protein spots were collected from 2-DE gels in each proteome, with one-third showing more than twofold differences in the expression values. Fifty-three such proteins were identified by mass spectrometry (MS)/MS and mapped into specific metabolic pathways and cellular processes. Most MpNEP2 upregulated proteins are involved in nucleotide-binding function and oxidoreductase activity, whereas the downregulated proteins are mostly involved in glycolysis, response to stress and protein folding. Thirty metabolites were detected by gas spectrometry (GC)/MS and semi-quantified, of which eleven showed significant differences between the treatments, including proline, alanine, myo-inositol, ethylene, threonine and hydroxylamine. The global changes described affect the reduction-oxidation reactions, ATP biosynthesis and key signaling molecules as calcium and hydrogen peroxide. These findings will help creating a broader understanding of NLP-mediated cell death signaling in plants.

Diversity, host associations, and phylogeography of temperate aurofusarin-producing Hypomyces/Cladobotryum including causal agents of cobweb disease of cultivated mushrooms.

Temperate species of Hypomyces and Cladobotryum that produce the red pigment aurofusarin are common on agaricoid and polyporoid basidiomata of species from five orders of Agaricomycetes. Several cause cobweb disease of commercially cultivated mushrooms resulting in serious losses. We sequenced rpb1, rpb2, tef1, and FG1093 regions in 90 wild strains and 30 strains from mushroom farms, isolated from Europe, North America, Africa, Asia, Australia, and New Zealand. Multigene analyses support the distinctness of five species but reveal Hypomyces rosellus to be paraphyletic, comprising several cryptic lineages. Hypomyces rosellus s. str. is characterised by wide dispersal and gene flow across Eurasia but does not occur in North America. Instead, the lineages from the West and the East Coast appear distinct, having given rise to species inhabiting the Southern Hemisphere. Our results reveal wide misuse of the name H. rosellus, especially for cobweb isolates. The majority of these belong to Hypomyces odoratus, including a weakly supported group of fungicide-resistant strains from Europe and North America sharing identical sequence data. New collections are presented for Cladobotryum rubrobrunnescens and Cladobotryum tenue as well as Cladobotryum multiseptatum and Hypomyces dactylarioides, all previously known only from their type material. The former species pair occurs in Europe and the latter in Australia and New Zealand. Separate lineages appear to be maintained by geographic isolation in North America and temperate Australasia but by host specialisation in the species occurring sympatrically in Europe and Asia. Both specialist and generalist host use strategies have evolved in the group. Although teleomorphs are known in most of the species and unnamed lineages, analyses of the five-gene regions suggest the prevalence of clonal reproduction in H. odoratus. This can be the reason for its success in mushroom farms, also facilitating the spread of fungicide resistance. While tef1 and rpb2 can be recommended for species delimitation, low variation, not exceeding 1 % in the whole ingroup, impeaches the use of ITS as a barcoding gene region in this group of fungi.

The ectomycorrhizal fungus Paxillus involutus converts organic matter in plant litter using a trimmed brown-rot mechanism involving Fenton chemistry.

Soils in boreal forests contain large stocks of carbon. Plants are the main source of this carbon through tissue residues and root exudates. A major part of the exudates are allocated to symbiotic ectomycorrhizal fungi. In return, the plant receives nutrients, in particular nitrogen from the mycorrhizal fungi. To capture the nitrogen, the fungi must at least partly disrupt the recalcitrant organic matter-protein complexes within which the nitrogen is embedded. This disruption process is poorly characterized. We used spectroscopic analyses and transcriptome profiling to examine the mechanism by which the ectomycorrhizal fungus Paxillus involutus degrades organic matter when acquiring nitrogen from plant litter. The fungus partially degraded polysaccharides and modified the structure of polyphenols. The observed chemical changes were consistent with a hydroxyl radical attack, involving Fenton chemistry similar to that of brown-rot fungi. The set of enzymes expressed by Pa. involutus during the degradation of the organic matter was similar to the set of enzymes involved in the oxidative degradation of wood by brown-rot fungi. However, Pa. involutus lacked transcripts encoding extracellular enzymes needed for metabolizing the released carbon. The saprotrophic activity has been reduced to a radical-based biodegradation system that can efficiently disrupt the organic matter-protein complexes and thereby mobilize the entrapped nutrients. We suggest that the released carbon then becomes available for further degradation and assimilation by commensal microbes, and that these activities have been lost in ectomycorrhizal fungi as an adaptation to symbiotic growth on host photosynthate. The interdependence of ectomycorrhizal symbionts and saprophytic microbes would provide a key link in the turnover of nutrients and carbon in forest ecosystems.

Preparation of Chaga medicinal mushroom, Inonotus obliquus-fermented rice using solid-state fermentation and its taste quality and antioxidant property.

Chaga medicinal mushroom, Inonotus obliquus (Pers.:Fr.) Pilat, was inoculated into cooked embryo rice and the mycelial growth in I. obliquus-fermented embryo rice (IER) was monitored. Besides, nonvolatile taste components and antioxidant properties of fruiting bodies, mycelia, IER, and embryo rice were studied. The optimal conditions for mycelial growth were determined to be: 30°C, an inoculation rate of 1 mL/15 g, water supplementation of 60%, and no extra nitrogen source added. IER showed similar proximate composition to embryo rice but contained a substantial amount of ergothioneine (101 mg/kg dry weight). IER contained higher amounts of soluble sugars and polyols, and umami taste components, including monosodium glutamate (MSG)-like components and flavor 5'-nucleotides, than embryo rice. Besides, IER showed a second level of equivalent umami concentrations (223.73 g MSG/100 g). Fruiting bodies did not contain umami components but showed the most effective antioxidant properties. Although some of EC50 values of IER were less than those of mycelia and embryo rice, IER still showed effective antioxidant properties. Based on the results obtained, IER will be a novel functional food.

Rhizomarasmius epidryas (Physalacriaceae): phylogenetic placement of an arctic-alpine fungus with obligate saprobic affinity to Dryas spp.

As a part of a large-scale biogeographical study we examined the evolutionary relationships and taxonomic position of Marasmius epidryas, one of the most typical circumpolar arctic-alpine fungi, characterized by a specific, saprobic affinity to dead tissues of Dryas spp. A phylogenetic analysis based on nLSU and RPB2 DNA regions unequivocally indicated the phylogenetic placement of this species within the Physalacriaceae. The Bayesian MCMCMC analysis as well as other inference methods tested (ML, NJ) revealed a well supported affinity of M. epidryas to Rhizomarasmius pyrrhocephalus, type species of a recently circumscribed genus, Rhizomarasmius. As a consequence, based on these results, we introduce a new combination, Rhizomarasmius epidryas (Kühner ex A. Ronikier) A. Ronikier and M. Ronikier. Thus our results demonstrate that neither the traditional taxonomic placement of the fungus in genus Marasmius nor the recent transfer into genus Mycetinis are phylogenetically correct. In contrast they support the importance of the third lineage of the polyphyletic Marasmius s. l., having evolutionary links with taxa forming the Physalacriaceae clade of agaricoid fungi. In addition the lineage of Rhizomarasmius was confirmed to be closely related to the representatives of Gloiocephala, comprising small, often narrowly specialized saprobic species previously also classified within Marasmius s. l.

Tolerance and stress response of Macrolepiota procera to nickel.

Nickel (Ni) is an essential element for many organisms; however, it is very toxic at high concentrations and also depending on the species. In macrofungi the mechanisms underlying their Ni tolerance are poorly documented. This study examines, for the first time, the participation of the antioxidative system in Macrolepiota procera exposed to different Ni2+ concentrations and their relation with Ni tolerance. The effect of the pH on Ni tolerance was also evaluated. The fungus was cultivated on solid medium with different NiCl2 concentrations (0.05, 0.2, 0.8 mM) at pH 4, 6, and 8, and fungi growth and Ni uptake were determined. The antioxidative enzymes catalase (CAT) and superoxide dismutase (SOD) and the production of hydrogen peroxide H2O2 were evaluated on fungal submerged cultures within the first hours of Ni2+ exposure. Results showed that M. procera growth decreased when Ni2+ concentrations increased, reaching a maximum growth inhibition (>80%) up to 0.2 mM of NiCl2. Ni uptake increased proportionally to Ni increase in the medium. Both Ni tolerance and Ni accumulation were affected by medium pH. Microscope observations showed differences in the size of spores produced by fungi at different Ni concentrations. Ni exposure induced oxidative stress, as indicated by the production of H2O2, the levels of which seem to be regulated by the antioxidant enzymes SOD and CAT. The time variation pattern of SOD and CAT activities indicated that the former has a greater role in alleviating the stress. The results obtained suggested that tolerance of M. procera to Ni2+ is associated with the ability of this macrofungus to initiate an efficient antioxidant defense system.

Selenium in edible mushrooms.

Selenium is vital to human health. This article is a compendium of virtually all the published data on total selenium concentrations, its distribution in fruitbody, bioconcentration factors, and chemical forms in wild-grown, cultivated, and selenium-enriched mushrooms worldwide. Of the 190 species reviewed (belonging to 21 families and 56 genera), most are considered edible, and a few selected data relate to inedible mushrooms. Most of edible mushroom species examined until now are selenium-poor (< 1 microg Se/g dry weight). The fruitbody of some species of wild-grown edible mushrooms is naturally rich in selenium; their occurrence data are reviewed, along with information on their suitability as a dietary source of selenium for humans, the impact of cooking and possible leaching out, the significance of traditional mushroom dishes, and the element's absorption rates and co-occurrence with some potentially problematic elements. The Goat's Foot (Albatrellus pes-caprae) with approximately 200 microg Se/g dw on average (maximum up to 370 microg/g dw) is the richest one in this element among the species surveyed. Several other representatives of the genus Albatrellus are also abundant in selenium. Of the most popular edible wild-grown mushrooms, the King Bolete (Boletus edulis) is considered abundant in selenium as well; on average, it contains approximately 20 microg Se/g dw (maximum up to 70 microg/g dw). Some species of the genus Boletus, such as B. pinicola, B. aereus, B. aestivalis, B. erythropus, and B. appendiculus, can also accumulate considerable amounts of selenium. Some other relatively rich sources of selenium include the European Pine Cone Lepidella (Amanita strobiliformis), which contains, on average, approximately 20 microg Se/g dw (up to 37 microg/g dw); the Macrolepiota spp., with an average range of approximately 5 to < 10 microg/g dw (an exception is M. rhacodes with < 10 microg/g dw); and the Lycoperdon spp., with an average of approximately 5 microg Se/g dw. For several wild-grown species of the genus Agaricus, the selenium content ( approximately 5 microg/g dw) is much greater than that from cultivated Champignon Mushroom; these include A. bisporus, A. bitorquis, A. campestris, A. cesarea, A. campestris, A. edulis, A. macrosporus, and A. silvaticus. A particularly rich source of selenium could be obtained from selenium-enriched mushrooms that are cultivated on a substrate fortified with selenium (as inorganic salt or selenized-yeast). The Se-enriched Champignon Mushroom could contain up to 30 or 110 microg Se/g dw, while the Varnished Polypore (Ganoderma lucidum) could contain up to 72 microg Se/g dw. An increasingly growing database on chemical forms of selenium of mushrooms indicates that the seleno-compounds identified in carpophore include selenocysteine, selenomethionine, Se-methylselenocysteine, selenite, and several unidentified seleno-compounds; their proportions vary widely. Some aspects of environmental selenium occurrence and human body pharmacokinetics and nutritional needs will also be briefly discussed in this review.

Wood-decay fungi in fine living roots of conifer seedlings.

The mycorrhizal basidiomycetes are known to have multiple, independent evolutionary origins from saprotrophic ancestors. To date, a number of studies have revealed functional resemblance of mycorrhizal fungi to free-living saprotrophs, but information on the ability of saprotrophic fungi to perform as mycorrhizal symbionts is scarce. Here, the objective was to investigate the ability of three wood-decay fungi, Phlebiopsis gigantea, Phlebia centrifuga and Hypholoma fasciculare, to colonize fine roots of conifer seedlings. For each fungus, mycorrhizal syntheses were attempted with Picea abies and Pinus sylvestris. After 24 wk, isolation of fungi and direct sequencing of fungal internal transcribed spacer (ITS) rDNA were carried out from healthy-looking surface-sterilized root tips that yielded both pure cultures and ITS sequences of each inoculated strain. Mycelial mantle of P. gigantea was frequently formed on root tips of P. abies, and microscopical examination has shown the presence of intercellular hyphae inside the roots. The results provide evidence of the ability of certain wood-decay fungi to colonise fine roots of tree seedlings.

The auxin-inducible GH3 homologue Pp-GH3.16 is downregulated in Pinus pinaster root systems on ectomycorrhizal symbiosis establishment.

In an attempt to determine whether auxin-regulated plant genes play a role in ectomycorrhizal symbiosis establishment, we screened a Pinus pinaster root cDNA library for auxin-upregulated genes. This allowed the identification of a cDNA, Pp-GH3.16, which encodes a polypeptide sharing extensive homologies with GH3 proteins of different plants. Pp-GH3.16 was specifically upregulated by auxins and was not affected by cytokinin, gibberellin, abscisic acid or ethylene, or by heat shock, water stress or anoxia. Pp-GH3.16 mRNAs were quantified in pine roots inoculated with two ectomycorrhizal fungi, Hebeloma cylindrosporum and Rhizopogon roseolus. Surprisingly, Pp-GH3.16 was downregulated following inoculation with both fungal species. The downregulation was most rapid on establishment of symbiosis with an indole-3-acetic acid (IAA)-overproducing mutant of H. cylindrosporum, which overproduced mycorrhizas characterized by a hypertrophic Hartig net. This indicates that, despite being auxin-inducible, Pp-GH3.16 can be downregulated on establishment of symbiosis with a fungus that releases auxin. By contrast, Pp-GH3.16 was not downregulated in pine root systems inoculated with a nonmycorrhizal mutant of H. cylindrosporum, suggesting that the downregulation we observed in mycorrhizal root systems was a component of the molecular cross-talk between symbiotic partners at the origin of differentiation of symbiotic structures.

Anamorphs of the Bolbitiaceae (Basidiomycota, Agaricales).

We describe and illustrate thallic conidiogenesis in 14 species of the Bolbitiaceae sensu Singer studied in culture. Conidiogenesis of 12 species is shown for the first time. Bolbitius vitellinus and the investigated species of Conocybe (C. albipes, C. appendiculata, C. magnicapitata, C. semiglobata, C. subovalis, C. subpubescens, C. sulcatipes and C. teneroides) possessed a similar mode of conidiogenesis. Species of both genera formed mostly coiled conidiogenous hyphae arising sympodially from differentiated conidiophores. The anamorphs of the Agrocybe species were not uniform and predominantly differed from those of Conocybe and Bolbitius. The conidia of Agrocybe dura, A. firma and A. praecox developed by the simple fragmentation of normally branched hyphae. Sympodially proliferating conidiophores occurred in Agrocybe arvalis and A. aegerita. Secretory cells of different size and shape were found in Agrocybe and in Conocybe. Our results corroborate a close phylogenetic relationship between Bolbitius and Conocybe as well as the polyphyly of the Bolbitiaceae as currently treated, which is consistent with recent molecular phylogenetic studies. Consequently we emend the family concept based on anamorphic characters.