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Determining the extent of mycoheterotrophy (MH) in plants, primarily through the use of stable isotope methods, has gained considerable attention in the last decade. The aim of this study was to characterize the rates of photosynthesis (PS) and several gas-exchange parameters, as well as stable carbon isotope composition (δ13C) of partially mycoheterotrophic (PMH) Pyroleae compared with autotrophic reference species of Ericaceae. An end-member mixing model was applied to δ13C, deriving estimates of % C gained via fungi (CDF). The δ13C was significantly enriched for Orthilia secunda and Pyrola chlorantha (relative to autotrophs) resulting in estimates of CDF ranging from 13.8% to 20.8%. Despite significantly lower PS rates for O. secunda and P. chlorantha, as well as lower conductance and transpiration, there were no significant differences in the Ci: Ca ratios across all of the species, suggesting that the C isotope inferences for these two species were reflective of fungal C gains. By contrast, results for all of the variables indicated primarily autotrophic C nutrition for Chimaphila umbellata. Further studies, such as isotope labelling experiments or assessments of biochemical constraints to autotrophy, may resolve the uncertainties in these species, allowing more accurate understanding of the complex nutritional mode of these plants. [ABSTRACT FROM AUTHOR]

Over the last decade, we have witnessed extraordinary progress in the understanding of molecular dialogues between the partners in plant root mutualisms and, as such, a considerable amount of new information now needs to be integrated into an already significant body of literature. The topic of symbiosis has become difficult to explore in a teaching venue, as there is seemingly so much to discuss, and yet students are truly interested in the discipline because of its potential applications in conservation, sustainable agriculture, and forestry. In this minireview targeted to instructors, senior students, and scientists, we offer a means of teaching the symbioses between mycorrhizal fungi and vascular plants, whereby we propose a conceptual staircase with three levels of incremental learning difficulty. At the first level, we describe the fundamentals of mycorrhizas with special emphasis on the plant-fungus interface. At the second level, we focus on the pre-communication between the two partners. At the third level, we discuss the physiology of the interface in terms of agriculture and forestry. At the end of each level, we provide a short summary where the most important concepts have been outlined for an instructor. As well, throughout the text, we raise questions of interest to the field at large. [ABSTRACT FROM AUTHOR]

The genus Drosera (sundews) is represented in British Columbia (BC), Canada, by Drosera rotundifolia (L.), Drosera anglica (Huds.), and their hybrid Drosera × obovata (Mert. & W.D.J. Koch). All three can be found in Sphagnum bogs of central BC, including those within the Aleza Lake Research Forest (ALRF) located 60 km east of Prince George. Vegetation patterns in bogs are known to be correlated with light, water, and nutrient gradients, and despite information being available on the influence of light and water on Drosera occurrence, little information is known about the role of nutrients. Here, we focused on a bog containing all three Drosera species, to determine whether nutrient levels are related to the abundance of the widespread species, D. rotundifolia. Univariate regression tree analysis between soil water chemistry and D. rotundifolia numbers indicates that D. rotundifolia is a calcifuge, preferring moderately acidic soil pH (>5.5) and relatively low calcium levels (<2.88 ppm). This study provides evidence that high soil water calcium and low pH limit the growth of D. rotundifolia in field populations. The physiology underlying this preference, how this is affected by hybridization between other sundew species, and how this mineralogical limitation interacts with other niche-defining factors to dictate the occurrence of D. rotundifolia are questions that remain to be answered. [ABSTRACT FROM AUTHOR]

Plant compensatory growth is a phenomenon of exaggerated vegetative growth that occurs in plants as a result of mechanical damage (e.g., cutting or browsing). Because shoots, leaves, and other plant parts grow larger on plants undergoing compensation, they typically fall outside of the normal ranges given in plant identification keys and confuse students who are attempting to classify them. Here, we describe the conundrum faced by students collecting compensatory materials and offer suggestions on how to help students identify their 'plant-in-hand' and how to seize a teaching moment to examine and explain the underlying processes that lead to this fascinating plant response. [ABSTRACT FROM AUTHOR]

Most species in the family Cistaceae are found in the Mediterranean basin. Several hosts are of special interest, owing to their associations with truffle species, while many are important as pioneer plants in disturbed areas and in soil stabilization. For these reasons, understanding their root systems and their associated fungal symbionts is important. Most studies of the structure of mycorrhizas in this family involve two genera, Cistus and Helianthemum. The present study examines structural features of mycorrhizas in two North American species, Hudsonia ericoides L. and Hudsonia tomentosa Nutt. Root systems of both species are highly branched with most fine roots colonized by mycorrhizal fungi. Based on morphological features, several mycorrhizal fungi were identified; structural details also provided evidence of more than one fungal symbiont for each host species. All mycorrhizas had a multi-layered fungal mantle and Hartig net hyphae confined to radially elongated epidermal cells; no intracellular hyphae were observed. Although the Hartig net was confined to the epidermis, the outer row of cortical cell walls lacked suberin, a known barrier to fungal penetration. Mycorrhizas in H. ericoides and H. tomentosa differed from those of Cistus and Helianthemum species that have a Hartig net that extends into the root cortex, as well as frequently present intracellular hyphae. La plupart des espèces de la famille des Cistaceae se retrouvent dans le bassin de la Méditerranée. Plusieurs hôtes présentent un intérêt particulier, compte tenu de leurs associations avec des espèces de truffes, alors que d'autres constituent des plantes pionnières importantes dans les endroits perturbés et pour la stabilisation des sols. Pour ces raisons, il importe de comprendre la biologie de leurs systèmes racinaires et de leurs champignons symbiotiques associés. La plupart des études publiées sur la structure des mycorhizes de cette famille portent sur les deux genres Cistus et Helianthemum. On examine ici les caractéristiques structurales des mycorhizes de deux espèces Nord-américaines, l'Hudsonia ericoides L. et l'Hudsonia tomentosa Nutt. Chez les deux espèces, l'on observe des systèmes racinaires fortement ramifiés, la plupart des racines fines étant colonisées par des champignons mycorhiziens. Sur la base des caractéristiques morphologiques, les auteurs ont pu identifier plusieurs espèces de champignons mycorhiziens; les détails des structures fournissent également des preuves de l'existence de plus d'un symbiote fongique chez chaque espèce hôte. Toutes les mycorhizes montrent un manteau fongique à plusieurs couches et des hyphes du réseau de Hartig confinées aux cellules épidermiques radialement allongées; on observe aucune pénétration intracellulaire. Bien que le réseau de Hartig soit confiné à l'épiderme, les parois cellulaires de la couche externe de cellules corticales ne possèdent pas de subérine, une barrière reconnue pour la pénétration fongique. Les mycorhizes chez les H. ericoides et H. tomentosa diffèrent de celles des espèces de Cistus et d'Helianthemum, lesquelles possèdent un réseau de Hartig s'étendant dans le cortex racinaire et montrent la présence d'hyphes intracellulaires souvent présentes. [ABSTRACT FROM AUTHOR]

The roots or other subterranean organs of most plants develop symbioses, mycorrhizas, with fungal symbionts. Historically, mycorrhizas have been placed into seven categories based primarily on structural characteristics. A new category has been proposed for symbiotic associations of some leafy liverworts. An important feature of mycorrhizas is the interface involved in nutrient exchange between the symbionts. With the exception of ectomycorrhizas, in which fungal hyphae remain external to plant cell walls, all mycorrhizas are characterized by fungal hyphae breaching cell walls but remaining separated from the cell cytoplasm by a plant-derived membrane and an interfacial matrix that forms an apoplastic compartment. The chemical composition of the interfacial matrix varies in complexity. In arbuscular mycorrhizas (both Arum-type and Paris-type), molecules typical of plant primary cell walls (i.e., cellulose, pectins, β-1,3-glucans, hydroxyproline-rich glycoproteins) are present. In ericoid mycorrhizas, only rhamnogalacturonans occur in the interfacial matrix surrounding intracellular hyphal complexes. The matrix around intracellular hyphal complexes in orchid mycorrhizas lacks plant cell wall compounds until hyphae begin to senesce, then molecules similar to those found in primary cell walls are deposited. The interfacial matrix has not been studied in arbutoid mycorrhizas and ectendomycorrhizas. In ectomycorrhizas, the apoplastic interface consists of plant cell wall and fungal cell wall; alterations in these may enhance nutrient transfer. In all mycorrhizas, nutrients must pass into the symplast of both partners at some point, and therefore current research is exploring the nature of the opposing membranes, particularly in relation to phosphorus and sugar transporters. [ABSTRACT FROM AUTHOR]

The morphology and anatomy of ectomycorrhizas of Rhizopogon parksii, Rhizopogon vinicolor and Rhizopogon subcaerulescens, and a hypogeous relative, Truncocolumella citrina, synthesized on Douglas fir in glasshouse conditions using spore slurries as inoculum, are described and compared. Mycorrhizas formed with R. parksii and R. vinicolor did not exhibit their characteristic subtuberculate morphology in these tests, but rather had a pinnate form. All species had diagnostic features of ectomycorrhizas: a well-developed Hartig net and a fungal mantle. In addition, several species exhibited crystal inclusions in the outer mantle, usually at the interface between the mantle and soil. Truncocolumella citrina had crystal-like inclusions within the mantle but external to fungal hyphae, a feature rarely described in ectomycorrhizas. [ABSTRACT FROM AUTHOR]

The morphology and anatomy of ectomycorrhizas of Rhizopogon arctostaphyli, R. elIenae, R. flavofibrillosus, R. accidenalis, R. rubescens, R .smithii, R. subcaerulescens and R. truncatus synthesized on Ponderosa pine (Pinus ponderosa) in glasshouse conditions using spore slurries, are described and compared. All species produced a well-developed Hartig net, and a well-developed fungal mantle. The mantles of R. arctostaphyli. R. smithii and R. subcaerulescens ectomycorrhizas were two-layered with outer mantle hyphac of wider diameter than inner mantle hyphae. The mantle of R. subcaerulescens ectomycorrhizas also had distinctive peg-like structures (cystidia) along peripheral hyphae. Rhizopogon truncatus ectomycorrhizas were tuberculate in morphology and had a rind-like mantle enclosing adjacent roots. In addition, several species exhibited crystal inclusions in the outer mantle, presumably at the interface between mantle and soil. [ABSTRACT FROM AUTHOR]

Seedlings of Abies grandis, Alnus rubra, Pinus ponderosa, Picea sitchensis, Pseudotsuga menziesii and Tsuga heterophylla were grown in monoculture and dual culture in the greenhouse and inoculated with spore slurries of 20 isolates representing 15 species of ectomycorrhizal hypogeous fungi (11 Rhizopogon species. Alpova diplophloeus, Truncocolumella citrina, Melanogaster euryspermus and Zelleromyces gilkeyae). The primary objectives were to assess and compare the pattern of host specificity between symbionts and to study the influence of neighbouring plants on ectomycorrhiza development. None of the fungal species had broad host range affinities. A variety of specificity responses were exhibited by the different fungal taxa, ranging from genus-restricted to intermediate host range. In monoculture, nine species of Rhizopogon (R. arctostaphyli, R. ellenae, R. flavofibrillosus, R. occidentalis, R. rubescens, R. smithii, R. subcaerulescens, R. truncatus and R. vulgaris) formed ectomycorrhizas on Pinus ponderosa whereas three Rhizopogon species (R. parksii. R. vinicolor and R. subcaerulescens) formed ectomycorrhizas on Pseudotsuga menziesii. Truncocolumella citrina associated with Pseudotsuga menziesii and Alpova diplophloeus with Alnus rubra, Melanogaster euryspermus and Z. gilkeyae did not form ectomycorrhizas with any hosts. None of the fungi tested developed ectomycorrhizas on Abies grandis, Tsuga heterophylla or Picea sitchensis in monoculture. In dual culture, the same nine Rhizopogon species that formed abundant ectomycorrhizas on Pinus ponderosa formed some ectomycorrhizas on secondary hosts such as Abies grandis, Tsuga heterophylla, Pseudotsuga menziesii and Picea sitchensis. Similarly, Truncocolumella citrina formed abundant ectomycorrhizas on Pseudotsuga menziesii and low levels on the secondary hosts Abies grundis, Tsuga heterophylla and Piceca sitchensis. Rhizopogon parksii and R. vinicolor only formed ectomycorrhizas on Pseudotsuga menziesii, and Alpova diptophloeus only formed tctomvcorrhtzas on Alnus rubra. The specificity pattern obtained by using this dual-culture appyoach is contrasted with previous pure-culture synthesis data and is discussed in terms of potential interplant linkages and community dynamics. [ABSTRACT FROM AUTHOR]

Many wild edible polypore mushrooms have medicinal value. In this study, we investigate the potential medicinal properties of the wild polypore mushroom Royoporus badius collected from north-central British Columbia, Canada. Water extract from R. badius was found to exhibit potent immunomodulatory activity. The extract was purified using DEAE-Sephadex anion-exchange chromatography as well as Sephacryl S-500 and HPLC BioSEC5 size-exclusion chromatography, to yield a novel polysaccharide-protein complex (IMPP-Rb).IMPP-Rb has a peak maxima molecular weight (Mp) of 950 kDa. GC-MS analyses showed that IMPP-Rb is composed predominantly of glucose (49.2%), galactose (11.3%), mannose (10.8%), rhamnose (9.6%), and galacturonic acid (8.2%), with smaller amounts of xylose (5.2%), fucose (2.8%), N-acetyl glucosamine (1.8%), and arabinose (1.2%). IMPP-Rb has multiple linkages, with 4-Glcp, 4-Manp, 6-Manp, 3,4-Manp, 4-Xylp, and 2-Rhap being the most prominent. IMPP-Rb is capable of inducing many cytokines in vitro and the protein component is indispensable for its immunomodulatory activity. IMPP-Rb has potential application as an immuno-stimulatory agent with pharmaceutical value. [ABSTRACT FROM AUTHOR]

A novel polysaccharide EtGIPL1a was purified from fruiting bodies of Echinodontium tinctorium, a fungus unique to western North America. EtGIPL1a has an estimated weight average molecular weight of 275 kDa and is composed of glucose (54.3%), galactose (19.6%), mannose (11.1%), fucose (10.3%), glucuronic acid (4%), and rhamnose (0.6%). It has multiple glycosidic linkages, with 3-Glcp (28.9%), 6-Glcp (18.3%), 3,6-Glcp (13%), 4-GlcpA (9.2%), 6-Galp (3.9%), 2,6-Galp (2.6%), 3-Fucp (2.5%), 6-Manp (2.4%) being the most prominent, and unsubstituted glucose (15.3%), mannose (1.3%) and fucose (0.9%) as major terminal sugars. EtGIPL1a has a backbone containing mostly 3-substituted β-glucopyranose with 4-substituted glucopyranosyluronic acid. EtGIPL1a showed anti-proliferative activity against multiple cancer cell lines, with IC50 ranging from 50.6 to 1446 nM. Flow cytometry analyses confirmed that apoptosis induction is one mechanism for its anti-proliferative activity. EtGIPL1a should be further investigated for its potential anti-cancer activity in animal models, and for its possible utility in differentiation cancer therapy. [ABSTRACT FROM AUTHOR]

Background:Serpentine ecosystems support different, often unique, plant communities; however, we know little about the soil organisms that associate with these ecosystems. Mycorrhizas, mutualistic symbioses between fungi and roots, are critical to nutrient cycling and energy exchange below ground. Aims:We address three hypotheses: H1, diversity of mycorrhizal fungi in serpentine soils mirrors above-ground plant diversity; H2, the morphology of mycorrhizas and fungi on serpentine soils differs from that on non-serpentine; and H3, mycorrhizal fungal communities of the same or closely related hosts differ between serpentine and non-serpentine soils. Methods:This review focuses on whether plant diversity on serpentine soils correlates with the below ground diversity of mycorrhizal fungi. Results:Studies show that plants and fungi formed abundant ectomycorrhizal and arbuscular mycorrhizal symbioses on and off serpentine soils. No serpentine-endemic fungi were identified. Molecular analyses indicate distinct serpentine isolates forCenococcum geophilumand forAcaulospora, suggesting adaptation to serpentine soils. While fungal sporocarp assemblages on serpentine sites resembled those off serpentine, fruiting of hypogeous fungi was greatly reduced. Conclusions:Ectomycorrhizal fungal communities did not differ between soil types; however, arbuscular mycorrhizal communities differed in some cases but not others. The additive response to multiple factors, described as the serpentine syndrome, may explain part of the response by fungi. [ABSTRACT FROM AUTHOR]

Propagation trials were completed using seeds, hardwood stem cuttings, and rhizome cuttings from black huckleberry (Vaccinium membranaceum Douglas ex Torr. [Ericaceae]) and velvetleaf blueberry (V. myrtilloides Michx. [Ericaceae]) growing in central British Columbia, Canada. Seed germination success rates for V. membranaceum were 26.0% in 2006, 4.7% in 2007, and 66.0% in 2008, compared with 14.7% in 2006, 13.0% in 2007, and 28.5% in 2008 for V. myrtilloides. Germination rates for seeds sown directly after extraction from fresh berries were similar to those that had been airdried for 48 h, and those stored for 1 y. Germination rates did vary significantly between Vaccinium species and among different years. Hardwood stem cuttings of both V. membranaceum and V. myrtilloides, taken in February, had low rooting rates (2.5%). Rooting hormone formulation, rooting substrate, and bottom heat failed to influence rooting success. Rhizome cuttings of V. myrtilloides had an 85% success rate, compared to 70% for V. membranaceum. Bottom heat significantly reduced the success rate of rhizome cuttings, whereas rooting substrate had no significant influence. Mass production of either V. membranaceum or V. myrtilloides plants was easiest by using seedlings grown from seeds; however, if clonal plants are desired (or a short production time required), rhizome cuttings might be the best option, rather than hardwood stem cuttings [ABSTRACT FROM AUTHOR]

Summary Petroleum hydrocarbon (PHC) contamination is becoming more common in boreal forest soils. However, linkages between PHC biodegradation and microbial community dynamics in the mycorrhizosphere of boreal forest soils are poorly understood. Seedlings (lodgepole pine, paper birch, lingonberry) were established in reconstructed soil systems, consisting of an organic layer (mor humus, coarse woody debris, or previously oil-contaminated mor humus) overlying mineral (Ae, Bf) horizons. Light crude oil was applied to the soil surface after 4 months; systems were destructively sampled at 1 and 16 weeks following treatment. Soil concentrations of four PHC fractions were determined using acetone-hexane extraction followed by gas chromatography - flame ionization detection analysis. Genotypic profiles of root-associated bacterial communities were generated using length heterogeneity-PCR of 16S rDNA. Most plant-soil treatments showed significant loss in the smaller fraction PHCs indicating an inherent capacity for biodegradation. Concentrations of total PHCs declined significantly only in planted (pine-woody debris and birch-humus) systems (averaging 59% and 82% loss between 1 and 16 weeks respectively), reinforcing the importance of the mycorrhizosphere for enhancing microbial catabolism. Bacterial community structure was correlated more with mycorrhizosphere type and complexity than with PHC contamination. However, results suggest that communities in PHC-contaminated and pristine soils may become distinct over time. [ABSTRACT FROM AUTHOR]

The importance of developing multi-disciplinary approaches to solving problems relating to anthropogenic pollution is now clearly appreciated by the scientific community, and this is especially evident in boreal ecosystems exposed to escalating threats of petroleum hydrocarbon (PHC) contamination through expanded natural resource extraction activities. This review aims to synthesize information regarding the fate and behaviour of PHCs in boreal forest soils in both ecological and sustainable management contexts. From this, we hope to evaluate potential management strategies, identify gaps in knowledge and guide future research. Our central premise is that mycorrhizal systems, the ubiquitous root symbiotic fungi and associated food-web communities, occupy the structural and functional interface between decomposition and primary production in northern forest ecosystems (i.e. underpin survival and productivity of the ecosystem as a whole), and, as such, are an appropriate focal point for such a synthesis. We provide pertinent basic information about mycorrhizas, followed by insights into the ecology of ecto- and ericoid mycorrhizal systems. Next, we review the fate and behaviour of PHCs in forest soils, with an emphasis on interactions with mycorrhizal fungi and associated bacteria. Finally, we summarize implications for ecosystem management. Although we have gained tremendous insights into understanding linkages between ecosystem functions and the various aspects of mycorrhizal diversity, very little is known regarding rhizosphere communities in PHC-contaminated soils. This makes it difficult to translate ecological knowledge into environmental management strategies. Further research is required to determine which fungal symbionts are likely to survive and compete in various ecosystems, whether certain fungal - plant associations gain in ecological importance following contamination events, and how PHC contamination may interfere with processes of nutrient acquisition and exchange and metabolic processes. Research is also needed to assess whether the metabolic capacity for intrinsic decomposition exists in these ecosystems, taking into account ecological variables such as presence of other organisms (and their involvement in syntrophic biodegradation), bioavailability and toxicity of mixtures of PHCs, and physical changes to the soil environment. [ABSTRACT FROM AUTHOR]

Various categories of mycorrhizas are recognized primarily by the structural changes that occur between fungi and roots. In all mycorrhiza categories, cytological modifications of root cells accompany the establishment of the functional symbiosis, and among these are alterations in the organization of the cytoskeleton. Using immuno labelling combined with confocal scanning laser microscopy, this study documents changes in microtubules (MTs) in root cells of ectendomycorrhizas and monotropoid mycorrhizas; in addition, ectomycorrhizas were reinvestigated to determine the effect of fungal colonization on host root cells. In Pinus banksiana L. – Laccaria bicolor (Maire) Orton ectomycorrhizas, MTs were present in epidermal and cortical cells adjacent to the Hartig net. The remaining cortical MTs had a different organization when compared with those of cortical cells of control roots. MTs were present in Hartig net hyphae. In ectendomycorrhizas formed when roots of P. banksiana were colonized by the ascomycete, Wilcoxina mikolae var. mikolae Yang & Korf, MTs were present adjacent to intracellular hyphae and host nuclei, but few cortical MTs were present. MTs were present within Hartig net and intracellular hyphae. In field-collected roots of Monotropa uniflora L., MTs were associated with fungal pegs, intracellular extensions of inner mantle hyphae within epidermal cells. The close association between MTs and fungal pegs may be related to the formation of the highly branched host-derived wall that envelops each fungal peg. The development of exchange interfaces in the three systems studied involve changes in the organization of microtubules. [ABSTRACT FROM AUTHOR]

To assess the effect of fire and salvage logging on the diversity of mycorrhizal–bacterial communities, bacteria associated with Cenococcum, Thelephora, Tomentella, Russulaceae, and E-strain ectomycorrhizae (ECM) of Abies lasiocarpa seedlings were characterized using two approaches. First, bacteria were isolated and characterized by Biolog[sup ©] , gas chromatography fatty acid methyl ester (GC-FAME), and amplified 16S rDNA restriction analysis (ARDRA). The bacterial communities retrieved from ECM from both sites were dominated by Proteobacteria (groups gamma and beta). Pseudomonas was the most common genus isolated, followed by Variovorax, Burkholderia, and Xanthomonas. Gram-positive isolates (mostly high-G+C Gram-positive bacteria) were more frequently retrieved on the burned-salvaged site, many commonly associated with the two ascomycete ECM, Cenococcum and E-strain. Pseudomonas species were retrieved more frequently from Thelephora. Although actinomycetes were isolated from all sites, almost no actinomycetes or other Gram-positive bacteria were isolated from either Thelephora or Tomentella. Second, amplified 16S rRNA gene sequences were amplified directly from root tips and then cloned into the plasmid vector pAMP1, followed by restriction analysis. This technique distinguished more genotypes than isolates retrieved by culturing methods, but generally, results were similar in that the largest proportion of the bacteria were putatively Gram-negative; putative Gram-positive bacteria were fewer and most were from the burned–salvaged site. Direct cloning resulted in many patterns that did not match any identified isolates, suggesting that a large proportion of clones were unique or not culturable by the methods used. Analysis for both protocols showed no significant difference in bacterial diversity between the burned–salvaged and unburned sites. Key words: rhizosphere bacteria, ARDRA, 16S rDNA, Biolog[sup ©] , GC-FAME.Afin d'évaluer l'impact d'un feu de forêt et d'une coupe de récupération sur la diversité des communautés de bactéries associées a des mycorhizes, nous avons caractérisé des bactéries associées avec des ectomycorhizes (ECM) de Cenococcum, Thelephora, Tomentella, des Russulacées et de la souche E de Abies lasiocarpa en ayant recours à deux approches. En premier lieu, des bactéries ont été isolées et caractérisées par Biolog[sup ©] , par chromatographie en phase gazeuse des dérivés d'esters méthyliques d'acides gras (GC-FAME) et par analyse de restriction de l'ADNr amplifié (ARDRA). Les communautés bactériennes obtenues des ECM des deux sites étaient dominées par des protéobactéries (groupes gamma et bêta). Le genre isolé le plus fréquemment était Pseudomonas, suivi par Variovorax, Burkholderia et Xanthomonas. Les isolats Gram-positifs (principalement des bactéries Gram-positives à haut taux G+C) ont été plus fréquemment retrouvés sur le site brûlé et récupéré, plusieurs d'entre eux étant en association avec les deux ascomycètes ECM, Cenococcum et la souche E. Les espèces de Pseudomonas étaient plus fréquemment récupérées à partir de Thelephora. Bien que des actinomycètes ont été isolés à partir de tous les sites, pratiquement aucun actinomycète et aucune autre bactérie Gram-positive n'ont été isolés de Thelephora ou de Tomentella. En second lieu, les séquences du gène 16S de l'ARNr ont été amplifiées directement à partir des extrémités racinaires, puis clonées dans le vecteur plasmidique pAMP1, pour ensuite subir une analyse de restriction. Cette technique a permis de distinguer davantage de génotypes que des isolats récupérés par des méthodes de culture, mais les résultats étaient généralement semblables et ont permis de constater que la grande majorité des bactéries étaient potentiellement Gram-négatives; les bactéries Gram-positives étaient moins nombreuses, et la plupart provenaient du site brûlé et récupéré. Le clonage direct a produit plusieurs motifs qui ne correspondaient à aucun isolat identifié, ce qui indique qu'un pourcentage important des clones étaient uniques ou non cultivables par les méthodes utilisées. Une analyse effectuée à l'aide des deux protocoles n'a pas démontré de différence significative de la diversité bactérienne entre le site brûlé et récupéré et le site non brûlé. Mots clés : bactéries de la rhizosphère, ARDRA, ADNr 16S, Biolog[sup ©] , GC-FAME. [Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]

• Immunostimulatory polysaccharide (EtISPFa) was purified from E. tinctorium. • EtISPFa is 1354 kDa and is a heteroglycan. • EtISPFa is a β -glucan containing high amount of glucuronic acid (10–20 %). • EtISPFa induces various cytokines production in macrophage cells. An immuno-stimulatory polysaccharide (EtISPFa) was purified from water extract of the fungus Echinodontium tinctorium. EtISPFa has an estimated weight average molecular weight (M w) of 1354 kDa and is composed of glucose (66.2 %), glucuronic acid (10.1 %), mannose (6.7 %), galactose (6.4 %), xylose (5.6 %), rhamnose (3.1 %), fucose (1.8 %), and arabinose (0.2 %). It has multiple glycosidic linkages, with 3-Glc p (19.8 %), 4-Glc p A (10.8 %), 6-Glc p (10.7 %), and 3,6-Glc p (8.7 %) being the most prominent. NMR analysis showed that EtISPFa has a backbone containing mostly of 3-substituted β -glucopyranose with 4-substituted glucopyranosyluronic acid. Short side chains consisting of an average of two β -glycopyranose residues, connected through 1→6 linkages, are attached to the 6-position of about every 4th or 5th backbone glucose residue. EtISPFa is a novel glucuronic acid-containing β -glucan capable of significantly inducing the production of cytokines IL-17, IL-16, MIP-2, G-CSF,GM-CSF, LIF, MIP-1α, MIP-1β, and RANTES in vitro. EtISPFa should be further explored for its immuno-stimulatory activity in vivo. [ABSTRACT FROM AUTHOR]

In our search for bioactive mushrooms native to British Columbia, we determined that the ethanol extracts from fruiting bodies of the terrestrial polypore Albatrellus flettii had potent anti-cell viability activity. Using bioassay-guided fractionation, mass spectrometry and nuclear magnetic resonance, we successfully isolated three known compounds (grifolin, neogrifolin and confluentin). These compounds represent the major anti-cell viability components from the ethanol extracts of A. flettii. We also identified a novel biological activity for these compounds, specifically in down-regulating KRAS expression in two human colon cancer cell lines. Relatively little is known about the anti-cell viability activity and mechanism of action of confluentin. For the first time, we show the ability of confluentin to induce apoptosis and arrest the cell cycle at the G2/M phase in SW480 human colon cancer cells. The oncogenic insulin-like growth factor 2 mRNA-binding protein 1 (IMP1) has been previously shown to regulate KRAS mRNA expression in colon cancer cells, possibly through its ability to bind to the KRAS transcript. Using a fluorescence polarization assay, we show that confluentin dose-dependently inhibits the physical interaction between KRAS RNA and full-length IMP1. The inhibition also occurs with truncated IMP1 containing the KH1 to KH4 domain (KH1to4 IMP1), but not with the di-domain KH3 and KH4 (KH3&4 IMP1). In addition, unlike the control antibiotic neomycin, grifolin, neogrifolin and confluentin do not bind to KRAS RNA. These results suggest that confluentin inhibits IMP1-KRAS RNA interaction by binding to the KH1&2 di-domains of IMP1. Since the molecular interaction between IMP1 and its target RNAs is a pre-requisite for the oncogenic function of IMP1, confluentin should be further explored as a potential inhibitor of IMP1 in vivo. [ABSTRACT FROM AUTHOR]

Cell-to-cell communication is a key element of microvascular blood flow control, including rapidly carrying signals through the vascular endothelium in response to local stimuli. This cell-to-cell communication is negatively impacted during inflammation through the disruption of junctional integrity. Such disruption is associated with promoting the onset of cardiovascular diseases as a result of altered microvascular blood flow regulation. Therefore, understanding the mechanisms how inflammation drives microvascular dysfunction and compounds that mitigate such inflammation and dysfunction are of great interest for development. As such we aimed to investigate extracts of mushrooms as potential novel compounds. Using intravital microscopy, the medicinal mushroom, Inonotus obliquus was observed, to attenuate histamine-induced inflammation conducted vasodilation in second-order arterioles in the gluteus maximus muscle of C57BL/6 mice. Mast cell activation by C48/80 similarly disrupted endothelial junctions and conducted vasodilation but only histamine was blocked by the histamine antagonist, pyrilamine not C48/80 suggesting the importance of mast cell activation. Data presented here supports that histamine induced inflammation is a major disruptor of junctional integrity, and highlights the important anti-inflammatory properties of Inonotus obliquus focusing future assessment of mast cells as putative target for Inonotus obliquus. [ABSTRACT FROM AUTHOR]

Highlights • Soil rehabilitation treatments increased bacterial saprotroph abundance 14 days after implementation. • Rehabilitation treatments showed strong fungal saprotroph abundance 5 months after implementation. • Ectomycorrhizal mycelia were a major necromass input due to soil manipulation. • Several microbial genera stimulated by rehabilitation treatments are previously described as mycelial decomposers. Abstract The replacement of mineral soil and capping with salvaged forest floor organic material (FFOM) is a site rehabilitation method applied over belowground installations such as pipelines. Such installations, when placed in mature forest soils, can be expected to disrupt ectomycorrhizal fungal communities when root-associated mycelia and exploratory hyphae are damaged during excavation. Soil fungal communities, bacterial communities, and soil enzymatic repertoires may be variably impacted by different site preparation schemes after disturbance. We compared effects of three rehabilitation schemes on fungal community composition, bacterial community composition, and potential hydrolase activities (N -acetyl-β- d -glucosaminidase, acid phosphatase, and cellobiohydrolase) at two times (14 days and 5 months post-site preparation) and two sampling depths (FFOM/"upper" versus mineral/"lower" soil). We observed declines in FFOM-associated fungal biomass (ergosterol) and declines in ectomycorrhizal fungi abundance across all site rehabilitation schemes compared to intact control plots. Fungal community composition strongly shifted to saprotroph dominance (i.e. increased Mortierella , and Umbelopsis) in rehabilitated plots at 5 months, while bacterial community composition did not distinguish control plots from rehabilitation plots ones at either sampling time. Bacterial saprotrophs previously associated with mycelial necromass colonization were higher in abundance across multiple site preparation regimens compared to control plots at 14 days. Our results indicate that reductions in ectomycorrhizal fungal abundance were a dominant community property in recently reconstructed soil profiles. Increases in bacteria associated with recently deposited fungal necromass were detectable within days to weeks of implementing site rehabilitation, while fungal necromass colonizers became dominant 5 months post-rehabilitation. Potential hydrolase activities increased in the site preparation regimen where FFOM was mixed into mineral soil, when compared to mineral soil activities in control plots. [ABSTRACT FROM AUTHOR]

In the boreal forest, open lichen woodlands have been described as an alternative stable state to closed-crown feather moss forest. In this study, we addressed the role of terricolous lichens in stabilizing open woodlands by hindering tree regeneration and/or growth. Based on field and greenhouse experiments, we compared germination and growth of jack pine (Pinus banksiana) on feather mosses (primarily Pleurozium schreberi) and lichens (primarily Cladonia stellaris), using bare mineral soil as a control. Drivers were investigated by (1) manipulating nutrient supply, (2) simulating shade of a closed canopy on the ground layer with the assumption this would mitigate lichen influence on pine growth, and (3) examining pine root ectomycorrhizal colonization and diversity as indicators of pine ability to take up nutrients. Total growth of 6-month-old greenhouse and 2-3-year-old field seedlings, as well as belowground growth of 2-year-old greenhouse seedlings, was significantly greater in moss than in lichen. Seed germination was not affected by ground cover type. Although field phosphorus and base cation availability was greater in mosses than in lichens, fertilization did not entirely compensate for the negative effects of lichens on pine growth in the greenhouse. Ground layer shading had no impact on pine growth. Lichens were associated with reduced abundance and modified composition of the root ectomycorrhizal community. By suggesting that terricolous lichens constitute a less favorable growth substrate than mosses for pine, our results support the hypothesis that lichens contribute to open woodland stability in the potentially closed-crown feather moss forest. [ABSTRACT FROM AUTHOR]

A growth-inhibitory polysaccharide (GIPinv) was purified using size-exclusion and ion-exchange chromatography from the fourth sodium hydroxide extraction step of a fungus found in British Columbia. The fungus was genetically identified as a member of the Paxillus involutus complex. GIPinv has an average molecular weight of 229 kDa and is a heteroglycan composed of glucose (65.9%), galactose (20.8%), mannose (7.8%), fucose (3.2%) and xylose (2.3%). GC–MS methylation analysis suggests that GIPinv has mixed linkages in the backbone containing (1 → 6)-Gal (25.5%), (1 → 4)-Glc (18.3%), (1 → 6)-Glc (8.3%), (1 → 3)-Glc (5.3%) and (1 → 2)-Xyl (4.5%). GIPinv has branching points at (1 → 2, 6)-Man (8.6%) and (1 → 3, 6)-Man (4.9%) having unsubstituted fucose (8.3%) and glucose (16.3%) as terminal sugars. GIPinv had growth-inhibitory activity against several cancer cell lines and triggered apoptosis. GIPinv should be further explored as a potential anti-cancer agent and a unique polysaccharide. [ABSTRACT FROM AUTHOR]

Physical disturbance of soil profiles, even at shallow depths, is a ubiquitous consequence of anthropogenic landscape modification, with short-term impacts on important ecological guilds of fungi. DNA-based methods for surveying community composition are widely incorporated into studies attempting to explain fungal responses to forest ecosystem disturbances. Here we compare fungal community composition between three distinct soil profile manipulations (20 cm depth) and undisturbed control plots in a sub-boreal spruce forest in the Central Interior region of British Columbia, Canada. Fungal community composition differences were tracked by internal transcribed spacer 2 (ITS2) amplicon sequencing, with comparisons drawn using genus-level annotations. Non-metric multidimensional scaling (NMDS) analysis indicated that disturbed-sample community compositions were similar to controls at 0-months and distinct from controls at 5- and 12-months post disturbance, but did not indicate clustering of samples according to disturbance regime. We used Linear Discriminant Effect Size (LEfSe) analysis to identify fungal genera that consistently indicate disturbed or undisturbed (control) treatments across 5- and 12-month sampling times. Four fungal genera ( Exophiala , Hyphodontiella , Mastigobasidium , and Umbelopsis ) were detected with higher ranges of relative abundance in all disturbance regimes when compared to control plots. Deliberate mixing of LFH into mineral horizon soils stimulated multiple genera that were more frequently detectable in replicate plots at 12 months, when compared to undisturbed and immediately re-assembled plots. Four ectomycorrhizal genera ( Amphinema , Cortinarius , Piloderma , and Russula ) were identified as strong indicators of control plot soils. A single genus, Capronia , was identified as differentially abundant between stockpiled LFH and immediately replaced LFH. Our results are consistent with declines in ectomycorrhizal fungal abundance and increases in saprotroph abundance previously reported in DNA-based community profiling studies of forest soil disturbance. This investigation demonstrates that bulk soil sampling can be used to evaluate soil-handling regimens to understand fungal community disruption/recovery and highlights LEfSe as an approach to indicator selection in DNA-dependent biodiversity surveys. [ABSTRACT FROM AUTHOR]

Ectomycorrhizal (ECM) communities of black spruce (Picea mariana (Mill.) BSP) seedlings were characterized from three habitats spanning a moisture gradient in central British Columbia: black spruce dominated wetlands, black spruce – tamarack wetlands, and black spruce – lodgepole pine uplands. Morphological and molecular (PCR-RFLP) analyses indicated a diverse community of root-associated ECM fungi consisting of 33 morphotypes and 65 genotypes. ECM abundance varied significantly between habitats for six morphotypes. Although many occurred in all three habitats, some occurred in only one or two, and some genotypes had distributions that suggested habitat specificity across the moisture gradient. Intraspecific variation (defined as genotype variation within morphotypes) ranged from one to seven genotypes, depending on ECM morphotype. Both morphological and molecular analyses showed that ECM diversity was greater in upland than in wetland habitats and greater in black spruce – tamarack wetlands than in black spruce dominated wetlands (α ≤ 0.05). Morphological assessment captured contributions to diversity by both abundant and less abundant ECM morphotypes, whereas molecular analysis revealed patterns of genetic variation and habitat distribution at a finer resolution. The study presents the first comprehensive information on black spruce ECM and suggests that ECM community composition and richness varies across the moisture gradient in response to soil heterogeneity and alternate hosts (tamarack and lodgepole pine). [ABSTRACT FROM AUTHOR]

We compared the relative impacts of light, soil N, and soil temperature on Engelmann spruce (Picea engelman nii Parry ex Engelm.) and subalpine fir (Abies lasiocarpa (Hook.) Nutt.) seedling growth by quantifying (i) microsite environment-growth relationships for N-fertilized and unfertilized planted seedlings in shelterwood, patch cut, and clearcut harvest treatments and (ii) growth, photosynthesis, and biomass allocation for greenhouse-grown seedlings at 5, 10, and 15 °C soil temperatures. Fertilization did not affect seedling growth. Furthermore, soil N availability did not vary among harvest treatments. In contrast, clearcut compared with shelterwood seedlings had greater mass (fivefold), light availability (twofold), and soil temperatures (1.6 °C). Across harvest treatments, spruce and fir mass increased linearly to 100% open-sky light (R2 = 0.51 and 0.57, respectively), and temperature and light combined explained more variation in mass than light alone (adjusted R2 = 0.58 for both species). Spruce growth was more sensitive to temperature than fir in both field and greenhouse experiments. Diminished growth at low soil temperature was associated with lower photosynthesis and not lower leaf fraction. Thus, soil temperature and light colimit seedling growth in subalpine forests, but responses were species-specific and consistent with microenvironment differences in spruce and fir regeneration niches. [ABSTRACT FROM AUTHOR]

Determines the effects of broadcast burning after clear-cutting on the diversity of ectomycorrhiza (ECM) on hybrid spruce seedlings in British Columbia. Abundance of Amphinema in planted seedlings from cut-burned and clear-cut sites; Relationship between mycorrhizal diversity and disturbance; Identification of fungal symbionts.

The aim of this study was to investigate the anti-inflammatory activity of a previously un-studied wild mushroom, Echinodontium tinctorium, collected from the forests of north-central British Columbia. The lipopolysaccharide (LPS)-induced RAW264.7 macrophage model was used to study the in vitro anti-inflammatory activity. The crude alkaline extract demonstrated potent anti-inflammatory activity, and was further purified using a "bio-activity-guided-purification" approach. The size-exclusion and ion-exchange chromatography yielded a water-soluble anti-inflammatory polysaccharide (AIPetinc). AIPetinc has an average molecular weight of 5 kDa, and is a heteroglucan composed of mainly glucose (88.6%) with a small amount of galactose (4.0%), mannose (4.4%), fucose (0.7%), and xylose (2.3%). In in vivo settings, AIPetinc restored the histamine-induced inflammatory event in mouse gluteus maximus muscle, thus confirming its anti-inflammatory activity in an animal model. This study constitutes the first report on the bioactivity of Echinodontium tinctorium, and highlights the potential medicinal benefits of fungi from the wild forests of northern British Columbia. Furthermore, it also reiterates the need to explore natural resources for alternative treatment to modern world diseases. [ABSTRACT FROM AUTHOR]