Jean Garbaye's research while affiliated with Centre Scientifique et Technique du Bâtiment and other places

Publications (166)

Article
1. Characterizing the ecological processes driving the assembly and functional composition of ectomycorrhizal (ECM) fungal communities is an area of active research. 2. Here, we applied a trait-based framework to address whether and how environmental filtering and niche differentiation influence the diversity of ECM fungal enzymatic activities in...
Article
The relatively recent evidences leading to the MHB concept (mycorrhization helper bacteria, which specificaly enhance mycorrhiza formation) ask many new questions about their degree of interdependence with the fungal symbionts, the mechanisms involved and their role in the competition between mycorrhizal fungi and in the specificity and evolution o...
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An ectomycorrhiza is a multitrophic association between a tree root, an ectomycorrhizal fungus, free-living fungi and the associated bacterial communities. Enzymatic activities of ectomycorrhizal root tips are therefore result of the contribution from different partners of the symbiotic organ. However, the functional potential of the fungus-associa...
Article
In deciduous oaks, spring reactivation modifies the capability of ectomycorrhizal fungi (EMf) to mobilise carbon from soil organic matter. Plant carbon budget is also unbalanced during spring reactivation: carbon demand is high to build new tissues and carbon may be provided by reserves only as new photoassimilates are not yet available. Using a st...
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Containerized red oak (Quercusrubra L.) seedlings were inoculated at the time of sowing with Laccariabicolor (Maire) Orton using two methods to compare the efficiency of two inoculum types: a mycelial suspension (Ecot-Sol®101) produced by Rhizotec Laboratories Inc. and calcium alginate beads containing this mycelial suspension. Red oak seedlings we...
Article
A sequence of ectomycorrhizal colonization was observed on lateral roots of Afzelia africana Sm. seedlings. Four ectomycorrhizal types were obtained by a baiting method. Among the four types, two were recognized as occurring first in the ectomycorrhizal colonization sequence and the others occurred later. This sequence of ectomycorrhizal colonizati...
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The aim of a joint effort by different research teams was to provide an improved procedure for enzyme activity profiling of field-sampled ectomycorrhizae, including recommendations on the best conditions and maximum duration for storage of ectomycorrhizal samples. A more simplified and efficient protocol compared to formerly published procedures wa...
Article
Roots of 75 tree species, belonging to 28 families, were sampled on different types of soil in the forest of French Guiana. Both seedlings and mature trees of each species were studied. The roots were first observed for ectomycorrhizas, then thinned and stained to observe and quantify endomycorrhizal associations. Ectomycorrhizas were found only on...
Article
Survival of Hebeloma crustuliniforme (Bulliard ex Fries) Quelet, grown in a liquid medium and subsequently entrapped in beads of calcium alginate, was tested under different conditions. Mycelium viability was not affected either by curing the beads for up to 22 h in 0.7 M CaCl2 or by the addition of either peat or bentonite to the alginate gel. Bot...
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Introduction Important nutrients in forest soils such as nitrogen and phosphorus are mostly recycled from natural polymeric compounds contained in litter and organic debris—for example nucleic acids, proteins, or chitin. Objectives Activities of enzymes such as phosphatases, proteases, cellulases, chitinases and laccase were shown in saprotrophic b...
Article
Liming is a forest practice used to counteract forest decline induced by soil acidification. It consists of direct Ca and Mg input in forest soil and restores tree mineral nutrition, but also causes drastic changes in nutrient availability in soil. Ectomycorrhizal (ECM) fungi significantly contribute in nutrient uptake by trees, and can recover the...
Article
The ectomycorrhizal community of an oak forest has been monitored monthly throughout fifteen months. Eight enzymatic activities secreted by the ectomycorrhizal root tips and involved in the mobilization of nutrients from soil organic matter have been measured using microplate assays, resulting in potential activity patterns of individual fungal spe...
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The impact of ectomycorrhiza formation on the secretion of exoenzymes by the host plant and the symbiont is unknown. Thirty-eight F(1) individuals from an interspecific Populus deltoides (Bartr.)×Populus trichocarpa (Torr. & A. Gray) controlled cross were inoculated with the ectomycorrhizal fungus Laccaria bicolor. The colonization of poplar roots...
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Full-text available
Liming is used to counteract forest decline induced by soil acidification. It consists of Ca and Mg input to forest soil and not only restores tree mineral nutrition but also modifies the availability of nutrients in soil. Ectomycorrhizal (ECM) fungi are involved in mineral nutrient uptake by trees and can recover them through dissolution of minera...
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The mycorrhiza helper bacterial strain Pseudomonas fluorescens BBc6R8 enhances the establishment of Laccaria bicolor S238N ectomycorrhizae by improving the pre-symbiotic growth and survival of the fungus. Nothing is known about the effect of the ectomycorrhizal fungus on the helper bacteria or the molecules that are involved in the interaction. In...
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In acidic forest soils, availability of inorganic nutrients is a tree-growth-limiting factor. A hypothesis to explain sustainable forest development proposes that tree roots select soil microbes involved in central biogeochemical processes, such as mineral weathering, that may contribute to nutrient mobilization and tree nutrition. Here we showed,...
Article
The fungal symbionts forming ectomycorrhizas, as well as their associated bacteria, benefit forest trees in a number of ways although the most important is enhancing soil nutrient mobilization and uptake. This is reciprocated by the allocation of carbohydrates by the tree to the fungus through the root interface, making the relationship a mutualist...
Article
The activities of nutrient-mobilising enzymes secreted by ectomycorrhizas of sessile oak (Quercus petraea) have been measured in 24 plots in a forested area in central France where many rural Gallo-Roman settlements (first to fifth centuries AD) have been discovered. Data have been related with tree growth and soil chemical properties. Although soi...
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• Liming is a forestry practice used to counteract forest decline in acidic soils. It consists of direct Ca and Mg input to forest soil, which restores tree mineral nutrition, but also modifies microbial communities in soil. The aim of this study was to assess the effects of liming on both belowground (ectomycorrhizal root tips) and aboveground (ep...
Article
The impact of past Roman occupation on the composition of ectomycorrhizal (ECM) communities was analysed in 12 Roman settlements in an oak forest in Central France. At each Roman settlement, soils and ECM roots were sampled from two plots (600 m2 each), one plot close to the remains of the buildings (<100 m), supposed to be impacted by ancient Roma...
Article
Liming is a forestry practice used to correct tree cation deficiency induced by soil acidity. Ectomycorrhizal (ECM) community structure and functioning is closely linked to soil nutrient availability, which is strongly affected by liming. The aim of this study was to assess the impact of liming on ECM community structure depending on soil horizon a...
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Full-text available
Liming (Ca-Mg soil amendment) is a forestry practice used to correct soil acidification and restore health and productivity in declining stands. Liming is known to modify tree mineral nutrition beyond the sole Ca and Mg. We hypothesized that liming also modifies the very functioning of the tree absorbing system (that is the ectomycorrhizal fine roo...
Article
In forest soils, ectomycorrhizal and saprotrophic Agaricales differ in their strategies for carbon acquisition, but share common gene families encoding multi-copper oxidases (MCOs). These enzymes are involved in the oxidation of a variety of soil organic compounds. The MCO gene family of the ectomycorrhizal fungus Laccaria bicolor is composed of 11...
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Bacterization effect of seeds on the growth of Cedrus atlantica Manetti plants. The beneficial effect of five rhizobacterial strains on the growth of Cedrus atlantica plants was evaluated at forest nursery before out-planting. The obtained results showed a significant effect of bacterial strains on cedar seedlings growth and only Pseudomonas fluore...
Article
The beneficial effect of five rhizobacterial strains on the growth of Cedrus atlantica plants was evaluated at forest nursery before out-planting. The obtained results showed a significant effect of bacterial strains on cedar seedlings growth and only Pseudomonas fluorescens A6RI and TGI252 significantly increased stem length, neck diameter, root d...
Article
La hêtraie roumaine est remarquable par la surface qu'elle occupe (2 millions d'ha) et par la qualité de ses peuplements. Presque partout le hêtre y est exceptionnel par sa forme, son état sanitaire et sa croissance. La densité du bois et le retrait sont très comparables aux valeurs trouvées en France. Les importations de provenance de hêtre roumai...
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Extracting fungal mRNA from ectomycorrhizas (ECMs) and forest soil samples for monitoring in situ metabolic activities is a significant challenge when studying the role of ECMs in biogeochemical cycles. A robust, simple, rapid, and effective method was developed for extracting RNA from rhizospheric soil and ECMs by adapting previous grinding and ly...
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The species structure of an ectomycorrhizal (ECM) community was assessed monthly for 15 months in the two horizons (A1 and A2) of an oak temperate forest in northeastern France. Ectomycorrhizal species were identified each month by internal transcribed spacer sequencing. Seventy-five fungal symbionts were identified. The community was dominated by...
Article
The ability of ectomycorrhizal (ECM) fungi to mobilize soil inorganic nutrients has been well documented for a diversity of species. However, most of these studies were performed with tree seedlings or fungal cultures, making them hardly comparable. We propose here three microplate assays to compare iron chelation, free iron uptake and oxalate prod...
Article
The initial stages of wood colonization and degradation by the white-rot Trametes versicolor have been investigated. T. versicolor was grown on Fagus sylvatica wood chips under solid-state fermentation in the presence of malt agar. The beginning of the colonization process was not associated with peroxidases production or hydrolytic activity. In co...
Presentation
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Présentées comme une des principales menaces pour la biodiversité, les invasions biologiques posent d’intéressantes questions théoriques et pratiques, abordées essentiellement chez les animaux et les plantes supérieures. Curieusement, les champignons, composantes qualitativement et quantitativement essentielles de la biodiversité, ne sont que rarem...
Article
In a declining oak forest, a thinning treatment was performed in August 2004, targeting trees belonging to two decline classes. The whole ectomycorrhizal (EM) community was dominated by the fungal symbionts Clavulina cinerea, Tomentella sublilacina and Russula spp. The potential activities of eight secreted enzymes, involved in mobilizing nutrients...
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Fungi represent an essential component of biodiversity, not only because of the large number of species, but also for their ecological, evolutionary and socio-economic significance. Yet, until recently, fungi received scant consideration in ecology, especially invasion ecology. Their under-representation is largely the result of a lack of scientifi...
Article
To test the hypothesis that, depending on the fungal symbiont, ectomycorrhizas are differentially affected by severe drought stress, we developed a simple method to quantify the loss of vitality of excised ectomycorrhizal tips subjected to drying under controlled conditions. The method uses 96-well microtitration plates with one single ectomycorrhi...
Article
Tuber magnatum, an ascomycetous fungus and obligate ectomycorrhizal symbiont, forms hypogeous fruit bodies, commonly called Italian white truffles. The diversity of bacterial communities associated with T. magnatum truffles was investigated using culture-independent and -dependent 16S rRNA gene-based approaches. Eighteen truffles were classified in...
Article
The species of an ectomycorrhizal (ECM) community were investigated in a temperate oak forest by morphotyping and ITS rDNA sequencing. Thirty-six ECM morphotypes were found at the site. The niche effect (as organic soil, mineral soil or dead woody debris artificially introduced in the soil) on the ECM community structure and on the potential catabo...
Article
The ectomycorrhizas (ECM) formed by Lactarius quietus, an ECM fungus specifically associated with Quercus spp., are abundant all the year long. Root and stem growth, beginning before bud break in oak, are strong carbon sinks partially fulfilled with carbohydrate reserves. We hypothesized that L. quietus contributes to providing trees with carbon at...
Article
The effects of a sylvicultural treatment (thinning) on the ectomycorrhizal community structure and diversity were studied each season for 2 years in a declining Quercus robur woodland in northern Italy. Sixteen dominant oak trees were chosen as representative of two decline classes (eight per class). Fine root status, ectomycorrhizal community comp...
Article
The mycorrhiza helper Pseudomonas fluorescens BBc6R8 promotes the presymbiotic survival and growth of the ectomycorrhizal fungus Laccaria bicolor S238N in the soil. An in vitro fungal-bacterial confrontation bioassay mimicking the promoting effects of the bacteria on fungal growth was set up to analyse the fungal morphological and transcriptional c...
Article
Summary 22 References 33 In natural conditions, mycorrhizal fungi are surrounded by complex microbial communities, which modulate the mycorrhizal symbiosis. Here, the focus is on the so-called ‘mycorrhiza helper bacteria’ (MHB). This concept is revisited, and the distinction is made between the helper bacteria, which assist mycorrhiza formation, an...
Article
The species of an ectomycorrhizal (ECM) community were investigated in a temperate oak forest by morphotyping and ITS rDNA sequencing. Thirty-six ECM morphotypes were found at the site. The niche effect (as organic soil, mineral soil or dead woody debris artificially introduced in the soil) on the ECM community structure and on the potential catabo...
Article
Full-text available
Mycorrhization helper bacteria (MHB), isolated from phylogenetically distinct ectomycorrhizal symbioses involving Lactarius rufus, Laccaria bicolor or Suillus luteus, were tested for fungus specificity to enhance L. rufus-Pinus sylvestris or L. bicolor-P. sylvestris mycorrhiza formation. As MHB isolated from the L. rufus and S. luteus mycorrhiza we...
Article
The year-round dynamics of laccase and acid phosphatase activities of ectomycorrhizas (EM) were monitored in an oak forest, with a microplate photometric method using individual EM root tips. Among the most frequent and abundant EM morphotypes, those of Lactarius quietus and Cortinarius anomalus showed a peak of laccase activity in spring, while th...
Book
The mycorrhiza is characterized by whitish to yellowish monopodial-pyramidal systems with smooth to loosely woolly surface, plectenchymatous outer mantle layers with clamped and irregularly arranged hyphae, undifferentiated rhizomorphs with smooth margins and paraepidermal Hartig net. These features are similar to those reported for other ectomycor...
Article
Full-text available
The mycorrhiza is characterized by whitish to yellowish monopodial-pyramidal systems with smooth to loosely woolly surface, plectenchymatous outer mantle layers with clamped and irregularly arranged hyphae, undifferentiated rhizomorphs with smooth margins and paraepidermal Hartig net. These features are similar to those reported for other ectomycor...
Article
Les champignons, par leur abondance et la diversité de formes, sont une composante importante du paysage de nos sous-bois en automne. Mais sait-on que pour la moitié d'entre elles, ces espèces vivent en symbiose avec les racines et qu'elles sont indispensables à la nutrition des arbres ? Chercheurs et forestiers s'intéressent de plus en plus à ce r...
Article
Fluorescence in situ hybridization, associated with confocal laser scanning microscopy or epifluorescence microscopy with deconvolution system, has allowed the detection of a community of intracellular bacteria in non-axenic samples of the ectomycorrhizal fungus Laccaria bicolor S238N. The endobacteria, mainly alpha-proteobacteria, were present in...
Article
Data on the diversity and distribution of enzyme activities in native ectomycorrhizal (ECM) communities are inadequate. A microplate multiple enzymatic test was developed which makes it possible to measure eight enzyme activities on 14 individual, excised ECM root tips. Hydrolytic and oxidative enzymes are involved in the decomposition of lignocell...
Article
We tested the response of seedlings of Dicorynia guianensis, a major timber tree species of French Guiana, to mycorrhizal symbiosis and water limitation in a semi-controlled experiment under natural light conditions. Under well-watered conditions, mycorrhizal colonization resulted in an increase of net photosynthesis, growth and phosphorus uptake....
Article
This work was aimed at understanding how the functional diversity of ectomycorrhizas (ECM) is driven by environmental factors and how it adapts to the structure of the forest stand. Superficial fine roots were sampled 21 times during an entire year in two adjacent plots (no thinning and strong thinning) of a mature beech (Fagus silvatica) forest. I...
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A plant’s capability to develop ectomycorrhizal symbiosis is under the control of both genetic and environmental factors. In order to determine the roles played by these different factors, we have performed a quantitative genetic analysis of the ability of poplar trees to form ectomycorrhizas. Quantitative genetics were applied to an interspecific...
Article
Here we characterized the effect of the ectomycorrhizal symbiosis on the genotypic and functional diversity of soil Pseudomonas fluorescens populations and analysed its possible consequences in terms of plant nutrition, development and health. Sixty strains of P. fluorescens were isolated from the bulk soil of a forest nursery, the ectomycorrhizosp...