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Sari Timonen - One of the best experts on this subject based on the ideXlab platform.
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microbial biofilms and catabolic plasmid harbouring degradative fluorescent pseudomonads in scots pine Mycorrhizospheres developed on petroleum contaminated soil
1998Co-Authors: Inga Sarand, Kielo Haahtela, Sari Timonen, Eevaliisa Nurmiaholassila, Teija Koivula, Martin Romantschuk, Robin SenAbstract:Abstract Cellular interactions and catabolic activities of mycorrhizal root associated non-sporulating bacteria were investigated in a simplified phytoremediation simulation involving a woody plant species. Mycorrhizal Scots pine ( Pinus sylvestris ) seedlings pre-colonised by Suillus bovinus or Paxillus involutus were grown in forest humus containing microcosms amended with petroleum hydrocarbon (PHC) contaminated soil. Fungal hyphae of both species, emanating from mycorrhizal roots, colonised the PHC contaminated soil over a 16-week period and dense long-lived patches of S. bovinus hyphae formed on the PHC contaminated soil. Transmission electron microscopy revealed a microbial biofilm at the PHC soil-fungal interface composed of differentiated pseudoparenchymous patch hyphae supporting a morphologically diverse bacterial population. Certain non-sporulating bacterial isolates closely associated with the S. bovinus patch hyphae or P. involutus `web' hyphae from the PHC soil harboured similar sized mega-plasmids (approx. 150 kb). Isolates of Pseudomonas fluorescens from the `patch' Mycorrhizospheres represented different biovars, displayed similar REP-PCR genomic fingerprints, grew on e.g. m -toluate and m -xylene as sole carbon sources, cleaved catechol, and harboured plasmid-borne catabolic marker genes, xylE and xylMA , involved in degradation of mono-aromatics. The plasmids were transmissible in vitro, and Pseudomonas putida transconjugants retained a similar catabolic profile. The identification of microbial biofilms containing catabolic bacteria in the external Mycorrhizosphere is discussed in relation to both phytoremediation mechanisms and normal efficient nutrient mobilisation from highly lignin-rich forest soils.
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bacterial community structure at defined locations of pinus sylvestris suillus bovinus and pinus sylvestris paxillus involutus Mycorrhizospheres in dry pine forest humus and nursery peat
1998Co-Authors: Sari Timonen, Kirsten S. Jørgensen, Kielo HaahtelaAbstract:Bacteria were isolated and characterized from uncolonized soil, nonmycorrhizal and mycorrhizal short roots, and soil-colonizing external mycelium from intact Pinus sylvestris - Suillus bovinus and Pinus sylvestris - Paxillus involutus Mycorrhizospheres developed in microcosms containing dry pine forest humus or nursery peat. Total numbers of colony-forming units (CFU/mg dry weight) in the different locations from all ectoMycorrhizospheres indicated an overall bacterial-enrichment gradient towards the roots, whereas sporeformers were more evenly distributed. Fluorescent pseudomonads were commonly isolated from all Mycorrhizosphere locations in nursery peat, but they were nearly absent from the forest humus community. In contrast, sporeformers were more abundant at all locations in the latter growth substrate. The bacterial species composition of forest and nursery Mycorrhizospheres was clearly divergent when characterized according to their carbon source utilization patterns in Biolog® GN or GP microplates...
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heterogeneity of fungal and plant enzyme expression in intact scots pine suillus bovinus and paxillus involutus Mycorrhizospheres developed in natural forest humus
1998Co-Authors: Sari TimonenAbstract:Isozyme expression of nutrient-mobilizing and defence-related enzymes were examined in different functional components of intact Scots pine (Pinus sylvestris L.) ectomycorrhizal root systems developed in natural unsterilized forest humus. Scots pine seedlings colonized by Suillus bovinus (L. ex Fr.) 0. Kuntze or Paxillus involutus (Batsch ex Fr.) strains were grown on humus in two-dimensional Perspexg microcosms to allow development of complete ectomycorrhizal root systems. Soluble proteins from uncolonized short roots, whole mycorrhizal root tips or dissected mantle and core fractions, fungal strands and the outermost soil colonizing fine hyphae were subjected to native polyacrylamide gel electrophoresis and stained to detect esterase, acid phosphatase, peroxidase and different polyphenoloxidase isozyme activities. Tissue-specific esterase isozymes were detected in all components and most, including unique Hartig net isozymes, were of fungal origin. High fungal acid phosphatase activities were detected in mycorrhiza and fine hyphae of S. bovinus, supporting earlier findings of active phosphatase activity at the fungal interface in the Hartig net region and in the fine hyphal margins of extramatrical mycelium actively colonizing the humus. All compartments in the P. involutus Mycorrhizosphere had weaker acid-phosphatase activities. Peroxidases formed a large part of the soluble-protein content in non-mycorrhizal short roots. The amount of peroxidases, on a tissue f. wt basis, was similar in mycorrhizal and non-mycorrhizal roots, but differential isozyme expression was detected, indicating a change in root peroxidase activities following mycorrhiza formation. The expression of DL-3,4-dihydroxyphenylalanine metabolizing polyphenol oxidase enzymes was reduced in mycorrhizas compared with non-mycorrhizal short roots. In the extramatrical mycelial components, fine hyphae expressed the highest polyphenoloxidase activity. P. involutus displayed some polyphenol-oxidizing isoenzymes not detected in S. bovinus systems. Laccase activity was not detected in the plant and fungal components examined. It is concluded that enzyme activities and isozyme expression are differentially regulated in the different functional components of Scots pine Mycorrhizospheres.
S H Jabajihare - One of the best experts on this subject based on the ideXlab platform.
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quantification of fusarium solani f sp phaseoli in mycorrhizal bean plants and surrounding Mycorrhizosphere soil using real time polymerase chain reaction and direct isolations on selective media
2003Co-Authors: Martin Filion, Marc Starnaud, S H JabajihareAbstract:ABSTRACT The capacity of the arbuscular mycorrhizal fungus Glomus intraradices in reducing the presence of Fusarium solani f. sp. phaseoli in bean plants and the surrounding Mycorrhizosphere soil was evaluated in a compartmentalized experimental system. Quantification of the pathogen and the symbiont in plant tissues, the soil regions of the Mycorrhizosphere (rhizosphere and mycosphere), and the bulk soil was accomplished using specific polymerase chain reaction (PCR) primers in real-time PCR assays, culture-dependant methods, and microscopic determination techniques. Nonmycorrhizal bean plants infected with the pathogen had distinctive Fusarium root rot symptoms, while infected plants previously colonized by G. intraradices remained healthy. The amount of F. solani f. sp. phaseoli genomic DNA was significantly reduced in mycorrhizal bean plants and in each Mycorrhizosphere soil compartment. The presence of G. intraradices in the Mycorrhizosphere was not significantly modified, although the mycorrhizal colonization of roots was slightly increased in the presence of the pathogen. The results suggest that the reduced presence of Fusarium as well as root rot symptoms are caused by biotic and/or abiotic modifications of the Mycorrhizosphere as a result of colonization with G. intraradices.
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quantification of fusarium solani f sp phaseoli in mycorrhizal bean plants and surrounding Mycorrhizosphere soil using real time polymerase chain reaction and direct isolations on selective media
2003Co-Authors: Martin Filion, Marc Starnaud, S H JabajihareAbstract:ABSTRACT The capacity of the arbuscular mycorrhizal fungus Glomus intraradices in reducing the presence of Fusarium solani f. sp. phaseoli in bean plants and the surrounding Mycorrhizosphere soil was evaluated in a compartmentalized experimental system. Quantification of the pathogen and the symbiont in plant tissues, the soil regions of the Mycorrhizosphere (rhizosphere and mycosphere), and the bulk soil was accomplished using specific polymerase chain reaction (PCR) primers in real-time PCR assays, culture-dependant methods, and microscopic determination techniques. Nonmycorrhizal bean plants infected with the pathogen had distinctive Fusarium root rot symptoms, while infected plants previously colonized by G. intraradices remained healthy. The amount of F. solani f. sp. phaseoli genomic DNA was significantly reduced in mycorrhizal bean plants and in each Mycorrhizosphere soil compartment. The presence of G. intraradices in the Mycorrhizosphere was not significantly modified, although the mycorrhizal co...
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suitability of glomus intraradices in vitro produced spores and root segment inoculum for the establishment of a Mycorrhizosphere in an experimental microcosm
2001Co-Authors: M Filion, Marc Starnaud, C Guillon, Chantal Hamel, S H JabajihareAbstract:Various experimental systems have been developed to study the Mycorrhizosphere. In this study, a micro- cosm experimental system was constructed and optimized to simulate the environments of the Mycorrhizosphere: the rhizosphere, the mycosphere, and the bulk soil, using beans (Phaseolus vulgaris L.) as host plants. We investigated, in a time-course study, the effect of axenically in vitro produced spore inoculum and root segment inoculum of the arbuscular mycorrhizal fungus, Glomus intraradices Schenck & Smith, on extraradical mycelium development, rapidity of mycorrhizal colonization, and plant growth under nonsterile soil conditions. Three concentrations of in vitro pro - duced spores and three concentrations of root segment inoculum produced from open pot cultures were used. The two highest concentrations of spores used as inoculum resulted in faster and more abundant colonization than when root segments were used. A significant correlation was obtained between hyphal densities present in the rhizosphere and mycosphere compartments, and the amount of spore inoculum used. The densities of roots in the rhizosphere compart- ment and hyphae in the rhizosphere and mycosphere compartments were comparable with field-grown plants; thus, the system realistically mimics a natural Mycorrhizosphere. The use of the microcosm described in this study, in combina- tion with the in vitro produced spore inoculum of G. intraradices, represents an experimental approach well adapted for studying the microbial ecology of the Mycorrhizosphere.
Martin Filion - One of the best experts on this subject based on the ideXlab platform.
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quantification of fusarium solani f sp phaseoli in mycorrhizal bean plants and surrounding Mycorrhizosphere soil using real time polymerase chain reaction and direct isolations on selective media
2003Co-Authors: Martin Filion, Marc Starnaud, S H JabajihareAbstract:ABSTRACT The capacity of the arbuscular mycorrhizal fungus Glomus intraradices in reducing the presence of Fusarium solani f. sp. phaseoli in bean plants and the surrounding Mycorrhizosphere soil was evaluated in a compartmentalized experimental system. Quantification of the pathogen and the symbiont in plant tissues, the soil regions of the Mycorrhizosphere (rhizosphere and mycosphere), and the bulk soil was accomplished using specific polymerase chain reaction (PCR) primers in real-time PCR assays, culture-dependant methods, and microscopic determination techniques. Nonmycorrhizal bean plants infected with the pathogen had distinctive Fusarium root rot symptoms, while infected plants previously colonized by G. intraradices remained healthy. The amount of F. solani f. sp. phaseoli genomic DNA was significantly reduced in mycorrhizal bean plants and in each Mycorrhizosphere soil compartment. The presence of G. intraradices in the Mycorrhizosphere was not significantly modified, although the mycorrhizal colonization of roots was slightly increased in the presence of the pathogen. The results suggest that the reduced presence of Fusarium as well as root rot symptoms are caused by biotic and/or abiotic modifications of the Mycorrhizosphere as a result of colonization with G. intraradices.
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quantification of fusarium solani f sp phaseoli in mycorrhizal bean plants and surrounding Mycorrhizosphere soil using real time polymerase chain reaction and direct isolations on selective media
2003Co-Authors: Martin Filion, Marc Starnaud, S H JabajihareAbstract:ABSTRACT The capacity of the arbuscular mycorrhizal fungus Glomus intraradices in reducing the presence of Fusarium solani f. sp. phaseoli in bean plants and the surrounding Mycorrhizosphere soil was evaluated in a compartmentalized experimental system. Quantification of the pathogen and the symbiont in plant tissues, the soil regions of the Mycorrhizosphere (rhizosphere and mycosphere), and the bulk soil was accomplished using specific polymerase chain reaction (PCR) primers in real-time PCR assays, culture-dependant methods, and microscopic determination techniques. Nonmycorrhizal bean plants infected with the pathogen had distinctive Fusarium root rot symptoms, while infected plants previously colonized by G. intraradices remained healthy. The amount of F. solani f. sp. phaseoli genomic DNA was significantly reduced in mycorrhizal bean plants and in each Mycorrhizosphere soil compartment. The presence of G. intraradices in the Mycorrhizosphere was not significantly modified, although the mycorrhizal co...
Marc Starnaud - One of the best experts on this subject based on the ideXlab platform.
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quantification of fusarium solani f sp phaseoli in mycorrhizal bean plants and surrounding Mycorrhizosphere soil using real time polymerase chain reaction and direct isolations on selective media
2003Co-Authors: Martin Filion, Marc Starnaud, S H JabajihareAbstract:ABSTRACT The capacity of the arbuscular mycorrhizal fungus Glomus intraradices in reducing the presence of Fusarium solani f. sp. phaseoli in bean plants and the surrounding Mycorrhizosphere soil was evaluated in a compartmentalized experimental system. Quantification of the pathogen and the symbiont in plant tissues, the soil regions of the Mycorrhizosphere (rhizosphere and mycosphere), and the bulk soil was accomplished using specific polymerase chain reaction (PCR) primers in real-time PCR assays, culture-dependant methods, and microscopic determination techniques. Nonmycorrhizal bean plants infected with the pathogen had distinctive Fusarium root rot symptoms, while infected plants previously colonized by G. intraradices remained healthy. The amount of F. solani f. sp. phaseoli genomic DNA was significantly reduced in mycorrhizal bean plants and in each Mycorrhizosphere soil compartment. The presence of G. intraradices in the Mycorrhizosphere was not significantly modified, although the mycorrhizal colonization of roots was slightly increased in the presence of the pathogen. The results suggest that the reduced presence of Fusarium as well as root rot symptoms are caused by biotic and/or abiotic modifications of the Mycorrhizosphere as a result of colonization with G. intraradices.
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quantification of fusarium solani f sp phaseoli in mycorrhizal bean plants and surrounding Mycorrhizosphere soil using real time polymerase chain reaction and direct isolations on selective media
2003Co-Authors: Martin Filion, Marc Starnaud, S H JabajihareAbstract:ABSTRACT The capacity of the arbuscular mycorrhizal fungus Glomus intraradices in reducing the presence of Fusarium solani f. sp. phaseoli in bean plants and the surrounding Mycorrhizosphere soil was evaluated in a compartmentalized experimental system. Quantification of the pathogen and the symbiont in plant tissues, the soil regions of the Mycorrhizosphere (rhizosphere and mycosphere), and the bulk soil was accomplished using specific polymerase chain reaction (PCR) primers in real-time PCR assays, culture-dependant methods, and microscopic determination techniques. Nonmycorrhizal bean plants infected with the pathogen had distinctive Fusarium root rot symptoms, while infected plants previously colonized by G. intraradices remained healthy. The amount of F. solani f. sp. phaseoli genomic DNA was significantly reduced in mycorrhizal bean plants and in each Mycorrhizosphere soil compartment. The presence of G. intraradices in the Mycorrhizosphere was not significantly modified, although the mycorrhizal co...
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suitability of glomus intraradices in vitro produced spores and root segment inoculum for the establishment of a Mycorrhizosphere in an experimental microcosm
2001Co-Authors: M Filion, Marc Starnaud, C Guillon, Chantal Hamel, S H JabajihareAbstract:Various experimental systems have been developed to study the Mycorrhizosphere. In this study, a micro- cosm experimental system was constructed and optimized to simulate the environments of the Mycorrhizosphere: the rhizosphere, the mycosphere, and the bulk soil, using beans (Phaseolus vulgaris L.) as host plants. We investigated, in a time-course study, the effect of axenically in vitro produced spore inoculum and root segment inoculum of the arbuscular mycorrhizal fungus, Glomus intraradices Schenck & Smith, on extraradical mycelium development, rapidity of mycorrhizal colonization, and plant growth under nonsterile soil conditions. Three concentrations of in vitro pro - duced spores and three concentrations of root segment inoculum produced from open pot cultures were used. The two highest concentrations of spores used as inoculum resulted in faster and more abundant colonization than when root segments were used. A significant correlation was obtained between hyphal densities present in the rhizosphere and mycosphere compartments, and the amount of spore inoculum used. The densities of roots in the rhizosphere compart- ment and hyphae in the rhizosphere and mycosphere compartments were comparable with field-grown plants; thus, the system realistically mimics a natural Mycorrhizosphere. The use of the microcosm described in this study, in combina- tion with the in vitro produced spore inoculum of G. intraradices, represents an experimental approach well adapted for studying the microbial ecology of the Mycorrhizosphere.
Martin Romantschuk - One of the best experts on this subject based on the ideXlab platform.
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effect of inoculation of a tol plasmid containing Mycorrhizosphere bacterium on development of scots pine seedlings their Mycorrhizosphere and the microbial flora in m toluate amended soil
2000Co-Authors: Inga Sarand, Kirsten S. Jørgensen, Heikki Haario, Martin RomantschukAbstract:The purpose of this study was to evaluate the influence of introduced bacteria containing a contaminant degrading plasmid on the growth and survival of pine seedlings and Mycorrhizosphere microbial flora in contaminated soil. The Pseudomonas fluorescens strain OS81, originally isolated from fungal hyphae in contaminated soil, was supplied with the TOL plasmid pWW0::Km (to generate OS81(pWW0::Km)) and inoculated in humus-soil microcosms with and without pine seedlings mycorrhized with Suillus bovinus. After 3 months of regular treatment with m-toluate (mTA) solutions, the introduced catabolic plasmid was found to be disseminated in the indigenous bacterial population of both Mycorrhizosphere and soil uncolonized by the fungus. Transconjugants were represented by bacteria of the genera Pseudomonas and Burkholderia and their number correlated positively with the concentration of mTA applied. Indigenous mTA degrading bacteria with low similarity to Burkholderia species were also enriched in microcosms. They were mostly associated with mycorrhizal soil or fungal structures and virtually absent in microcosms without pines. The total number of Tol+ bacteria was higher in mycorrhizospheric soil compared with bulk soil. Inoculation with P. fluorescens OS81(pWW0::Km) had a positive effect on the development of roots and fungus in contaminated soil. Both inoculation with the P. fluorescens OS81(pWW0::Km) and mTA contamination as well as the presence of mycorrhized pine roots and fungal hyphae had an effect on the microbial community structure of soil as measured by carbon source oxidation patterns. However, the impact of mTA on the microbial community was more prominent. The study indicates that an effect on plant and fungal development can be obtained by manipulating the Mycorrhizosphere. Both introduction of the bacterium carrying the degradative plasmid and the plasmid itself are likely to have a positive effect not only on the organisms involved, but also on bioremediation of contaminated soil, a factor that was not directly monitored here.
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microbial biofilms and catabolic plasmid harbouring degradative fluorescent pseudomonads in scots pine Mycorrhizospheres developed on petroleum contaminated soil
1998Co-Authors: Inga Sarand, Kielo Haahtela, Sari Timonen, Eevaliisa Nurmiaholassila, Teija Koivula, Martin Romantschuk, Robin SenAbstract:Abstract Cellular interactions and catabolic activities of mycorrhizal root associated non-sporulating bacteria were investigated in a simplified phytoremediation simulation involving a woody plant species. Mycorrhizal Scots pine ( Pinus sylvestris ) seedlings pre-colonised by Suillus bovinus or Paxillus involutus were grown in forest humus containing microcosms amended with petroleum hydrocarbon (PHC) contaminated soil. Fungal hyphae of both species, emanating from mycorrhizal roots, colonised the PHC contaminated soil over a 16-week period and dense long-lived patches of S. bovinus hyphae formed on the PHC contaminated soil. Transmission electron microscopy revealed a microbial biofilm at the PHC soil-fungal interface composed of differentiated pseudoparenchymous patch hyphae supporting a morphologically diverse bacterial population. Certain non-sporulating bacterial isolates closely associated with the S. bovinus patch hyphae or P. involutus `web' hyphae from the PHC soil harboured similar sized mega-plasmids (approx. 150 kb). Isolates of Pseudomonas fluorescens from the `patch' Mycorrhizospheres represented different biovars, displayed similar REP-PCR genomic fingerprints, grew on e.g. m -toluate and m -xylene as sole carbon sources, cleaved catechol, and harboured plasmid-borne catabolic marker genes, xylE and xylMA , involved in degradation of mono-aromatics. The plasmids were transmissible in vitro, and Pseudomonas putida transconjugants retained a similar catabolic profile. The identification of microbial biofilms containing catabolic bacteria in the external Mycorrhizosphere is discussed in relation to both phytoremediation mechanisms and normal efficient nutrient mobilisation from highly lignin-rich forest soils.
