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Marc Ducousso - One of the best experts on this subject based on the ideXlab platform.
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a leguminous species exploiting alpha and beta rhizobia for adaptation to ultramafic and volcano Sedimentary Soils an endemic acacia spirorbis model from new caledonia
FEMS Microbiology Ecology, 2019Co-Authors: Bryan Vincent, Laure Hannibal, Antoine Galiana, Farid Juillot, Emmanuel Fritsch, Agnieszka Klonowska, Noemie Gerbert, Sarah Acherar, Cedric Grangeteau, Marc DucoussoAbstract:Acacia spirorbis subsp. spirorbis Labill. is a widespread tree legume endemic to New Caledonia that grows in ultramafic (UF) and volcano-Sedimentary (VS) Soils. The aim of this study was to assess the symbiotic promiscuity of A. spirorbis with nodulating and nitrogen-fixing rhizobia in harsh edaphic conditions. Forty bacterial strains were isolated from root nodules and characterized through (i) multilocus sequence analyses, (ii) symbiotic efficiency and (iii) tolerance to metals. Notably, 32.5% of the rhizobia belonged to the Paraburkholderia genus and were only found in UF Soils. The remaining 67.5%, isolated from both UF and VS Soils, belonged to the Bradyrhizobium genus. Strains of the Paraburkholderia genus showed significantly higher nitrogen-fixing capacities than those of Bradyrhizobium genus. Strains of the two genera isolated from UF Soils showed high metal tolerance and the respective genes occurred in 50% of strains. This is the first report of both alpha- and beta-rhizobia strains associated to an Acacia species adapted to UF and VS Soils. Our findings suggest that A. spirorbis is an adaptive plant that establishes symbioses with whatever rhizobia is present in the soil, thus enabling the colonization of contrasted ecosystems.
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Ectomycorrhizal Communities Associated with the Legume Acacia spirorbis Growing on Contrasted Edaphic Constraints in New Caledonia
Microbial Ecology, 2018Co-Authors: Anne Houles, Laure Hannibal, Marc Ducousso, Antoine Galiana, Bryan Vincent, Magali David, Farid Juillot, Fabian Carriconde, Emmanuel Fritsch, Philippe JourandAbstract:This study aims to characterize the ectomycorrhizal (ECM) communities associated with Acacia spirorbis , a legume tree widely spread in New Caledonia that spontaneously grows on contrasted edaphic constraints, i.e. calcareous, ferralitic and volcano-Sedimentary Soils. Soil geochemical parameters and diversity of ECM communities were assessed in 12 sites representative of the three mains categories of Soils. The ectomycorrhizal status of Acacia spirorbis was confirmed in all studied Soils, with a fungal community dominated at 92% by Basidiomycota, mostly represented by /tomentella-thelephora (27.6%), /boletus (15.8%), /sebacina (10.5%), /russula-lactarius (10.5%) and /pisolithus-scleroderma (7.9%) lineages. The diversity and the proportion of the ECM lineages were similar for the ferralitic and volcano-Sedimentary Soils but significantly different for the calcareous Soils. These differences in the distribution of the ECM communities were statistically correlated with pH, Ca, P and Al in the calcareous Soils and with Co in the ferralitic Soils . Altogether, these data suggest a high capacity of A. spirorbis to form ECM symbioses with a large spectrum of fungi regardless the soil categories with contrasted edaphic parameters.
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Ectomycorrhizal fungal diversity associated with endemic Tristaniopsis spp. (Myrtaceae) in ultramafic and volcano-Sedimentary Soils in New Caledonia
Mycorrhiza, 2017Co-Authors: Muhammad Waseem, Philippe Jourand, Laure Hannibal, Odile Domergue, Marc Ducousso, Clarisse Majorel, Yves Prin, Antoine GalianaAbstract:New Caledonian serpentine (ultramafic) Soils contain high levels of toxic heavy metals, in particular nickel, (up to 20 g kg(-1)) and are deficient in essential elements like carbon, nitrogen and phosphorus while having a high magnesium/calcium ratio. Although previous studies showed that ectomycorrhizal symbioses could play an important role in the adaptation of the endemic plants to ultramafic Soils (FEMS Microbiol Ecol 72:238-49, 2010), none of them have compared the diversity of microbial communities from ultramafic vs non-ultramafic Soils in New Caledonia. We explored the impact of edaphic characteristics on the diversity of ectomycorrhizal (ECM) fungi associated with different endemic species of Tristaniopsis (Myrtaceae) growing under contrasting soil conditions in the natural ecosystems of New Caledonia. ECM root tips were thus sampled from two different ultramafic sites (Koniambo massif and Desmazures forest) vs two volcano-Sedimentary ones (Arama and Mont Ninndo). The molecular characterization of the ECM fungi through partial sequencing of the ITS rRNA gene revealed the presence of different dominant fungal genera including, both soil types combined, Cortinarius (36.1%), Pisolithus (18.5%), Russula (13.4%), Heliotales (8.2%) and Boletellus (7.2%). A high diversity of ECM taxa associated with Tristaniopsis species was found in both ultramafic and volcano-Sedimentary Soils but no significant differences in ECM genera distribution were observed between both soil types. No link could be established between the phylogenetic clustering of ECM taxa and their soil type origin, thus suggesting a possible functional-rather than taxonomical-adaptation of ECM fungal communities to ultramafic Soils.
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Ultramafic Soils from New Caledonia structure Pisolithus albus in ecotype
FEMS Microbiology Ecology, 2010Co-Authors: Philippe Jourand, Clarisse Loulergue-majorel, Laure Hannibal, Sylvain Santoni, Marc Ducousso, Yves Prin, Michel LebrunAbstract:Isolates of ectomycorrhizal Pisolithus albus were sampled from both ultramafic and volcano-Sedimentary Soils in New Caledonia, a tropical hotspot of biodiversity, to investigate the relationships between genetic diversity and edaphic constraint through tolerance to nickel (Ni). Carpophore description, spore morphology and phylogenetic analysis based on internal transcribed spacer (ITS) rDNA sequences confirmed that all isolates belong to P. albus and are closely related to other Australasian specimens. Using molecular tools, ITS-restriction fragment length polymorphism and amplified fragment length polymorphism markers, we showed the existence of two distinct genetic clusters within P. albus: ultramafic and volcano-Sedimentary. Mycelia response to Ni toxicity supports such a population structure. Pisolithus albus from ultramafic Soils included isolates with a high diversity of in vitro Ni tolerance, with both Ni-tolerant isolates (average Ni EC(50) at 575 microM) and Ni-sensitive isolates (average Ni EC(50) at 37 microM). In contrast, all isolates from volcano-Sedimentary Soils were found to be Ni sensitive (average Ni EC(50) at 32 microM). We highlight that (1) P. albus population from ultramafic Soils of New Caledonia are genetically structured in ecotype, and that (2) Ni tolerance among ultramafic isolates suggests an adaptive physiological response to Ni toxicity.
Laure Hannibal - One of the best experts on this subject based on the ideXlab platform.
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a leguminous species exploiting alpha and beta rhizobia for adaptation to ultramafic and volcano Sedimentary Soils an endemic acacia spirorbis model from new caledonia
FEMS Microbiology Ecology, 2019Co-Authors: Bryan Vincent, Laure Hannibal, Antoine Galiana, Farid Juillot, Emmanuel Fritsch, Agnieszka Klonowska, Noemie Gerbert, Sarah Acherar, Cedric Grangeteau, Marc DucoussoAbstract:Acacia spirorbis subsp. spirorbis Labill. is a widespread tree legume endemic to New Caledonia that grows in ultramafic (UF) and volcano-Sedimentary (VS) Soils. The aim of this study was to assess the symbiotic promiscuity of A. spirorbis with nodulating and nitrogen-fixing rhizobia in harsh edaphic conditions. Forty bacterial strains were isolated from root nodules and characterized through (i) multilocus sequence analyses, (ii) symbiotic efficiency and (iii) tolerance to metals. Notably, 32.5% of the rhizobia belonged to the Paraburkholderia genus and were only found in UF Soils. The remaining 67.5%, isolated from both UF and VS Soils, belonged to the Bradyrhizobium genus. Strains of the Paraburkholderia genus showed significantly higher nitrogen-fixing capacities than those of Bradyrhizobium genus. Strains of the two genera isolated from UF Soils showed high metal tolerance and the respective genes occurred in 50% of strains. This is the first report of both alpha- and beta-rhizobia strains associated to an Acacia species adapted to UF and VS Soils. Our findings suggest that A. spirorbis is an adaptive plant that establishes symbioses with whatever rhizobia is present in the soil, thus enabling the colonization of contrasted ecosystems.
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Ectomycorrhizal Communities Associated with the Legume Acacia spirorbis Growing on Contrasted Edaphic Constraints in New Caledonia
Microbial Ecology, 2018Co-Authors: Anne Houles, Laure Hannibal, Marc Ducousso, Antoine Galiana, Bryan Vincent, Magali David, Farid Juillot, Fabian Carriconde, Emmanuel Fritsch, Philippe JourandAbstract:This study aims to characterize the ectomycorrhizal (ECM) communities associated with Acacia spirorbis , a legume tree widely spread in New Caledonia that spontaneously grows on contrasted edaphic constraints, i.e. calcareous, ferralitic and volcano-Sedimentary Soils. Soil geochemical parameters and diversity of ECM communities were assessed in 12 sites representative of the three mains categories of Soils. The ectomycorrhizal status of Acacia spirorbis was confirmed in all studied Soils, with a fungal community dominated at 92% by Basidiomycota, mostly represented by /tomentella-thelephora (27.6%), /boletus (15.8%), /sebacina (10.5%), /russula-lactarius (10.5%) and /pisolithus-scleroderma (7.9%) lineages. The diversity and the proportion of the ECM lineages were similar for the ferralitic and volcano-Sedimentary Soils but significantly different for the calcareous Soils. These differences in the distribution of the ECM communities were statistically correlated with pH, Ca, P and Al in the calcareous Soils and with Co in the ferralitic Soils . Altogether, these data suggest a high capacity of A. spirorbis to form ECM symbioses with a large spectrum of fungi regardless the soil categories with contrasted edaphic parameters.
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Ectomycorrhizal fungal diversity associated with endemic Tristaniopsis spp. (Myrtaceae) in ultramafic and volcano-Sedimentary Soils in New Caledonia
Mycorrhiza, 2017Co-Authors: Muhammad Waseem, Philippe Jourand, Laure Hannibal, Odile Domergue, Marc Ducousso, Clarisse Majorel, Yves Prin, Antoine GalianaAbstract:New Caledonian serpentine (ultramafic) Soils contain high levels of toxic heavy metals, in particular nickel, (up to 20 g kg(-1)) and are deficient in essential elements like carbon, nitrogen and phosphorus while having a high magnesium/calcium ratio. Although previous studies showed that ectomycorrhizal symbioses could play an important role in the adaptation of the endemic plants to ultramafic Soils (FEMS Microbiol Ecol 72:238-49, 2010), none of them have compared the diversity of microbial communities from ultramafic vs non-ultramafic Soils in New Caledonia. We explored the impact of edaphic characteristics on the diversity of ectomycorrhizal (ECM) fungi associated with different endemic species of Tristaniopsis (Myrtaceae) growing under contrasting soil conditions in the natural ecosystems of New Caledonia. ECM root tips were thus sampled from two different ultramafic sites (Koniambo massif and Desmazures forest) vs two volcano-Sedimentary ones (Arama and Mont Ninndo). The molecular characterization of the ECM fungi through partial sequencing of the ITS rRNA gene revealed the presence of different dominant fungal genera including, both soil types combined, Cortinarius (36.1%), Pisolithus (18.5%), Russula (13.4%), Heliotales (8.2%) and Boletellus (7.2%). A high diversity of ECM taxa associated with Tristaniopsis species was found in both ultramafic and volcano-Sedimentary Soils but no significant differences in ECM genera distribution were observed between both soil types. No link could be established between the phylogenetic clustering of ECM taxa and their soil type origin, thus suggesting a possible functional-rather than taxonomical-adaptation of ECM fungal communities to ultramafic Soils.
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Ultramafic Soils from New Caledonia structure Pisolithus albus in ecotype
FEMS Microbiology Ecology, 2010Co-Authors: Philippe Jourand, Clarisse Loulergue-majorel, Laure Hannibal, Sylvain Santoni, Marc Ducousso, Yves Prin, Michel LebrunAbstract:Isolates of ectomycorrhizal Pisolithus albus were sampled from both ultramafic and volcano-Sedimentary Soils in New Caledonia, a tropical hotspot of biodiversity, to investigate the relationships between genetic diversity and edaphic constraint through tolerance to nickel (Ni). Carpophore description, spore morphology and phylogenetic analysis based on internal transcribed spacer (ITS) rDNA sequences confirmed that all isolates belong to P. albus and are closely related to other Australasian specimens. Using molecular tools, ITS-restriction fragment length polymorphism and amplified fragment length polymorphism markers, we showed the existence of two distinct genetic clusters within P. albus: ultramafic and volcano-Sedimentary. Mycelia response to Ni toxicity supports such a population structure. Pisolithus albus from ultramafic Soils included isolates with a high diversity of in vitro Ni tolerance, with both Ni-tolerant isolates (average Ni EC(50) at 575 microM) and Ni-sensitive isolates (average Ni EC(50) at 37 microM). In contrast, all isolates from volcano-Sedimentary Soils were found to be Ni sensitive (average Ni EC(50) at 32 microM). We highlight that (1) P. albus population from ultramafic Soils of New Caledonia are genetically structured in ecotype, and that (2) Ni tolerance among ultramafic isolates suggests an adaptive physiological response to Ni toxicity.
Antoine Galiana - One of the best experts on this subject based on the ideXlab platform.
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a leguminous species exploiting alpha and beta rhizobia for adaptation to ultramafic and volcano Sedimentary Soils an endemic acacia spirorbis model from new caledonia
FEMS Microbiology Ecology, 2019Co-Authors: Bryan Vincent, Laure Hannibal, Antoine Galiana, Farid Juillot, Emmanuel Fritsch, Agnieszka Klonowska, Noemie Gerbert, Sarah Acherar, Cedric Grangeteau, Marc DucoussoAbstract:Acacia spirorbis subsp. spirorbis Labill. is a widespread tree legume endemic to New Caledonia that grows in ultramafic (UF) and volcano-Sedimentary (VS) Soils. The aim of this study was to assess the symbiotic promiscuity of A. spirorbis with nodulating and nitrogen-fixing rhizobia in harsh edaphic conditions. Forty bacterial strains were isolated from root nodules and characterized through (i) multilocus sequence analyses, (ii) symbiotic efficiency and (iii) tolerance to metals. Notably, 32.5% of the rhizobia belonged to the Paraburkholderia genus and were only found in UF Soils. The remaining 67.5%, isolated from both UF and VS Soils, belonged to the Bradyrhizobium genus. Strains of the Paraburkholderia genus showed significantly higher nitrogen-fixing capacities than those of Bradyrhizobium genus. Strains of the two genera isolated from UF Soils showed high metal tolerance and the respective genes occurred in 50% of strains. This is the first report of both alpha- and beta-rhizobia strains associated to an Acacia species adapted to UF and VS Soils. Our findings suggest that A. spirorbis is an adaptive plant that establishes symbioses with whatever rhizobia is present in the soil, thus enabling the colonization of contrasted ecosystems.
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Ectomycorrhizal Communities Associated with the Legume Acacia spirorbis Growing on Contrasted Edaphic Constraints in New Caledonia
Microbial Ecology, 2018Co-Authors: Anne Houles, Laure Hannibal, Marc Ducousso, Antoine Galiana, Bryan Vincent, Magali David, Farid Juillot, Fabian Carriconde, Emmanuel Fritsch, Philippe JourandAbstract:This study aims to characterize the ectomycorrhizal (ECM) communities associated with Acacia spirorbis , a legume tree widely spread in New Caledonia that spontaneously grows on contrasted edaphic constraints, i.e. calcareous, ferralitic and volcano-Sedimentary Soils. Soil geochemical parameters and diversity of ECM communities were assessed in 12 sites representative of the three mains categories of Soils. The ectomycorrhizal status of Acacia spirorbis was confirmed in all studied Soils, with a fungal community dominated at 92% by Basidiomycota, mostly represented by /tomentella-thelephora (27.6%), /boletus (15.8%), /sebacina (10.5%), /russula-lactarius (10.5%) and /pisolithus-scleroderma (7.9%) lineages. The diversity and the proportion of the ECM lineages were similar for the ferralitic and volcano-Sedimentary Soils but significantly different for the calcareous Soils. These differences in the distribution of the ECM communities were statistically correlated with pH, Ca, P and Al in the calcareous Soils and with Co in the ferralitic Soils . Altogether, these data suggest a high capacity of A. spirorbis to form ECM symbioses with a large spectrum of fungi regardless the soil categories with contrasted edaphic parameters.
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Ectomycorrhizal fungal diversity associated with endemic Tristaniopsis spp. (Myrtaceae) in ultramafic and volcano-Sedimentary Soils in New Caledonia
Mycorrhiza, 2017Co-Authors: Muhammad Waseem, Philippe Jourand, Laure Hannibal, Odile Domergue, Marc Ducousso, Clarisse Majorel, Yves Prin, Antoine GalianaAbstract:New Caledonian serpentine (ultramafic) Soils contain high levels of toxic heavy metals, in particular nickel, (up to 20 g kg(-1)) and are deficient in essential elements like carbon, nitrogen and phosphorus while having a high magnesium/calcium ratio. Although previous studies showed that ectomycorrhizal symbioses could play an important role in the adaptation of the endemic plants to ultramafic Soils (FEMS Microbiol Ecol 72:238-49, 2010), none of them have compared the diversity of microbial communities from ultramafic vs non-ultramafic Soils in New Caledonia. We explored the impact of edaphic characteristics on the diversity of ectomycorrhizal (ECM) fungi associated with different endemic species of Tristaniopsis (Myrtaceae) growing under contrasting soil conditions in the natural ecosystems of New Caledonia. ECM root tips were thus sampled from two different ultramafic sites (Koniambo massif and Desmazures forest) vs two volcano-Sedimentary ones (Arama and Mont Ninndo). The molecular characterization of the ECM fungi through partial sequencing of the ITS rRNA gene revealed the presence of different dominant fungal genera including, both soil types combined, Cortinarius (36.1%), Pisolithus (18.5%), Russula (13.4%), Heliotales (8.2%) and Boletellus (7.2%). A high diversity of ECM taxa associated with Tristaniopsis species was found in both ultramafic and volcano-Sedimentary Soils but no significant differences in ECM genera distribution were observed between both soil types. No link could be established between the phylogenetic clustering of ECM taxa and their soil type origin, thus suggesting a possible functional-rather than taxonomical-adaptation of ECM fungal communities to ultramafic Soils.
Philippe Jourand - One of the best experts on this subject based on the ideXlab platform.
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Ectomycorrhizal Communities Associated with the Legume Acacia spirorbis Growing on Contrasted Edaphic Constraints in New Caledonia
Microbial Ecology, 2018Co-Authors: Anne Houles, Laure Hannibal, Marc Ducousso, Antoine Galiana, Bryan Vincent, Magali David, Farid Juillot, Fabian Carriconde, Emmanuel Fritsch, Philippe JourandAbstract:This study aims to characterize the ectomycorrhizal (ECM) communities associated with Acacia spirorbis , a legume tree widely spread in New Caledonia that spontaneously grows on contrasted edaphic constraints, i.e. calcareous, ferralitic and volcano-Sedimentary Soils. Soil geochemical parameters and diversity of ECM communities were assessed in 12 sites representative of the three mains categories of Soils. The ectomycorrhizal status of Acacia spirorbis was confirmed in all studied Soils, with a fungal community dominated at 92% by Basidiomycota, mostly represented by /tomentella-thelephora (27.6%), /boletus (15.8%), /sebacina (10.5%), /russula-lactarius (10.5%) and /pisolithus-scleroderma (7.9%) lineages. The diversity and the proportion of the ECM lineages were similar for the ferralitic and volcano-Sedimentary Soils but significantly different for the calcareous Soils. These differences in the distribution of the ECM communities were statistically correlated with pH, Ca, P and Al in the calcareous Soils and with Co in the ferralitic Soils . Altogether, these data suggest a high capacity of A. spirorbis to form ECM symbioses with a large spectrum of fungi regardless the soil categories with contrasted edaphic parameters.
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Ectomycorrhizal fungal diversity associated with endemic Tristaniopsis spp. (Myrtaceae) in ultramafic and volcano-Sedimentary Soils in New Caledonia
Mycorrhiza, 2017Co-Authors: Muhammad Waseem, Philippe Jourand, Laure Hannibal, Odile Domergue, Marc Ducousso, Clarisse Majorel, Yves Prin, Antoine GalianaAbstract:New Caledonian serpentine (ultramafic) Soils contain high levels of toxic heavy metals, in particular nickel, (up to 20 g kg(-1)) and are deficient in essential elements like carbon, nitrogen and phosphorus while having a high magnesium/calcium ratio. Although previous studies showed that ectomycorrhizal symbioses could play an important role in the adaptation of the endemic plants to ultramafic Soils (FEMS Microbiol Ecol 72:238-49, 2010), none of them have compared the diversity of microbial communities from ultramafic vs non-ultramafic Soils in New Caledonia. We explored the impact of edaphic characteristics on the diversity of ectomycorrhizal (ECM) fungi associated with different endemic species of Tristaniopsis (Myrtaceae) growing under contrasting soil conditions in the natural ecosystems of New Caledonia. ECM root tips were thus sampled from two different ultramafic sites (Koniambo massif and Desmazures forest) vs two volcano-Sedimentary ones (Arama and Mont Ninndo). The molecular characterization of the ECM fungi through partial sequencing of the ITS rRNA gene revealed the presence of different dominant fungal genera including, both soil types combined, Cortinarius (36.1%), Pisolithus (18.5%), Russula (13.4%), Heliotales (8.2%) and Boletellus (7.2%). A high diversity of ECM taxa associated with Tristaniopsis species was found in both ultramafic and volcano-Sedimentary Soils but no significant differences in ECM genera distribution were observed between both soil types. No link could be established between the phylogenetic clustering of ECM taxa and their soil type origin, thus suggesting a possible functional-rather than taxonomical-adaptation of ECM fungal communities to ultramafic Soils.
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Ultramafic Soils from New Caledonia structure Pisolithus albus in ecotype
FEMS Microbiology Ecology, 2010Co-Authors: Philippe Jourand, Clarisse Loulergue-majorel, Laure Hannibal, Sylvain Santoni, Marc Ducousso, Yves Prin, Michel LebrunAbstract:Isolates of ectomycorrhizal Pisolithus albus were sampled from both ultramafic and volcano-Sedimentary Soils in New Caledonia, a tropical hotspot of biodiversity, to investigate the relationships between genetic diversity and edaphic constraint through tolerance to nickel (Ni). Carpophore description, spore morphology and phylogenetic analysis based on internal transcribed spacer (ITS) rDNA sequences confirmed that all isolates belong to P. albus and are closely related to other Australasian specimens. Using molecular tools, ITS-restriction fragment length polymorphism and amplified fragment length polymorphism markers, we showed the existence of two distinct genetic clusters within P. albus: ultramafic and volcano-Sedimentary. Mycelia response to Ni toxicity supports such a population structure. Pisolithus albus from ultramafic Soils included isolates with a high diversity of in vitro Ni tolerance, with both Ni-tolerant isolates (average Ni EC(50) at 575 microM) and Ni-sensitive isolates (average Ni EC(50) at 37 microM). In contrast, all isolates from volcano-Sedimentary Soils were found to be Ni sensitive (average Ni EC(50) at 32 microM). We highlight that (1) P. albus population from ultramafic Soils of New Caledonia are genetically structured in ecotype, and that (2) Ni tolerance among ultramafic isolates suggests an adaptive physiological response to Ni toxicity.
Yves Prin - One of the best experts on this subject based on the ideXlab platform.
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Ectomycorrhizal fungal diversity associated with endemic Tristaniopsis spp. (Myrtaceae) in ultramafic and volcano-Sedimentary Soils in New Caledonia
Mycorrhiza, 2017Co-Authors: Muhammad Waseem, Philippe Jourand, Laure Hannibal, Odile Domergue, Marc Ducousso, Clarisse Majorel, Yves Prin, Antoine GalianaAbstract:New Caledonian serpentine (ultramafic) Soils contain high levels of toxic heavy metals, in particular nickel, (up to 20 g kg(-1)) and are deficient in essential elements like carbon, nitrogen and phosphorus while having a high magnesium/calcium ratio. Although previous studies showed that ectomycorrhizal symbioses could play an important role in the adaptation of the endemic plants to ultramafic Soils (FEMS Microbiol Ecol 72:238-49, 2010), none of them have compared the diversity of microbial communities from ultramafic vs non-ultramafic Soils in New Caledonia. We explored the impact of edaphic characteristics on the diversity of ectomycorrhizal (ECM) fungi associated with different endemic species of Tristaniopsis (Myrtaceae) growing under contrasting soil conditions in the natural ecosystems of New Caledonia. ECM root tips were thus sampled from two different ultramafic sites (Koniambo massif and Desmazures forest) vs two volcano-Sedimentary ones (Arama and Mont Ninndo). The molecular characterization of the ECM fungi through partial sequencing of the ITS rRNA gene revealed the presence of different dominant fungal genera including, both soil types combined, Cortinarius (36.1%), Pisolithus (18.5%), Russula (13.4%), Heliotales (8.2%) and Boletellus (7.2%). A high diversity of ECM taxa associated with Tristaniopsis species was found in both ultramafic and volcano-Sedimentary Soils but no significant differences in ECM genera distribution were observed between both soil types. No link could be established between the phylogenetic clustering of ECM taxa and their soil type origin, thus suggesting a possible functional-rather than taxonomical-adaptation of ECM fungal communities to ultramafic Soils.
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Ultramafic Soils from New Caledonia structure Pisolithus albus in ecotype
FEMS Microbiology Ecology, 2010Co-Authors: Philippe Jourand, Clarisse Loulergue-majorel, Laure Hannibal, Sylvain Santoni, Marc Ducousso, Yves Prin, Michel LebrunAbstract:Isolates of ectomycorrhizal Pisolithus albus were sampled from both ultramafic and volcano-Sedimentary Soils in New Caledonia, a tropical hotspot of biodiversity, to investigate the relationships between genetic diversity and edaphic constraint through tolerance to nickel (Ni). Carpophore description, spore morphology and phylogenetic analysis based on internal transcribed spacer (ITS) rDNA sequences confirmed that all isolates belong to P. albus and are closely related to other Australasian specimens. Using molecular tools, ITS-restriction fragment length polymorphism and amplified fragment length polymorphism markers, we showed the existence of two distinct genetic clusters within P. albus: ultramafic and volcano-Sedimentary. Mycelia response to Ni toxicity supports such a population structure. Pisolithus albus from ultramafic Soils included isolates with a high diversity of in vitro Ni tolerance, with both Ni-tolerant isolates (average Ni EC(50) at 575 microM) and Ni-sensitive isolates (average Ni EC(50) at 37 microM). In contrast, all isolates from volcano-Sedimentary Soils were found to be Ni sensitive (average Ni EC(50) at 32 microM). We highlight that (1) P. albus population from ultramafic Soils of New Caledonia are genetically structured in ecotype, and that (2) Ni tolerance among ultramafic isolates suggests an adaptive physiological response to Ni toxicity.