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Janusz J. Zwiazek - One of the best experts on this subject based on the ideXlab platform.
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Hebeloma Crustuliniforme facilitates ammonium and nitrate assimilation in trembling aspen (Populus tremuloides) seedlings
Tree physiology, 2011Co-Authors: J. Aurea Siemens, Mónica Calvo-polanco, Janusz J. ZwiazekAbstract:This study examined the role of ectomycorrhizal associations in nitrogen assimilation of Populus tremuloides seedlings. Seedlings were inoculated with Hebeloma Crustuliniforme and compared with non-inoculated plants. Nitrogen-metabolizing enzymatic properties were also determined in H. Crustuliniforme grown in sterile culture. The seedlings and fungal cultures were subjected to nitrogen treatments (including NO₃⁻, NH₄⁺ and a combination of NO₃⁻ + NH₄⁺) for 2 months to examine the effects on growth, nitrogen-assimilating enzyme activities and xylem sap concentrations of NH₄⁺ and NO₃⁻. Seedlings were also provided for 3 days with ¹⁵N-labeled NH₄⁺ and NO₃⁻, and leaf and root ¹⁵N content relative to total nitrogen was measured. Both NO₃⁻ and NH₄⁺ were effective in supporting seedling growth when either form was provided separately. When NO₃⁻ and NH₄⁺ were provided together, seedling growth decreased while enzymatic assimilation of NH₄⁺ increased. Additionally, nitrogen assimilation in inoculated seedlings was less affected by the form of nitrogen compared with non-inoculated plants. Fungal ability to enzymatically respond to and assimilate NH₄⁺ combined with aspen's enzymatic responsiveness to NO₃⁻ was likely the reason for efficient assimilation of both nitrogen forms by mycorrhizal plants.
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Hebeloma Crustuliniforme modifies root hydraulic responses of trembling aspen (Populus tremuloides) seedlings to changes in external pH
Plant and Soil, 2011Co-Authors: J. Aurea Siemens, Janusz J. ZwiazekAbstract:The main objective of the study was to compare the effects of short-duration pH treatments on root hydraulic properties in trembling aspen (Populus tremuloides) seedlings that were either inoculated with the ectomycorrhizal fungus Hebeloma Crustuliniforme or remained non-inoculated (control). Inoculated and non-inoculated plants were exposed in solution culture to the root zone pH ranging from 4 to 9 and their root hydraulic conductivity was examined using the hydrostatic method and after subjecting the plants to treatments with 100 μM HgCl2 (aquaporin blocker) and 0.02% trisodium 3-hydroxy-5,8,10-pyrenetrisulfonic acid (apoplastic transport tracer). In a separate experiment, pure cultures of H. Crustuliniforme were also grown on a slid medium with the pH ranging from 4 to 9 to determine their pH growth optimum and changes in medium pH over time in the presence and absence of 8 mM NH4NO3. When grown in pure culture, H. Crustuliniforme demonstrated maximum growth at pH 7–8 and was capable of modifying the pH of its growth media, especially in the presence of NH4NO3. The plants that were inoculated with H. Crustuliniforme had a maximum root hydraulic conductivity at pH 7. At this pH, root hydraulic conductivity was significantly higher compared with non-inoculated plants and showed greater sensitivity of root water transport to pH changes relative to non-inoculated seedlings. Relative apoplastic flux was largely unaffected by pH in inoculated seedlings. Fungal inoculation modified the response of root hydraulic conductivity to pH. The increased root hydraulic conductivity in inoculated seedlings was likely due to an increase in aquaporin-mediated cell-to-cell water transport, particularly at the higher pH. A possible role of fungal aquaporins in the root hydraulic conductivity responses of mycorrhizzal plants should be examined.
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effects of ph on nacl tolerance of american elm ulmus americana seedlings inoculated with Hebeloma Crustuliniforme and laccaria bicolor
Acta Physiologiae Plantarum, 2009Co-Authors: Monica Calvopolanco, Melanie D. Jones, Janusz J. ZwiazekAbstract:In the present study, we investigated the effects of pH treatments on NaCl tolerance in mycorrhizal and non-mycorrhizal American elm. American elm (Ulmus americana) seedlings were inoculated with Hebeloma Crustuliniforme, Laccaria bicolor or with both mycorrhizal fungi and subsequently subjected to different pH solutions (pH 3, 6 and 9) containing 0 mM (control) and 60 mM NaCl for 4 weeks. Inoculation with the mycorrhizal fungi did not have a large effect on seedling dry weights when the pH and NaCl treatments were considered independently. However, when the inoculated seedlings were treated with 60 mM NaCl at pH 3 or 6, shoot to root ratios and root hydraulic conductivity were higher compared with non-inoculated plants, likely reflecting changes in seedling water flow properties. At pH 6, transpiration rates were about twofold lower in non-inoculated plants treated with NaCl compared with non-treated controls. For NaCl-treated H. Crustuliniforme- and L. bicolor-inoculated plants, the greatest reduction of transpiration rates was at pH 9. Treatment with 60 mM NaCl reduced leaf chlorophyll concentrations more in non-inoculated compared with inoculated plants, with the greatest, twofold, decrease occurring at pH 6. At pH 3, root Na concentrations were higher in inoculated than non-inoculated seedlings; however, there was no effect of inoculation on root Na concentrations at pH 6 and 9. Contrary to the roots, the leaves of inoculated plants had lower Na concentrations at pH 6 and 9, but not at pH 3. The results point to an interaction between ECM fungi and root zone pH for salt tolerance of American elm.
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effects of ph on nacl tolerance of american elm ulmus americana seedlings inoculated with Hebeloma Crustuliniforme and laccaria bicolor
Acta Physiologiae Plantarum, 2009Co-Authors: Monica Calvopolanco, Melanie D. Jones, Janusz J. ZwiazekAbstract:In the present study, we investigated the effects of pH treatments on NaCl tolerance in mycorrhizal and non-mycorrhizal American elm. American elm (Ulmus americana) seedlings were inoculated with Hebeloma Crustuliniforme, Laccaria bicolor or with both mycorrhizal fungi and subsequently subjected to different pH solutions (pH 3, 6 and 9) containing 0 mM (control) and 60 mM NaCl for 4 weeks. Inoculation with the mycorrhizal fungi did not have a large effect on seedling dry weights when the pH and NaCl treatments were considered independently. However, when the inoculated seedlings were treated with 60 mM NaCl at pH 3 or 6, shoot to root ratios and root hydraulic conductivity were higher compared with non-inoculated plants, likely reflecting changes in seedling water flow properties. At pH 6, transpiration rates were about twofold lower in non-inoculated plants treated with NaCl compared with non-treated controls. For NaCl-treated H. Crustuliniforme- and L. bicolor-inoculated plants, the greatest reduction of transpiration rates was at pH 9. Treatment with 60 mM NaCl reduced leaf chlorophyll concentrations more in non-inoculated compared with inoculated plants, with the greatest, twofold, decrease occurring at pH 6. At pH 3, root Na concentrations were higher in inoculated than non-inoculated seedlings; however, there was no effect of inoculation on root Na concentrations at pH 6 and 9. Contrary to the roots, the leaves of inoculated plants had lower Na concentrations at pH 6 and 9, but not at pH 3. The results point to an interaction between ECM fungi and root zone pH for salt tolerance of American elm.
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Root hydraulic properties and growth of balsam poplar (Populus balsamifera) mycorrhizal with Hebeloma Crustuliniforme and Wilcoxina mikolae var. mikolae
Mycorrhiza, 2008Co-Authors: J. Aurea Siemens, Janusz J. ZwiazekAbstract:The effects of an E-strain fungus ( Wilcoxina mikolae var. mikolae ) and an ectomycorrhizal fungus ( Hebeloma Crustuliniforme ) on growth and water relations of balsam poplar were examined and compared in the present study. Balsam poplar roots inoculated with W. mikolae var. mikolae (Wm) exhibited structures consistent with ectendomycorrhizal (EEM) associations, including a mantle surrounding the outside of the root and an extensive Hartig net that was located between cortical cells and extended to the vascular cylinder. Roots colonized with H. Crustuliniforme (Hc) developed a mantle layer, indicative of an ectomycorrhizal (ECM) association, around the outer part of the root, but no distinct Hartig net was present. Wm-colonized balsam poplar also showed increased shoot growth, stomatal conductance ( g _s), and root volumes compared with non-inoculated and Hc-inoculated plants. However, Hc-inoculated plants had higher root hydraulic conductivity ( L _pr) compared with non-inoculated plants and Wm-inoculated plants. These results suggest that L _pr was not a growth-limiting factor in balsam poplar and that hyphal penetration of the root cortex in itself may have little influence on root hydraulic properties.
J. Aurea Siemens - One of the best experts on this subject based on the ideXlab platform.
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Hebeloma Crustuliniforme facilitates ammonium and nitrate assimilation in trembling aspen (Populus tremuloides) seedlings
Tree physiology, 2011Co-Authors: J. Aurea Siemens, Mónica Calvo-polanco, Janusz J. ZwiazekAbstract:This study examined the role of ectomycorrhizal associations in nitrogen assimilation of Populus tremuloides seedlings. Seedlings were inoculated with Hebeloma Crustuliniforme and compared with non-inoculated plants. Nitrogen-metabolizing enzymatic properties were also determined in H. Crustuliniforme grown in sterile culture. The seedlings and fungal cultures were subjected to nitrogen treatments (including NO₃⁻, NH₄⁺ and a combination of NO₃⁻ + NH₄⁺) for 2 months to examine the effects on growth, nitrogen-assimilating enzyme activities and xylem sap concentrations of NH₄⁺ and NO₃⁻. Seedlings were also provided for 3 days with ¹⁵N-labeled NH₄⁺ and NO₃⁻, and leaf and root ¹⁵N content relative to total nitrogen was measured. Both NO₃⁻ and NH₄⁺ were effective in supporting seedling growth when either form was provided separately. When NO₃⁻ and NH₄⁺ were provided together, seedling growth decreased while enzymatic assimilation of NH₄⁺ increased. Additionally, nitrogen assimilation in inoculated seedlings was less affected by the form of nitrogen compared with non-inoculated plants. Fungal ability to enzymatically respond to and assimilate NH₄⁺ combined with aspen's enzymatic responsiveness to NO₃⁻ was likely the reason for efficient assimilation of both nitrogen forms by mycorrhizal plants.
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Hebeloma Crustuliniforme modifies root hydraulic responses of trembling aspen (Populus tremuloides) seedlings to changes in external pH
Plant and Soil, 2011Co-Authors: J. Aurea Siemens, Janusz J. ZwiazekAbstract:The main objective of the study was to compare the effects of short-duration pH treatments on root hydraulic properties in trembling aspen (Populus tremuloides) seedlings that were either inoculated with the ectomycorrhizal fungus Hebeloma Crustuliniforme or remained non-inoculated (control). Inoculated and non-inoculated plants were exposed in solution culture to the root zone pH ranging from 4 to 9 and their root hydraulic conductivity was examined using the hydrostatic method and after subjecting the plants to treatments with 100 μM HgCl2 (aquaporin blocker) and 0.02% trisodium 3-hydroxy-5,8,10-pyrenetrisulfonic acid (apoplastic transport tracer). In a separate experiment, pure cultures of H. Crustuliniforme were also grown on a slid medium with the pH ranging from 4 to 9 to determine their pH growth optimum and changes in medium pH over time in the presence and absence of 8 mM NH4NO3. When grown in pure culture, H. Crustuliniforme demonstrated maximum growth at pH 7–8 and was capable of modifying the pH of its growth media, especially in the presence of NH4NO3. The plants that were inoculated with H. Crustuliniforme had a maximum root hydraulic conductivity at pH 7. At this pH, root hydraulic conductivity was significantly higher compared with non-inoculated plants and showed greater sensitivity of root water transport to pH changes relative to non-inoculated seedlings. Relative apoplastic flux was largely unaffected by pH in inoculated seedlings. Fungal inoculation modified the response of root hydraulic conductivity to pH. The increased root hydraulic conductivity in inoculated seedlings was likely due to an increase in aquaporin-mediated cell-to-cell water transport, particularly at the higher pH. A possible role of fungal aquaporins in the root hydraulic conductivity responses of mycorrhizzal plants should be examined.
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Root hydraulic properties and growth of balsam poplar (Populus balsamifera) mycorrhizal with Hebeloma Crustuliniforme and Wilcoxina mikolae var. mikolae
Mycorrhiza, 2008Co-Authors: J. Aurea Siemens, Janusz J. ZwiazekAbstract:The effects of an E-strain fungus ( Wilcoxina mikolae var. mikolae ) and an ectomycorrhizal fungus ( Hebeloma Crustuliniforme ) on growth and water relations of balsam poplar were examined and compared in the present study. Balsam poplar roots inoculated with W. mikolae var. mikolae (Wm) exhibited structures consistent with ectendomycorrhizal (EEM) associations, including a mantle surrounding the outside of the root and an extensive Hartig net that was located between cortical cells and extended to the vascular cylinder. Roots colonized with H. Crustuliniforme (Hc) developed a mantle layer, indicative of an ectomycorrhizal (ECM) association, around the outer part of the root, but no distinct Hartig net was present. Wm-colonized balsam poplar also showed increased shoot growth, stomatal conductance ( g _s), and root volumes compared with non-inoculated and Hc-inoculated plants. However, Hc-inoculated plants had higher root hydraulic conductivity ( L _pr) compared with non-inoculated plants and Wm-inoculated plants. These results suggest that L _pr was not a growth-limiting factor in balsam poplar and that hyphal penetration of the root cortex in itself may have little influence on root hydraulic properties.
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Root hydraulic properties and growth of balsam poplar (Populus balsamifera) mycorrhizal with Hebeloma Crustuliniforme and Wilcoxina mikolae var. mikolae
Mycorrhiza, 2008Co-Authors: J. Aurea Siemens, Janusz J. ZwiazekAbstract:The effects of an E-strain fungus ( Wilcoxina mikolae var. mikolae ) and an ectomycorrhizal fungus ( Hebeloma Crustuliniforme ) on growth and water relations of balsam poplar were examined and compared in the present study. Balsam poplar roots inoculated with W. mikolae var. mikolae (Wm) exhibited structures consistent with ectendomycorrhizal (EEM) associations, including a mantle surrounding the outside of the root and an extensive Hartig net that was located between cortical cells and extended to the vascular cylinder. Roots colonized with H. Crustuliniforme (Hc) developed a mantle layer, indicative of an ectomycorrhizal (ECM) association, around the outer part of the root, but no distinct Hartig net was present. Wm-colonized balsam poplar also showed increased shoot growth, stomatal conductance ( g _s), and root volumes compared with non-inoculated and Hc-inoculated plants. However, Hc-inoculated plants had higher root hydraulic conductivity ( L _pr) compared with non-inoculated plants and Wm-inoculated plants. These results suggest that L _pr was not a growth-limiting factor in balsam poplar and that hyphal penetration of the root cortex in itself may have little influence on root hydraulic properties.
Ivano Brunner - One of the best experts on this subject based on the ideXlab platform.
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Aluminum effects on Picea abies at low solution concentrations
Soil Science Society of America Journal, 2003Co-Authors: Alexander Heim, Ivano Brunner, Emmanuel Frossard, Jörg LusterAbstract:The usual way to evaluate Al toxicity in forest ecosystems is to consider the concentration of Al 3+ in soil solution. The objective of this paper is to show that Al may affect tree seedlings even under conditions of very low bulk-soil solution concentrations of Al. Picea abies (L.) H. Karst. seedlings, with or without ectomycorrhizal inoculation [Hebeloma Crustuliniforme (Bull.: St. Amans) Quel.], were grown in perlite substrate with addition of 0, 0.1, and 0.5 mM Al. The perlite buffered the pH at values > 5 and no soluble Al was detected in the system. However, plant biomass was significantly reduced when 0.5 mM Al was added without fungal inoculation, and Al uptake was 2 to 3 times higher than in the control treatment. Fungal inoculation compensated the growth reduction, but did not reduce Al uptake. These results indicate that spruce seedlings are able to mobilize and take up Al from solid phases.
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extracellular complexation of cd in the hartig net and cytosolic zn sequestration in the fungal mantle of picea abies Hebeloma Crustuliniforme ectomycorrhizas
Plant Cell and Environment, 2000Co-Authors: Beat Frey, Karl Zierold, Ivano BrunnerAbstract:Compartmentation of heavy metals on or within mycorrhizal fungi may serve as a protective function for the roots of forest trees growing in soils containing elevated concentrations of metals such as Cd and Zn. In this paper we present the first quantitative measurements by X-ray microanalysis of heavy metals in high-pressure frozen and cryosectioned ectomycorrhizal fungal hyphae. We used this technique to analyse the main sites of Cd and Zn in fungal cells of mantle and Hartig net hyphae and in cortical root cells of symbiotic Picea abies - Hebeloma Crustuliniforme associations to gain new insights into the mechanisms of detoxification of these two metals in Norway spruce seedlings. The mycorrhizal seedlings were exposed in growth pouches to either 1 mM Cd or 2 mM Zn for 5 weeks. The microanalytical data revealed that two distinct Cd- and Zn-binding mechanisms are involved in cellular compartmentation of Cd and Zn in the mycobiont. Whereas extracellular complexation of Cd occurred predominantly in the Hartig net hyphae, both extracellular complexation and cytosolic sequestration of Zn occurred in the fungal tissue. The vacuoles were presumed not to be a significant pool for Cd and Zn storage. Cadmium was almost exclusively localized in the cell walls of the Hartig net (up to 161 mmol kg -1 DW) compared with significantly lower concentrations in the cell walls of mantle hyphae (22 mmol kg -1 DW) and in the cell walls of cortical cells (15 mmol kg -1 DW). This suggests that the apoplast of the Hartig net is a primary accumulation site for Cd. Zinc accumulated mainly in the cell walls of the mantle hyphae (111 mmol kg -1 DW), the Hartig net hyphae (130 mmol kg -1 DW) and the cortical cells (152 mmol kg -1 DW). In addition, Zn occurred in high concentrations in the cytoplasm of the fungal mantle hyphae (up to 164 mmol kg -1 DW) suggesting that both the cell walls and the cytoplasm of fungal tissue are the main accumulation sites for Zn in P. abies resulting in decreased Zn transfer from the fungus to the root.
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Extracellular complexation of Cd in the Hartig net and cytosolic Zn sequestration in the fungal mantle of Picea abies – Hebeloma Crustuliniforme ectomycorrhizas
Plant Cell and Environment, 2000Co-Authors: Beat Frey, Karl Zierold, Ivano BrunnerAbstract:Compartmentation of heavy metals on or within mycorrhizal fungi may serve as a protective function for the roots of forest trees growing in soils containing elevated concentrations of metals such as Cd and Zn. In this paper we present the first quantitative measurements by X-ray microanalysis of heavy metals in high-pressure frozen and cryosectioned ectomycorrhizal fungal hyphae. We used this technique to analyse the main sites of Cd and Zn in fungal cells of mantle and Hartig net hyphae and in cortical root cells of symbiotic Picea abies - Hebeloma Crustuliniforme associations to gain new insights into the mechanisms of detoxification of these two metals in Norway spruce seedlings. The mycorrhizal seedlings were exposed in growth pouches to either 1 mM Cd or 2 mM Zn for 5 weeks. The microanalytical data revealed that two distinct Cd- and Zn-binding mechanisms are involved in cellular compartmentation of Cd and Zn in the mycobiont. Whereas extracellular complexation of Cd occurred predominantly in the Hartig net hyphae, both extracellular complexation and cytosolic sequestration of Zn occurred in the fungal tissue. The vacuoles were presumed not to be a significant pool for Cd and Zn storage. Cadmium was almost exclusively localized in the cell walls of the Hartig net (up to 161 mmol kg -1 DW) compared with significantly lower concentrations in the cell walls of mantle hyphae (22 mmol kg -1 DW) and in the cell walls of cortical cells (15 mmol kg -1 DW). This suggests that the apoplast of the Hartig net is a primary accumulation site for Cd. Zinc accumulated mainly in the cell walls of the mantle hyphae (111 mmol kg -1 DW), the Hartig net hyphae (130 mmol kg -1 DW) and the cortical cells (152 mmol kg -1 DW). In addition, Zn occurred in high concentrations in the cytoplasm of the fungal mantle hyphae (up to 164 mmol kg -1 DW) suggesting that both the cell walls and the cytoplasm of fungal tissue are the main accumulation sites for Zn in P. abies resulting in decreased Zn transfer from the fungus to the root.
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production of ectomycorrhizal ppicea abies Hebeloma Crustuliniforme seedlings for ecological studies effects of synthesis techniques on the morphology of the symbiosis
Water Air and Soil Pollution, 1993Co-Authors: Ivano BrunnerAbstract:Various in vitro synthesis techniques were applied to produce numerous ectomycorrhizal Picea abies — Hebeloma Crustuliniforme seedlings which could be later used for experiments in the field of environmental research. Included synthesis methods are the Erlenmeyer flask technique, the cuvette technique, and the growth pouch technique. A mantle and a Hartig net were present in all synthesized and naturally grown symbioses. Stable features were the white color of the mantle, its two-layered structure, and the structure of the Hartig net. A few characters such as the thickness of the mantle and the development of the Hartig net formation were variable due to the synthesis method. The techniques suitable for producing ectomycorrhizal seedlings are the Erlenmeyer flask technique using vermiculite and peat moss and the growth pouch technique: the first technique because of sterility and good ectomycorrhizal formation within approximately two months, the second technique because of direct observation of ectomycorrhizal formation within one to two months and complete removing of ectomycorrhizae including extramatrical mycelia.
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Effects of root exudates and humic substances on weathering kinetics
Water Air and Soil Pollution, 1993Co-Authors: Michael Ochs, Ivano Brunner, Werner Stumm, BoŽena ćosovićAbstract:The effect of complex natural organic ligands on the weathering kinetics of aluminum oxide was investigated in laboratory experiments. A peat-derived humic substance and root exudates obtained from ectomycorrhizal (Picea abies — Hebeloma Crustuliniforme) and non-mycorrhizal Norway Spruce trees; and γ-Al2O3 were used as a model system. The experimental weathering rates are in accordance with a surface-controlled dissolution mechanism. The effect of the humic material on dissolution rates appears to depend on the degree of protonation of the humic (macro)molecules: we observed dissolution-enhancement or -inhibition at pH 3 and 4, respectively. Ectomycorrhizal exudates proved to be effective weathering agents at pH 4, as opposed to humic material and non-mycorrhizal exudates. Our results suggest that (i) the role of humic materials in mineral weathering and podzolization is different from what is commonly thought, and (ii) mineral weathering rates in the rhizosphere may be higher than in the bulk soil.
Cristián E. Hernández - One of the best experts on this subject based on the ideXlab platform.
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Comunidad ectomicorrícica en una cronosecuencia de Pinus radiata (Pinophyta: Pinaceae) de la zona de transición climática mediterráneo-templada de Chile central
Revista chilena de historia natural, 2012Co-Authors: Yussi M Palacios, Götz Palfner, Cristián E. HernándezAbstract:En ecosistemas naturales y plantaciones, las coniferas establecen asociaciones mutualistas con una comunidad diversa de hongos micorricicos. El estudio de este tema en Sudamerica es aun incipiente, y no existen antecedentes sobre la dinamica temporal de esta comunidad, y menos de sus potenciales causas, a pesar de su importancia para un pais forestal como Chile. En el presente trabajo se evaluo la dinamica de la comunidad ectomicorricica, identificando y cuantificando los hongos formadores de esta asociacion en raices finas de Pinus radiata en plantaciones de 3, 10 y 20 anos. Los resultados confirman que la comunidad ectomicorricica de P. radiata cambia con la edad de los arboles, la cual difiere mas bien en el patron de dominancia que en la riqueza de especies, separandose un primer grupo de arboles de 3 y 10 anos de un segundo grupo de 20 anos. Un total de once morfotipos de micorrizas fueron diferenciados. Cuatro de ellos, identificados como Hebeloma Crustuliniforme, Inocybe sp., Russula sardonia y Pinirhiza spinulosa, fueron los mas abundantes (77, 29, 78 y 8 % respectivamente), mientras las otras se encontraron colonizando menos de 100 puntas de raiz (< 7 %), mostrando ademas una distribucion en parches. La especie Inocybe sp. fue encontrada exclusivamente en apices radicales de arboles de tres anos, caracterizandose como micobionte de estado temprano. Hebeloma Crustuliniforme, como colonizador de estado multiple, estuvo presente en raicillas de todas las clases de edad, sin embargo fue dominante en arboles de 3 y 10 anos, mientras R! sardonia, como especie de estado tardio, domino en los arboles de 20 anos junto con el morfotipo no identificado Pinirhiza spinulosa que fue registrado por primera vez en Chile. Nuestros resultados sugieren que no es el sitio per se el que genera el cambio de la comunidad ectomicorricica, sino la interaccion del bosque con el entorno.
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Comunidad ectomicorrícica en una cronosecuencia de Pinus radiata (Pinophyta: Pinaceae) de la zona de transición climática mediterráneo-templada de Chile central The ectomycorrhizal community in a chronosequence of Pinus radiata (Pinophyta: Pinaceae)
BMC, 2012Co-Authors: Yussi M Palacios, Götz Palfner, Cristián E. HernándezAbstract:En ecosistemas naturales y plantaciones, las coníferas establecen asociaciones mutualistas con una comunidad diversa de hongos micorrícicos. El estudio de este tema en Sudamérica es aún incipiente, y no existen antecedentes sobre la dinámica temporal de esta comunidad, y menos de sus potenciales causas, a pesar de su importancia para un país forestal como Chile. En el presente trabajo se evaluó la dinámica de la comunidad ectomicorrícica, identificando y cuantificando los hongos formadores de esta asociación en raíces finas de Pinus radiata en plantaciones de 3, 10 y 20 años. Los resultados confirman que la comunidad ectomicorrícica de P. radiata cambia con la edad de los árboles, la cual difiere más bien en el patrón de dominancia que en la riqueza de especies, separándose un primer grupo de árboles de 3 y 10 años de un segundo grupo de 20 años. Un total de once morfotipos de micorrizas fueron diferenciados. Cuatro de ellos, identificados como Hebeloma Crustuliniforme, Inocybe sp., Russula sardonia y Pinirhiza spinulosa, fueron los más abundantes (77, 29, 78 y 8 % respectivamente), mientras las otras se encontraron colonizando menos de 100 puntas de raíz (< 7 %), mostrando además una distribución en parches. La especie Inocybe sp. fue encontrada exclusivamente en ápices radicales de árboles de tres años, caracterizándose como micobionte de estado temprano. Hebeloma Crustuliniforme, como colonizador de estado múltiple, estuvo presente en raicillas de todas las clases de edad, sin embargo fue dominante en árboles de 3 y 10 años, mientras R! sardonia, como especie de estado tardío, dominó en los árboles de 20 años junto con el morfotipo no identificado Pinirhiza spinulosa que fue registrado por primera vez en Chile. Nuestros resultados sugieren que no es el sitio per se el que genera el cambio de la comunidad ectomicorrícica, sino la interacción del bosque con el entorno.In natural forest ecosystems and plantations, most trees live in mutualistic association with mycorrhizal fungi. Studies of this association in South America are still scarce, especially when referring to the causes of temporal dynamics of this symbiotic community, despite its importance in countries with a thriving forestry industry like Chile. This study evaluates the dynamics of the ectomycorrhizal community of Pinus radiata stands of 3, 10 and 20 years of age, identifying and quantifying the most common fungal colonizers of fine roots in each age class. The results confirm that the mycobiont community changes with host tree age but that age classes differ in dominance patterns rather than in species richness, with the three- and ten-year-old tree cohorts forming a group separate from the 20-year-old trees. A total of eleven ectomycorrhizal root morphotypes could be distinguished. Four of them which were identified as Hebeloma Crustuliniforme, Inocybe sp., Russula sardonia and Pinirhiza spinulosa, were the most abundant (77, 29, 78 and 8 % respectively) and were found in more than one root sample whereas the remaining morphotypes accounted for less than 100 (< 7 %) root tips and showed a patchy distribution. Inocybe sp. was only found on root tips of three-year-old trees, characterizing as an early-stage mycobiont. H! Crustuliniforme appeared as a multi-stage colonizer in all three age classes but was clearly dominant on roots of three- and ten-year-old trees, whereas R! sardonia was mainly found on roots of 20-year-old trees, classifying as a late-stage species together with the unidentified morphotype Pinirhiza spinulosa which is reported for the first time from Chile. Our results suggest that the observed changes in the ectomycorrhizal community are not induced by the site per se, but are rather an effect of the interaction between the trees and their environment
Peter Salzer - One of the best experts on this subject based on the ideXlab platform.
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Elicitor‐induced changes of wall‐bound and secreted peroxidase activities in suspension‐cultured spruce (Picea abies) cells are attenuated by auxins
Physiologia Plantarum, 1998Co-Authors: Ruth Mensen, Achim Hager, Peter SalzerAbstract:In ectomycorrhizae auxins are proposed to attenuate elicitor-induced defence reactions in the host plant. To examine this hypothesis we compared the elicitor-induced accumulation of peroxidase isoforms between suspension-cultured spruce (Picea abies [L.] Karst.) cells incubated in media with and without auxins. In spruce cells changes in ionically and covalently wall-bound as well as symplasmic peroxidase (EC 1.11.1.7) activities were observed when elicitors from the following fungal species were applied: (1) Hebeloma Crustuliniforme, an ectomycorrhizal partner of spruce; (2) Suillus variegatus, an ectomycorrhizal fungus incompatible with spruce; (3) Heterobasidion annosum, a spruce pathogen. Activity staining after SDS-PAGE and western blotting showed an accumulation of an ionically wall-bound 38-kDa peroxidase isoform. In addition, two covalently wall-bound isoforms (34 and 53 kDa) that could be released from spruce cell walls by cellulase and pectinase treatment were also induced by elicitors from these fungi. Moreover, in cells cultured without auxins all the elicitors triggered a rapid and transient accumulation of ionically wall-bound peroxidases, which reached a maximum activity 48 h after elicitor application. This early and transient peroxidase accumulation was diminished and delayed in cells cultured in the presence of auxins. In contrast, activity of peroxidases released into the culture medium of spruce cells or into the medium of protoplasts was suppressed by the elicitors of Hebeloma Crustuliniforme. However, this suppression was attenuated by the action of auxins. It is suggested that under natural conditions, in infected spruce roots, the elicitors of the compatible fungus cause both suppression of the peroxidase (which is secreted to the free space of the roots), and induction of wall-bound and symplasmic peroxidases. On the other hand, auxins synthesized by the fungus could weaken these different elicitor-mediated effects.
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Cleavage of chitinous elicitors from the ectomycorrhizal fungus Hebeloma Crustuliniforme by host chitinases prevents induction of K+ and Cl− release, extracellular alkalinization and H2O2 synthesis of Picea abies cells
Planta, 1997Co-Authors: Peter Salzer, Gerhard Hebe, Achim HagerAbstract:Rapid reactions comprising efflux of K+ and Cl−, phosphorylation of a 63-kDa protein (pp63), extracellular alkalinization and synthesis of H2O2 are equally induced in cells of Picea abies (L.) Karst. by chitotetraose, colloidal chitin and cell wall elicitors from the ectomycorrhizal fungus Hebeloma Crustuliniforme (Bull. ex Fries.) Quel. an ectomycorrhizal partner of spruce. Cleavage of fungal cell wall elicitors and of artificial chitin elicitors to monomeric and dimeric fragments by apoplasmic spruce chitinases (36-kDa class I chitinase, pI 8.0, and 28-kDa chitinase, pI 8.7; EC 3.2.1.14) equally prevented induction of these rapid reactions. Also, N-acetylglucosamine oligomers and elicitors from the fungal cell walls showed a similar dependence of their activity on the degree of polymerisation. From these results it is suggested that, during ectomycorrhiza formation, only some of the chitin-derived elicitors reach their receptors at the plant plasma membrane, initiating reactions of the hypersensitive response in the host cells. The remaining fungal elicitors will be degraded to varying extents by wall-localized chitinases of the host root, reducing the defence reactions of the plant and allowing symbiotic interactions of both organisms.
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cleavage of chitinous elicitors from the ectomycorrhizal fungus Hebeloma Crustuliniforme by host chitinases prevents induction of k and cl release extracellular alkalinization and h2o2 synthesis of picea abies cells
Planta, 1997Co-Authors: Peter Salzer, Gerhard Hebe, Achim HagerAbstract:Rapid reactions comprising efflux of K+ and Cl−, phosphorylation of a 63-kDa protein (pp63), extracellular alkalinization and synthesis of H2O2 are equally induced in cells of Picea abies (L.) Karst. by chitotetraose, colloidal chitin and cell wall elicitors from the ectomycorrhizal fungus Hebeloma Crustuliniforme (Bull. ex Fries.) Quel. an ectomycorrhizal partner of spruce. Cleavage of fungal cell wall elicitors and of artificial chitin elicitors to monomeric and dimeric fragments by apoplasmic spruce chitinases (36-kDa class I chitinase, pI 8.0, and 28-kDa chitinase, pI 8.7; EC 3.2.1.14) equally prevented induction of these rapid reactions. Also, N-acetylglucosamine oligomers and elicitors from the fungal cell walls showed a similar dependence of their activity on the degree of polymerisation. From these results it is suggested that, during ectomycorrhiza formation, only some of the chitin-derived elicitors reach their receptors at the plant plasma membrane, initiating reactions of the hypersensitive response in the host cells. The remaining fungal elicitors will be degraded to varying extents by wall-localized chitinases of the host root, reducing the defence reactions of the plant and allowing symbiotic interactions of both organisms.
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Control of Elicitor-Induced Reactions in Spruce Cells by Auxin and by Enzymatic Elicitor Degradation
Eukaryotism and Symbiosis, 1997Co-Authors: Peter Salzer, Gerhard Hebe, Katja Gaschler, R. Mensen, Achim HagerAbstract:Elicitors from the ectomycorrhizal fungi Hebeloma Crustuliniforme (Bull.) Quel., Amanita muscaria (L.) Pers., Suillus variegatus (Sw.: Fr.) O. K. and the spruce pathogenic fungus Heterobasidion annosum (Fr.) Bref. induced an extracellular alkalinization response in suspension-cultured cells of Picea abies (L.) Karst. within 4 to 6 min. In addition, phosphorylation of a 63-kDa protein and dephosphorylation of a 65-kDa protein were induced in spruce cells by 4 min after elicitor application. Both the alkalinization and the protein phosphorylation were inhibited by nanomolar concentrations of the protein kinase inhibitor staurosporine. Furthermore, the elicitors induced the synthesis of chitinase and extracellular s-1,3-glucanase as well as the accumulation of peroxidase in the walls of spruce cells. On the other hand, auxins prevented the induction of peroxidase accumulation in spruce cell walls. This inhibiting effect was found for elicitors from Hebeloma Hebeloma Crustuliniforme, Suillus variegatus and Heterobasidion annosum. Moreover, enzymes which were secreted by the spruce cells decreased the effectiveness of the elicitors from both the ectomycorrhizal and the pathogenic fungus. These findings indicate that no fundamental difference exists in the reactions which are induced in host cells by elicitors from the ectomycorrhizal fungi Hebeloma Crustuliniforme, Amanita muscaria, and Suillus variegatus and the pathogenic fungus Heterobasidion annosum. We assume that the production of auxin by the invading fungus and the inactivation of fungal elicitors by extracellular enzymes of the plant itself could be inductive to root colonization and ectomycorrhiza formation.
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Rapid reactions of spruce cells to elicitors released from the ectomycorrhizal fungus Hebeloma Crustuliniforme, and inactivation of these elicitors by extracellular spruce cell enzymes
Planta, 1996Co-Authors: Peter Salzer, Gerhard Hebe, Andreas Reith, Barbara Zitterell-haid, Harald Stransky, Katja Gaschler, Achim HagerAbstract:Elicitors released from hyphae or cell walls of the ectomycorrhizal fungus Hebeloma Crustuliniforme (Bull. ex Fries.) Quel. induced in suspension-cultured cells of Picea abies (L.) Karst. a set of fast reactions: (i) an immediate efflux of Cl− into the medium, followed by a K+ efflux; (ii) an influx of Ca2+ (measured as accumulation of 45Ca2+ in the cells); (iii) a phosphorylation of a 63-kDa protein and dephosphorylation of a 65-kDa protein (detectable by 4 min after elicitor application); (iv) an alkalinization of the medium, and (v) a transient synthesis of H2O2. The removal of extracellular Ca2+ by EGTA delayed the elicitor-induced alkalinization. A further reduction of this response could be achieved by TMB-8 an inhibitor of Ca2+ release from intracellular stores. Moreover, the inhibition of protein kinase activity by staurosporine prevented the extracellular alkalinization completely. However, the effectiveness of the elicitors in inducing the extracellular alkalinization was strongly impaired by constitutively secreted enzymes of spruce cells which cleaved the elicitors to inactive fragments. It is suggested that in ectomycorrhizae the efficacy of elicitors released from fungal cell walls is controlled by apoplastic enzymes of the host; the plant itself is able to reduce the activity of fungal elicitors on their way through the plant cell wall. But those elicitors which finally reach the plasma membrane of host cells induce reactions that are similar to the early defense reactions in plant-pathogen interactions.