| 1. |
- Ahonen-Jonnarth, Ulla, et al.
(author)
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Organic acids produced by mycorrhizal Pinus sylvestris exposed to elevated aluminium and heavy metals concentrations
- 2000
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In: New Phytologist. - : Wiley. - 0028-646X .- 1469-8137. ; 146:3, s. 557-567
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Journal article (peer-reviewed)abstract
- A cultivation method was developed to enable exposure of ectomycorrhizal plants with intact extramatrical mycelium to solutions containing different concentrations of aluminium or heavy metals. Pinus sylvestris seedlings colonized by Suillus variegatus (two isolates), Rhizopogon roseolus or Paxillus involutus (two isolates) were used. Seedlings were transferred to Petri dishes containing glass beads and exposed to elevated concentrations of Al, Cd, Cu, or Ni in two ways: immediately following transfer; and after allowing mycorrhizal seedlings to develop an extraradical mycelium that colonized the interface between the upper surface of the beads and the metal-containing solution. Production of organic acids in mycorrhizal and non-mycorrhizal systems was measured by withdrawing samples from the solution and analyzing by HPLC. In most experiments, levels of oxalic acid were significantly higher in mycorrhizal treatments than in non-mycorrhizal controls. The measured levels of organic acids were variable, but the results obtained suggest that production of oxalic acid is stimulated by exposure to elevated Al in mycorrhizal seedlings colonized by S. variegatus and R. roseolus. Elevated Al concentrations also increased oxalic acid production by non-mycorrhizal seedlings significantly in two of four Al experiments performed, but the measured concentrations were significantly lower than in corresponding mycorrhizal treatments in both cases. Malonic acid was found in the culture solution of non-mycorrhizal had P. involutus-colonized seedlings, but only trace amounts were found in S. variegatus or R. roseolus-infected seedlings. Citric, shikimic, lactic, acetic, propionic, fumaric, formic, iso-butyric and butyric acid were found in variable concentrations. Production of oxalic acid by seedlings ColoniZed by S. variegatus BL or P. involutus was not stimulated by exposure to 0.44 μM Cd or 17 μM Ni. Exposure to 0.157 mM CU in two separate experiments using P. involutus 87.017 and two strains of S. variegatus (BL and 159) appeared to stimulate production of oxalic acid irrespective of mycorrhizal status or species.
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| 2. |
- Arnebrant, Kristina, et al.
(author)
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Nitrogen translocation between Alnus glutinosa (L.) Gaertn. seedlings inoculated with Frankia sp and Pinus contorta Doug ex Loud seedlings connected by a common ectomycorrhizal mycelium
- 1993
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In: New Phytologist. - : Wiley. - 1469-8137 .- 0028-646X. ; 124:2, s. 231-242
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Journal article (peer-reviewed)abstract
- Uptake and translocation of nitrogen was studied in laboratory microcosms consisting of Alnus glutinosa (L.) Gaertn., Frankia sp., Paxillus involutus (Fr.) Fr. and Pinus contorta Dougl. ex Loud. P. involutus was shown to form a fully functional ectomycorrhizal association with alder as well as pine, and the seedlings thus became interconnected by a common mycelium. When microcosms were exposed to N-15(2) gas, interplant translocation of N-15 was observed in two out of three experiments. N-15(2) was fixed by Frankia and translocated to all other parts of the system. In the two experiments in which interplant translocation occurred, between 5 and 15 % of the N-15 recovered was found in the pine seedlings. Within seven days, fixed N2 was incorporated into amino acids in the Frankia nodules, translocated to both the A. glutinosa and P. contorta seedlings and incorporated into macromolecules. In alder seedlings, citrulline and ornithine were the free amino acids that had both the highest N-15 enrichment levels and concentrations. In pine, glutamine and citrulline had the highest N-15 concentrations, and glutamine had the highest level of N-15 enrichment. N-15 enrichment levels were greatest in the nodules, at between 5.5 and 29 % in the different amino acids and 12 % in the macromolecular fraction. Enrichment levels decreased with increasing distance from the nodules. The uptake and translocation of N-15 applied as (NH4Cl)-N-15 to the mycelium was also studied. N-15 was incorporated into amino acids in the mycelium and translocated further in this form. Generally, free amino acids had high N-15 enrichment levels in the mycelium, decreasing along the translocation pathway. Citrulline and glutamine were the amino acids with highest N-15 concentrations in all parts of the system. N-15 was also found in the macromolecular fraction.
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| 3. |
- Duddridge, J.A., et al.
(author)
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The structure and function of the vegetative mycelium of ectomycorrhizal plants .3. Ultrastructural and autoradiographic analysis of inter-plant carbon distribution through intact mycelial systems
- 1988
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In: New Phytologist. - 1469-8137. ; 108:2, s. 183-188
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Journal article (peer-reviewed)abstract
- Plants of Pinus sylvestris L. were grown in mycorrhizal association with Suillus bovinus (Fr.) O. Kuntze in observation chambers until an interconnecting mycelial network had developed between the seedlings. The shoot of an individual seedling was then sealed in a perspex cuvette and exposed to 14CO2. After incubation for 48 h, the 'donor' shoot was removed and components of the mycelial network and mycorrhizal roots of connected and unconnected 'receiver' seedlings were harvested, fixed, embedded and sectioned prior to being autoradiographed and examined by transmission electron microscopy. The patterns of distribution of 14C-labelled material within the mycelial strands, the sheath and root tissues was examined. The results are discussed in relation to carbon metabolism of the fungus and of the interconnected host plant.
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| 4. |
- Ek, H., et al.
(author)
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Determination of N-15-labeled ammonium and total nitrogen in plant and fungal systems using mass-spectrometry
- 1990
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In: Journal of Microbiological Methods. - 1872-8359. ; 11:3-4, s. 169-176
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Journal article (peer-reviewed)abstract
- A selected ion-monitoring method to measure 15N-labelled ammonia in biological samples was improved to simplify sample handling, to obviate interference from ammonia due to the decomposition of glutamine and to allow the determination of total N. Ammonia is derivatized with pentafluorobenzoylchloride to yield pentafluorobenzamide which is analysed by gas chromatography/mass spectrometry after clean-up using disposable silicic acid columns. The sensitivity achieved when operating in the negative ion-chemical ionization mode was somewhat higher than when using electron-impact ionization. Use of methyl amine as an internal standard improved the accuracy and precision of the measurements. The method was applied to samples taken from an intact ectomycorrhizal system fed with ISN-labelled ammonium and used to determine patterns of N assimilation into ammonium, free amino acids and macromolecular compounds.
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| 5. |
- Finlay, R.D., et al.
(author)
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Mycelial uptake, translocation and assimilation of N-15-labeled nitrogen by ectomycorrhizal Pinus sylvestris plants
- 1990
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In: Agriculture, Ecosystems & Environment. - 1873-2305. ; 28:1-4, s. 133-137
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Journal article (peer-reviewed)abstract
- Mycolial uptake, translocation and assimilation of 15N-labelled ammonium was followed in Pinus sylvestris plants infected with the ectomycorrhizal fungus. Paxillus involutus. The distribution of labelled compounds within the systems was examined using gas chromatography / mass spectrometry. Labelled nitrogen was incorporated into a range of free amino acids in the fungal mycelium, the principal sinks being alanine and glutamatelglutamine. Levels of 15 N enrichment declined throughout the transport pathway from 30-45% in the mycelium a~d mycorrhlzal root lips to 3-11% in the plant shoots. A significant proportion of the total assimilated nitrogen (27%) was incorporated into proteinaceous material and the proportion of label present in this fraction increased from 27% in the mycelium to 32% and 58% in the plant roots and needles respectively. The protein-incorporated amino acids showed a wider spectrum of labelling with significant amounts of 15N incorporated into valine, isoleucine, phenylalanine and lysine.
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| 6. |
- Finlay, R.D., et al.
(author)
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Mycelial uptake, translocation and assimilation of nitrogen from N-15-labelled ammonium by Pinus sylvestris plants infected with 4 different ectomycorrhizal fungi
- 1988
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In: New Phytologist. - 1469-8137. ; 110:1, s. 59-66
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Journal article (peer-reviewed)abstract
- The uptake and assimilation of 15N-labelled ammonium was followed in Pinus sylvestris L. plants infected with four different ectomycorrhizal fungi, Rhizopogon roseolus Fr. Suillus bovinus (Fr.) O. Kuntze, Pisolithus tinctorius (Fr.) Fr. and Paxillus involutus (Mich. ex Pers.) Cohen & Couch. Plants were grown in flat perspex observation chambers or in Petri dishes containing non-sterile peat; in each case the fungal mycelium growing from a host plant was allowed to cross a barrier and to colonize an area of peat from which roots had been excluded. Labelled ammonium was fed to the mycelium, and the shoot, root and mycelial tissues analysed for total and 15N-labelled free amino acid contents after a feeding period of 72 h. High proportions of 15N-labelled glutamate/glutamine, aspartate/asparagine, and alanine were found in the fungal mycelia of all species except Pax. involutus where labelled aspartate/asparagine was not found. Lower proportions of labelled serine, threonine, tyrosine, lysine, ornithine and arginine were also found in the mycelium. The degree of 15N enrichment declined throughout the transport pathway but between 5 and 50% of the amino acids were 15N-labelled in the plant shoots. In total, at least 2-3% of the nitrogen supplied was assimilated as labelled amino acid during the 3 day feeding period, the largest amounts of labelling occurred in glutamic acid/glutamine and aspartic acid/asparagine.
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| 7. |
- Finlay, R.D., et al.
(author)
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Uptake, translocation and assimilation of nitrogen from 15N-labeled ammonium and nitrate sources by intact ectomycorrhizal systems of Fagus sylvatica infected with Paxillus involutus
- 1989
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In: New Phytologist. - 1469-8137. ; 113:1, s. 47-55
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Journal article (peer-reviewed)abstract
- The uptake and assimilation of nitrogen from 15N-labelled ammonium and nitrate sources was followed in intact ectomycorrhizal systems containing Fagus sylvatica L. plants infected with the fungus Paxillus involutus (Mich. ex Pers.) Cohen & Couch. Plants were grown in flat perspex observation chambers containing non-sterile peat; the fungal mycelium growing from a host plant was allowed to cross a barrier and to colonize an area of peat from which roots had been excluded. Labelled ammonium chloride or sodium nitrate was fed to the mycelium, and the shoot, root and mycelial tissues analysed for total and 15N-labelled amino acid contents after a feeding period of 72 h. Both free and protein-incorporated amino acids were analysed. Labelled nitrogen was incorporated into a range of free amino acids, the principal sinks for assimilation being alanine, aspartate/asparagine and glutamate/glutamine. The spectrum of labelling in protein-incorporated amino acids was wider with significant incorporation into the above compounds but additional assimilation of nitrogen as glycine, valine, serine, leucine, isoleucine and arginine. In total 78% of the nitrogen assimilated was incorporated into proteinaceous material. Label was incorporated from both nitrogen sources but the levels of enrichment in most free and protein-bound amino acids were usually higher in systems supplied with ammonium than in those supplied with nitrate. The mean amount of nitrogen assimilated from nitrate was only 62% of that assimilated from ammonium.
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| 8. |
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| 9. |
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| 10. |
- Mahmood, Shahid, et al.
(author)
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Ectomycorrhizal colonisation of roots and ash granules in a spruce forest treated with granulated wood ash
- 2002
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In: Forest Ecology and Management. - 1872-7042. ; 160:1-3, s. 65-74
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Journal article (peer-reviewed)abstract
- Granulated wood ash has been proposed as a slow release fertiliser suitable for forest soils. In this study ectomycorrhizal colonisation of roots and ash granules was studied in a 40-year-old spruce forest treated with 0, 3 or 6 t ha(-1) granulated wood ash. We used PCR-RFLP methods for ITS-typing and identification of ectomycorrhizal fungi. In total 20 different ITS-types were recognised on roots in the organic soil horizon. Five of these were identified to species and two to genus. Six species, Tylospora fibrillosa Donk, Cortinarius sp. 3, Piloderma sp. 1, and three unidentified ITS-types (Ve-95-1, To-95-3 and Ve-95-9) each occurred on over 5% of the total root tips analysed. Together these comprised 557c of the ectomycorrhizal community on the screened roots. Ash granules collected from the fertilised plots were normally colonised by fungal mycelia. PCR-RFLP analysis of these mycelia revealed the presence of four ITS-types. Three of these (Piloderma sp. 1, Ha-96-3 and Tor-97-1) were also present on the mycorrhizal roots. Piloderma sp. I was the most abundant species colonising roots. A possible role of ectomycorrhizal mycelia in the direct mobilisation of nutrients from ash granules is discussed. (C) 2002 Elsevier Science B.V. All rights reserved.
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