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- Gavito, Mayra, et al.
(författare)
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Allocation of plant carbon to foraging and storage in arbuscular mycorrhizal fungi
- 2003
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Ingår i: FEMS Microbiology Ecology. - 1574-6941. ; 45:2, s. 181-187
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Tidskriftsartikel (refereegranskat)abstract
- Foraging strategies, the cost-benefit associated with the search for new resources, have only begun to be explored in arbuscular mycorrhizal fungi (AMF). We show the use of C-13-labelling, via shoot photosynthesis, of the 16: 1omega5 fatty acid biomarker (the dominant and rather specific fatty acid in AMF storage lipids) to study the immediate patterns of carbon allocation to fungal lipids in response to inorganic and organic nutrient amendments. Signature fatty acid measurements, the incorporation of the label and complementary hyphal length density measurements showed that the extraradical mycelium of AMF proliferated in response to all the amendments provided whereas its development into unamended sand was minor in all treatments. We demonstrate the foraging capacity of AMF, linked to plant carbon, through their hyphal proliferation and accumulation of energy reserves.
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| 3. |
- Gavito, Mayra, et al.
(författare)
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Foraging strategies of the external mycelium of the arbuscular mycorrhizal fungi Glomus intraradices and Scutellospora calospora
- 2008
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Ingår i: Applied Soil Ecology. - : Elsevier BV. - 0929-1393. ; 39:3, s. 282-290
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Tidskriftsartikel (refereegranskat)abstract
- The responsiveness of the external mycelium of Glomus intraradices and Scutellospora calospora was tested in a multiple-choice experimental system in which mycelium encountered patches amended with nitrogen (N) or phosphorus (P), either alone or in combination with a host plant. We hypothesised that only AMF mycelium with sufficient supply of photo-synthate from an actively growing host would respond to the amendments provided. Mycelium was allowed to grow either 11 or 21 weeks before we analysed hyphal proliferation in amended patches introduced in mesh bags that were not reached by roots but by foraging mycelium only. Hyphal length, the AMF signature fatty acid 16:1w5, and root colonisation in new host plant seedlings were used to measure AMF growth and resource allocation in the patches. Mycelium from both fungal strains was able to colonise new host roots and sand in all patches but S. calospora was overall more responsive to the amendments than G. intraradices. G. intraradices grew equally into all patches, including the unamended control, whereas S. calospora produced significantly more hyphal length in the patch containing a host plant than in the rest of the patches. Both strains showed lower hyphal growth at the second harvest and mycelium of G. intraradices lost almost entirely its capacity to develop new mycelium in all choices presented. Lipid measurements showed this fungus did not use storage lipids to exploit the patches. S. calospora mycelium had reduced growth and colonisation ability but still showed some growth in the patches at the second harvest. A reduction in the content of NLFA 16:1w5 from the first to the second harvest suggested that S. calospora mycelium likely used storage lipids to sustain proliferation in the patches. The results indicated that S. calospora was more active and used more resources for foraging than G. intraradices; and that external mycelium foraging was maintained mainly with recently acquired plant carbon (C). This supported in general our hypothesis but showed as well that the two AMF strains had different strategies and resource allocation to forage. The overall low response of both AMF to the choices presented suggested that the responsiveness of mycelium searching freely in the substrate is lower than that observed in experimental systems in which the amendments have been placed in close contact with actively growing mycelium fronts in close vicinity with host roots.
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| 4. |
- Gavito, Mayra, et al.
(författare)
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Temperature constraints on the growth and functioning of root organ cultures with arbuscular mycorrhizal fungi
- 2005
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Ingår i: New Phytologist. - : Wiley. - 1469-8137 .- 0028-646X. ; 168:1, s. 179-188
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Tidskriftsartikel (refereegranskat)abstract
- (.) In this study we investigated the effects of temperature on fungal growth and tested whether the differences in fungal growth were related to the effects of temperature on carbon movement to, or within, the fungus. (.) Growth curves and C uptake-transfer-translocation measurements were obtained for three arbuscular mycorrhizal fungi (AMF) isolates cultured within a 6-30 degrees C temperature range. A series of experiments with a model fungal isolate, Glomus intraradices, was used to examine the effects of temperature on lipid body and 33 P movement, and to investigate the role of acclimation and incubation time. (.) Temperature effects on AMF growth were both direct and indirect because, despite clear independent root and AMF growth responses in some cases, the uptake and translocation of 13 C was also affected within the temperature range tested. Root C uptake and, to a lesser extent, C translocation in the fungus, were reduced by low temperatures (< 18 C). Uptake and translocation of 33 P by fungal hyphae were, by contrast, similar between 10 and 25 C. (.) We conclude that temperature, between 6 and 18 C, reduces AMF growth, and that C movement to the fungus is involved in this response.
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