| 1. |
- Berner, Christoffer, et al.
(författare)
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Long-term effect of apatite on ectomycorrhizal growth and community structure.
- 2012
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Ingår i: Mycorrhiza. - : Springer Science and Business Media LLC. - 1432-1890 .- 0940-6360. ; 22:8, s. 615-621
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Tidskriftsartikel (refereegranskat)abstract
- Ectomycorrhizal (ECM) fungi are efficient at taking up phosphorus (P) from mineral sources, such as apatite, which are not easily available to the host trees. Since ECM fungal species differ in P uptake rates, it can be expected that the composition of the ECM fungal community will change upon exposure to apatite, provided that the P transfer is rewarded by more carbon being transferred to the fungal symbiont. Control and apatite-amended mesh bags were buried in pairs in the humus layer of a P-poor Norway spruce forest. The ECM fungal community that colonized these bags was analyzed by DNA extraction, PCR amplification of the internal transcribed spacer (ITS) region, cloning, and random sequencing. Fungal biomass was estimated by ergosterol analysis. No change in the ECM fungal community structure was seen after 5 years of apatite exposure, although the fungal biomass increased threefold upon apatite amendment. Our results indicate that host trees enhance carbon allocation to ECM fungi colonizing P sources in P-poor forests but the lack of change in the composition of the ECM fungal community suggests that P transfer rates were similar among the species. Alternatively, higher P transfer among certain species was not rewarded with higher carbon transfer from the host.
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| 2. |
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| 3. |
- Hammer, Edith, et al.
(författare)
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Elemental composition of arbuscular mycorrhizal fungi at high salinity.
- 2011
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Ingår i: Mycorrhiza. - : Springer Science and Business Media LLC. - 1432-1890 .- 0940-6360. ; 21, s. 117-129
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Tidskriftsartikel (refereegranskat)abstract
- We investigated the elemental composition of spores and hyphae of arbuscular mycorrhizal fungi (AMF) collected from two saline sites at the desert border in Tunisia, and of Glomus intraradices grown in vitro with or without addition of NaCl to the medium, by proton-induced X-ray emission. We compared the elemental composition of the field AMF to those of the soil and the associated plants. The spores and hyphae from the saline soils showed strongly elevated levels of Ca, Cl, Mg, Fe, Si, and K compared to their growth environment. In contrast, the spores of both the field-derived AMF and the in vitro grown G. intraradices contained lower or not elevated Na levels compared to their growth environment. This resulted in higher K:Na and Ca:Na ratios in spores than in soil, but lower than in the associated plants for the field AMF. The K:Na and Ca:Na ratios of G. intraradices grown in monoxenic cultures were also in the same range as those of the field AMF and did not change even when those ratios in the growth medium were lowered several orders of magnitude by adding NaCl. These results indicate that AMF can selectively take up elements such as K and Ca, which act as osmotic equivalents while they avoid uptake of toxic Na. This could make them important in the alleviation of salinity stress in their plant hosts.
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| 4. |
- Hasselquist, Niles
(författare)
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First report of the ectomycorrhizal status of boletes on the Northern Yucatan Peninsula, Mexico determined using isotopic methods
- 2011
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Ingår i: Mycorrhiza. - : Springer Science and Business Media LLC. - 0940-6360 .- 1432-1890. ; 21, s. 465-471
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Tidskriftsartikel (refereegranskat)abstract
- Despite their prominent role for tree growth, few studies have examined the occurrence of ectomycorrhizal fungi in lowland, seasonally dry tropical forests (SDTF). Although fruiting bodies of boletes have been observed in a dry tropical forest on the Northern Yucatan Peninsula, Mexico, their occurrence is rare and their mycorrhizal status is uncertain. To determine the trophic status (mycorrhizal vs. saprotrophic) of these boletes, fruiting bodies were collected and isotopically compared to known saprotrophic fungi, foliage, and soil from the same site. Mean delta N-15 and delta C-13 values differed significantly between boletes and saprotrophic fungi, with boletes 8.0% enriched and 2.5% depleted in N-15 and C-13, respectively relative to saprotrophic fungi. Foliage was depleted in C-13 relative to both boletes and saprotrophic fungi. Foliar delta N-15 values, on the other hand, were similar to saprotrophic fungi, yet were considerably lower relative to bolete fruiting bodies. Results from this study provide the first isotopic evidence of ectomycorrhizal fungi in lowland SDTF and emphasize the need for further research to better understand the diversity and ecological importance of ectomycorrhizal fungi in these forested ecosystems.
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| 5. |
- Heller, Gregory, et al.
(författare)
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Expression analysis of Clavata1-like and Nodulin21-like genes from Pinus sylvestris during ectomycorrhiza formation
- 2012
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Ingår i: Mycorrhiza. - : Springer Science and Business Media LLC. - 0940-6360 .- 1432-1890. ; 22, s. 271-277
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Tidskriftsartikel (refereegranskat)abstract
- The ecology and physiology of ectomycorrhizal (EcM) symbiosis with conifer trees are well documented. In comparison, however, very little is known about the molecular regulation of these associations. In an earlier study, we identified three EcM-regulated Pinus expressed sequence tags (EST), two of which were identified as homologous to the Medicago truncatula nodulin MtN21. The third EST was a homologue to the receptor-like kinase Clavata1. We have characterized the expression patterns of these genes and of auxin- and mycorrhiza-regulated genes after induction with indole-3-butyric acid in Pinus sylvestris and in a time course experiment during ectomycorrhizal initiation with the co-inoculation of 2,3,5-triiodobenzoic acid, an auxin transport inhibitor. Our results suggest that different P. sylvestris nodulin homologues are associated with diverse processes in the root. The results also suggest a potential role of the Clv1-like gene in lateral root initiation by the ectomycorrhizal fungus.
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| 6. |
- Izumi, Hironari, et al.
(författare)
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Suillus mycelia under elevated atmospheric CO2 support increased bacterial communities and scarce nifH gene activity in contrast to Hebeloma mycelia
- 2013
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Ingår i: Mycorrhiza. - : Springer Science and Business Media LLC. - 0940-6360 .- 1432-1890. ; 23, s. 155-165
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Tidskriftsartikel (refereegranskat)abstract
- Bacterial communities associated with mycorrhizal roots are likely to respond to rising atmospheric CO2 levels in terms of biomass, community composition and activity since they are supported by the carbon (C) flow outside the root tips, especially by exudation of low molecular weight organic compounds. We studied how general bacterial and diazotrophic communities associated with ectomycorrhizal (ECM) fungi respond to different belowground C supply conditions, mediated by elevated atmospheric CO2 concentration under nitrogen (N) limited conditions. Microcosm systems were constructed using forest soil and Scots pine seedlings, which were either pre-inoculated with one of the ECM fungal species Hebeloma velutipes or Suillus variegatus, or non-inoculated. These fungal species differ in C allocation and exudation patterns. Seedlings were maintained under ambient (380 ppm) or elevated (700 ppm) CO2 levels for 6 months. Quantitative polymerase chain reaction (PCR) showed a significant increase in 16S rRNA gene copy numbers for Suillus-inoculated microcosms under elevated CO2 compared to ambient CO2. The copy numbers of the nitrogenase reductase (nifH) gene were under the detection limit in all samples regardless the CO2 treatments. Denaturing gradient gel electrophoresis analysis of PCR-amplified nifH genes revealed simple and consistent communities in all samples throughout the incubation period. A nested reverse transcription PCR approach revealed that expression of nifH genes were detected in some microcosms. Our findings suggest that the effect of mycorrhizal fungi on soil bacteria may vary depending on C supply and fungal species.
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| 7. |
- Kohout, Petr, et al.
(författare)
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Ericaceous dwarf shrubs affect ectomycorrhizal fungal community of the invasive Pinus strobus and native Pinus sylvestris in a pot experiment.
- 2011
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Ingår i: Mycorrhiza. - : Springer Science and Business Media LLC. - 0940-6360 .- 1432-1890. ; 21:5, s. 403-12
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Tidskriftsartikel (refereegranskat)abstract
- This study aimed to elucidate the relationship between ericaceous understorey shrubs and the diversity and abundance of ectomycorrhizal fungi (EcMF) associated with the invasive Pinus strobus and native Pinus sylvestris. Seedlings of both pines were grown in mesocosms and subjected to three treatments simulating different forest microhabitats: (a) grown in isolation and grown with (b) Vaccinium myrtillus or (c) Vaccinium vitis-idaea. Ericaceous plants did not act as a species pool of pine mycobionts and inhibited the ability of the potentially shared species Meliniomyces bicolor to form ectomycorrhizae. Similarly, Ericaceae significantly reduced the formation of Thelephora terrestris ectomycorrhizae in P. sylvestris. EcMF species composition in the mesocosms was strongly affected by both the host species and the presence of an ericaceous neighbour. When grown in isolation, P. strobus root tips were predominantly colonised by Wilcoxina mikolae, whereas those of P. sylvestris were more commonly colonised by Suillus and Rhizopogon spp. Interestingly, these differences were less evident (Suillus + Rhizopogon spp.) or absent (W. mikolae) when the pines were grown with Ericaceae. P. strobus exclusively associated with Rhizopogon salebrosus s.l., suggesting the presence of host specificity at the intrageneric level. Ericaceous plants had a positive effect on colonisation of P. strobus root tips by R. salebrosus s.l. This study demonstrates that the interaction of selective factors such as host species and presence of ericaceous plants may affect the realised niche of the ectomycorrhizal fungi.
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| 8. |
- Menkis, Audrius, et al.
(författare)
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Effects of stump and slash removal on growth and mycorrhization of Picea abies seedlings outplanted on a forest clear-cut
- 2010
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Ingår i: Mycorrhiza. - : Springer Science and Business Media LLC. - 0940-6360 .- 1432-1890. ; 20, s. 505-509
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Tidskriftsartikel (refereegranskat)abstract
- The objectives of this study were to investigate impact of stump and slash removal on growth and mycorrhization of Picea abies seedlings outplanted on a forest clear-cut. Four non-replicated site preparation treatments included: (1) mounding (M), (2) removal of stumps (K), (3) mounding and removal of logging slash (HM) and (4) removal of logging slash and stumps (HK). Results showed that height increment of the seedlings was highest in K and lowest in M after the third growing season, and similar pattern remained after the fourth season. Ectomycorrhizal (ECM) colonisation of seedling roots was highest in M (96.6%) and lowest in K (72.3%), and even in HK (76.0%) and HM (76.3%). Morphotyping and sequencing of internal transcribed spacer of fungal ribosomal DNA revealed a total of 13 ECM species. Among those, Thelephora terrestris and Cenococcum geophilum were the most common, found on 27.4% and 26.3% of roots, respectively. The rest of species colonised 26.6% of roots. Richness of ECM species was highest in M (10 species) and lowest in K (three species). Consequently, stump and slash removal from clear-felled sites had a positive effect on growth of outplanted spruce seedlings, but negative effect on their mycorrhization. This suggests that altered soil conditions due to site disturbance by stump and slash removal might be more favourable for tree growth than more abundant mycorrhization of their root systems in less disturbed soil.
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| 9. |
- Olsson, Ola, et al.
(författare)
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Phosphorus and carbon availability regulate structural composition and complexity of AM fungal mycelium.
- 2014
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Ingår i: Mycorrhiza. - : Springer Science and Business Media LLC. - 1432-1890 .- 0940-6360. ; 24:6, s. 443-451
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Tidskriftsartikel (refereegranskat)abstract
- The regulation of the structural composition and complexity of the mycelium of arbuscular mycorrhizal (AM) fungi is not well understood due to their obligate biotrophic nature. The aim of this study was to investigate the structure of extraradical mycelium at high and low availability of carbon (C) to the roots and phosphorus (P) to the fungus. We used monoxenic cultures of the AM fungus Rhizophagus irregularis (formerly Glomus intraradices) with transformed carrot roots as the host in a cultivation system including a root-free compartment into which the extraradical mycelium could grow. We found that high C availability increased hyphal length and spore production and anastomosis formation within individual mycelia. High P availability increased the formation of branched absorbing structures and reduced spore production and the overall length of runner hyphae. The complexity of the mycelium, as indicated by its fractal dimensions, increased with both high C and P availability. The results indicate that low P availability induces a growth pattern that reflects foraging for both P and C. Low C availability to AM roots could still support the explorative development of the mycelium when P availability was low. These findings help us to better understand the development of AM fungi in ecosystems with high P input and/or when plants are subjected to shading, grazing or any management practice that reduces the photosynthetic ability of the plant.
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| 10. |
- Ryberg, Martin, 1976, et al.
(författare)
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Weak habitat specificity in ectomycorrhizal communities associated with Salix herbacea and Salix polaris in alpine tundra
- 2011
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Ingår i: Mycorrhiza. - : Springer Science and Business Media LLC. ; 21:4, s. 289-96
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Tidskriftsartikel (refereegranskat)abstract
- This study explores mid-alpine ectomycorrhizal communities on Salix herbacea and Salix polaris in plant communities differing in nutrient status and snow conditions. Plant species were identified by tracking roots back to above ground structures while fungal species were identified using molecular methods. The fungi were identified to 34 molecular operational taxonomic units (MOTUs)/species but species accumulation curves indicated that the communities were only partially sampled. The estimated total species richness was 49 (±9 SD) MOTUs/ species. No significant ectomycorrhizal community specificity was found between the two plant species and only weak specificity between different plant communities. Furthermore, no difference in proportion of colonized root tips could be demonstrated between plant communities. However, some fungal taxa showed tendencies to associate with specific environmental conditions. Sebacinaceae, Inocybe egenula, Russula cf.emetica, and a Tomentella sp. were found in meadow communities but not in the heath communities. Sistotrema cf. alboluteum and Tomentella cf. terrestris were only found in the dry and mesic heath communities. Classifications into exploration types showedthat the contact type is more abundant in the dry heath community than the other communities. Cenococcum geophilum was the most common species but Cortinarius spp., Russula spp., Tomentella spp., and Lactarius spp. were also common. This study confirms that alpine communities are rich in ectomycorrhizal fungi including species from a wide variety of fungal lineages and also show that many dominant species have wide ecological amplitude.
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