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Wang Y, Chen H, Shao M, Zhu T, Li S, Olsson PA, Hammer EC. Arbuscular mycorrhizal fungi trigger danger-associated peptide signaling and inhibit carbon-phosphorus exchange with nonhost plants. Plant Cell Environ 2023. [PMID: 37151160 DOI: 10.1111/pce.14600] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Revised: 04/14/2023] [Accepted: 04/23/2023] [Indexed: 05/09/2023]
Abstract
In soil, arbuscular mycorrhizal fungi (AMF) meet the roots of both host and presumed nonhost plants, but the interactional mechanisms of AMF with and functional relevance for nonhost plants is little known. Here we show AMF can colonize an individually grown nonhost plant, Arabidopsis thaliana, and suppress the growth of Arabidopsis and two nonhost Brassica crops. This inhibitory effect increased with increasing AMF inoculum density, and was independent of AMF species or nutrient availability. 13 C isotope labeling and physiological analyses revealed no significant carbon-phosphorus exchange between Arabidopsis and AMF, indicating a lack of nutritional function in this interaction. AMF colonization activated the danger-associated peptide Pep-PEPR signaling pathway, and caused clear defense responses in Arabidopsis. The impairment of Pep-PEPR signaling in nonhost plants greatly compromised AMF-triggered defensive responses and photosynthesis suppression, leading to higher colonization rates and reduced growth suppression upon AMF inoculation. Pretreatment with Pep peptide decreased AMF colonization, and largely substituted for AMF-induced growth suppression in nonhosts, confirming that the Pep-PEPR pathway is a key participant in resistance to AMF colonization and in mediating growth suppression of nonhost plants. This work greatly increases our knowledge about the functional relevance of AMF and their mechanisms of interactions with nonhost plants.
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Affiliation(s)
- Yutao Wang
- Key Laboratory of Ecology and Environmental Science in Guangdong Higher Education & Guangdong Provincial Key Laboratory of Biotechnology for Plant Development, School of Life Sciences, South China Normal University, Guangzhou, China
| | - Hanwen Chen
- Key Laboratory of Ecology and Environmental Science in Guangdong Higher Education & Guangdong Provincial Key Laboratory of Biotechnology for Plant Development, School of Life Sciences, South China Normal University, Guangzhou, China
| | - Meishuang Shao
- Key Laboratory of Ecology and Environmental Science in Guangdong Higher Education & Guangdong Provincial Key Laboratory of Biotechnology for Plant Development, School of Life Sciences, South China Normal University, Guangzhou, China
| | - Ting Zhu
- Key Laboratory of Ecology and Environmental Science in Guangdong Higher Education & Guangdong Provincial Key Laboratory of Biotechnology for Plant Development, School of Life Sciences, South China Normal University, Guangzhou, China
| | - Shaoshan Li
- Key Laboratory of Ecology and Environmental Science in Guangdong Higher Education & Guangdong Provincial Key Laboratory of Biotechnology for Plant Development, School of Life Sciences, South China Normal University, Guangzhou, China
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2
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Wittwer RA, Bender SF, Hartman K, Hydbom S, Lima RAA, Loaiza V, Nemecek T, Oehl F, Olsson PA, Petchey O, Prechsl UE, Schlaeppi K, Scholten T, Seitz S, Six J, van der Heijden MGA. Organic and conservation agriculture promote ecosystem multifunctionality. Sci Adv 2021; 7:eabg6995. [PMID: 34417179 PMCID: PMC8378818 DOI: 10.1126/sciadv.abg6995] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Accepted: 06/29/2021] [Indexed: 05/22/2023]
Abstract
Ecosystems provide multiple services to humans. However, agricultural systems are usually evaluated on their productivity and economic performance, and a systematic and quantitative assessment of the multifunctionality of agroecosystems including environmental services is missing. Using a long-term farming system experiment, we evaluated and compared the agronomic, economic, and ecological performance of the most widespread arable cropping systems in Europe: organic, conservation, and conventional agriculture. We analyzed 43 agroecosystem properties and determined overall agroecosystem multifunctionality. We show that organic and conservation agriculture promoted ecosystem multifunctionality, especially by enhancing regulating and supporting services, including biodiversity preservation, soil and water quality, and climate mitigation. In contrast, conventional cropping showed reduced multifunctionality but delivered highest yield. Organic production resulted in higher economic performance, thanks to higher product prices and additional support payments. Our results demonstrate that different cropping systems provide opposing services, enforcing the productivity-environmental protection dilemma for agroecosystem functioning.
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Affiliation(s)
- Raphaël A Wittwer
- Agroscope, Research Division Agroecology and Environment, Plant-Soil-Interactions, Reckenholzstrasse 191, 8046 Zürich, Switzerland
- Department of Plant and Microbial Biology, University of Zurich, Zollikersrasse 107, 8008 Zürich, Switzerland
| | - S Franz Bender
- Agroscope, Research Division Agroecology and Environment, Plant-Soil-Interactions, Reckenholzstrasse 191, 8046 Zürich, Switzerland
- Department of Plant and Microbial Biology, University of Zurich, Zollikersrasse 107, 8008 Zürich, Switzerland
| | - Kyle Hartman
- Agroscope, Research Division Agroecology and Environment, Plant-Soil-Interactions, Reckenholzstrasse 191, 8046 Zürich, Switzerland
| | - Sofia Hydbom
- Department of Biology, Lund University, Ecology Building, SE-223 62 Lund, Sweden
| | - Ruy A A Lima
- Agroscope, Research Division Agroecology and Environment, Plant-Soil-Interactions, Reckenholzstrasse 191, 8046 Zürich, Switzerland
| | - Viviana Loaiza
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, 8057 Zürich, Switzerland
| | - Thomas Nemecek
- Agroscope, Research Division Competitiveness and System Evaluation, Life Cycle Assessment, Reckenholzstrasse 191, 8046 Zürich, Switzerland
| | - Fritz Oehl
- Agroscope, Competence Division for Plants and Plant Products, Ecotoxicology, Müller-Thurgau-Strasse 29, 8820 Wädenswil, Switzerland
| | - Pål Axel Olsson
- Department of Biology, Lund University, Ecology Building, SE-223 62 Lund, Sweden
| | - Owen Petchey
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, 8057 Zürich, Switzerland
| | | | - Klaus Schlaeppi
- Department of Environmental Sciences, University of Basel, Bernoullistrasse 32, 4056 Basel, Switzerland
- University of Bern, Institute of Plant Sciences, Altenbergrain 21, 3013 Bern, Switzerland
| | - Thomas Scholten
- Soil Science and Geomorphology, Institute of Geography, University of Tübingen, Rümelinstrasse 19-23, 72070 Tübingen, Germany
| | - Steffen Seitz
- Soil Science and Geomorphology, Institute of Geography, University of Tübingen, Rümelinstrasse 19-23, 72070 Tübingen, Germany
| | - Johan Six
- Department of Environmental Systems Science, ETH-Zürich, Universitätstrasse 2, 8092 Zürich, Switzerland
| | - Marcel G A van der Heijden
- Agroscope, Research Division Agroecology and Environment, Plant-Soil-Interactions, Reckenholzstrasse 191, 8046 Zürich, Switzerland.
- Department of Plant and Microbial Biology, University of Zurich, Zollikersrasse 107, 8008 Zürich, Switzerland
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3
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Ven A, Verlinden MS, Fransen E, Olsson PA, Verbruggen E, Wallander H, Vicca S. Phosphorus addition increased carbon partitioning to autotrophic respiration but not to biomass production in an experiment with Zea mays. Plant Cell Environ 2020; 43:2054-2065. [PMID: 32400909 DOI: 10.1111/pce.13785] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2019] [Revised: 03/19/2020] [Accepted: 05/05/2020] [Indexed: 05/29/2023]
Abstract
Plant carbon (C) partitioning-the relative use of photosynthates for biomass production, respiration, and other plant functions-is a key but poorly understood ecosystem process. In an experiment with Zea mays, with or without arbuscular mycorrhizal fungi (AMF), we investigated the effect of phosphorus (P) fertilization and AMF on plant C partitioning. Based on earlier studies, we expected C partitioning to biomass production (i.e., biomass production efficiency; BPE) to increase with increasing P addition due to reduced C partitioning to AMF. However, although plant growth was clearly stimulated by P addition, BPE did not increase. Instead, C partitioning to autotrophic respiration increased. These results contrasted with our expectations and with a previous experiment in the same set-up where P addition increased BPE while no effect on autotropic respiration was found. The comparison of both experiments suggests a key role for AMF in explaining these contrasts. Whereas in the previous experiment substantial C partitioning to AMF reduced BPE under low P, in the current experiment, C partitioning to AMF was too low to directly influence BPE. Our results illustrate the complex influence of nutrient availability and mycorrhizal symbiosis on plant C partitioning.
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Affiliation(s)
- Arne Ven
- Research Centre of Excellence Plants and Ecosystems, Ecology in a Time of Change, University of Antwerp, Wilrijk, Belgium
| | - Melanie S Verlinden
- Research Centre of Excellence Plants and Ecosystems, Ecology in a Time of Change, University of Antwerp, Wilrijk, Belgium
| | - Erik Fransen
- StatUa Center for Statistics, University of Antwerp, Antwerp, Belgium
| | - Pål Axel Olsson
- Department of Biology, Ecology Building, Lund University, Lund, Sweden
| | - Erik Verbruggen
- Research Centre of Excellence Plants and Ecosystems, Ecology in a Time of Change, University of Antwerp, Wilrijk, Belgium
| | - Håkan Wallander
- Department of Biology, Ecology Building, Lund University, Lund, Sweden
| | - Sara Vicca
- Research Centre of Excellence Plants and Ecosystems, Ecology in a Time of Change, University of Antwerp, Wilrijk, Belgium
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4
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Heidarianpour MB, Aliasgharzad N, Olsson PA. Positive effects of co-inoculation with Rhizophagus irregularis and Serendipita indica on tomato growth under saline conditions, and their individual colonization estimated by signature lipids. Mycorrhiza 2020; 30:455-466. [PMID: 32472206 DOI: 10.1007/s00572-020-00962-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Accepted: 04/21/2020] [Indexed: 06/11/2023]
Abstract
Tomato roots can be colonized by both mycorrhizal fungi and the endophytic fungus Serendipita indica. This study was aimed at assessment of the impact of single or dual inoculation with R. irregularis and S. indica on tomato growth under saline conditions. We used signature compounds to estimate the abundance of each of these two fungi (fatty acid 16:1ω5 for R. irregularis and ergosterol for S. indica) in roots. A randomized block design was applied with four types of inoculation (no fungus, R. irregularis, S. indica or S. indica + R. irregularis) at different levels of salinity (1.2, 5, and 10 dS/m) with four replications per treatment. The plant dry weight was slightly higher in R. irregularis- than S. indica-inoculated plants, and the highest plant biomass was achieved with dual inoculation. R. irregularis increased the content of the neutral lipid fatty acid 16:1ω5 from 97 to 5300 nmol/g and phospholipid fatty acid 16:1ω5 from 8 to 141 nmol/g in roots (at a salinity level of 1.2 dS m-1), but the increases were lower at higher levels of salinity. Moreover, both these arbuscular mycorrhizal fungal markers were slightly decreased in the presence of S. indica. Root ergosterol increased from 7 to 114 μg g-1 with S. indica inoculation. With increasing salinity, the concentration of ergosterol in roots decreased. Inoculation with R. irregularis caused a decrease in root ergosterol. Increasing salinity resulted in an increase of Cl and Na in tomato shoots, but the increase was significantly lower in single- or dual-inoculated plants in contrast to the control plants.
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Affiliation(s)
| | - Nasser Aliasgharzad
- Department of Soil Science, Faculty of Agriculture, University of Tabriz, Tabriz, Iran.
| | - Pål Axel Olsson
- Biodiversity, Biology Department, Lund University, Lund, Sweden
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5
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Vahter T, Bueno CG, Davison J, Herodes K, Hiiesalu I, Kasari‐Toussaint L, Oja J, Olsson PA, Sepp S, Zobel M, Vasar M, Öpik M. Co‐introduction of native mycorrhizal fungi and plant seeds accelerates restoration of post‐mining landscapes. J Appl Ecol 2020. [DOI: 10.1111/1365-2664.13663] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Tanel Vahter
- Institute of Ecology and Earth Sciences University of Tartu Tartu Estonia
| | | | - John Davison
- Institute of Ecology and Earth Sciences University of Tartu Tartu Estonia
| | - Koit Herodes
- Institute of Chemistry University of Tartu Tartu Estonia
| | - Inga Hiiesalu
- Institute of Ecology and Earth Sciences University of Tartu Tartu Estonia
| | | | - Jane Oja
- Institute of Ecology and Earth Sciences University of Tartu Tartu Estonia
| | - Pål Axel Olsson
- Biodiversity Department of Biology Lund University Lund Sweden
| | - Siim‐Kaarel Sepp
- Institute of Ecology and Earth Sciences University of Tartu Tartu Estonia
| | - Martin Zobel
- Zoology Department College of Science King Saud University Riyadh Saudi Arabia
- Department of Botany University of Tartu Tartu Estonia
| | - Martti Vasar
- Institute of Ecology and Earth Sciences University of Tartu Tartu Estonia
| | - Maarja Öpik
- Institute of Ecology and Earth Sciences University of Tartu Tartu Estonia
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6
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Sheldrake M, Rosenstock NP, Mangan S, Revillini D, Sayer EJ, Olsson PA, Verbruggen E, Tanner EVJ, Turner BL, Wright SJ. Responses of arbuscular mycorrhizal fungi to long-term inorganic and organic nutrient addition in a lowland tropical forest. ISME J 2018; 12:2433-2445. [PMID: 29899509 PMCID: PMC6155082 DOI: 10.1038/s41396-018-0189-7] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2017] [Revised: 03/13/2018] [Accepted: 03/18/2018] [Indexed: 11/09/2022]
Abstract
Improved understanding of the nutritional ecology of arbuscular mycorrhizal (AM) fungi is important in understanding how tropical forests maintain high productivity on low-fertility soils. Relatively little is known about how AM fungi will respond to changes in nutrient inputs in tropical forests, which hampers our ability to assess how forest productivity will be influenced by anthropogenic change. Here we assessed the influence of long-term inorganic and organic nutrient additions and nutrient depletion on AM fungi, using two adjacent experiments in a lowland tropical forest in Panama. We characterised AM fungal communities in soil and roots using 454-pyrosequencing, and quantified AM fungal abundance using microscopy and a lipid biomarker. Phosphorus and nitrogen addition reduced the abundance of AM fungi to a similar extent, but affected community composition in different ways. Nutrient depletion (removal of leaf litter) had a pronounced effect on AM fungal community composition, affecting nearly as many OTUs as phosphorus addition. The addition of nutrients in organic form (leaf litter) had little effect on any AM fungal parameter. Soil AM fungal communities responded more strongly to changes in nutrient availability than communities in roots. This suggests that the 'dual niches' of AM fungi in soil versus roots are structured to different degrees by abiotic environmental filters, and biotic filters imposed by the plant host. Our findings indicate that AM fungal communities are fine-tuned to nutrient regimes, and support future studies aiming to link AM fungal community dynamics with ecosystem function.
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Affiliation(s)
- Merlin Sheldrake
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge, CB2 3EA, UK.
- Smithsonian Tropical Research Institute, Apartado 0843-03092, Balboa, Ancón, Republic of Panama.
| | | | - Scott Mangan
- Smithsonian Tropical Research Institute, Apartado 0843-03092, Balboa, Ancón, Republic of Panama
- Department of Biology, Washington University in St. Louis, St. Louis, MO, 63130, USA
| | - Daniel Revillini
- Department of Biological Sciences, Northern Arizona University, PO BOX 5640, Flagstaff, AZ, 86011, USA
| | - Emma J Sayer
- Smithsonian Tropical Research Institute, Apartado 0843-03092, Balboa, Ancón, Republic of Panama
- Lancaster Environment Centre, Lancaster University, Lancaster, LA1 4YQ, UK
| | | | - Erik Verbruggen
- Research Group Plants and Ecosystems (PLECO), Department of Biology, University of Antwerp, Wilrijk, Belgium
| | - Edmund V J Tanner
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge, CB2 3EA, UK
| | - Benjamin L Turner
- Smithsonian Tropical Research Institute, Apartado 0843-03092, Balboa, Ancón, Republic of Panama
| | - S Joseph Wright
- Smithsonian Tropical Research Institute, Apartado 0843-03092, Balboa, Ancón, Republic of Panama
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7
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Birgander J, Olsson PA, Rousk J. The responses of microbial temperature relationships to seasonal change and winter warming in a temperate grassland. Glob Chang Biol 2018; 24:3357-3367. [PMID: 29345091 DOI: 10.1111/gcb.14060] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Revised: 12/11/2017] [Accepted: 01/09/2018] [Indexed: 05/26/2023]
Abstract
Microorganisms dominate the decomposition of organic matter and their activities are strongly influenced by temperature. As the carbon (C) flux from soil to the atmosphere due to microbial activity is substantial, understanding temperature relationships of microbial processes is critical. It has been shown that microbial temperature relationships in soil correlate with the climate, and microorganisms in field experiments become more warm-tolerant in response to chronic warming. It is also known that microbial temperature relationships reflect the seasons in aquatic ecosystems, but to date this has not been investigated in soil. Although climate change predictions suggest that temperatures will be mostly affected during winter in temperate ecosystems, no assessments exist of the responses of microbial temperature relationships to winter warming. We investigated the responses of the temperature relationships of bacterial growth, fungal growth, and respiration in a temperate grassland to seasonal change, and to 2 years' winter warming. The warming treatments increased winter soil temperatures by 5-6°C, corresponding to 3°C warming of the mean annual temperature. Microbial temperature relationships and temperature sensitivities (Q10 ) could be accurately established, but did not respond to winter warming or to seasonal temperature change, despite significant shifts in the microbial community structure. The lack of response to winter warming that we demonstrate, and the strong response to chronic warming treatments previously shown, together suggest that it is the peak annual soil temperature that influences the microbial temperature relationships, and that temperatures during colder seasons will have little impact. Thus, mean annual temperatures are poor predictors for microbial temperature relationships. Instead, the intensity of summer heat-spells in temperate systems is likely to shape the microbial temperature relationships that govern the soil-atmosphere C exchange.
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Affiliation(s)
| | - Pål Axel Olsson
- Department of Biology, Biodiversity, Lund University, Lund, Sweden
| | - Johannes Rousk
- Department of Biology, MEMEG - Microbial Ecology, Lund University, Lund, Sweden
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8
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Tyler T, Herbertsson L, Olsson PA, Fröberg L, Olsson KA, Svensson Å, Olsson O. Climate warming and land-use changes drive broad-scale floristic changes in Southern Sweden. Glob Chang Biol 2018; 24:2607-2621. [PMID: 29282822 DOI: 10.1111/gcb.14031] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Revised: 12/15/2017] [Accepted: 12/18/2017] [Indexed: 06/07/2023]
Abstract
Land-use changes, pollution and climate warming during the 20th century have caused changes in biodiversity across the world. However, in many cases, the environmental drivers are poorly understood. To identify and rank the drivers currently causing broad-scale floristic changes in N Europe, we analysed data from two vascular plant surveys of 200 randomly selected 2.5 × 2.5 km grid-squares in Scania, southernmost Sweden, conducted 1989-2006 and 2008-2015, respectively, and related the change in frequency (performance) of the species to a wide range of species-specific plant traits. We chose traits representing all plausible drivers of recent floristic changes: climatic change (northern distribution limit, flowering time), land-use change (light requirement, response to grazing/mowing, response to soil disturbance), drainage (water requirement), acidification (pH optimum), nitrogen deposition and eutrophication (N requirement, N fixation ability, carnivory, parasitism, mycorrhizal associations), pollinator decline (mode of reproduction) and changes in CO2 levels (photosynthetic pathway). Our results suggest that climate warming and changes in land-use were the main drivers of changes in the flora during the last decades. Climate warming appeared as the most influential driver, with northern distribution limit explaining 30%-60% of the variance in the GLMM models. However, the relative importance of the drivers differed among habitat types, with grassland species being affected the most by cessation of grazing/mowing and species of ruderal habitats by on-going concentration of both agriculture and human population to the most productive soils. For wetland species, only pH optimum was significantly related to species performance, possibly an effect of the increasing humification of acidic water bodies. An observed relative decline of mycorrhizal species may possibly be explained by decreasing nitrogen deposition resulting in less competition for phosphorus. We found no effect of shortage or decline of pollinating lepidopterans and bees.
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Affiliation(s)
- Torbjörn Tyler
- Department of Biology, The Biological Museum, Lund University, Lund, Sweden
| | - Lina Herbertsson
- Centre for Environmental and Climate Research, Lund University, Lund, Sweden
| | - Pål Axel Olsson
- Biodiversity Unit, Department of Biology, Lund University, Lund, Sweden
| | | | | | | | - Ola Olsson
- Biodiversity Unit, Department of Biology, Lund University, Lund, Sweden
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9
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Sheldrake M, Rosenstock NP, Revillini D, Olsson PA, Wright SJ, Turner BL. Correction to 'A phosphorus threshold for mycoheterotrophic plants in tropical forests'. Proc Biol Sci 2017; 284:rspb.2017.2372. [PMID: 29237863 DOI: 10.1098/rspb.2017.2372] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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10
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Birgander J, Rousk J, Olsson PA. Warmer winters increase the rhizosphere carbon flow to mycorrhizal fungi more than to other microorganisms in a temperate grassland. Glob Chang Biol 2017; 23:5372-5382. [PMID: 28675677 DOI: 10.1111/gcb.13803] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2017] [Accepted: 05/30/2017] [Indexed: 06/07/2023]
Abstract
A decisive set of steps in the terrestrial carbon (C) cycle is the fixation of atmospheric C by plants and the subsequent C-transfer to rhizosphere microorganisms. With climate change winters are expected to become milder in temperate ecosystems. Although the rate and pathways of rhizosphere C input to soil could be impacted by milder winters, the responses remain unknown. To address this knowledge-gap, a winter-warming experiment was established in a seminatural temperate grassland to follow the C flow from atmosphere, via the plants, to different groups of soil microorganisms. In situ 13 CO2 pulse labelling was used to track C into signature fatty acids of microorganisms. The winter warming did not result in any changes in biomass of any of the groups of microorganisms. However, the C flow from plants to arbuscular mycorrhizal (AM) fungi, increased substantially by winter warming. Saprotrophic fungi also received large amounts of plant-derived C-indicating a higher importance for the turnover of rhizosphere C than biomass estimates would suggest-still, this C flow was unaffected by winter warming. AM fungi was the only microbial group positively affected by winter warming-the group with the closest connection to plants. Winter warming resulted in higher plant productivity earlier in the season, and this aboveground change likely induced plant nutrient limitation in warmed plots, thus stimulating the plant dependence on, and C allocation to, belowground nutrient acquisition. The preferential C allocation to AM fungi was at the expense of C flow to other microbial groups, which were unaffected by warming. Our findings imply that warmer winters may shift rhizosphere C-fluxes to become more AM fungal-dominated. Surprisingly, the stimulated rhizosphere C flow was matched by increased microbial turnover, leading to no accumulation of soil microbial biomass.
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Affiliation(s)
- Johanna Birgander
- Department of Biology and Biodiversity, Lund University, Lund, Sweden
| | - Johannes Rousk
- Department of Biology and Microbial Ecology, Lund University, Lund, Sweden
| | - Pål Axel Olsson
- Department of Biology and Biodiversity, Lund University, Lund, Sweden
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11
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Sheldrake M, Rosenstock NP, Revillini D, Olsson PA, Mangan S, Sayer EJ, Wallander H, Turner BL, Tanner EVJ. Arbuscular mycorrhizal fungal community composition is altered by long-term litter removal but not litter addition in a lowland tropical forest. New Phytol 2017; 214:455-467. [PMID: 28042878 DOI: 10.1111/nph.14384] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2016] [Accepted: 11/14/2016] [Indexed: 06/06/2023]
Abstract
Tropical forest productivity is sustained by the cycling of nutrients through decomposing organic matter. Arbuscular mycorrhizal (AM) fungi play a key role in the nutrition of tropical trees, yet there has been little experimental investigation into the role of AM fungi in nutrient cycling via decomposing organic material in tropical forests. We evaluated the responses of AM fungi in a long-term leaf litter addition and removal experiment in a tropical forest in Panama. We described AM fungal communities using 454-pyrosequencing, quantified the proportion of root length colonised by AM fungi using microscopy, and estimated AM fungal biomass using a lipid biomarker. AM fungal community composition was altered by litter removal but not litter addition. Root colonisation was substantially greater in the superficial organic layer compared with the mineral soil. Overall colonisation was lower in the litter removal treatment, which lacked an organic layer. There was no effect of litter manipulation on the concentration of the AM fungal lipid biomarker in the mineral soil. We hypothesise that reductions in organic matter brought about by litter removal may lead to AM fungi obtaining nutrients from recalcitrant organic or mineral sources in the soil, besides increasing fungal competition for progressively limited resources.
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Affiliation(s)
- Merlin Sheldrake
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge, CB2 3EA, UK
- Smithsonian Tropical Research Institute, Apartado 0843-03092, Balboa, Ancón, Panama
| | - Nicholas P Rosenstock
- Center for Environmental and Climate Research, Lund University, Lund, 22362, Sweden
- Department of Biology, Lund University, Lund, 22362, Sweden
| | - Daniel Revillini
- Smithsonian Tropical Research Institute, Apartado 0843-03092, Balboa, Ancón, Panama
- Department of Biological Sciences, Northern Arizona University, PO BOX 5640, Flagstaff, AZ, 86011, USA
| | | | - Scott Mangan
- Smithsonian Tropical Research Institute, Apartado 0843-03092, Balboa, Ancón, Panama
- Department of Biology, Washington University in St Louis, St Louis, MO, 63130, USA
| | - Emma J Sayer
- Smithsonian Tropical Research Institute, Apartado 0843-03092, Balboa, Ancón, Panama
- Lancaster Environment Centre, Lancaster University, Lancaster, LA1 4YQ, UK
| | | | - Benjamin L Turner
- Smithsonian Tropical Research Institute, Apartado 0843-03092, Balboa, Ancón, Panama
| | - Edmund V J Tanner
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge, CB2 3EA, UK
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12
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Sheldrake M, Rosenstock NP, Revillini D, Olsson PA, Wright SJ, Turner BL. A phosphorus threshold for mycoheterotrophic plants in tropical forests. Proc Biol Sci 2017; 284:20162093. [PMID: 28148744 PMCID: PMC5310599 DOI: 10.1098/rspb.2016.2093] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2016] [Accepted: 01/04/2017] [Indexed: 11/12/2022] Open
Abstract
The majority of terrestrial plants associate with arbuscular mycorrhizal (AM) fungi, which typically facilitate the uptake of limiting mineral nutrients by plants in exchange for plant carbon. However, hundreds of non-photosynthetic plant species-mycoheterotrophs-depend entirely on AM fungi for carbon as well as mineral nutrition. Mycoheterotrophs can provide insight into the operation and regulation of AM fungal relationships, but little is known about the factors, fungal or otherwise, that affect mycoheterotroph abundance and distribution. In a lowland tropical forest in Panama, we conducted the first systematic investigation into the influence of abiotic factors on the abundance and distribution of mycoheterotrophs, to ask whether the availability of nitrogen and phosphorus altered the occurrence of mycoheterotrophs and their AM fungal partners. Across a natural fertility gradient spanning the isthmus of Panama, and also in a long-term nutrient-addition experiment, mycoheterotrophs were entirely absent when soil exchangeable phosphate concentrations exceeded 2 mg P kg-1 Experimental phosphorus addition reduced the abundance of AM fungi, and also reduced the abundance of the specific AM fungal taxa required by the mycoheterotrophs, suggesting that the phosphorus sensitivity of mycoheterotrophs is underpinned by the phosphorus sensitivity of their AM fungal hosts. The soil phosphorus concentration of 2 mg P kg-1 also corresponds to a marked shift in tree community composition and soil phosphatase activity across the fertility gradient, suggesting that our findings have broad ecological significance.
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Affiliation(s)
- Merlin Sheldrake
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EA, UK
- Smithsonian Tropical Research Institute, Apartado 0843-03092, Balboa, Ancón, Republic of Panama
| | | | - Daniel Revillini
- Smithsonian Tropical Research Institute, Apartado 0843-03092, Balboa, Ancón, Republic of Panama
- Department of Biological Sciences, Northern Arizona University, PO BOX 5640, Flagstaff, AZ 86011, USA
| | | | - S Joseph Wright
- Smithsonian Tropical Research Institute, Apartado 0843-03092, Balboa, Ancón, Republic of Panama
| | - Benjamin L Turner
- Smithsonian Tropical Research Institute, Apartado 0843-03092, Balboa, Ancón, Republic of Panama
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Williams A, Manoharan L, Rosenstock NP, Olsson PA, Hedlund K. Long-term agricultural fertilization alters arbuscular mycorrhizal fungal community composition and barley (Hordeum vulgare) mycorrhizal carbon and phosphorus exchange. New Phytol 2017; 213:874-885. [PMID: 27643809 DOI: 10.1111/nph.14196] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2016] [Accepted: 08/08/2016] [Indexed: 05/22/2023]
Abstract
Agricultural fertilization significantly affects arbuscular mycorrhizal fungal (AMF) community composition. However, the functional implications of community shifts are unknown, limiting understanding of the role of AMF in agriculture. We assessed AMF community composition at four sites managed under the same nitrogen (N) and phosphorus (P) fertilizer regimes for 55 yr. We also established a glasshouse experiment with the same soils to investigate AMF-barley (Hordeum vulgare) nutrient exchange, using carbon (13 C) and 33 P isotopic labelling. N fertilization affected AMF community composition, reducing diversity; P had no effect. In the glasshouse, AMF contribution to plant P declined with P fertilization, but was unaffected by N. Barley C allocation to AMF also declined with P fertilization. As N fertilization increased, C allocation to AMF per unit of P exchanged increased. This occurred with and without P fertilization, and was concomitant with reduced barley biomass. AMF community composition showed no relationship with glasshouse experiment results. The results indicate that plants can reduce C allocation to AMF in response to P fertilization. Under N fertilization, plants allocate an increasing amount of C to AMF and receive relatively less P. This suggests an alteration in the terms of P-C exchange under N fertilization regardless of soil P status.
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Affiliation(s)
- Alwyn Williams
- Centre for Environmental and Climate Research, Lund University, Lund, SE-223 62, Sweden
| | | | - Nicholas P Rosenstock
- Centre for Environmental and Climate Research, Lund University, Lund, SE-223 62, Sweden
- Department of Biology, Lund University, Lund, SE-223 62, Sweden
| | - Pål Axel Olsson
- Department of Biology, Lund University, Lund, SE-223 62, Sweden
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Ekroos J, Ödman AM, Andersson GKS, Birkhofer K, Herbertsson L, Klatt BK, Olsson O, Olsson PA, Persson AS, Prentice HC, Rundlöf M, Smith HG. Sparing Land for Biodiversity at Multiple Spatial Scales. Front Ecol Evol 2016. [DOI: 10.3389/fevo.2015.00145] [Citation(s) in RCA: 99] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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15
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Schnoor T, Bruun HH, Olsson PA. Soil disturbance as a grassland restoration measure-effects on plant species composition and plant functional traits. PLoS One 2015; 10:e0123698. [PMID: 25875745 PMCID: PMC4395216 DOI: 10.1371/journal.pone.0123698] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2014] [Accepted: 03/06/2015] [Indexed: 11/18/2022] Open
Abstract
Soil disturbance is recognized as an important driver of biodiversity in dry grasslands, and can therefore be implemented as a restoration measure. However, because community re-assembly following disturbance includes stochastic processes, a focus only on species richness or establishment success of particular species will not inform on how plant communities respond ecologically to disturbance. We therefore evaluated vegetation development following disturbance by quantifying species richness, species composition and functional trait composition. Degraded calcareous sandy grassland was subjected to experimental disturbance treatments (ploughing or rotavation), and the vegetation was surveyed during four subsequent years of succession. Treated plots were compared with control plots representing untreated grassland, as well as nearby plots characterized by plant communities representing the restoration target. Species richness and functional diversity both increased in response to soil disturbance, and rotavation, but not ploughing, had a persistent positive effect on the occurrence of specialist species of calcareous sandy grassland. However, no type of soil disturbance caused the plant species composition to develop towards the target vegetation. The disturbance had an immediate and large impact on the vegetation, but the vegetation developed rapidly back towards the control sites. Plant functional composition analysis indicated that the treatments created habitats different both from control sites and target sites. Community-weighted mean Ellenberg indicator values suggested that the observed plant community response was at least partially due to an increase in nitrogen and water availability following disturbance. This study shows that a mild type of disturbance, such as rotavation, may be most successful in promoting specialist species in calcareous sandy grassland, but that further treatments are needed to reduce nutrient availability. We conclude that a functional trait based analysis provides additional information of the vegetation response and the abiotic conditions created, complementing the information from the species composition.
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Affiliation(s)
- Tim Schnoor
- Biodiversity, Department of Biology, Lund University. The Ecology Building, SE-223 62 Lund, Sweden
| | - Hans Henrik Bruun
- Department of Biology, University of Copenhagen, Universitetsparken 15, 2100 Copenhagen Ø, Denmark
| | - Pål Axel Olsson
- Biodiversity, Department of Biology, Lund University. The Ecology Building, SE-223 62 Lund, Sweden
- * E-mail:
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Wang Y, Li T, Li Y, Björn LO, Rosendahl S, Olsson PA, Li S, Fu X. Community dynamics of arbuscular mycorrhizal fungi in high-input and intensively irrigated rice cultivation systems. Appl Environ Microbiol 2015; 81:2958-65. [PMID: 25681190 PMCID: PMC4375330 DOI: 10.1128/aem.03769-14] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2014] [Accepted: 02/11/2015] [Indexed: 11/20/2022] Open
Abstract
Application of a mycorrhizal inoculum could be one way to increase the yield of rice plants and reduce the application of fertilizer. We therefore studied arbuscular mycorrhizal fungi (AMF) in the roots of wetland rice (Oryza sativa L.) collected at the seedling, tillering, heading, and ripening stages in four paddy wetlands that had been under a high-input and intensively irrigated rice cultivation system for more than 20 years. It was found that AMF colonization was mainly established in the heading and ripening stages. The AMF community structure was characterized in rhizosphere soils and roots from two of the studied paddy wetlands. A fragment covering the partial small subunit (SSU), the whole internal transcribed spacer (ITS), and the partial large subunit (LSU) rRNA operon regions of AMF was amplified, cloned, and sequenced from roots and soils. A total of 639 AMF sequences were obtained, and these were finally assigned to 16 phylotypes based on a phylogenetic analysis, including 12 phylotypes from Glomeraceae, one phylotype from Claroideoglomeraceae, two phylotypes from Paraglomeraceae, and one unidentified phylotype. The AMF phylotype compositions in the soils were similar between the two surveyed sites, but there was a clear discrepancy between the communities obtained from root and soil. The relatively high number of AMF phylotypes at the surveyed sites suggests that the conditions are suitable for some species of AMF and that they may have an important function in conventional rice cultivation systems. The species richness of root-colonizing AMF increased with the growth of rice, and future studies should consider the developmental stages of this crop in the exploration of AMF function in paddy wetlands.
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Affiliation(s)
- Yutao Wang
- Key Laboratory of Ecology and Environmental Science in Guangdong Higher Education, School of Life Sciences, South China Normal University, Guangzhou, China
| | - Ting Li
- Key Laboratory of Ecology and Environmental Science in Guangdong Higher Education, School of Life Sciences, South China Normal University, Guangzhou, China
| | - Yingwei Li
- Key Laboratory of Ecology and Environmental Science in Guangdong Higher Education, School of Life Sciences, South China Normal University, Guangzhou, China
| | - Lars Olof Björn
- Key Laboratory of Ecology and Environmental Science in Guangdong Higher Education, School of Life Sciences, South China Normal University, Guangzhou, China Department of Biology, Lund University, Lund, Sweden
| | - Søren Rosendahl
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | | | - Shaoshan Li
- Key Laboratory of Ecology and Environmental Science in Guangdong Higher Education, School of Life Sciences, South China Normal University, Guangzhou, China
| | - Xuelin Fu
- College of Agriculture, South China Agricultural University, Guangzhou, China
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Lekberg Y, Rosendahl S, Olsson PA. The fungal perspective of arbuscular mycorrhizal colonization in 'nonmycorrhizal' plants. New Phytol 2015; 205:1399-1403. [PMID: 25298202 DOI: 10.1111/nph.13118] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Affiliation(s)
- Ylva Lekberg
- MPG Ranch, 1001 S. Higgins Ave, Missoula, MT, 59801, USA
- Department for Ecosystem and Conservation Sciences, University of Montana, Missoula, MT, 59812, USA
| | - Søren Rosendahl
- Department of Biology, University of Copenhagen, Universitetsparken 15, DK-2100, Copenhagen, Denmark
| | - Pål Axel Olsson
- Biodiversity, Department of Biology, Lund University, Ecology Building, SE-223 62, Lund, Sweden
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Olsson O, Olsson PA, Hammer EC. Phosphorus and carbon availability regulate structural composition and complexity of AM fungal mycelium. Mycorrhiza 2014; 24:443-451. [PMID: 24435931 DOI: 10.1007/s00572-014-0557-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2013] [Accepted: 01/06/2014] [Indexed: 06/03/2023]
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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Affiliation(s)
- Ola Olsson
- Department of Biology, Lund University, Sölvegatan 37, 223 62, Lund, Sweden
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Abstract
Understanding the land use history has proven crucial for the conservation of biodiversity in the agricultural landscape. In southern Sweden, very small and fragmented areas of the disturbance-dependent habitat xeric sand calcareous grassland support a large number of threatened and rare plants and animals. In order to find out if historical land use could explain variation in present-day habitat quality, the land use on eight such sites was traced back to the 18th century and compared with key factors such as the amount of bare sand, lime content and P availability. There was no support for the common explanation of the decline in xeric sand calcareous grassland being caused by abandonment of agricultural fields during the last century. Instead, fertilization history was the main explanation for the difference in depletion depth of CaCO3 seen between the sites. The decline in xeric sand calcareous grassland since the 18th century is most probably the result of the drastic changes in land use during the 19th century, which put an end to the extensive sand drift. Since cultivation was shown to have played an important role in the historical land use of xeric sand calcareous grassland, grazing alone may not be the optimal management option for these grasslands. Instead more drastic measures are needed to restore the high calcium content and maintain proper disturbance levels.
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Affiliation(s)
- Anja Madelen Ödman
- Biodiversity, Department of Biology, Lund University, Lund, Sweden
- * E-mail:
| | - Pål Axel Olsson
- Biodiversity, Department of Biology, Lund University, Lund, Sweden
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Olsson PA, Ödman AM. Natural Establishment of Specialist Plant Species after Topsoil Removal and Soil Perturbation in Degraded Calcareous Sandy Grassland. Restor Ecol 2013. [DOI: 10.1111/rec.12024] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Pål Axel Olsson
- Biodiversity, Department of Biology; Lund University, Ecology Building; SE 223 62 Lund Sweden
| | - Anja Madelen Ödman
- Biodiversity, Department of Biology; Lund University, Ecology Building; SE 223 62 Lund Sweden
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Olsson PA, Hammer EC, Pallon J, van Aarle IM, Wallander H. Elemental composition in vesicles of an arbuscular mycorrhizal fungus, as revealed by PIXE analysis. Fungal Biol 2011; 115:643-8. [DOI: 10.1016/j.funbio.2011.03.008] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2010] [Revised: 03/21/2011] [Accepted: 03/26/2011] [Indexed: 11/29/2022]
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Schnoor TK, Lekberg Y, Rosendahl S, Olsson PA. Mechanical soil disturbance as a determinant of arbuscular mycorrhizal fungal communities in semi-natural grassland. Mycorrhiza 2011; 21:211-20. [PMID: 20593293 DOI: 10.1007/s00572-010-0325-3] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2010] [Accepted: 06/15/2010] [Indexed: 05/16/2023]
Abstract
While the effect of disturbance on overall abundance and community composition of arbuscular mycorrhizal (AM) fungi has been researched in agricultural fields, less is known about the impact in semi-natural grasslands. We sampled two AM plant species, Festuca brevipila and Plantago lanceolata, from an ongoing grassland restoration experiment that contained replicated plowed and control plots. The AM fungal community in roots was determined using nested PCR and LSU rDNA primers. We identified 38 phylotypes within the Glomeromycota, of which 29 belonged to Glomus A, six to Glomus B, and three to Diversisporaceae. Only three phylotypes were closely related to known morphospecies. Soil disturbance significantly reduced phylotype richness and changed the AM fungal community composition. Most phylotypes, even closely related ones, showed little or no overlap in their distribution and occurred in either the control or disturbed plots. We found no evidence of host preference in this system, except for one phylotype that preferentially seemed to colonize Festuca. Our results show that disturbance imposed a stronger structuring force for AM fungal communities than did host plants in this semi-natural grassland.
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Affiliation(s)
- Tim Krone Schnoor
- Plant Ecology and Systematics, Department of Biology, Lund University, The Ecology Building, Sölvegatan 47, 223 62 Lund, Sweden.
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Hammer EC, Pallon J, Wallander H, Olsson PA. Tit for tat? A mycorrhizal fungus accumulates phosphorus under low plant carbon availability. FEMS Microbiol Ecol 2011; 76:236-44. [PMID: 21223336 DOI: 10.1111/j.1574-6941.2011.01043.x] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
The exchange of carbohydrates and mineral nutrients in the arbuscular mycorrhizal (AM) symbiosis must be controlled by both partners in order to sustain an evolutionarily stable mutualism. Plants downregulate their carbon (C) flow to the fungus when nutrient levels are sufficient, while the mechanism controlling fungal nutrient transfer is unknown. Here, we show that the fungus accumulates nutrients when connected to a host that is of less benefit to the fungus, indicating a potential of the fungus to control the transfer of nutrients. We used a monoxenic in vitro model of root organ cultures associated with Glomus intraradices, in which we manipulated the C availability to the plant. We found that G. intraradices accumulated up to seven times more nutrients in its spores, and up to nine times more in its hyphae, when the C pool available to the associated roots was halved. The strongest effect was found for phosphorus (P), considered to be the most important nutrient in the AM symbiosis. Other elements such as potassium and chorine were also accumulated, but to a lesser extent, while no accumulation of iron or manganese was found. Our results suggest a functional linkage between C and P exchange.
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Affiliation(s)
- Edith C Hammer
- Microbial Ecology, Department of Biology, Lund University, Lund, Sweden.
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Hammer EC, Nasr H, Pallon J, Olsson PA, Wallander H. Elemental composition of arbuscular mycorrhizal fungi at high salinity. Mycorrhiza 2011; 21:117-29. [PMID: 20499112 DOI: 10.1007/s00572-010-0316-4] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2010] [Accepted: 04/26/2010] [Indexed: 05/07/2023]
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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Affiliation(s)
- Edith C Hammer
- Microbial Ecology, Department of Ecology, Lund University, SE-223 62 Lund, Sweden
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Olsson PA, Schnoor TK, Hanson SÅ. pH preferences of red-listed gasteromycetes in calcareous sandy grasslands: Implications for conservation and restoration. FUNGAL ECOL 2010. [DOI: 10.1016/j.funeco.2010.01.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Lekberg Y, Hammer EC, Olsson PA. Plants as resource islands and storage units - adopting the mycocentric view of arbuscular mycorrhizal networks. FEMS Microbiol Ecol 2010; 74:336-45. [DOI: 10.1111/j.1574-6941.2010.00956.x] [Citation(s) in RCA: 91] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
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Olsson PA, Rahm J, Aliasgharzad N. Carbon dynamics in mycorrhizal symbioses is linked to carbon costs and phosphorus benefits. FEMS Microbiol Ecol 2010; 72:125-31. [DOI: 10.1111/j.1574-6941.2009.00833.x] [Citation(s) in RCA: 110] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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Abstract
The nutrient and carbon (C) allocation dynamics in mycorrhizal hyphal networks cause variation in costs and benefits for individual plants and fungi and influence the productivity, diversity and C cycling in ecosystems. We manipulated light and phosphorus (P) availability in a pot experiment with Trifolium subterraneum colonised by the arbuscular mycorrhizal (AM) fungus Glomus intraradices. Stable (13)C-labelling was used to trace assimilated CO(2) to the mycorrhizal fungus in roots and soil using compound-specific isotope ratio mass spectrometry. We used the neutral lipid fatty acid 16:1omega5 as a signature for AM fungal storage lipids. Both P and shading reduced the AM fungal lipid accumulation in the intraradical mycelium, while only P reduced the amount of lipids in the extraradical mycelium. Recently assimilated plant C was only allocated to the mycorrhizal fungus to a small extent when plant mycorrhizal benefit was reduced by P fertilization, while increasing the plant C cost by shading did not reduce the C flow to the fungus. These results are of importance for our conception of mycorrhizal dynamics during periods of shade in nature.
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Affiliation(s)
- Pål Axel Olsson
- Department of Plant Ecology and Systematics, Lund University, Lund, Sweden.
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Olsson PA, Rahm J, Aliasgharzad N. Carbon dynamics in mycorrhizal symbioses is linked to carbon costs and phosphorus benefits. FEMS Microbiol Ecol 2010. [DOI: 10.1111/j.1574-6941.2010.00833.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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30
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Olsson PA, Hammer EC, Wallander H, Pallon J. Phosphorus availability influences elemental uptake in the mycorrhizal fungus Glomus intraradices, as revealed by particle-induced X-ray emission analysis. Appl Environ Microbiol 2008; 74:4144-8. [PMID: 18469133 PMCID: PMC2446498 DOI: 10.1128/aem.00376-08] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2008] [Accepted: 05/04/2008] [Indexed: 11/20/2022] Open
Abstract
We investigated element accumulation in the arbuscular mycorrhizal fungus Glomus intraradices. Fungal spores and mycelia growing in monoxenic cultures were analyzed. The elemental composition was quantified using particle-induced X-ray emission (PIXE) in combination with scanning transmission ion microscopy. In the spores, Ca and Fe were associated mainly with the spore wall, while P and K showed patchy distributions and their concentrations were correlated. Excess of P in the hyphal growth medium increased the P and Si concentrations in spores and increased the K/Ca ratio in spores. Increased P availability decreased the concentration of Zn and Mn in spores. We concluded that the availability of P influences the uptake and accumulation of several elements in spores. It is demonstrated that PIXE analysis is a powerful tool for quantitative analysis of elemental accumulation in fungal mycelia.
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Affiliation(s)
- Pål Axel Olsson
- Department of Plant Ecology and Systematics, Ecology Building, Lund University, SE-223 62 Lund, Sweden.
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Troedsson U, Olsson PA, Jarl-Sunesson CI. Application of antisense transformation of a barley chitinase in studies of arbuscule formation by a mycorrhizal fungus. Hereditas 2006; 142:65-72. [PMID: 16970614 DOI: 10.1111/j.1601-5223.2005.01903.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Barley (Hordeum vulgare L.) plants of two commercial cultivars were transformed with sense and antisense constructs of a chitinase class II gene in order to develop a transformation system for this gene in barley. Transformation of embryos with the two antisense constructs resulted in ten regenerated plants, while no plants could be obtained using the sense construct. The presence of the inserted construct could be confirmed for six of the plants by PCR analysis. This system was used to study the role of class II chitinase in the regulation of mycorrhizal symbiosis. The colonization of two of the antisense transformants by the arbuscular mycorrhizal fungus Glomus intraradices was investigated microscopically and by use of signature fatty acids. The arbuscular incidence increased in transformed barley, and one transformant supported higher extraradical mycelium biomass. It is concluded that antisense transformation of barley could be a useful tool in investigations on the symbiosis between barley and mycorrhizal fungi.
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Affiliation(s)
- U Troedsson
- Lund University, Department of Cell and Organism Biology, Sölvegatan 35B, SE-223 62, Lund, Sweden
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Olsson PA, Hansson MC, Burleigh SH. Effect of P availability on temporal dynamics of carbon allocation and glomus intraradices high-affinity P transporter gene induction in arbuscular mycorrhiza. Appl Environ Microbiol 2006; 72:4115-20. [PMID: 16751522 PMCID: PMC1489668 DOI: 10.1128/aem.02154-05] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2005] [Accepted: 03/22/2006] [Indexed: 11/20/2022] Open
Abstract
Arbuscular mycorrhizal (AM) fungi depend on a C supply from the plant host and simultaneously provide phosphorus to the colonized plant. We therefore evaluated the influence of external P on C allocation in monoxenic Daucus carota-Glomus intraradices cultures in an AM symbiosis. Fungal hyphae proliferated from a solid minimal medium containing colonized roots into a C-free liquid minimal medium with high or low P availability. Roots and hyphae were harvested periodically, and the flow of C from roots to fungus was measured by isotope labeling. We also measured induction of a G. intraradices high-affinity P transporter to estimate fungal P demand. The prevailing hypothesis is that high P availability reduces mycorrhizal fungal growth, but we found that C flow to the fungus was initially highest at the high P level. Only at later harvests, after 100 days of in vitro culture, were C flow and fungal growth limited at high P availability. Thus, AM fungi can benefit initially from P-enriched environments in terms of plant C allocation. As expected, the P transporter induction was significantly greater at low P availability and greatest in very young mycelia. We found no direct link between C flow to the fungus and the P transporter transcription level, which indicates that a good C supply is not essential for induction of the high-affinity P transporter. We describe a mechanism by which P regulates symbiotic C allocation, and we discuss how this mechanism may have evolved in a competitive environment.
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Affiliation(s)
- Pål Axel Olsson
- Department of Ecology, Ecology Building, Lund University, SE 223 62 Lund, Sweden.
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Olsson PA, Burleigh SH, van Aarle IM. The influence of external nitrogen on carbon allocation to Glomus intraradices in monoxenic arbuscular mycorrhiza. New Phytol 2005; 168:677-86. [PMID: 16313649 DOI: 10.1111/j.1469-8137.2005.01532.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
The influence of external nitrogen (N) on carbon (C) allocation and processes related to phosphorus (P) metabolism were studied in monoxenic arbuscular mycorrhiza (AM) cultures of Daucus carota. Fungal hyphae of Glomus intraradices proliferated from colonized roots growing on solid medium into C-free liquid minimal medium with two different N and P levels. Furthermore, we exposed the colonized roots to high or low N availability and then studied the mycelial development. Roots were provided with (13)C-glucose in order to follow the C allocation. The mycelium was analysed for phosphatase activity and transcription levels of two nutrient regulated genes. High N availability to the monoxenic AM root reduced the C allocation to the AM fungus while N availability to the mycelium was important for the upregulation of the fungal inorganic phosphorus (Pi)-transporter GiPT. We found that N availability can regulate nutritional processes in arbuscular mycorrhiza. We conclude that negative impacts of N on AM abundance are caused by reduced C allocation from the plant. Upregulation of the fungal Pi-transporter GiPT indicated that increased N availability might induce P limitation in the mycelium.
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Affiliation(s)
- Pål Axel Olsson
- Department of Microbial Ecology, Ecology Building, Lund University, SE-223 62 Lund, Sweden. ,se
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Olsson PA, van Aarle IM, Gavito ME, Bengtson P, Bengtsson G. 13C incorporation into signature fatty acids as an assay for carbon allocation in arbuscular mycorrhiza. Appl Environ Microbiol 2005; 71:2592-9. [PMID: 15870350 PMCID: PMC1087529 DOI: 10.1128/aem.71.5.2592-2599.2005] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2004] [Accepted: 11/19/2004] [Indexed: 11/20/2022] Open
Abstract
The ubiquitous arbuscular mycorrhizal fungi consume significant amounts of plant assimilated C, but this C flow has been difficult to quantify. The neutral lipid fatty acid 16:1omega5 is a quantitative signature for most arbuscular mycorrhizal fungi in roots and soil. We measured carbon transfer from four plant species to the arbuscular mycorrhizal fungus Glomus intraradices by estimating (13)C enrichment of 16:1omega5 and compared it with (13)C enrichment of total root and mycelial C. Carbon allocation to mycelia was detected within 1 day in monoxenic arbuscular mycorrhizal root cultures labeled with [(13)C]glucose. The (13)C enrichment of neutral lipid fatty acid 16:1omega5 extracted from roots increased from 0.14% 1 day after labeling to 2.2% 7 days after labeling. The colonized roots usually were more enriched for (13)C in the arbuscular mycorrhizal fungal neutral lipid fatty acid 16:1omega5 than for the root specific neutral lipid fatty acid 18:2omega6,9. We labeled plant assimilates by using (13)CO(2) in whole-plant experiments. The extraradical mycelium often was more enriched for (13)C than was the intraradical mycelium, suggesting rapid translocation of carbon to and more active growth by the extraradical mycelium. Since there was a good correlation between (13)C enrichment in neutral lipid fatty acid 16:1omega5 and total (13)C in extraradical mycelia in different systems (r(2) = 0.94), we propose that the total amount of labeled C in intraradical and extraradical mycelium can be calculated from the (13)C enrichment of 16:1omega5. The method described enables evaluation of C flow from plants to arbuscular mycorrhizal fungi to be made without extraction, purification and identification of fungal mycelia.
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Affiliation(s)
- Pål Axel Olsson
- Department of Ecology, Lund University, SE-223 62 Lund, Sweden.
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Belluardo N, Olsson PA, Mudo' G, Sommer WH, Amato G, Fuxe K. Transcription factor gene expression profiling after acute intermittent nicotine treatment in the rat cerebral cortex. Neuroscience 2005; 133:787-96. [PMID: 15890456 DOI: 10.1016/j.neuroscience.2005.01.061] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2004] [Revised: 12/22/2004] [Accepted: 01/26/2005] [Indexed: 10/25/2022]
Abstract
Several studies in different in vitro and in vivo models have demonstrated neuroprotective effects of nicotinic receptor agonists and indirect trophic actions of nicotine on brain are suggested from observations describing nicotine as a cognitive enhancer by increasing vigilance and improving learning and memory. While an increasing number of studies have given evidence of neuroprotective and neurotrophic effects of nicotine treatment, the molecular mechanism mediating the neurotrophic effects of nicotine are not fully understood. Previously in an analysis of several neurotrophic factors as possible mediators of nicotine-induced neuroprotection and/or neurotrophic effects we could reveal that an acute intermittent nicotine treatment increases fibroblast growth factor-2 mRNA and protein in several brain regions of rat brain. Even if other studies have demonstrated in different paradigms that nicotine administration modulates expression level of a variety of genes, there is still a lack of indication which candidate genes, involved in neuroprotective responses are modulated by nicotine. In the present work we have used a microarray assay to further find and characterize new genes responsive to acute intermittent nicotine treatment and linked to neuroprotection. Therefore, we used Rat Genome U34A Affymetrix GeneChip arrays containing about 8800 probe sets to characterize transcriptional responses in the rat parietal cortex after acute intermittent nicotine treatment. We focused our attention to expression of transcription factors and several of them were up- or down-regulated by nicotine, among these Nr4a1 (Nurr77), Egr-1 and Egr-2. In situ hybridization was used to corroborate the microarray data and to reveal further spatial and temporal patterns of these nicotine induced genes. Taken together the present results identified several novel candidate genes modified by acute intermittent nicotine exposure and as such potentially involved in neuroprotective-neurotrophic actions.
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Affiliation(s)
- N Belluardo
- Department of Experimental Medicine, Division of Human Physiology, University of Palermo, Corso Tukory 129, 90134 Palermo, Italy.
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Olsson PA, Eriksen B, Dahlberg A. Colonization by arbuscular mycorrhizal and fine endophytic fungi in herbaceous vegetation in the Canadian High Arctic. ACTA ACUST UNITED AC 2004. [DOI: 10.1139/b04-111] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The occurrence of arbuscular mycorrhizal (AM) fungi was surveyed along a latitudinal gradient in Arctic Canada including Banks Island (73°N), Devon Island (74°N), Ellesmere Island (76°N), and the Magnetic North Pole at Ellef Ringnes Island (78°N). At Banks Island, AM fungi were present and colonized at a high intensity in all specimens of Potentilla hookeriana Lehm. – Potentilla pulchella R.Br., Arnica angustifolia Vahl, and Erigeron uniflorus L. ssp. eriocephalus (Vahl ex Hornen.) Cronq. sampled. The soil collected under these plants showed a high inoculum potential when tested at greenhouse conditions using Plantago lanceolata L. as a bait plant. Occasional occurrence of AM fungi was recorded in Festuca hyperborea Holmen ex Frederiksen, Trisetum spicatum (L.) Richt., and Potentilla hookeriana – Potentilla pulchella at Devon Island. Despite the fact that potential AM plants are present, no AM was found at the two most northern sites, Ellesmere Island and Ellef Ringnes Island. There seems to be climatic or dispersal limitations to AM colonization at these northern sites. Fine endophytic fungi, formerly named Glomus tenue (Grenall) I.R. Hall, were recorded at all four sites, but most frequently at Banks Island. We thereby provide further evidence that fine endophytes are more frequent in harsh climatic conditions than AM fungi. There was a relatively high proportion of nonmycorrhizal plant species at all sites, and this proportion increased towards the north.Key words: arctic, arbuscular mycorrhiza, fine endophytes, dark septate fungi.
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Nielsen KB, Kjøller R, Olsson PA, Schweiger PF, Andersen FO, Rosendahl S. Colonisation and molecular diversity of arbuscular mycorrhizal fungi in the aquatic plants Littorella uniflora and Lobelia dortmanna in southern Sweden. ACTA ACUST UNITED AC 2004; 108:616-25. [PMID: 15323243 DOI: 10.1017/s0953756204000073] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The colonisation intensity and composition of the mycorrhizal community in the aquatic plants Lobelia dortmanna and Littorella uniflora were studied. The mycorrhizal fungi were characterised by fungal specific nested PCR and sequencing using the 5'-end of the LSU rDNA as target. For this, primers for the clade of Acaulospora, the clade including Glomus mosseae and G. intraradices and the clade containing G. etunicatum and G. claroideum were used. The nested PCR products were screened for different sequence types using single stranded conformation polymorphism (SSCP) and representatives for each type were sequenced. A phylogenetic analysis of the sequences showed two phylotypes of Acaulospora, one phylotype within the clade of G. etunicatum/G. claroideum and five within the G. mosseae/ G. intraradices clade. The colonisation intensity was comparable to that seen in typical grassland vegetation. The neutral lipid fatty acid 16: 1omega5 was seen to be indicative of mycorrhizal colonisation with concentrations up to 35 nmol mg(-1) root DW, which indicates that the fungi are active.
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Affiliation(s)
- Kit Bjerregaard Nielsen
- Institute of Biology, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark
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van Aarle IM, Olsson PA. Fungal lipid accumulation and development of mycelial structures by two arbuscular mycorrhizal fungi. Appl Environ Microbiol 2003; 69:6762-7. [PMID: 14602638 PMCID: PMC262256 DOI: 10.1128/aem.69.11.6762-6767.2003] [Citation(s) in RCA: 111] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2003] [Accepted: 08/25/2003] [Indexed: 11/20/2022] Open
Abstract
We monitored the development of intraradical and extraradical mycelia of the arbuscular mycorrhizal (AM) fungi Scutellospora calospora and Glomus intraradices when colonizing Plantago lanceolata. The occurrence of arbuscules (branched hyphal structures) and vesicles (lipid storage organs) was compared with the amounts of signature fatty acids. The fatty acid 16:1omega5 was used as a signature for both AM fungal phospholipids (membrane constituents) and neutral lipids (energy storage) in roots (intraradical mycelium) and in soil (extraradical mycelium). The formation of arbuscules and the accumulation of AM fungal phospholipids in intraradical mycelium followed each other closely in both fungal species. In contrast, the neutral lipids of G. intraradices increased continuously in the intraradical mycelium, while vesicle occurrence decreased after initial rapid root colonization by the fungus. S. calospora does not form vesicles and accumulated more neutral lipids in extraradical than in intraradical mycelium, while the opposite pattern was found for G. intraradices. G. intraradices allocated more of its lipids to storage than did S. calospora. Thus, within a species, the fatty acid 16:1omega5 is a good indicator for AM fungal development. The phospholipid fatty acid 16:1omega5 is especially suitable for indicating the frequency of arbuscules in the symbiosis. We propose that the ratio of neutral lipids to phospholipids is more important than is the presence of vesicles in determining the storage status of AM fungi.
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Affiliation(s)
- Ingrid M van Aarle
- Department of Microbial Ecology, Lund University, SE-223 62 Lund, Sweden
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van Aarle IM, Olsson PA. Fungal lipid accumulation and development of mycelial structures by two arbuscular mycorrhizal fungi. Appl Environ Microbiol 2003. [PMID: 14602638 DOI: 10.1128/aem.69.11.6762] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/14/2023] Open
Abstract
We monitored the development of intraradical and extraradical mycelia of the arbuscular mycorrhizal (AM) fungi Scutellospora calospora and Glomus intraradices when colonizing Plantago lanceolata. The occurrence of arbuscules (branched hyphal structures) and vesicles (lipid storage organs) was compared with the amounts of signature fatty acids. The fatty acid 16:1omega5 was used as a signature for both AM fungal phospholipids (membrane constituents) and neutral lipids (energy storage) in roots (intraradical mycelium) and in soil (extraradical mycelium). The formation of arbuscules and the accumulation of AM fungal phospholipids in intraradical mycelium followed each other closely in both fungal species. In contrast, the neutral lipids of G. intraradices increased continuously in the intraradical mycelium, while vesicle occurrence decreased after initial rapid root colonization by the fungus. S. calospora does not form vesicles and accumulated more neutral lipids in extraradical than in intraradical mycelium, while the opposite pattern was found for G. intraradices. G. intraradices allocated more of its lipids to storage than did S. calospora. Thus, within a species, the fatty acid 16:1omega5 is a good indicator for AM fungal development. The phospholipid fatty acid 16:1omega5 is especially suitable for indicating the frequency of arbuscules in the symbiosis. We propose that the ratio of neutral lipids to phospholipids is more important than is the presence of vesicles in determining the storage status of AM fungi.
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Affiliation(s)
- Ingrid M van Aarle
- Department of Microbial Ecology, Lund University, SE-223 62 Lund, Sweden
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Affiliation(s)
- Pål Axel Olsson
- Department of Microbial Ecology, Ecology Building, Lund University, SE-223 62 Lund, Sweden
- (Author for correspondence tel +46 46 2229614; fax +46 46 2224158;email )
| | - Lennart Larsson
- Department of Medical Microbiology, Division of Bacteriology, Lund University, Sölvegatan 23, SE 223 62 Lund, Sweden
| | - Bert Bago
- Centro de Investigaciones sobre Desertification (CSIC/UV/GV), Valencia, Spain
| | - Håkan Wallander
- Department of Microbial Ecology, Ecology Building, Lund University, SE-223 62 Lund, Sweden
| | - Ingrid M Van Aarle
- Department of Microbial Ecology, Ecology Building, Lund University, SE-223 62 Lund, Sweden
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Olsson PA, van Aarle IM, Allaway WG, Ashford AE, Rouhier H. Phosphorus effects on metabolic processes in monoxenic arbuscular mycorrhiza cultures. Plant Physiol 2002; 130:1162-71. [PMID: 12427983 PMCID: PMC166637 DOI: 10.1104/pp.009639] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2002] [Accepted: 07/20/2002] [Indexed: 05/19/2023]
Abstract
The influence of external phosphorus (P) on carbon (C) allocation and metabolism as well as processes related to P metabolism was studied in monoxenic arbuscular mycorrhiza cultures of carrot (Daucus carota). Fungal hyphae of Glomus intraradices proliferated from the solid minimal medium containing the colonized roots into C-free liquid minimal medium with different P treatments. The fungus formed around three times higher biomass in P-free liquid medium than in medium with 2.5 mM inorganic P (high-P). Mycelium in the second experiment was harvested at an earlier growth stage to study metabolic processes when the mycelium was actively growing. P treatment influenced the root P content and [(13)C]glucose administered to the roots 7 d before harvest gave a negative correlation between root P content and (13)C enrichment in arbuscular mycorrhiza fungal storage lipids in the extraradical hyphae. Eighteen percent of the enriched (13)C in extraradical hyphae was recovered in the fatty acid 16:1omega5 from neutral lipids. Polyphosphate accumulated in hyphae even in P-free medium. No influence of P treatment on fungal acid phosphatase activity was observed, whereas the proportion of alkaline-phosphatase-active hyphae was highest in high-P medium. We demonstrated the presence of a motile tubular vacuolar system in G. intraradices. This system was rarely seen in hyphae subjected to the highest P treatment. We concluded that the direct responses of the extraradical hyphae to the P concentration in the medium are limited. The effects found in hyphae seemed instead to be related to increased availability of P to the host root.
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Affiliation(s)
- Pål Axel Olsson
- Department of Microbial Ecology, Ecology Building, Lund University, SE-223 62 Lund, Sweden.
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Van Aarle IM, Olsson PA, Söderström B. Arbuscular mycorrhizal fungi respond to the substrate pH of their extraradical mycelium by altered growth and root colonization. New Phytol 2002; 155:173-182. [PMID: 33873298 DOI: 10.1046/j.1469-8137.2002.00439.x] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
• To test the response of arbuscular mycorrhizal (AM) fungi to a difference in soil pH, the extraradical mycelium of Scutellospora calospora or Glomus intraradices, in association with Plantago lanceolata, was exposed to two different pH treatments, while the root substrate pH was left unchanged. • Seedlings of P. lanceolata, colonized by one or other of the fungal symbionts, and nonmycorrhizal controls, were grown in mesh bags placed in pots containing pH-buffered sand (pH around 5 or 6). The systems were harvested at approximately 2-wk intervals between 20 and 80 d. • Both fungi formed more extraradical mycelium at the higher pH. Glomus intraradices formed almost no detectable extraradical mycelium at lower pH. The extraradical mycelium of S. calospora had higher acid phosphatase activity than that of G. intraradices. Total AM root colonization decreased for both fungi at the higher pH, and high pH also reduced arbuscule and vesicle formation in G. intraradices. • In conclusion, soil pH influences AM root colonization as well as the growth and phosphatase activities of extraradical mycelium, although the two fungi responded differently.
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Affiliation(s)
- Ingrid M Van Aarle
- Department of Microbial Ecology, Ecology Building, Lund University, SE-223 62 Lund, Sweden
| | - Pål Axel Olsson
- Department of Microbial Ecology, Ecology Building, Lund University, SE-223 62 Lund, Sweden
| | - Bengt Söderström
- Department of Microbial Ecology, Ecology Building, Lund University, SE-223 62 Lund, Sweden
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Olsson PA, Kjellbom P, Rosendahl L. Rhizobium colonization induced changes in membrane-bound and soluble hydroxyproline-rich glycoprotein composition in pea. Physiol Plant 2002; 114:652-660. [PMID: 11975741 DOI: 10.1034/j.1399-3054.2002.1140420.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Abundance and distribution of plant cell surface proteins of the hydroxyproline-rich glycoprotein (HRGP) class were studied in the pea-Rhizobium symbiosis using immunoblot analysis. The MAC 265-epitope was especially abundant in pea root nodules containing nitrogen-fixing Rhizobium bacteria. A 180-kDa MAC 265-HRGP dominated in pea shoot plasma membranes, while almost no MAC 265-HRGP was detected in root plasma membranes. We show here that a major difference between the plant-derived peribacteroid membrane of the symbiosomes and the root plasma membrane was the presence of a 100-kDa MAC 265-HRGP in the former. Arabinogalactan proteins (AGPs), as recognized by the monoclonal antibodies MAC 207 and JIM 8, were not detected in the peribacteroid membrane, while two isoforms (100 and 220 kDa) were detected in shoot and root plasma membranes. Specific MAC 265-HRGP isoforms were found in the peribacteroid space fraction of the symbiosomes and thus as soluble proteins in the interface between the symbionts. The abundance of the MAC 265-epitope was much reduced in non-nitrogen-fixing nodules when this phenotype resulted from a dicarboxylate transport mutation in Rhizobium. There was no reduction in the abundance of the MAC 265-epitope in non-fixing phenotypes resulting from a mutation in the plant. The results suggest that bacterial signals related to the bacterial ability to fix nitrogen, might be responsible for the regulation of HRGP expression in root nodules.
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Affiliation(s)
- Pål Axel Olsson
- aPlant-Microbe Symbioses, Plant Biology and Biogeochemistry Department, Risø National Laboratory, PO Box 49, DK-4000 Roskilde, Denmark bDepartment of Plant Biochemistry, Lund University, PO Box 117, SE-22100 Lund, Sweden 1Present address: Department of Microbial Ecology, Ecology Building, Lund University, SE-223 62 Lund, Sweden
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Olsson PA, Jakobsen I, Wallander H. Foraging and Resource Allocation Strategies of Mycorrhizal Fungi in a Patchy Environment. Ecological Studies 2002. [DOI: 10.1007/978-3-540-38364-2_4] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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Olsson PA. A psychoanalytic study of integrity and "good character". J Am Acad Psychoanal 2001; 28:397-407. [PMID: 11109222 DOI: 10.1521/jaap.1.2000.28.3.397] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
When we assess a patient for analysis or reflect on our ongoing work as analysts or teachers of analysis, it seems helpful to consider the complex issues of truthfulness and courage within the self (i.e., integrity) and what it means to have "good character."
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Aarle IMV, Olsson PA, Söderström B. Microscopic detection of phosphatase activity of saprophytic and arbuscular mycorrhizal fungi using a fluorogenic substrate. Mycologia 2001. [DOI: 10.1080/00275514.2001.12061275] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Affiliation(s)
- Ingrid M. van Aarle
- Department of Microbial Ecology, Ecology Building, Lund University, SE-223 62 Lund, Sweden
| | - Pål Axel Olsson
- Department of Microbial Ecology, Ecology Building, Lund University, SE-223 62 Lund, Sweden
| | - Bengt Söderström
- Department of Microbial Ecology, Ecology Building, Lund University, SE-223 62 Lund, Sweden
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Olsson PA, Bornhauser BC, Korhonen L, Lindholm D. Neuronal expression of the ERM-like protein MIR in rat brain and its localization to human chromosome 6. Biochem Biophys Res Commun 2000; 279:879-83. [PMID: 11162443 DOI: 10.1006/bbrc.2000.4028] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The ERM proteins, ezrin, radixin, and moesin, regulate cell motility by linking cortical F-actin to the plasma membrane in different cell types. Myosin regulatory light chain interacting protein (MIR) is a recently cloned ERM-like protein which was shown to be involved in neurite outgrowth. Here we have studied the occurrence and expression of MIR in rats during brain development. As shown using Western blotting, MIR is present in different regions both in developing and adult brain. Immunohistochemistry and double labelling studies showed that MIR is localized especially to neurons in hippocampus and cerebellum. A search using the gene bank showed that the MIR gene localised to human chromosome 6 in the interval 6p22.3-23, the loss of which is characterized by mental retardation and different malformations in man. The presence of MIR in brain neurons during development together with its known effects on neurite outgrowth suggest an important function of the protein in the regulation of nerve cell motility and cytoskeletal interactions.
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Affiliation(s)
- P A Olsson
- Department of Neuroscience, Neurobiology, Uppsala University, Uppsala, S-751 23, Sweden
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Mercer EA, Korhonen L, Skoglösa Y, Olsson PA, Kukkonen JP, Lindholm D. NAIP interacts with hippocalcin and protects neurons against calcium-induced cell death through caspase-3-dependent and -independent pathways. EMBO J 2000; 19:3597-607. [PMID: 10899114 PMCID: PMC313967 DOI: 10.1093/emboj/19.14.3597] [Citation(s) in RCA: 108] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Inhibitor-of-apoptosis proteins (IAPs), including neuronal apoptosis inhibitory protein (NAIP), inhibit cell death. Other IAPs inhibit key caspase proteases which effect cell death, but the mechanism by which NAIP acts is unknown. Here we report that NAIP, through its third baculovirus inhibitory repeat domain (BIR3), binds the neuron-restricted calcium-binding protein, hippocalcin, in an interaction promoted by calcium. In neuronal cell lines NSC-34 and Neuro-2a, over-expression of the BIR domains of NAIP (NAIP-BIR1-3) counteracted the calcium-induced cell death induced by ionomycin and thapsigargin. This protective capacity was significantly enhanced when NAIP-BIR1-3 was co-expressed with hippocalcin. Over-expression of the BIR3 domain or hippocalcin alone did not substantially enhance cell survival, but co-expression greatly increased their protective effects. These data suggest synergy between NAIP and hippocalcin in facilitating neuronal survival against calcium-induced death stimuli mediated through the BIR3 domain. Analysis of caspase activity after thapsigargin treatment revealed that caspase-3 is activated in NSC-34, but not Neuro-2a, cells. Thus NAIP, in conjunction with hippocalcin, can protect neurons against calcium-induced cell death in caspase-3-activated and non-activated pathways.
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Affiliation(s)
- E A Mercer
- Department of Neuroscience, Neurobiology, Box 587, Biomedical Centre, Uppsala University, S-751 23 Uppsala, Sweden
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Olsson PA, Korhonen L, Mercer EA, Lindholm D. MIR is a novel ERM-like protein that interacts with myosin regulatory light chain and inhibits neurite outgrowth. J Biol Chem 1999; 274:36288-92. [PMID: 10593918 DOI: 10.1074/jbc.274.51.36288] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The ERM protein family members ezrin, radixin, and moesin are cytoskeletal effector proteins linking actin to membrane-bound proteins at the cell surface. Here we report on the cloning of myosin regulatory light chain interacting protein (MIR), a protein with an ERM-homology domain and a carboxyl-terminal RING finger, that is expressed, among other tissues, in brain. MIR is distributed in cultured COS cells, in a punctuated manner as shown using enhanced green fluorescent protein (EGFP)-tagged MIR and by staining with a specific antibody for MIR. In the yeast two-hybrid system and in transfected COS cells, MIR interacts with myosin regulatory light chain B, which in turn regulates the activity of the actomyosin complex. Overexpression of MIR cDNA in PC12 cells abrogated neurite outgrowth induced by nerve growth factor (NGF) without affecting TrkA signaling. The results show that MIR, a novel ERM-like protein, affects cytoskeleton interactions regulating cell motility, such as neurite outgrowth.
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Affiliation(s)
- P A Olsson
- Department of Neuroscience, Neurobiology, Uppsala University, Box 587 Biomedical Center, S-75123 Uppsala, Sweden
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Affiliation(s)
- P A Olsson
- Monadnuck Family Services, Keene, N.H., USA
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