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Functional ecology of ectomycorrhizal fungi

peroxidases, decomposition, spatial community patterns

Bödeker, Inga (2012). Functional ecology of ectomycorrhizal fungi. Diss. (sammanfattning/summary) Uppsala : Sveriges lantbruksuniv., Acta Universitatis Agriculturae Sueciae, 1652-6880 ; 2012:36
ISBN 978-91-576-7672-6
[Doctoral thesis]

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Boreal forest ecosystems constitute a globally important carbon (C) sink, due to
accumulation of complex organic matter, persistent to decomposition. Nitrogen (N) is
immobilized in these complex compounds and, thereby, unavailable to the plant
community. Fungal peroxidases (ClassII) are oxidative enzymes, predominantly
studied in white-rot wood decomposers and known to efficiently mineralize phenolic
complexes, such as lignin, to CO2. Peroxidase activity is also commonly measured in
forest soil, where typical white-rotters are absent and ectomycorrhizal fungi
predominate. Peroxidase activity is known to increases under low inorganic N
availability. The aim of this study was to explore the ectomycorrhizal decomposer
potential in boreal forest ecosystems. The central hypothesis is that ectomycorrhizal
fungi produce ClassII peroxidases to mobilize N, bound to phenolic complexes in
boreal forest litter and humus.

Genes coding for ClassII peroxidases were found to be widely spread among
ectomycorrhizal taxa, particularly within the genus of Cortinarius. Gene transcription
of peroxidases in forest humus could be linked directly to the species Cortinarius
semisanguineus. In a field experiment, colorimetric enzyme assays showed a halving of
peroxidase activity in short-term response to N-amendment. In non-treated control
samples, Cortinarius species and other rhizomorph forming ectomycorrhizal fungi
were co-localized with peroxidase activity hotspots. Ectomycorrhizal Cortinarius
species may, thus, be key players in N-acquisition, from organic macromolecules, and
central decomposers of complex organic matter in boreal forest ecosystems.

Root-associated fungi, including ectomycorrhizal ones, were able to compete with
free-living saprotrophs for colonization of litter. However, they were less efficient
decomposers than specialized litter saprotrophs.

It is concluded that some mycorrhizal fungi may release C while foraging for N.
They may also indirectly act to preserve soil C by suppressing more efficient
saprotrophic decomposers. The findings highlight ectomycorrhizal fungi as central
regulators of C dynamics in boreal forests. Ectomycorrhizal symbiosis, thus, constitutes
a direct link between above-ground photosynthesis and below-ground decomposition.

Authors/Creators:Bödeker, Inga
Title:Functional ecology of ectomycorrhizal fungi
Subtitle:peroxidases, decomposition, spatial community patterns
Series Name/Journal:Acta Universitatis Agriculturae Sueciae
Year of publishing :8 May 2012
Number of Pages:65
I.I.T.M. Bödeker, C. M. R. Nygren, A. F. S. Taylor, Å. Olson, B. D. Lindahl. (2009). ClassII peroxidase-encoding genes are present in a phylogenetically wide range of ectomycorrhizal fungi. The ISME Journal 3(12), 1387-1395
II.I. T. M. Bödeker, K. E. Clemmensen, W. deBoer, Å. Olson, B. D. Lindahl Ectomycorrhizal fungi drive enzymatic oxidation in humus layers of northern forest ecosystems with low nitrogen availability. (Manuscript).
III.I. T. M. Bödeker, Å. Olson, B. D. Lindahl, K. E. Clemmensen. Impact of substrate quality, vertical placement and fungal community composition for organic matter decomposition in boreal forest. (Manuscript).
Place of Publication:Uppsala
Publisher:Institutionen för skoglig mykologi och patologi, Sveriges lantbruksuniversitet
Associated Programs and Other Stakeholders:SLU - Environmental assessment > Programme Biodiversity
SLU - Environmental assessment > Programme Climate
SLU - Environmental assessment > Programme Forest
SLU - Agricultural Sciences for Global Development > Land use and climate change
ISBN for printed version:978-91-576-7672-6
Publication Type:Doctoral thesis
Full Text Status:Public
Agris subject categories.:F Plant production > F40 Plant ecology
K Forestry > K01 Forestry - General aspects
P Natural resources > P34 Soil biology
Subjects:(A) Swedish standard research categories 2011 > 1 Natural sciences > 106 Biological Sciences (Medical to be 3 and Agricultural to be 4) > Microbiology (Microbiology in the medical area to be 30109)
(A) Swedish standard research categories 2011 > 1 Natural sciences > 106 Biological Sciences (Medical to be 3 and Agricultural to be 4) > Ecology
Agrovoc terms:ectomycorrhizae, fungi, boreal forests, forest soils, peroxidases, enzyme activity, organic matter, degradation, carbon sequestration
Keywords:ectomycorrhizal fungi, oxidative enzymes, organic matter, decomposition, N-acquisition, boreal forest
Permanent URL:
ID Code:8829
Department:(NL, NJ) > Dept. of Forest Mycology and Plant Pathology
(S) > Dept. of Forest Mycology and Plant Pathology
Deposited By: Inga Bödeker
Deposited On:09 May 2012 09:16
Metadata Last Modified:02 Dec 2014 10:50

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