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Ectomycorrhizal C ortinarius species participate in enzymatic oxidation of humus in northern forest ecosystems
Author(s) -
Bödeker Inga T. M.,
Clemmensen Karina E.,
Boer Wietse,
Martin Francis,
Olson Åke,
Lindahl Björn D.
Publication year - 2014
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/nph.12791
Subject(s) - peroxidase , decomposer , biology , humus , oxidative enzyme , botany , taiga , ecosystem , enzyme , biochemistry , ecology , soil water
Summary In northern forests, belowground sequestration of nitrogen ( N ) in complex organic pools restricts nutrient availability to plants. Oxidative extracellular enzymes produced by ectomycorrhizal fungi may aid plant N acquisition by providing access to N in macromolecular complexes. We test the hypotheses that ectomycorrhizal C ortinarius species produce M n‐dependent peroxidases, and that the activity of these enzymes declines at elevated concentrations of inorganic N . In a boreal pine forest and a sub‐arctic birch forest, C ortinarius DNA was assessed by 454‐sequencing of ITS amplicons and related to M n‐peroxidase activity in humus samples with‐ and without previous N amendment. Transcription of C ortinarius M n‐peroxidase genes was investigated in field samples. Phylogenetic analyses of C ortinarius peroxidase amplicons and genome sequences were performed. We found a significant co‐localization of high peroxidase activity and DNA from C ortinariu s species. Peroxidase activity was reduced by high ammonium concentrations. Amplification of m RNA sequences indicated transcription of C ortinarius M n‐peroxidase genes under field conditions. The C ortinarius glaucopus genome encodes 11 peroxidases – a number comparable to many white‐rot wood decomposers. These results support the hypothesis that some ectomycorrhizal fungi – C ortinarius species in particular – may play an important role in decomposition of complex organic matter, linked to their mobilization of organically bound N .