Ectomycorrhizal Cortinarius species participate in enzymatic oxidation of humus in northern forest ecosystems

I.T.M. Bodeker, K.E. Clemmensen, W. De Boer, F. Martin, A. Olson, B.D. Lindahl

Research output: Contribution to journal/periodicalArticleScientificpeer-review

Abstract

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 Cortinarius species produce Mn-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, Cortinarius DNA was assessed by 454-sequencing of ITS amplicons and related to Mn-peroxidase activity in humus samples with- and without previous N amendment. Transcription of Cortinarius Mn-peroxidase genes was investigated in field samples. Phylogenetic analyses of Cortinarius peroxidase amplicons and genome sequences were performed. We found a significant co-localization of high peroxidase activity and DNA from Cortinarius species. Peroxidase activity was reduced by high ammonium concentrations. Amplification of mRNA sequences indicated transcription of Cortinarius Mn-peroxidase genes under field conditions. The Cortinarius glaucopus genome encodes 11 peroxidases - a number comparable to many white-rot wood decomposers. These results support the hypothesis that some ectomycorrhizal fungi - Cortinarius species in particular - may play an important role in decomposition of complex organic matter, linked to their mobilization of organically bound N. [KEYWORDS: carbon sequestration Class II peroxidases decomposition ectomycorrhizal fungi high throughput sequencing nitrogen limitation priming effect transcription SOIL ORGANIC-MATTER DEGRADING HEME PEROXIDASES MYCORRHIZAL FUNGI BOREAL FOREST
Original languageEnglish
Pages (from-to)245-256
JournalNew Phytologist
Volume203
Issue number1
DOIs
Publication statusPublished - 2014

Keywords

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