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

TY - JOUR

T1 - Ectomycorrhizal Cortinarius species participate in enzymatic oxidation of humus in northern forest ecosystems

AU - Bodeker, I.T.M.

AU - Clemmensen, K.E.

AU - De Boer, W.

AU - Martin, F.

AU - Olson, A.

AU - Lindahl, B.D.

N1 - Reporting year: 2014 Metis note: 5647, ME; Data archiving: data archived at publisher

PY - 2014

Y1 - 2014

N2 - 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

AB - 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

KW - international

U2 - 10.1111/nph.12791

DO - 10.1111/nph.12791

M3 - Article

SN - 0028-646X

VL - 203

SP - 245

EP - 256

JO - New Phytologist

JF - New Phytologist

IS - 1

ER -