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Research article - Peer-reviewed, 2016

Ectomycorrhizal fungi decompose soil organic matter using oxidative mechanisms adapted from saprotrophic ancestors

Shah, Firoz; Nicolas, Cesar; Bentzer, Johan; Ellstrom, Magnus; Smits, Mark; Rineau, Francois; Canback, Bjorn; Floudas, Dimitrios; Carleer, Robert; Lackner, Gerald; Braesel, Jana; Hoffmeister, Dirk; Henrissat, Bernard; Ahren, Dag; Johansson, Tomas; Hibbett, David S.; Martin, Francis; Persson, Per; Tunlid, Anders


Ectomycorrhizal fungi are thought to have a key role in mobilizing organic nitrogen that is trapped in soil organic matter (SOM). However, the extent to which ectomycorrhizal fungi decompose SOM and the mechanism by which they do so remain unclear, considering that they have lost many genes encoding lignocellulose-degrading enzymes that are present in their saprotrophic ancestors.Spectroscopic analyses and transcriptome profiling were used to examine the mechanisms by which five species of ectomycorrhizal fungi, representing at least four origins of symbiosis, decompose SOM extracted from forest soils.In the presence of glucose and when acquiring nitrogen, all species converted the organic matter in the SOM extract using oxidative mechanisms. The transcriptome expressed during oxidative decomposition has diverged over evolutionary time. Each species expressed a different set of transcripts encoding proteins associated with oxidation of lignocellulose by saprotrophic fungi. The decomposition 'toolbox' has diverged through differences in the regulation of orthologous genes, the formation of new genes by gene duplications, and the recruitment of genes from diverse but functionally similar enzyme families.The capacity to oxidize SOM appears to be common among ectomycorrhizal fungi. We propose that the ancestral decay mechanisms used primarily to obtain carbon have been adapted in symbiosis to scavenge nutrients instead.


decomposition; ectomycorrhizal fungi; evolution; soil organic matter; spectroscopy; transcriptome

Published in

New Phytologist
2016, volume: 209, number: 4, pages: 1705-1719

Authors' information

Lund University
Nicolas, Cesar
Lund Univ
Bentzer, Johan
Lund Univ
Ellstrom, Magnus
Lund Univ
Smits, Mark
Hasselt Univ
Rineau, Francois
Hasselt Univ
Canback, Bjorn
Lund Univ
Floudas, Dimitrios
Clark Univ
Carleer, Robert
Hasselt Univ
Lackner, Gerald
Univ Jena
Braesel, Jana
Univ Jena
Hoffmeister, Dirk
Univ Jena
Henrissat, Bernard
King Abdulaziz Univ
Ahren, Dag
Lund Univ
Johansson, Tomas
Lund Univ
Hibbett, David S.
Clark Univ
Martin, Francis
Univ Lorraine Interact Arbres Microorganismes
Persson, Per
Lund Univ
Tunlid, Anders
Lund Univ

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