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Ectomycorrhizal fungi and the enzymatic liberation of nitrogen from soil organic matter: why evolutionary history matters
Author(s) -
Pellitier Peter T.,
Zak Donald R.
Publication year - 2018
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.14598
Subject(s) - biogeochemical cycle , biology , organic matter , ecosystem , lineage (genetic) , enzyme , extracellular , symbiosis , botany , ectomycorrhiza , ecology , horizontal gene transfer , evolutionary ecology , host (biology) , gene , phylogenetics , mycorrhiza , bacteria , biochemistry , genetics
ContentsSummary 68 I. Introduction 68 II. Have ECM fungi retained genes with lignocellulolytic potential from saprotrophic ancestors? 69 III. Are genes with saprotrophic function expressed by ECM fungi when in symbiosis? 71 IV. Do transcribed enzymes operate to obtain N from SOM? 71 V. Is the organic N derived from SOM transferred to the plant host? 71 VI. Concluding remarks 72Acknowledgements 72References 72Summary The view that ectomycorrhizal ( ECM ) fungi commonly participate in the enzymatic liberation of nitrogen (N) from soil organic matter ( SOM ) has recently been invoked as a key mechanism governing the biogeochemical cycles of forest ecosystems. Here, we provide evidence that not all evolutionary lineages of ECM have retained the genetic potential to produce extracellular enzymes that degrade SOM , calling into question the ubiquity of the proposed mechanism. Further, we discuss several untested conditions that must be empirically validated before it is certain that any lineage of ECM fungi actively expresses extracellular enzymes in order to degrade SOM and transfer N contained therein to its host plant.