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Per Persson. Photo.

Per Persson

Director

Per Persson. Photo.

Fenton reaction facilitates organic nitrogen acquisition by an ectomycorrhizal fungus

Author

  • Michiel Op De Beeck
  • Carl Troein
  • Carsten Peterson
  • Per Persson
  • Anders Tunlid

Summary, in English

Boreal trees rely on their ectomycorrhizal fungal symbionts to acquire growth-limiting nutrients, such as nitrogen (N), which mainly occurs as proteins complexed in soil organic matter (SOM). The mechanisms for liberating this N are unclear as ectomycorrhizal fungi have lost many genes encoding lignocellulose-degrading enzymes present in their saprotrophic ancestors. We hypothesized that hydroxyl radicals (bullOH), produced by the ectomycorrhizal fungus Paxillus involutus during growth on SOM, are involved in liberating organic N. Paxillus involutus was grown for 7 d on N-containing or N-free substrates that represent major organic compounds of SOM. bullOH production, ammonium assimilation, and proteolytic activity were measured daily. bullOH production was strongly induced when P. involutus switched from ammonium to protein as the main N source. Extracellular proteolytic activity was initiated shortly after the oxidation. Oxidized protein substrates induced higher proteolytic activity than unmodified proteins. Dynamic modeling predicted that bullOH production occurs in a burst, regulated mainly by ammonium and ferric iron concentrations. We propose that the production of bullOH and extracellular proteolytic enzymes are regulated by similar nutritional signals. Oxidation works in concert with proteolysis, improving N liberation from proteins in SOM. Organic N mining by ectomycorrhizal fungi has, until now, only been attributed to proteolysis.

Department/s

  • MEMEG
  • Computational Biology and Biological Physics
  • Centre for Environmental and Climate Science (CEC)
  • BECC - Biodiversity and Ecosystem services in a Changing Climate
  • Microbial Ecology

Publishing year

2018-01-03

Language

English

Pages

335-343

Publication/Series

New Phytologist

Volume

218

Issue

1

Document type

Journal article

Publisher

Wiley-Blackwell

Topic

  • Microbiology
  • Botany

Keywords

  • Fenton reaction
  • Nitrogen (N)
  • Paxillus involutus
  • Proteolysis
  • Soil organic matter (SOM)

Status

Published

Project

  • MICCS - Molecular Interactions Controlling soil Carbon Sequestration

Research group

  • Microbial Ecology

ISBN/ISSN/Other

  • ISSN: 0028-646X