Fenton reaction facilitates organic nitrogen acquisition by an ectomycorrhizal fungus
(2018) In New Phytologist 218(1). p.335-343- Abstract
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... (More)
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.
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- author
- Op De Beeck, Michiel LU ; Troein, Carl LU ; Peterson, Carsten LU ; Persson, Per LU and Tunlid, Anders LU
- organization
- publishing date
- 2018-01-03
- type
- Contribution to journal
- publication status
- published
- subject
- keywords
- Fenton reaction, Nitrogen (N), Paxillus involutus, Proteolysis, Soil organic matter (SOM)
- in
- New Phytologist
- volume
- 218
- issue
- 1
- pages
- 335 - 343
- publisher
- Wiley-Blackwell
- external identifiers
-
- pmid:29297591
- scopus:85039988426
- ISSN
- 0028-646X
- DOI
- 10.1111/nph.14971
- project
- MICCS - Molecular Interactions Controlling soil Carbon Sequestration
- language
- English
- LU publication?
- yes
- id
- 4a9fdeeb-5b3b-427d-8ffd-5dfcbddd824b
- date added to LUP
- 2018-01-15 08:47:11
- date last changed
- 2024-04-15 01:20:22
@article{4a9fdeeb-5b3b-427d-8ffd-5dfcbddd824b, abstract = {{<p>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 (<sup>bull</sup>OH), 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. <sup>bull</sup>OH production, ammonium assimilation, and proteolytic activity were measured daily. <sup>bull</sup>OH 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 <sup>bull</sup>OH production occurs in a burst, regulated mainly by ammonium and ferric iron concentrations. We propose that the production of <sup>bull</sup>OH 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.</p>}}, author = {{Op De Beeck, Michiel and Troein, Carl and Peterson, Carsten and Persson, Per and Tunlid, Anders}}, issn = {{0028-646X}}, keywords = {{Fenton reaction; Nitrogen (N); Paxillus involutus; Proteolysis; Soil organic matter (SOM)}}, language = {{eng}}, month = {{01}}, number = {{1}}, pages = {{335--343}}, publisher = {{Wiley-Blackwell}}, series = {{New Phytologist}}, title = {{Fenton reaction facilitates organic nitrogen acquisition by an ectomycorrhizal fungus}}, url = {{http://dx.doi.org/10.1111/nph.14971}}, doi = {{10.1111/nph.14971}}, volume = {{218}}, year = {{2018}}, }