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Molybdenum threshold for ecosystem scale alternative vanadium nitrogenase activity in boreal forests.

Publication ,  Journal Article
Darnajoux, R; Magain, N; Renaudin, M; Lutzoni, F; Bellenger, J-P; Zhang, X
Published in: Proceedings of the National Academy of Sciences of the United States of America
December 2019

Biological nitrogen fixation (BNF) by microorganisms associated with cryptogamic covers, such as cyanolichens and bryophytes, is a primary source of fixed nitrogen in pristine, high-latitude ecosystems. On land, low molybdenum (Mo) availability has been shown to limit BNF by the most common form of nitrogenase (Nase), which requires Mo in its active site. Vanadium (V) and iron-only Nases have been suggested as viable alternatives to countering Mo limitation of BNF; however, field data supporting this long-standing hypothesis have been lacking. Here, we elucidate the contribution of vanadium nitrogenase (V-Nase) to BNF by cyanolichens across a 600-km latitudinal transect in eastern boreal forests of North America. Widespread V-Nase activity was detected (∼15-50% of total BNF rates), with most of the activity found in the northern part of the transect. We observed a 3-fold increase of V-Nase contribution during the 20-wk growing season. By including the contribution of V-Nase to BNF, estimates of new N input by cyanolichens increase by up to 30%. We find that variability in V-based BNF is strongly related to Mo availability, and we identify a Mo threshold of ∼250 ng·glichen-1 for the onset of V-based BNF. Our results provide compelling ecosystem-scale evidence for the use of the V-Nase as a surrogate enzyme that contributes to BNF when Mo is limiting. Given widespread findings of terrestrial Mo limitation, including the carbon-rich circumboreal belt where global change is most rapid, additional consideration of V-based BNF is required in experimental and modeling studies of terrestrial biogeochemistry.

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Published In

Proceedings of the National Academy of Sciences of the United States of America

DOI

EISSN

1091-6490

ISSN

0027-8424

Publication Date

December 2019

Volume

116

Issue

49

Start / End Page

24682 / 24688

Related Subject Headings

  • Vanadium
  • United States
  • Taiga
  • Symbiosis
  • Soil
  • Nostoc
  • Nitrogenase
  • Nitrogen Fixation
  • Molybdenum
  • Lichens
 

Citation

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Darnajoux, R., Magain, N., Renaudin, M., Lutzoni, F., Bellenger, J.-P., & Zhang, X. (2019). Molybdenum threshold for ecosystem scale alternative vanadium nitrogenase activity in boreal forests. Proceedings of the National Academy of Sciences of the United States of America, 116(49), 24682–24688. https://doi.org/10.1073/pnas.1913314116
Darnajoux, Romain, Nicolas Magain, Marie Renaudin, François Lutzoni, Jean-Philippe Bellenger, and Xinning Zhang. “Molybdenum threshold for ecosystem scale alternative vanadium nitrogenase activity in boreal forests.Proceedings of the National Academy of Sciences of the United States of America 116, no. 49 (December 2019): 24682–88. https://doi.org/10.1073/pnas.1913314116.
Darnajoux R, Magain N, Renaudin M, Lutzoni F, Bellenger J-P, Zhang X. Molybdenum threshold for ecosystem scale alternative vanadium nitrogenase activity in boreal forests. Proceedings of the National Academy of Sciences of the United States of America. 2019 Dec;116(49):24682–8.
Darnajoux, Romain, et al. “Molybdenum threshold for ecosystem scale alternative vanadium nitrogenase activity in boreal forests.Proceedings of the National Academy of Sciences of the United States of America, vol. 116, no. 49, Dec. 2019, pp. 24682–88. Epmc, doi:10.1073/pnas.1913314116.
Darnajoux R, Magain N, Renaudin M, Lutzoni F, Bellenger J-P, Zhang X. Molybdenum threshold for ecosystem scale alternative vanadium nitrogenase activity in boreal forests. Proceedings of the National Academy of Sciences of the United States of America. 2019 Dec;116(49):24682–24688.
Journal cover image

Published In

Proceedings of the National Academy of Sciences of the United States of America

DOI

EISSN

1091-6490

ISSN

0027-8424

Publication Date

December 2019

Volume

116

Issue

49

Start / End Page

24682 / 24688

Related Subject Headings

  • Vanadium
  • United States
  • Taiga
  • Symbiosis
  • Soil
  • Nostoc
  • Nitrogenase
  • Nitrogen Fixation
  • Molybdenum
  • Lichens