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Biological nitrogen fixation by alternative nitrogenases in boreal cyanolichens: importance of molybdenum availability and implications for current biological nitrogen fixation estimates
Author(s) -
Darnajoux Romain,
Zhang Xinning,
McRose Darcy L.,
Miadlikowska Jolanta,
Lutzoni François,
Kraepiel Anne M. L.,
Bellenger JeanPhilippe
Publication year - 2017
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.14166
Subject(s) - nitrogenase , nitrogen fixation , nostoc , lichen , ecology , biology , ecosystem , cyanobacteria , nitrogen cycle , biogeochemistry , molybdenum , botany , environmental chemistry , nitrogen , chemistry , inorganic chemistry , bacteria , organic chemistry , genetics
Summary Cryptogamic species and their associated cyanobacteria have attracted the attention of biogeochemists because of their critical roles in the nitrogen cycle through symbiotic and asymbiotic biological fixation of nitrogen ( BNF ). BNF is mediated by the nitrogenase enzyme, which, in its most common form, requires molybdenum at its active site. Molybdenum has been reported as a limiting nutrient for BNF in many ecosystems, including tropical and temperate forests. Recent studies have suggested that alternative nitrogenases, which use vanadium or iron in place of molybdenum at their active site, might play a more prominent role in natural ecosystems than previously recognized. Here, we studied the occurrence of vanadium, the role of molybdenum availability on vanadium acquisition and the contribution of alternative nitrogenases to BNF in the ubiquitous cyanolichen Peltigera aphthosa s.l. We confirmed the use of the alternative vanadium‐based nitrogenase in the Nostoc cyanobiont of these lichens and its substantial contribution to BNF in this organism. We also showed that the acquisition of vanadium is strongly regulated by the abundance of molybdenum. These findings show that alternative nitrogenase can no longer be neglected in natural ecosystems, particularly in molybdenum‐limited habitats.