<i>Stigonema</i> associated with boreal <i>Stereocaulon</i> possesses the alternative vanadium nitrogenase

Renaudin, Marie; Beaulieu-Laliberté, A.; Bellenger, Jean‐Philippe

doi:10.1017/s0024282921000062

Cited by 7 publications

(3 citation statements)

References 24 publications

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“…To our knowledge, only one other study had shown a correlation between V and N 2 ‐fixation in tropical tree litter and phyllosphere (Moreira et al, 2021). V is a co‐factor of the alternative V‐nitrogenase (‐Nase) enzyme that has been discovered in the genome of many N 2 fixers in tropical, temperate and boreal ecosystems (Betancourt et al, 2008; McRose et al, 2017; Villarreal et al, 2021), including cyanobacteria associated with mosses (Nelson et al, 2019). Given that V is much more abundant than Mo in the environment, including in feather mosses (Table 1), the V‐Nase enzyme can support N 2 ‐fixation, which represents an advantage for diazotrophs living in Mo‐limited ecosystems.…”

Section: Discussionmentioning

confidence: 99%

New insights into the drivers of moss‐associated nitrogen fixation and cyanobacterial biomass in the eastern Canadian boreal forest

et al. 2022

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Moss‐associated cyanobacteria nitrogen (N2‐) fixation can contribute to support moss growth and constitutes a major source of new N in boreal forest ecosystems. The biomass of moss‐colonizing cyanobacteria and their N2‐fixation are usually considered linearly correlated. Yet, recent evidence has shown that cyanobacterial biomass and N2‐fixation can be decoupled, suggesting that they are not necessary affected by the same environmental and ecological drivers. Climate and nutrients were reported as affecting moss‐associated N2‐fixation, with equivocal results, whereas drivers of moss cyanobacterial biomass remain unclear. In addition, these drivers are often determined through manipulative experiments (e.g. fertilization and incubation) and remain to be validated with complementary observational studies to help us better understand future impacts of global change on the moss–cyanobacteria symbiosis. We hypothesized that moss‐associated cyanobacterial biomass is controlled in situ by factors affecting bacterial growth, whereas N2‐fixation is controlled by factors affecting enzymatic reactions. Using random forests, Spearman correlations and linear mixed‐effects models, we determined the main drivers of cyanobacterial biomass and N2‐fixation of two feather moss species, which were collected over 3 years along a 1000‐km latitudinal transect in the eastern Canadian boreal forest. We found that temperature, precipitation and phosphorus were the main positive drivers of moss cyanobacterial biomass and that temperature and molybdenum were the main positive drivers of N2‐fixation. Vanadium was a negative driver of N2‐fixation, suggesting the use of alternative nitrogenases by cyanobacteria. Both cyanobacterial biomass and N2‐fixation were strongly influenced by the moss species and were negatively correlated with moss C:N stoichiometry, highlighting the role of N2‐fixation in moss N enrichment. Synthesis. We identified for the first time some environmental drivers of moss‐associated cyanobacterial biomass and showed that they contrast with the drivers of N2‐fixation, which should be considered in further research and confirmed in other experimental settings. This is an important advance in our knowledge of moss–cyanobacteria associations, which would greatly help in better predicting the impacts of global change on this symbiosis and on nitrogen inputs in boreal forest ecosystems.

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Section: Discussionmentioning

confidence: 99%

New insights into the drivers of moss‐associated nitrogen fixation and cyanobacterial biomass in the eastern Canadian boreal forest

et al. 2022

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“…For boreal feather mosses, P and Mo content enhance the cyanobacterial biomass, and the latter is positively associated with N 2 -fixation rates (Rousk et al 2017a;Renaudin et al 2022a). In addition, V is a co-factor of the complementary V-nitrogenase enzyme triggered in Mo-limited conditions and accounts for up to 50% of the N 2 -fixation by cryptogams in cold environments (Zhang et al 2016;Darnajoux et al 2019;Bellenger et al 2020;Harwood 2020;Villarreal A. et al 2021). This switch from Mo to V-nase activity is exemplified when analyzing Mo:V ratios at a regional scale in Eastern Canada, resulting in a positive relationship with mossrelated N 2 -fixation ability in Mo-depleted and colder environments (Renaudin et al 2022a).…”

Section: Introductionmentioning

confidence: 97%

Differentially abundant bacteria drive the N₂-fixation of a widespread moss in the forest-tundra transition zone

Escolástico-Ortiz

Blasi

Bellenger

et al. 2023

Preprint

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Bryophytes maintain symbiosis with epiphytic bacteria influencing the local nutrient budget. Moss bacterial communities are composed of a core microbiome and bacteria recruited from environmental sources. Notably, symbiotic N2-fixing bacteria contribute to the N budget in northern ecosystems through biological nitrogen fixation. This process may be affected by the abundance of diazotrophs and moss nutrient content. We used the abundant mossRacomitrium lanuginosumin a forest tundra and shrub tundra in Northern Quebec, Canada, to investigate the bacterial and diazotrophic communities associated with habitat type using amplicon sequencing of the bacterial 16S rRNA andnifHgenes and test whether the moss core microbiome has recruitment from the soil bacteria community. ThenifHamplicons and element analysis were used to test the effect of diazotrophic abundance and moss nutrient content on N2-fixation activity estimated by acetylene reduction assays. Moss microbial communities between tundra types hosted similar bacterial diversity but differentially abundant groups. The core microbiome ofR. lanuginosumis composed of bacteria strongly associated with northern mosses with no significant recruitment from the soil. The relative abundances of dominant diazotrophs are significantly correlated with acetylene reduction rates. In contrast, the moss nutrient content did not significantly drive N2-fixation. The proteobacterial generaAzorhizobiumandRhodomicrobiumrepresent newly reported bacteria associated with N2-fixation rates in the tundra. We identified critical bacterial groups related to moss-bacterial symbiosis and N2-fixation in the forest-tundra transition zone, a changing environment susceptible to climate warming.

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“…Additionally, low ratios of acetylene to nitrogen reduction activity (i.e., R ratios), suggestive of complementary BNF, have been observed for temperate soil 9 , boreal moss 11 , 18 , and decaying wood 19 . Further, complementary and uncharacterized nitrogenase genes have been detected in wood mulch 20 , termite hindguts 21 , soil 9 , moss 22 , and cyanolichens 23 , 24 . These studies along with accumulating examples of Mo-limited BNF in boreal 18 , 25 , 26 , temperate, and tropical forest biomes 27 – 33 suggest that Mo-independent, complementary BNF could play a global role.…”

Section: Introductionmentioning

confidence: 99%

Quantification of biological nitrogen fixation by Mo-independent complementary nitrogenases in environmental samples with low nitrogen fixation activity

Haynes

Darnajoux

Han

et al. 2022

Sci Rep

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Biological nitrogen fixation (BNF) by canonical molybdenum and complementary vanadium and iron-only nitrogenase isoforms is the primary natural source of newly fixed nitrogen. Understanding controls on global nitrogen cycling requires knowledge of the isoform responsible for environmental BNF. The isotopic acetylene reduction assay (ISARA), which measures carbon stable isotope (13C/12C) fractionation between ethylene and acetylene in acetylene reduction assays, is one of the few methods that can quantify isoform-specific BNF fluxes. Application of classical ISARA has been challenging because environmental BNF activity is often too low to generate sufficient ethylene for isotopic analyses. Here we describe a high sensitivity method to measure ethylene δ13C by in-line coupling of ethylene preconcentration to gas chromatography-combustion-isotope ratio mass spectrometry (EPCon-GC-C-IRMS). Ethylene requirements in samples with 10% v/v acetylene are reduced from > 500 to ~ 20 ppmv (~ 2 ppmv with prior offline acetylene removal). To increase robustness by reducing calibration error, single nitrogenase-isoform Azotobacter vinelandii mutants and environmental sample assays rely on a common acetylene source for ethylene production. Application of the Low BNF activity ISARA (LISARA) method to low nitrogen-fixing activity soils, leaf litter, decayed wood, cryptogams, and termites indicates complementary BNF in most sample types, calling for additional studies of isoform-specific BNF.

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Stigonema associated with boreal Stereocaulon possesses the alternative vanadium nitrogenase

Cited by 7 publications

References 24 publications

New insights into the drivers of moss‐associated nitrogen fixation and cyanobacterial biomass in the eastern Canadian boreal forest

New insights into the drivers of moss‐associated nitrogen fixation and cyanobacterial biomass in the eastern Canadian boreal forest

Differentially abundant bacteria drive the N₂-fixation of a widespread moss in the forest-tundra transition zone

Quantification of biological nitrogen fixation by Mo-independent complementary nitrogenases in environmental samples with low nitrogen fixation activity

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Stigonema associated with boreal Stereocaulon possesses the alternative vanadium nitrogenase

Cited by 7 publications

References 24 publications

New insights into the drivers of moss‐associated nitrogen fixation and cyanobacterial biomass in the eastern Canadian boreal forest

New insights into the drivers of moss‐associated nitrogen fixation and cyanobacterial biomass in the eastern Canadian boreal forest

Differentially abundant bacteria drive the N2-fixation of a widespread moss in the forest-tundra transition zone

Quantification of biological nitrogen fixation by Mo-independent complementary nitrogenases in environmental samples with low nitrogen fixation activity

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Differentially abundant bacteria drive the N₂-fixation of a widespread moss in the forest-tundra transition zone