Heterotrophic N-2-fixation contributes to nitrogen economy of a common wetland sedge, Schoenoplectus californicus

0495233 - BC 2019 RIV US eng J - Journal Article
Rejmánková, E. - Sirová, Dagmara - Castle, S.T. - Bárta, J. - Carpenter, H.
Heterotrophic N-2-fixation contributes to nitrogen economy of a common wetland sedge, Schoenoplectus californicus.
PLoS ONE. Roč. 13, č. 4 (2018), č. článku e0195570. ISSN 1932-6203. E-ISSN 1932-6203
Institutional support: RVO:60077344
Keywords : n-2 fixation * bacterial endophytes * plant * soil * phosphorus
OECD category: Plant sciences, botany
Impact factor: 2.776, year: 2018

A survey of the ecological variability within 52 populations of Schoenoplectus californicus (C.A. Mey.) Sojak across its distributional range revealed that it is commonly found in nitrogen (N) limited areas, but rarely in phosphorus limited soils. We explored the hypothesis that S. californicus supplements its nitrogen demand by bacterial N-2-fixation processes associated with its roots and rhizomes. We estimated N-2-fixation of diazotrophs associated with plant rhizomes and roots from several locations throughout the species' range and conducted an experiment growing plants in zero, low, and high N additions. Nitrogenase activity in rhizomes and roots was measured using the acetylene reduction assay. The presence of diazotrophs was verified by the detection of the nifHgene. Nitrogenase activity was restricted to rhizomes and roots and it was two orders of magnitude higher in the latter plant organs (81 and 2032 nmol C2H4 g DW-1 d(-1), respectively). Correspondingly, 40x more nifH gene copies were found on roots compared to rhizomes. The proportion of the nifHgene copies in total bacterial DNA was positively correlated with the nitrogenase activity. In the experiment, the contribution of fixed N to the plant N content ranged from 13.8% to 32.5% among clones from different locations. These are relatively high values for a non-cultivated plant and justify future research on the link between N-fixing bacteria and S. californicus production.
Permanent Link: http://hdl.handle.net/11104/0288777