1
|
Sirová D, Santrůček J, Adamec L, Bárta J, Borovec J, Pech J, Owens SM, Santrůčková H, Schäufele R, Storchová H, Vrba J. Dinitrogen fixation associated with shoots of aquatic carnivorous plants: is it ecologically important? Ann Bot 2014; 114:125-33. [PMID: 24817095 PMCID: PMC4071093 DOI: 10.1093/aob/mcu067] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/29/2013] [Accepted: 03/11/2014] [Indexed: 05/08/2023]
Abstract
BACKGROUND AND AIMS Rootless carnivorous plants of the genus Utricularia are important components of many standing waters worldwide, as well as suitable model organisms for studying plant-microbe interactions. In this study, an investigation was made of the importance of microbial dinitrogen (N2) fixation in the N acquisition of four aquatic Utricularia species and another aquatic carnivorous plant, Aldrovanda vesiculosa. METHODS 16S rRNA amplicon sequencing was used to assess the presence of micro-organisms with known ability to fix N2. Next-generation sequencing provided information on the expression of N2 fixation-associated genes. N2 fixation rates were measured following (15)N2-labelling and were used to calculate the plant assimilation rate of microbially fixed N2. KEY RESULTS Utricularia traps were confirmed as primary sites of N2 fixation, with up to 16 % of the plant-associated microbial community consisting of bacteria capable of fixing N2. Of these, rhizobia were the most abundant group. Nitrogen fixation rates increased with increasing shoot age, but never exceeded 1·3 μmol N g(-1) d. mass d(-1). Plant assimilation rates of fixed N2 were detectable and significant, but this fraction formed less than 1 % of daily plant N gain. Although trap fluid provides conditions favourable for microbial N2 fixation, levels of nif gene transcription comprised <0·01 % of the total prokaryotic transcripts. CONCLUSIONS It is hypothesized that the reason for limited N2 fixation in aquatic Utricularia, despite the large potential capacity, is the high concentration of NH4-N (2·0-4·3 mg L(-1)) in the trap fluid. Resulting from fast turnover of organic detritus, it probably inhibits N2 fixation in most of the microorganisms present. Nitrogen fixation is not expected to contribute significantly to N nutrition of aquatic carnivorous plants under their typical growth conditions; however, on an annual basis the plant-microbe system can supply nitrogen in the order of hundreds of mg m(-2) into the nutrient-limited littoral zone, where it may thus represent an important N source.
Collapse
Affiliation(s)
- Dagmara Sirová
- Department of Ecosystem Biology, Department of Experimental Plant Biology, Faculty of Science, University of South Bohemia, Branišovská 31, CZ-37005 České Budějovice, Czech Republic
| | - Jiří Santrůček
- Department of Ecosystem Biology, Department of Experimental Plant Biology, Faculty of Science, University of South Bohemia, Branišovská 31, CZ-37005 České Budějovice, Czech Republic Institute of Plant Molecular Biology, Biology Centre AS CR, Branišovská 31, CZ-37005 České Budějovice, Czech Republic
| | - Lubomír Adamec
- Section of Plant Ecology, Institute of Botany AS CR, Dukelská 135, CZ-37982 Třeboň, Czech Republic
| | - Jiří Bárta
- Department of Ecosystem Biology, Department of Experimental Plant Biology, Faculty of Science, University of South Bohemia, Branišovská 31, CZ-37005 České Budějovice, Czech Republic
| | - Jakub Borovec
- Institute of Hydrobiology, Biology Centre AS CR, Na Sádkách 7, CZ-37005 České Budějovice, Czech Republic
| | - Jiří Pech
- Institute of Applied Informatics, Faculty of Science, University of South Bohemia, Branišovská 31, CZ-37005 České Budějovice, Czech Republic
| | - Sarah M Owens
- Institute of Genomics and Systems Biology, Argonne National Laboratory, Argonne, and Computation Institute, University of Chicago, Chicago, IL, USA
| | - Hana Santrůčková
- Department of Ecosystem Biology, Department of Experimental Plant Biology, Faculty of Science, University of South Bohemia, Branišovská 31, CZ-37005 České Budějovice, Czech Republic
| | - Rudi Schäufele
- Department of Grassland Study, Technical University Munich, Alte Akademie 12, Freising-Weihenstephan, Germany
| | - Helena Storchová
- Institute of Experimental Botany AS CR, Rozvojová 263, CZ-16502 Prague 6-Lysolaje, Czech Republic
| | - Jaroslav Vrba
- Department of Ecosystem Biology, Department of Experimental Plant Biology, Faculty of Science, University of South Bohemia, Branišovská 31, CZ-37005 České Budějovice, Czech Republic Institute of Hydrobiology, Biology Centre AS CR, Na Sádkách 7, CZ-37005 České Budějovice, Czech Republic
| |
Collapse
|