TitleDinitrogen fixation associated with shoots of aquatic carnivorous plants: is it ecologically important?
Publication TypeMiscellaneous
Year of Publication2014
AuthorsSirová, D, Santrucek, J, Adamec, L, Bárta, J, Borovec, J, Pech, J, Owens, SM, Schaeufele, R, Štorchová, H, Vrba, J
KeywordsAldrovanda vesiculosa, aquatic carnivorous plants, australis, daily nitrogen gain, intermedia, N nutrition, N-15(2) labelling, nitrogen fixation, Periphyton, reflexa, traps, U, Utricularia vulgaris

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 (N-2) fixation in the N acquisition of four aquatic Utricularia species and another aquatic carnivorous plant, Aldrovanda vesiculosa. 16S rRNA amplicon sequencing was used to assess the presence of micro-organisms with known ability to fix N-2. Next-generation sequencing provided information on the expression of N-2 fixation-associated genes. N-2 fixation rates were measured following N-15(2)-labelling and were used to calculate the plant assimilation rate of microbially fixed N-2. Utricularia traps were confirmed as primary sites of N-2 fixation, with up to 16 % of the plant-associated microbial community consisting of bacteria capable of fixing N-2. Of these, rhizobia were the most abundant group. Nitrogen fixation rates increased with increasing shoot age, but never exceeded 1 center dot 3 mu mol N g(-1) d. mass d(-1). Plant assimilation rates of fixed N-2 were detectable and significant, but this fraction formed less than 1 % of daily plant N gain. Although trap fluid provides conditions favourable for microbial N-2 fixation, levels of nif gene transcription comprised