%ASchvarcz, Christopher%AWilson, Samuel%ACaffin, Mathieu%AStancheva, Rosalina%ALi, Qian%ATurk-Kubo, Kendra%AWhite, Angelicque%AKarl, David%AZehr, Jonathan%ASteward, Grieg%BJournal Name: Nature Communications; Journal Volume: 13; Journal Issue: 1; Related Information: CHORUS Timestamp: 2023-11-17 03:07:43 %D2022%INature Publishing Group %JJournal Name: Nature Communications; Journal Volume: 13; Journal Issue: 1; Related Information: CHORUS Timestamp: 2023-11-17 03:07:43 %K %MOSTI ID: 10379324 %PMedium: X %TOverlooked and widespread pennate diatom-diazotroph symbioses in the sea %XAbstract

Persistent nitrogen depletion in sunlit open ocean waters provides a favorable ecological niche for nitrogen-fixing (diazotrophic) cyanobacteria, some of which associate symbiotically with eukaryotic algae. All known marine examples of these symbioses have involved either centric diatom or haptophyte hosts. We report here the discovery and characterization of two distinct marine pennate diatom-diazotroph symbioses, which until now had only been observed in freshwater environments. Rhopalodiaceae diatomsEpithemia pelagicasp. nov. andEpithemia catenatasp. nov. were isolated repeatedly from the subtropical North Pacific Ocean, and analysis of sequence libraries reveals a global distribution. These symbioses likely escaped attention because the endosymbionts lack fluorescent photopigments, havenifHgene sequences similar to those of free-living unicellular cyanobacteria, and are lost in nitrogen-replete medium. Marine Rhopalodiaceae-diazotroph symbioses are a previously overlooked but widespread source of bioavailable nitrogen in marine habitats and provide new, easily cultured model organisms for the study of organelle evolution.

%0Journal Article