Cyanobacterial symbionts diverged in the late Cretaceous towards lineage-specific nitrogen fixation factories in single-celled phytoplankton
Cornejo-Castillo, F.M.; Cabello, A.M.; Salazar, G.; Sánchez-Baracaldo, P.; Lima-Mendez, G.; Hingamp, P.; Alberti, A.; Sunagawa, S.; Bork, P.; de Vargas, C.; Raes, J.; Bowler, C.; Wincker, P.; Zehr, J.P.; Gasol, J.M.; Massana, R.; Acinas, S.G. (2016). Cyanobacterial symbionts diverged in the late Cretaceous towards lineage-specific nitrogen fixation factories in single-celled phytoplankton. Nature Comm. 7(11071). http://dx.doi.org/10.1038/ncomms11071
In: Nature Communications. Nature Publishing Group: London. ISSN 2041-1723; e-ISSN 2041-1723, more
|   |
| Authors | | Top |
- Cornejo-Castillo, F.M.
- Cabello, A.M.
- Salazar, G.
- Sánchez-Baracaldo, P.
- Lima-Mendez, G., more
- Hingamp, P.
|
- Alberti, A.
- Sunagawa, S.
- Bork, P.
- de Vargas, C.
- Raes, J., more
- Bowler, C.
|
- Wincker, P.
- Zehr, J.P.
- Gasol, J.M.
- Massana, R.
- Acinas, S.G.
|
| Abstract |
The unicellular cyanobacterium UCYN-A, one of the major contributors to nitrogen fixation in the open ocean, lives in symbiosis with single-celled phytoplankton. UCYN-A includes several closely related lineages whose partner fidelity, genome-wide expression and time of evolutionary divergence remain to be resolved. Here we detect and distinguish UCYN-A1 and UCYN-A2 lineages in symbiosis with two distinct prymnesiophyte partners in the South Atlantic Ocean. Both symbiotic systems are lineage specific and differ in the number of UCYN-A cells involved. Our analyses infer a streamlined genome expression towards nitrogen fixation in both UCYN-A lineages. Comparative genomics reveal a strong purifying selection in UCYN-A1 and UCYN-A2 with a diversification process ~91 Myr ago, in the late Cretaceous, after the low-nutrient regime period occurred during the Jurassic. These findings suggest that UCYN-A diversified in a co-evolutionary process, wherein their prymnesiophyte partners acted as a barrier driving an allopatric speciation of extant UCYN-A lineages. |
|
