Marine <i>Synechococcus</i> picocyanobacteria: Light utilization across latitudes
Christophe Six, Morgane Ratin, Dominique Marie, Erwan Corre
Abstract
Significance Phytoplankton drives most of the carbon pumping of the world ocean through the photosynthesis process. We show how Synechococcus picocyanobacteria, a very abundant marine phytoplankton, have adapted the light utilization process to colonize different thermal niches. At high temperature, tropical Synechococcus induce strong synthesis of most photosynthetic complexes and can thus considerably increase growth. By contrast, subpolar Synechococcus grow more slowly but are capable of surviving at low temperature. To do so, they notably use the photoprotective orange carotenoid protein, and we show that temperature has been a major factor in the molecular evolution of this protein in the oceans. Our study can allow the improving of current models predicting the changes in carbon fluxes in a warming ocean.