The most ubiquitous cyanobacteria, Synechococcus, have colonized different marine thermal niches through the evolutionary specialization of lineages adapted to different ranges of temperature seawater. We used the strains of Synechococcus temperature ecotypes to study how light utilization has evolved in the function of temperature. The tropical Synechococcus (clade II) was unable to grow under 16 °C but, at temperatures >25 °C, induced very high growth rates that relied on a strong synthesis of the components of the photosynthetic machinery, leading to a large increase in photosystem cross-section and electron flux. By contrast, the Synechococcus adapted to subpolar habitats (clade I) grew more slowly but was able to cope with temperatures <10 °C. We show that growth at such temperatures was accompanied by a large increase of the photoprotection capacities using the orange carotenoid protein (OCP). Metagenomic analyzes revealed that Synechococcus natural communities show the highest prevalence of the ocp genes in low-temperature niches, whereas most tropical clade II Synechococcus have lost the gene. Moreover, bioinformatic analyzes suggested that the OCP variants of the two cold-adapted Synechococcus clades I and IV have undergone evolutionary convergence through the adaptation of the molecular flexibility. Our study points to an important role of temperature in the evolution of the OCP. We, furthermore, discuss the implications of the different metabolic cost of these physiological strategies on the competitiveness of Synechococcus in a warming ocean. This study can help improve the current hypotheses and models aimed at predicting the changes in ocean carbon fluxes in response to global warming.

最普遍的蓝细菌——聚球藻，通过适应不同海水温度范围的谱系的进化专门化，已经在不同的海洋热生态位中定居。我们使用聚球藻温度生态型菌株来研究光利用在温度函数中的演变。热带聚球藻（进化枝 II）在 16 °C 以下无法生长，但在温度 >25 °C 时，会诱导非常高的生长速率，这依赖于光合机制组件的强力合成，导致光系统大幅增加横截面和电子通量。相比之下，适应亚极地生境的聚球藻（进化枝 I）生长速度较慢，但​​能够应对温度<10 id=15>聚球藻自然群落显示出在低温生态位中ocp基因的最高流行率，而大多数热带进化枝II聚球藻失去了该基因。此外，生物信息学分析表明，两个冷适应聚球藻分支I和IV的OCP变体通过分子灵活性的适应经历了进化趋同。我们的研究指出了温度在 OCP 演化中的重要作用。此外，我们还讨论了这些生理策略的不同代谢成本对聚球藻在变暖海洋中的竞争力的影响。这项研究有助于改进当前的假设和模型，旨在预测海洋碳通量因全球变暖而发生的变化。