Light affects the cellular iron (Fe) requirement of phytoplankton because of its presence in major photosynthetic proteins. Thus, interactions between variable Fe concentrations and light intensities could restrict photosynthetic carbon fixation in the ocean. Here we show a narrowing of the optimal light range for growth of a marine cyanobacterium, Prochlorococcus strain NATL1A, a member of LLI ecotype, under Fe limitation. The response of the cells to variations in Fe and light involved differential changes in the cellular content of low‐Fe photosystem II (PSII) and Fe‐rich photosystem I (PSI), and associated up to 23‐fold changes in PSII : PSI ratios, showing an unprecedented extreme plasticity of the photosynthetic apparatus. Our study demonstrated the physiological effects of Fe and light interactions on this low‐light‐adapted Prochlorococcus strain, and increases our understanding of the reasons for the wide distribution of this and possibly other Prochlorococcus strains in the ocean.

中文翻译：

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弱光原绿球菌生态型的光系统组成对铁和光的响应具有极大的可塑性


光影响浮游植物对细胞铁 (Fe) 的需求，因为它存在于主要的光合蛋白质中。因此，不同的铁浓度和光强度之间的相互作用可能会限制海洋中的光合作用碳固定。在这里，我们展示了在铁限制下，海洋蓝藻原绿球菌菌株 NATL1A（LLI 生态型的成员）生长的最佳光照范围的缩小。细胞对 Fe 和光变化的反应涉及低 Fe 光系统 II (PSII) 和富 Fe 光系统 I (PSI) 的细胞含量的差异变化，并且与 PSII : PSI 比率高达 23 倍的变化相关，显示出光合作用器官前所未有的极端可塑性。我们的研究证明了铁和光相互作用对这种低光适应的原绿球菌菌株的生理影响，并增加了我们对这种以及可能的其他原绿球菌菌株在海洋中广泛分布的原因的理解。