The poorly understood filamentous cyanobacterium Pseudanabaena is commonly epiphytic on Microcystis colonies and their abundances are often highly correlated during blooms. The response and adaptation of Microcystis to iron limitation have been extensively studied, but the strategies Pseudanabaena uses to respond to iron limitation are largely unknown. Here, physiological responses to iron limitation were compared between one Pseudanabaena and two Microcystis strains grown under different light intensities. The results showed that low‐intensity light exacerbated, but high‐intensity light alleviated, the negative effect of iron limitation on Pseudanabaena growth relative to two Microcystis strains. It was found that robust light‐harvesting and photosynthetic efficiency allowed adaptation of Pseudanabaena to low light availability relative to two Microcystis strains only during iron sufficiency. The results also indicated that a larger investment in the photosynthetic antenna probably contributed to light/iron co‐limitation of Pseudanabaena relative to two Microcystis strains under both light and iron limitation. Furthermore, the lower antenna pigments/chlorophyll a ratio and photosynthetic efficiency, and higher nonphotochemical quenching and saturation irradiance provided Pseudanabaena photoadaptation and photoprotection advantages over the two Microcystis strains under the high‐light condition. The lower investment in antenna pigments of Pseudanabaena than the two Microcystis strains under high‐light intensity is likely an efficient strategy for both saving iron quotas and decreasing photosensitivity. Therefore, when compared with Microcystis, the high plasticity of antenna pigments, along with the excellent photoadaptation and photoprotection ability of Pseudanabaena, probably ensures its ecological success under iron limitation when light is sufficient.

中文翻译：

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光合作用对光利用的适应性决定了形成花的蓝藻假单胞菌对铁的限制的生态成功。

鲜为人知的丝状蓝藻假单胞菌通常在微囊藻菌落上是附生的，它们的丰度在开花期间通常高度相关。微囊藻对铁限制的反应和适应性已被广泛研究，但是假单胞菌用于响应铁限制的策略在很大程度上是未知的。在这里，比较了在一个假单胞菌和两个在不同光照强度下生长的微囊藻菌株对铁限制的生理反应。结果表明，低强度光会加剧，但高强度光会减轻，铁限制对假单胞菌的负面影响相对于两个微囊藻菌株的生长。研究发现，相对于两个微囊藻菌株，仅在铁充足的情况下，强大的采光和光合作用效率就使假单胞菌适应低光利用率。结果还表明，在光和铁限制下，相对于两个微囊藻菌株，光合天线的较大投资可能有助于假单胞菌的光/铁共限制。此外，较低的触角色素/叶绿素a比率和光合作用效率，以及较高的非光化学猝灭和饱和辐照度提供了假单胞菌在高光照条件下，与两种微囊藻菌株相比，其光适应性和光保护性优势。在高光强度下，比两个微囊藻菌株在Pseudanabaena天线色素上的投资要低，这可能是节省铁配额和降低光敏性的有效策略。因此，与微囊藻相比，触角颜料的高可塑性，以及假单胞菌的出色的光适应性和光保护能力，可能在光充足的铁限制下确保其生态学上的成功。