ABSTRACT

Iron (Fe) is involved in multiple processes that contribute to the maintenance of the cellular homeostasis of all living beings. In photosynthetic organisms, Fe is notably required for photosynthesis. Although iron is generally abundant in the environment, it is frequently poorly bioavailable. This review focuses on the molecular strategies that photosynthetic organisms have evolved to optimize iron acquisition, using Arabidopsis thaliana, rice (Oryza sativa), and some unicellular algae as models. Non-graminaceous plants, including Arabidopsis, take up iron from the soil by an acidification-reduction-transport process (strategy I) requiring specific proteins that were recently shown to associate in a dedicated complex. On the other hand, graminaceous plants, such as rice, use the so-called strategy II to acquire iron, which relies on the uptake of Fe³⁺ chelated by phytosiderophores that are secreted by the plant into the rhizosphere. However, apart these main strategies, accessory mechanisms contribute to robust iron uptake in both Arabidopsis and rice. Unicellular algae combine reductive and non-reductive mechanisms for iron uptake and present important specificities compared to land plants. Since the majority of the molecular actors required for iron acquisition in algae are not conserved in land plants, questions arise about the evolution of the Fe uptake processes upon land colonization.

摘要

铁 (Fe) 参与了有助于维持所有生物的细胞稳态的多个过程。在光合生物中，铁是光合作用所必需的。尽管铁通常在环境中含量丰富，但它的生物利用度通常很差。这篇综述着重于光合生物进化以优化铁获取的分子策略，使用拟南芥、水稻 ( Oryza sativa ) 和一些单细胞藻类作为模型。非禾本科植物，包括拟南芥，通过酸化 - 还原 - 运输过程（策略 I）从土壤中吸收铁，该过程需要特定的蛋白质，这些蛋白质最近被证明可以在专门的复合物中结合。另一方面，禾本科植物，如水稻，使用所谓的策略 II 来获取铁，这依赖于植物分泌到根际的植物铁载体螯合的 Fe ^{3+的吸收。}然而，除了这些主要策略之外，辅助机制有助于拟南芥对铁的强烈吸收和米饭。单细胞藻类结合了铁吸收的还原和非还原机制，与陆地植物相比具有重要的特异性。由于在藻类中获取铁所需的大多数分子参与者在陆地植物中并不保守，因此出现了关于陆地殖民化后铁吸收过程的演变的问题。