Unraveling the new biological roles and possible applications of phytosiderophores in plants and mammals

抄録

Iron is an essential element for all living organisms. The ability of plants to absorb inorganic iron from soil is important not only for plants but also for mammals, which ultimately rely on plants as their nutrient source. In contrast to most plant species, Poaceae plants, including rice, have developed a distinct chelation strategy to efficiently acquire insoluble soil iron using iron-chelating substances such as mugineic acid (MAs), called phytosiderophores. Genes involved in the biosynthesis and transport of MAs and their resulting iron(III)-MA complexes across membranes have been identified. On the other hand, an efficient short-step synthesis of the substrates MA and 2′-deoxymugineic acid (DMA) has enabled a sufficient supply of these compounds. Furthermore, owing to the chemical synthesis of proline-2′-deoxymugineic acid (PDMA), a cost-effective analog of DMA, the effectiveness of phytosiderophores in promoting rice growth in alkaline soil has been demonstrated at an experimental field scale. Nicotianamine (NA), an MAs precursor essential for metal translocation within plant tissues, was recently shown to be absorbed as an iron(II) complex in the mouse small intestine by an amino acid transporter. The discovery of the biological role of NA in iron absorption by the small intestine not only highlights the biological significance of NA across the plant and animal kingdoms but also opens new possibilities for biofortification approaches. Here, we discuss the recent findings in MA research in terms of plant growth, application in agriculture, and the emerging nutraceutical value of NA in iron absorption in mammals.