In addition, transporters involved in the absorption and translocation of Fe in rice have been characterized. The biosynthetic pathway of mugineic acid (MA) has been studied in detail and all the genes involved in the biosynthesis of DMA have been cloned 11. Furthermore, rice is capable of absorbing Fe as Fe(II) 10 as well as Fe(III)-deoxymugineic acid (DMA). Graminaceous plants use a chelation strategy to acquire Fe from soil and secrete mugineic acid family phytosiderophores. Plants have developed sophisticated mechanisms to acquire Fe from soil 9. Thus the uptake, translocation and storage/recycling of Fe is extremely important for normal growth of plants. As a result, the Fe uptake system is triggered ultimately accumulating more Fe 7.Īlthough Fe is abundant in soils, it is not easily available, as it is mainly present as oxidized compounds which are poorly soluble in neutral to alkaline soils. To avoid this, the activity of yeast vacuolar Fe transporter Ccc1 increases resulting in increased Fe accumulation in vacuole and rendering the cytoplasm Fe deficient 8. The disturbance in mitochondrial Fe transport may result in high Fe accumulation in cytoplasm. MRS3-MRS4 knockout yeast (Δ mrs3Δ mrs4) accumulates more Fe compared with wild-type (WT) strain and unable to grow well in Fe-limiting medium. Mrs3 and Mrs4 are yeast ( Saccharomyces cerevisiae) mitochondrial solute carrier family proteins transporting Fe into mitochondria under conditions of low-Fe availability 6, 7. In yeast, the alteration of mitochondrial activity by the inhibition of mitochondrial Fe transport leads to Fe accumulation in vacuoles and Fe deficiency in the cytoplasm. #SHIMO FUJIMOTO FREE#Free Fe ions might be particularly harmful to mitochondria, where free reactive oxygen species are generated as a side reaction of electron transport. On the other hand, excess Fe is toxic through the generation of reactive oxygen species. Thus, limiting the supply of Fe to mitochondria impairs the metabolic and respiratory activities of this organelle and also affects Fe-S proteins in the cytoplasm 5. In mitochondria, Fe is essential for the synthesis of heme by ferrochelatase 2, and for the synthesis of Fe–sulphur cluster-containing proteins (Fe-S proteins) of both the matrix (for example, aconitase and homoaconitate hydratase) and the inner membrane 3, 4. Fe exists in multiple redox states, readily accepting and donating electrons, permitting it to serve as a cofactor for several proteins such as components of the electron transport chain in mitochondria and chloroplast. Fe is essential for several cellular processes, such as respiration, chlorophyll biosynthesis and photosynthetic electron transport 1. Like other organisms, plants require iron (Fe) to complete their life cycle.
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