Micronutrient Use Efficiency – Cell Biology of Iron and Its Metabolic Interactions in Plants

Abstract

Iron (Fe) is an intriguing nutrient due to its dual nature. Its redox properties make it essential for different vital processes in plant cells. But an excess of Fe can be toxic as it catalyses the formation of reactive oxygen species. Therefore Fe homeostasis must be tightly regulated. Different mechanisms contribute to the regulation, including the control of uptake, the intracellular chelation by different molecules and the partitioning into the organelles and storage locations. Despite its high abundance in soil, Fe solubility is extremely low. Fe availability represents a significant constraint to plant growth and plants have developed distinct strategies to ensure Fe solubilisation and uptake. The Fe-S clusters in the electron transport chain of mitochondria and chloroplasts represent an important sink of Fe. Recent observations suggest that a co-regulation exists between Fe and sulfur metabolism. This is most likely the outcome of the high demand for Fe and S required for the biosynthesis of Fe-S clusters. In the following chapter the uptake strategies and their regulation mechanisms will be introduced. Moreover, different aspects of the regulation of Fe homeostasis in the cell will be presented, including the partitioning in the organelles. In the last section different evidences towards the interaction between Fe and S metabolism will be discussed.