Agriculture Reference
In-Depth Information
Chapter 5
Micronutrient Use Efficiency - Cell Biology
of Iron and Its Metabolic Interactions
in Plants
Ilaria Forieri and Ruediger Hell
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 con-
tribute to the regulation, including the control of uptake, the intracellular chelation
by different molecules and the partitioning into the organelles and storage loca-
tions. 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.
Keywords Iron • Micronutrients • Homeostasis • Regulation • Iron transporters
• Deficiency • Partitioning
Introduction: Fe Importance for Plant Nutrition
Iron (Fe) is a chemical element with atomic number 26, which belongs, together
with manganese, cobalt, nickel, copper and zinc, to the metals of the first transition
series in the periodic table. Fe is the most abundant element found on planet Earth,
as it constitutes a significant part of the inner and outer core. It is the fourth most
