Iron uptake, signaling, and sensing in plants

Iron (Fe) is an essential micronutrient that affects the growth and development of plants because it participates as a cofactor in numerous physiological and biochemical reactions. As a transition metal, Fe is redoxactive. Fe often exists in soil in the form of insoluble ferric hydroxides that are not bioavailable to plants.Plants have developed sophisticated mechanisms to ensure an adequate supply of Fe in a fluctuating environment. Plants can sense Fe status and modulate the transcription of Fe uptake-associated genes, finallycontrolling Fe uptake from soil to root. There is a critical need to understand the molecular mechanisms bywhich plants maintain Fe homeostasis in response to Fe fluctuations. This review focuses on recentadvances in elucidating the functions of Fe signaling components. Taking Arabidopsis thaliana and Oryzasativa as examples, this review begins by discussing the Fe acquisition systems that control Fe uptake fromsoil, the major components that regulate Fe uptake systems, and the perception of Fe status. Future explorations of Fe signal transduction will pave the way for understanding the regulatory mechanisms that underlie the maintenance of plant Fe homeostasis.