Résumé
Iron is an essential micronutrient for plant metabolism, playing a key role in photosynthesis and respiration. However, at high concentrations it becomes toxic, promoting the formation of reactive oxygen species and disturbing cellular balance. Iron concentration is then well control by compartmentalization or sequestration mechanisms. Beyond its structural function, the cell wall is a key interface for ion exchanges with the external environment. For the essential iron nutrient, the apoplastic compartment constitutes the main pool, accounting for up to 70% of the total iron in plant roots [1]. Using fluorescents probes to detect redox state of labile iron (Fe2+ and Fe3+) [2], we show that Fe2+ is mainly localized at epidermis cell wall, with a polarized distribution that differ between the young and mature regions of the 7 day-old Arabidopsis seedling root. This suggests a finely tuned regulation of iron at cell wall for maintaining root development and adapting to local physiological needs. The aim of this work is to decipher this mechanism underlying this specific iron distribution within the cell wall and to explore its physiological significance, with a particular focus on the role of pectins in iron binding and the dynamic mobilization of this iron pool.