Phosphate (Pi) is an essential element for plant development and metabolism. Due to its low availability and mobility in soils, it is often a limiting nutrient for their growth. This phenomenon is reinforced by the fort-nation of insoluble complexes in the environment with many cations, affecting the solubility of both phosphate and associated ions. This interaction is investigated here for iron, a strong phosphate chelator. Depleting the medium in phosphate clearly resulted in an increase of iron content in Arabidopsis. These modifications triggered molecular responses linked with iron status (transport, homeostasis and accumulation). Interestingly, physiological modifications affecting iron storage were also observed. The accumulation of phosphate/iron complexes in the vacuoles of plants grown in Pi-rich medium disappeared in Pi-depleted medium in favor of accumulation of iron inside the chloroplasts, likely associated with ferritin. (c) 2006 Elsevier Masson SAS. All rights reserved.