Ferritin in bean leaves with constant and changing iron status.

Normal green leaves contain low levels of ferritin which stores 5 to 10% of the total iron (approximately 350 iron atoms/molecule). Chlorotic leaves do not have measurable amounts of ferritin, whereas iron-loaded leaves contain high levels of well-filled ferritin (1,500 to 2,500 iron atoms/molecule). The role of ferritin during a transient iron surplus in leaves was investigated. It is suggested that a short-term overdose of iron transported into the leaf is largely stored in or near the vessels in such a form that it can be quickly mobilized for export. Iron that reaches the mesophyll cells in an overdose situation is stored in ferritin and, when released, is most likely used for the leaf cells themselves and not for export.