The dynamics of iron in the leaf apoplast

Abstract

The leaf apoplast plays an important physiological role in nutrient transport and storage, however, its significance for the iron (Fe) nutrition is not sufficiently understood. There are only few studies in the literature primarily on the mechanism of Fe absorption by leaf cells; even less information is available on the mobility and binding forms of Fe in the leaf apoplast. This review summarizes current knowledge (sometimes very controversial) of the role of leaf apoplastic features (e.g. pH and organic acids) in modulating both the physiological availability of apoplastic Fe and reduction-mediated Fe uptake into the mesophyll cells. The conclusions drawn from our own studies contrast with the hypothesis of Fe inactivation in leaves induced by high bicarbonate or/and nitrate supply to roots.