Iron stress responses in roots of strategy i plants

Abstract

In concert with phosphorus and nitrogen, iron belongs to the nutrients that most commonly restrict growth of plants. Being rapidly oxidized and immobilized, the more soluble ferrous species is rarely available in sufficient amounts; instead, ferric iron is mainly present in oxi-hydrates that cannot be taken up by plants. Plants have evolved a syndrome of responses to balance iron levels within cells, comprising of sensing the levels of available iron in leaves and roots, mobilization of iron pools in the immediate vicinity of root epidermal cells, and uptake and distribution within the plant. This system appears to be conserved among plants. When iron sources are limited, in dicots and non-graminaceous monocots a reduction-based iron uptake mechanism is induced which is not iron-regulated in grasses. The major differences between these two groups of plants seems to be related i) to the control of the iron reduction/iron uptake step in iron acquisition, and ii) in the evolution of the formation of iron-Avid phytosiderophores in grasses, which allows uptake of iron without prior reduction. © 2006 Springer.