Role of FRD3 in iron translocation and homeostasis

Abstract

Relatively little is known about the process of root to shoot iron translocation. This chapter discusses what is known about iron translocation, especially about iron transport in the xylem, and about iron status signaling between roots and shoots. It also reviews what is known about the FRD3 gene of Arabidopsis thaliana, which appears to be involved in iron translocation. The frd3 mutant phenotype includes chlorosis and constitutive expression of iron uptake responses. These appear to be the result of mislocalization of iron in both the root and the shoot of frd3 mutant plants. This and other evidence indicates that the FRD3 protein is likely to play a role in delivering iron to the shoot in a usable form. Specifically, FRD3 is likely to function in root xylem loading of an iron chelator or other factor necessary for efficient iron uptake out of the xylem or apoplastic space and into leaf cells. Potentially, much can be learned about both iron movement within plants and about iron status signaling from the phenotypes of Arabidopsis plants carrying mutations in the FRD3 gene and from the biochemical properties of the FRD3 protein. © 2006 Springer.