Date of Award

1-1-2013

Document Type

Open Access Thesis

Department

Biological Sciences

First Advisor

Erin Connolly

Abstract

Iron deficiency is the most common human nutritional disorder in the world today, affecting approximately 2 billon people worldwide, almost a third of the world's population. For most of the world's population, plant foods serve as the major source of dietary iron. One approach that may contribute towards the solution of iron deficiency is the development of crop plants that contain higher levels of bioavailable iron. This project focuses on FRO6, a ferric chelate reductase in Arabidopsis thaliana that is thought to reduce apoplastic iron for transport across the plasma membrane in leaf cells. We hypothesize therefore that FRO6 controls iron content of leaves and provides iron needed for photosynthesis, a vital process in plants. In order to examine the proposed function of FRO6, we obtained two FRO6 loss-of-function lines, fro6-1 and fro6-2 and compared these lines to the WT to determine the role of FRO6 in iron homeostasis in plants. fro6-1 contains an insertion in the 8th intron of the gene, while fro6-2 contains an insertion in the 8th exon of the gene. We demonstrate that fro6-1 and fro6-2 are both homozygous for the insertion. Despite this, fro6-1 and fro6-2 mutants express FRO6 transcript, possibly because the insertion does not destabilize the transcript. Leaf disks prepared from fro6-1 and fro6-2 show a significant decrease in ferric reductase activity compared to WT leaf disks, indicating a putative role for FRO6 in reduction of apoplastic Fe in leaves. Consistent with the fact that FRO6 is not expressed in roots, fro6-1 mutant roots did not show a significant decrease in ferric reductase activity compared to the roots of WT plants. The fro6-1 plants show a reduced flowering time as compared to WT plants. Taken together, these data indicate that FRO6 is likely responsible for mediating the reduction of ferric iron to ferrous iron at the plasma membrane of leaf cells.

Rights

© 2013, Margo Ellen Maynes

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