Assistant Professor Amherst College Amherst, Massachusetts
Body of Abstract: Iron is an essential mineral nutrient for plant growth and development. However, iron is potentially cytotoxic. To cope with such a paradox, plants have evolved delicate mechanisms to regulate iron at the inter and intracellular levels. In the plant cell, mitochondria and chloroplasts have a considerable iron demand, but they are highly susceptible to iron-induced oxidative stress. Despite the necessity of strict iron regulation in these organelles, much remains unknown about mitochondrial and chloroplast iron transport and regulation. We identified that Arabidopsis Ferroportin 3 (FPN3) is an iron exporter that is dual-targeted to mitochondria and chloroplasts. FPN3 is expressed in shoots regardless of iron conditions, but its expression in roots is increased under iron deficiency. We observed that iron accumulates in fpn3 mutant mitochondria and chloroplasts, but these mutants contain less iron in their shoot and cannot grow as well as wild type under iron deficiency. Furthermore, fpn3 mutants grown under iron deficient conditions exhibit abnormal mitochondrial ultrastructure, implying a critical role of FPN3 in mitochondrial iron homeostasis. Using higher order mutants of fpn3, we are further investigating the potential role of FPN3 in mitigating oxidative stress, as well as inter-organellar iron homeostasis between chloroplasts and mitochondria.