Undergraduate Amherst College Amherst, Massachusetts
Body of Abstract: Iron is a micronutrient essential for plant survival, but excess iron is cytotoxic as it facilitates the formation of reactive oxygen species. Thus, iron in plants is highly regulated to ensure proper homeostasis. In Arabidopsis thaliana, iron is acquired through the root epidermal cells following the reduction of ferric iron chelates to soluble ferrous iron, which is then transported across the plasma membrane. After import into the root epidermis, iron is transported towards the endodermis via symplastic and apoplastic routes until it reaches the Casparian strip that blocks apoplastic transport. Symplastic transport involves cytoplasmic diffusion through plasmodesmata. Previous research has suggested a correlation between oxidative stress and rates of cytoplasmic flux. In this study, we are investigating a potential relationship between iron treatment and rates of intercellular diffusion in wildtype and a mutant of Ferroportin 3 (FPN3). FPN3 is a dual-targeted mitochondria and chloroplast iron exporter, which is potentially involved in the management of oxidative stress and might affect intercellular transport. We have been optimizing a procedure that utilizes Fluorescence Recovery After Photobleaching (FRAP) to characterize differences in cytoplasmic flux. The cytoplasmic dye carboxyfluorescein diacetate (CFDA) is being used to illuminate samples, with the recovery of samples’ fluorescence after photobleaching due to an influx of cytoplasm from cells neighboring the bleached area. The recovery of wild type Col0 and mutant fpn3-1 seedlings in growth media, iron sufficient and iron deficient conditions are being considered. Preliminary results suggest that seedlings grown in iron deficient media display a trend of increased fluorescence recovery relative to those grown in iron sufficient conditions, which imply higher rates of cytoplasmic flux in the roots of iron deficient seedlings. Col0 and fpn3-1 seedlings exhibited similar recovery patterns. Future work will involve further optimizing the procedure to understand variations in cytoplasmic flux across different iron conditions.