Iron economy in Arabidopsis thaliana rosettes

Abstract

Iron is important for plant growth and lack of iron negatively affects crop productivity. When we understand more about how plants prioritize their iron use we can use this knowledge to benefit the people of the world. Plant metabolism can be altered to allocate iron in such a way creating larger and/or healthier edible parts. In the first chapter of this thesis I briefly discuss the biological roles of iron and its function in plants with an emphasis on photosynthesis. In the second chapter I investigated the potential prioritization of iron-dependent proteins in Arabidopsis thaliana plants that were grown hydroponically and exposed to one week of iron deprivation followed by one week of iron resupply. Through the one week of iron depletion the treated plants became visually chlorotic and after one week of iron recovery the treated plants appeared to have fully recovered from the chlorosis. At the end of the recovery week treated plants had significantly less biomass than the control plants yet suffered no indirect effects. To investigate if the decrease in biomass was caused by defects in photosynthetic electron transport chlorophyll fluorescence was measured as well as the photooxidation-reduction values of photosystem I (PSI). Indeed photosynthesis was affected and it was found that there was a decrease in electrons flowing to PSI. With the use of immunoblots it was discovered that the cytochrome b6f complex proteins were strongly affected by iron depletion followed by the subunits of PSI. Furthermore, I found that the abundance of sulfur metabolism proteins decreased in reaction to decreased iron nutrition. In the third chapter I discuss the implications of my findings for plant science and society and I give recommendations for follow up work on this project.