Manganese homeostasis and detoxification in plants: the role of Cation Diffusion Facilitators

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Manganese (Mn) is an essential element for plants, but excessive availability of Mn can cause toxicity symptoms. Imbalances in Mn nutrition can therefore severely limit crop growth and productivity. Efficiency of Mn use and detoxification depend on uptake, (re-)translocation and intracellular distribution of the metal. As these processes involve the movement of Mn across membranes, Mn transporters are a major determinant for Mn homeostasis. However, the control of Mn homeostasis in plants is poorly understood because the identity of the Mn transport proteins is largely unknown. The Cation Diffusion Facilitator (CDF) protein family encodes transport proteins for various transition metals, including Mn. The family includes multiple putatively Mn-transporting members in plants which have not yet been characterized. Initial experiments showed that these genes are involved in Mn-related processes. To reveal the roles of those genes in Mn homeostasis and detoxification, we will study (1) their selectivites and transport activities by expressing the genes in yeast mutants, (2) their expression patterns in the model plant Arabidopsis, (3) their subcellular localization, (4) their function in Mn-dependent processes, and (5) their effect on Mn translocation and accumulation. The improved understanding of Mn transport resulting from this project can be utilized to design crops better adapted to the prevalent conditions of Mn availability.