Coordinated homeostasis of essential mineral nutrients: a focus on iron.

In plants, iron (Fe) transport and homeostasis are highly regulated processes. Fe deficiency or excess dramatically limit plant and algae productivity. Interestingly, complex and unexpected interconnections between Fe and various macro- and micronutrient homeostatic networks, supposedly maintaining general ionic equilibrium and balanced nutrition, are currently uncovered. Although these phenomena have profound consequences on our understanding of Fe homeostasis and its regulation, the molecular bases and biological significance of these interactions remain poorly understood. Here, we review recent knowledge gained on how Fe interacts with micronutrient (e.g. zinc, manganese) and macronutrient (e.g. sulfur, phosphate) homeostasis, and on how these interactions affect Fe uptake and trafficking. We finally highlight the importance of developing an improved model of how Fe signaling pathways are integrated into functional networks to control plant growth and development in response to fluctuating environments.