Homeostasis of the micronutrients Ni, Mo and Cl with specific biochemical functions

Homeostasis of three elements nickel, molybdenum and chloride is analysed. These micronutrients, at amounts varying in orders of magnitude, fulfil important cell functions. In general terms, cells use similar strategies to ensure that the elements are within physiological ranges avoiding high toxic concentrations. These strategies correspond to specific carriers, channels and pumps, intermediate steps (chelating/sequestration/binding/metabolic conversion/storage), final steps related to specific enzyme functionality and putative sensing proteins. Single cell homeostasis, coordinated with an efficient redistribution by xylem loading, ensures in turn homeostasis at the whole plant level. Recent advances are based on the molecular identification of some key components.