Molecular pieces to the puzzle of the interaction between potassium and sodium uptake in plants.

Potassium uptake is vital for plant growth but in saline soils sodium competes with potassium for uptake across the plasma membrane of plant cells. This can result in high Na+:K+ ratios that reduce plant growth and eventually become toxic. Our understanding of the molecular basis underlying the interaction between essential potassium and toxic sodium was limited until the recent cloning and electrophysiological characterization of several genes encoding different types of molecules that are involved in K+ and Na+ transport. These molecules, and their regulation, are important in determining the K+:Na+ homeostasis of plants in saline soils, although it is not yet known which is most critical in determining the K+:Na+ ratios in whole plants.