The role of ion channels in plant salt tolerance

Salinisation of agricultural land threatens world food production because it exposes crops to low water potential and high concentration of toxic ions in the soil. In particular, all major crops are sensitive to high concentrations of sodium (Na+). Due to the negative electrical potential inside cells Na+ influx into plant roots can occur through ion channels or other membrane transport proteins that facilitate passive diffusion of Na+ across the plasma membrane. In this chapter, we discuss the contribution of different types of ion channels to Na+ influx. In the first part of the chapter, we recapitulate the basic properties of different types of plant ion channels such as voltage-dependence of gating and relative selectivity for Na+ and potassium and build a simple model to assess how these channels contribute to whole-cell ionic current and Na+ uptake. In the second part of the chapter, we describe a number of experimental studies that have investigated Na+ flux and ion channel currents in different plant species. The combined evidence suggests that salt tolerance in plants is based on the restriction of Na+ influx through voltage-independent ion channels