Adaptation of plants to salt stress: the role of the ion transporters

Abstract

Adaptation to high salinity is achieved by cellular ion homeostasis which involves regulation of toxic sodium ion (Na+) and Chloride ion (Cl−) uptake, preventing the transport of these ions to the aerial parts of the plants and vacuolar sequestration of these toxic ions. Ion transporters have long been known to play roles in maintaining ion homeostasis. Na+ enters the cell through various voltage dependent selective and non-selective ion channels. High Na+ concentration in the plasma membrane is balanced either by uptake of potassium ion (K+) by various potassium importing channels, by salt exclusion mechanism or by sequestration of Na+ in the vacuoles. Therefore, the role of high-affinity potassium transporter, the salt overly sensitive pathway, the most well-defined Na+ exclusion pathway that exports Na+ from cell into xylem and tonoplast localized cation transporters that compartmentalizes Na+ in vacuoles need to be studied in detail and applied to make the plant adaptable to saline soil. Knowledge on the regulation of expression of these transporters by the hormones, microRNAs and other non-coding RNAs can be utilized to manipulate the ion transport. Here, we reviewed paradigm of the ion transporters in salt stress signalling pathways from the recent and past studies aiding transformation of basic knowledge into biotechnological applications to generate engineered salt stress tolerant crops.