The Role of Ion Channels in Plant Salt Tolerance

Abstract

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. Abbreviations VICVoltage-independent channel IRC Inward-rectifying channel ORC Outward-rectifying channel GHK

Mechanisms underlying turgor regulation in the estuarine alga Vaucheria erythrospora (Xanthophyceae) exposed to hyperosmotic shock

“…). Greater H + ‐ATPase pumping rates have been reported in C. corralina under high external Ca 2+ concentrations in response to NaCl shock (Amtmann & Beilby ). In the salt‐tolerant L. succinctum and C. longifolia , an influx of Ca 2+ into the cytosol was found to be necessary for turgor regulation under hypotonic stress (Okazaki & Tazawa ; Bisson et al .…”

“…; Beilby et al . ; Al Khazaaly & Beilby ; Amtmann & Beilby ). The highly negative membrane potential of these algae (up to −200 mV) is thought to allow for H + ‐based co‐transport even in habitats with alkaline pH.…”

“…In green algae and higher plants, non‐selective cation channels (NSCCs) are known to be major routes for passive influx of Na + (Shabala et al . ; Amtmann & Beilby ). While Na + fluxes after a hyperosmotic shock with NaCl could not be measured in this study, turgor recovery was inhibited in a dose‐dependent manner by Gd 3+ (50 and 100 μ m ; Fig.…”

“…Calcium is known to mediate ion transport during turgor regulation by acting as a signalling molecule, for example, through regulation of Ca 2+ -dependent Cl − channels in C. longifolia . Greater H + -ATPase pumping rates have been reported in C. corralina under high external Ca 2+ concentrations in response to NaCl shock (Amtmann & Beilby 2010). In the salt-tolerant L. succinctum and C. longifolia, an influx of Ca 2+ into the cytosol was found to be necessary for turgor regulation under hypotonic stress (Okazaki & Tazawa 1990;.…”

Biochemical Response of Rice Plant to Biotic and Abiotic Stress under Silica Ions and Nanoparticles Application

“…This can further affect PM permeability. Moreover, stress-induced changes in lipid microenvironment around transport proteins affect their kinetic properties and the efficiency of the transport systems (reflected in increased PMP) (Amtmann and Beilby, 2010). It is reasonable, therefore, to conclude that membrane protein alterations under stress might be enhanced in untreated samples and nano silica treated samples, but not so much in silica ions treated ones (Jacobs et al, 2011).…”