Ion Transporters and Abiotic Stress Tolerance in Plants.

Faïçal Brini,Khaled Masmoudi

doi:10.5402/2012/927436

Faïçal Brini, Khaled Masmoudi

Open Access

https://doi.org/10.5402/2012/927436

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Abstract

Adaptation of plants to salt stress requires cellular ion homeostasis involving net intracellular Na+ and Cl− uptake and subsequent vacuolar compartmentalization without toxic ion accumulation in the cytosol. Sodium ions can enter the cell through several low- and high-affinity K+ carriers. Some members of the HKT family function as sodium transporter and contribute to Na+ removal from the ascending xylem sap and recirculation from the leaves to the roots via the phloem vasculature. Na+ sequestration into the vacuole depends on expression and activity of Na+/H+ antiporter that is driven by electrochemical gradient of protons generated by the vacuolar H+-ATPase and the H+-pyrophosphatase. Sodium extrusion at the root-soil interface is presumed to be of critical importance for the salt tolerance. Thus, a very rapid efflux of Na+ from roots must occur to control net rates of influx. The Na+/H+ antiporter SOS1 localized to the plasma membrane is the only Na+ efflux protein from plants characterized so far. In this paper, we analyze available data related to ion transporters and plant abiotic stress responses in order to enhance our understanding about how salinity and other abiotic stresses affect the most fundamental processes of cellular function which have a substantial impact on plant growth development.

Highlights

Agricultural productivity is severely affected by soil salinity
We analyze available data related to ion transporters and plant abiotic stress responses in order to enhance our understanding about how salinity and other abiotic stresses affect the most fundamental processes of cellular function which have a substantial impact on plant growth development
Yeast complementation screens led to the isolation of plant transporters such as the vacuolar Na+/H+ antiporter AtNHX1 [11] and the plasma membrane K+/Na+ symporter TaHKT1 [12]

Summary

Introduction

Agricultural productivity is severely affected by soil salinity. Environmental stress due to salinity is one of the most serious factors limiting the productivity of agricultural crops, most of which are sensitive to the presence of high concentrations of salts in the soil. The physicochemical similarities between Na+ and K+ lead to a competition at transport and catalytic sites that normally bind the essential cation K+ and maintaining a high cytosolic K+/Na+ ratio is believed to improve salt tolerance [4, 5] Oxidative stress is another aspect of salinity stress which is a consequence of salinity-induced osmotic and/or ionic stress [6]. A common theme of tolerance is the adequate control of salt uptake at the root level, regulation of influx into cells, control over long distance transport, and the compartmentation at both cellular and tissue levels [8, 9] These processes are mediated by membrane transporters and manipulating the activity of this class of proteins has enormous potential to affect plant performance in saline conditions [10]. The paper critically evaluates the reported data to assess which proteins may be suitable as engineering targets to improve crop salt tolerance

Sodium Uptake from Soil

Transporters Involved in Salt Efflux

Sodium Compartmentation

Engineering Plant Salinity Tolerance

Findings

Conclusion