Root Plasma Membrane Transporters Controlling K⁺/Na⁺ Homeostasis in Salt-Stressed Barley

• Published in: Plant physiology (Bethesda) Vol. 145; no. 4; pp. 1714 - 1725
• Main Authors: Chen, Zhonghua, Pottosin, Igor I, Cuin, Tracey A, Fuglsang, Anja T, Tester, Mark, Jha, Deepa, Zepeda-Jazo, Isaac, Zhou, Meixue, Palmgren, Michael G, Newman, Ian A, Shabala, Sergey
• Format: Journal Article
• Language: English
• Published: Rockville, MD American Society of Plant Biologists 01.12.2007; American Society of Plant Physiologists
• Subjects: Adaptation, Physiological; Barley; Biological and medical sciences; Cell Membrane - metabolism; Cell physiology; cytosol; Electric potential; Environmental Stress and Adaptation to Stress; Fundamental and applied biological sciences. Psychology; genetic traits; Genotype; Genotypes; Homeostasis; Homeostasis - physiology; Hordeum - genetics; Hordeum - metabolism; Hordeum - physiology; Hordeum vulgare; membrane potential; Membrane Potentials; Patch-Clamp Techniques; Plant cells; Plant Epidermis - metabolism; Plant physiology and development; Plant roots; Plant Roots - metabolism; Plant Roots - physiology; Plants; plasma membrane; Plasma membrane and permeation; Potassium - metabolism; Potassium Channels - metabolism; Proton Pumps - metabolism; Protoplasts; Protoplasts - metabolism; roots; Salinity; Salt tolerance; Sodium - metabolism; Sodium Chloride - metabolism; Sodium Radioisotopes - metabolism; Tetraethylammonium; transporters; Homeostasis; Root; Stress; Plasma membrane; Salinity
• ISSN: 0032-0889; 1532-2548; 1532-2548
• DOI: 10.1104/pp.107.110262

Plant salinity tolerance is a polygenic trait with contributions from genetic, developmental, and physiological interactions, in addition to interactions between the plant and its environment. In this study, we show that in salt-tolerant genotypes of barley (Hordeum vulgare), multiple mechanisms are well combined to withstand saline conditions. These mechanisms include: (1) better control of membrane voltage so retaining a more negative membrane potential; (2) intrinsically higher H⁺ pump activity; (3) better ability of root cells to pump Na⁺ from the cytosol to the external medium; and (4) higher sensitivity to supplemental Ca²⁺. At the same time, no significant difference was found between contrasting cultivars in their unidirectional ²²Na⁺ influx or in the density and voltage dependence of depolarization-activated outward-rectifying K⁺ channels. Overall, our results are consistent with the idea of the cytosolic K⁺-to-Na⁺ ratio being a key determinant of plant salinity tolerance, and suggest multiple pathways of controlling that important feature in salt-tolerant plants.