Loss of Halophytism by Interference with SOS1 Expression

• Published in: Plant physiology (Bethesda) Vol. 151; no. 1; pp. 210 - 222
• Main Authors: Oh, Dong-Ha, Leidi, Eduardo, Zhang, Quan, Hwang, Sung-Min, Li, Youzhi, Quintero, Francisco J, Jiang, Xingyu, D'Urzo, Matilde Paino, Lee, Sang Yeol, Zhao, Yanxiu, Bahk, Jeong Dong, Bressan, Ray A, Yun, Dae-Jin, Pardo, José M, Bohnert, Hans J
• Format: Journal Article
• Language: English
• Published: Rockville, MD American Society of Plant Biologists 01-09-2009
• Subjects: Arabidopsis - genetics; Arabidopsis - metabolism; Arabidopsis Proteins; Biological and medical sciences; Brassicaceae - genetics; Brassicaceae - metabolism; Cell Death - drug effects; Cell membranes; Down-Regulation; Endocytosis; Environmental Stress and Adaptation to Stress; Fluorescence; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation, Plant - physiology; Plant physiology and development; Plant roots; Plant Roots - cytology; Plant Roots - metabolism; Plant Shoots - metabolism; Plants; RNA Interference; Saccharomyces cerevisiae - genetics; Saccharomyces cerevisiae - metabolism; Salt tolerance; Salt-Tolerant Plants - genetics; Salt-Tolerant Plants - physiology; Salts; Seedlings; Sodium; Sodium - metabolism; Sodium Chloride - pharmacology; Sodium-Hydrogen Exchangers - genetics; Sodium-Hydrogen Exchangers - metabolism; Stress, Physiological; Vacuoles; Plant physiology
• ISSN: 0032-0889; 1532-2548; 1532-2548
• DOI: 10.1104/pp.109.137802

The contribution of SOS1 (for Salt Overly Sensitive 1), encoding a sodium/proton antiporter, to plant salinity tolerance was analyzed in wild-type and RNA interference (RNAi) lines of the halophytic Arabidopsis (Arabidopsis thaliana)-relative Thellungiella salsuginea. Under all conditions, SOS1 mRNA abundance was higher in Thellungiella than in Arabidopsis. Ectopic expression of the Thellungiella homolog ThSOS1 suppressed the salt-sensitive phenotype of a Saccharomyces cerevisiae strain lacking sodium ion (Na⁺) efflux transporters and increased salt tolerance of wild-type Arabidopsis. thsos1-RNAi lines of Thellungiella were highly salt sensitive. A representative line, thsos1-4, showed faster Na⁺ accumulation, more severe water loss in shoots under salt stress, and slower removal of Na⁺ from the root after removal of stress compared with the wild type. thsos1-4 showed drastically higher sodium-specific fluorescence visualized by CoroNa-Green, a sodium-specific fluorophore, than the wild type, inhibition of endocytosis in root tip cells, and cell death in the adjacent elongation zone. After prolonged stress, Na⁺ accumulated inside the pericycle in thsos1-4, while sodium was confined in vacuoles of epidermis and cortex cells in the wild type. RNAi-based interference of SOS1 caused cell death in the root elongation zone, accompanied by fragmentation of vacuoles, inhibition of endocytosis, and apoplastic sodium influx into the stele and hence the shoot. Reduction in SOS1 expression changed Thellungiella that normally can grow in seawater-strength sodium chloride solutions into a plant as sensitive to Na⁺ as Arabidopsis.