plasma membrane Na⁺/H⁺ antiporter SOS1 is essential for salt tolerance in tomato and affects the partitioning of Na⁺ between plant organs

• Published in: Plant, cell and environment Vol. 32; no. 7; pp. 904 - 916
• Main Authors: OLÍAS, RAQUEL, ELJAKAOUI, ZAKIA, LI, JUN, DE MORALES, PAZ ALVAREZ, MARÍN-MANZANO, MARI CARMEN, PARDO, JOSE M, BELVER, ANDRÉS
• Format: Journal Article
• Language: English
• Published: Oxford, UK Oxford, UK : Blackwell Publishing Ltd 01-07-2009; Blackwell Publishing Ltd; Blackwell
• Subjects: Arabidopsis; Biological and medical sciences; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation, Plant; long‐distance Na+ and K+ transport; Lycopersicon esculentum; Lycopersicon esculentum - genetics; Lycopersicon esculentum - metabolism; Plant Leaves - metabolism; Plant Proteins - genetics; Plant Proteins - metabolism; Plant Roots - metabolism; Plants, Genetically Modified - genetics; Plants, Genetically Modified - metabolism; post‐transcriptional gene silencing; RNA Interference; RNA, Plant - genetics; Salt-Tolerant Plants - genetics; Salt-Tolerant Plants - metabolism; SlSOS1; Sodium - metabolism; Sodium-Hydrogen Exchangers - genetics; Sodium-Hydrogen Exchangers - metabolism; Solanum; Solanum lycopersicum (tomato); Xylem - metabolism; RNA interference; Salt resistance; Long distance; Potassium ion; and K; Tomato; Solanum lycopersicum (tomato); Partitioning; Dicotyledones; Angiospermae; Sodium ion; Lycopersicon esculentum; Solanaceae; Halotolerance; Partition; S1SOS1; Plant ecology; transport; post-transcriptional gene silencing; Gene silencing; Vegetable crop; long-distance Na; Plasma membrane; Spermatophyta; Organ
• ISSN: 0140-7791; 1365-3040
• DOI: 10.1111/j.1365-3040.2009.01971.x

We have identified a plasma membrane Na⁺/H⁺ antiporter gene from tomato (Solanum lycopersicum), SlSOS1, and used heterologous expression in yeast to confirm that SlSOS1 was the functional homolog of AtSOS1. Using post-transcriptional gene silencing, we evaluated the role played by SlSOS1 in long-distance Na⁺ transport and salt tolerance of tomato. Tomato was used because of its anatomical structure, more complex than that of Arabidopsis, and its agricultural significance. Transgenic tomato plants with reduced expression of SlSOS1 exhibited reduced growth rate compared to wild-type (WT) plants in saline conditions. This sensitivity correlated with higher accumulation of Na⁺ in leaves and roots, but lower contents in stems of silenced plants under salt stress. Differential distribution of Na⁺ and lower net Na⁺ flux were observed in the xylem sap in the suppressed plants. In addition, K⁺ concentration was lower in roots of silenced plants than in WT. Our results demonstrate that SlSOS1 antiporter is not only essential in maintaining ion homeostasis under salinity, but also critical for the partitioning of Na⁺ between plant organs. The ability of tomato plants to retain Na⁺ in the stems, thus preventing Na⁺ from reaching the photosynthetic tissues, is largely dependent on the function of SlSOS1.