SOS1 and halophytism

Abstract

Much is already known about the function and functioning of the three genes that make up the SOS (Salt-Overly-Sensitive) pathway in plants, but recent studies indicate that the linkage between external increases in salinity and stress protection provided by genes SOS1, SOS2 and SOS3 is more complex than previously appreciated. It has recently been shown that the engineered reduced expression of the sodium/proton antiporter SOS1 affected several pathways indicating a role for SOS1 that exceeds its known function as an antiporter. Interference with expression of SOS1, characterized as a sodium/proton antiporter in the halophyte Thellungiella salsuginea converted Thellungiella into an essentially glycophytic species.

Figure 1

Compromised vacuolar alkalization in the root cortex cells under salt stress by inhibition of SOS1 expression in Thellungiella salsuginea. Root cells were loaded with carboxyl-SNARF, a fluorescence pH indicator whose emission spectrum shifts from 580 nm (green) to 640 nm (red) as the pH increases. Confocal images were collected at 580 nm and 640 nm separately and merged. Seedlings of five day-old Thellungiella wild type (A) and the thsos1-4 line (B) were subjected to 150 mM NaCl. Root cortex cells are shown.