Role of the plasma membrane NA+/H+ ANTIPORTER SOS1 in tomato plants under saline conditions

TL;DRAbstract

Maintaining a high K+/Na+ ratio in the cell cytosol, along with the processes of transport implicated in the xylem and phloem loading/unloading of Na+ in plants (long-distance transport) are key aspects in plant salt tolerance. The Ca2+-dependent regulatory SOS pathway involved in salinity tolerance has been reported in Arabidopsis, by regulating Na+ and K+ homeostasis as well as long-distance Na+ transport. We recently isolated the SlSOS1 gene, encoding a Na+/H+ antiporter from tomato. By silencing of SlSOS1 in tomato plants we have shown that, besides its main action in extruding Na+ out the root, SlSOS1 is critical for the partitioning of Na+ in plant organs and the ability of tomato plants to retain Na+ in the stems, having an effect on K+ nutrition. We hypothesized that the action of SOS1 to achieve Na+ (and K+) homeostasis should be coordinated with class I HKT1 transporters, as previously suggested in Arabidopsis. Thus, dysfunction of either system might alter long-distance tran

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