Drought, high salinity and freezing impose osmotic stress on plants. Plants respond to the stress in part by modulating gene expression, which eventually leads to the restoration of cellular homeostasis, detoxification of toxins and recovery of growth. The signal transduction pathways mediating these adaptations can be dissected by combining forward and reverse genetic approaches with molecular, biochemical and physiological studies. Arabidopsis is a useful genetic model system for this purpose and its relatives including the halophyte Thellungiella halophila, can serve as valuable complementary genetic model systems.