Osmotic adjustment and plant adaptation to environmental changes related to drought and salinity.
The salinization and water deficit of soil are widespread environmental problems in limiting plant survival, growth, and productivity. However, some plants could adopt some strategies to resist salinity and drought stresses. Among these strategies, the mechanism of osmotic adjustment could help plants and algae to avoid ion toxicity and maintain water uptake in both stresses by accumulating large quantities of osmolytes. Two types of osmolytes, organic solutes and inorganic ions, play a key role in osmotic adjustment. Different osmolytes and their osmotic adjustment actions are different according to their distribution in different plants. Organic solutes, known as compatible solutes, include amino acids, glycerol, sugars, and other low molecular weight metabolites, serve a function in cells to lower or balance the osmotic potential of intracellular and extracellular ions in resistance to osmotic stresses. Inorganic ions for osmotic adjustment are mainly Na+, K+, Ca2+, and Cl–. Inorganic ions make great c...