ABSTRACT
Salinity is a widespread environmental problem. It alters the quality of soil and challenges the plant in completion of its life cycle. A high load of salt in the rhizosphere causes a decline in its water potential as compared to that of the plant’s. This leads to osmotic stress, causing cellular dehydration in plants. However, plants being a dynamic system can regulate osmotic balance to adapt and tolerate salt stress. To maintain osmotic homeostasis, plants synthesize and accumulate organic solutes, such as amino acids, methylamines, sugars and polyols. These solutes are water-soluble, non-toxic and low molecular weight metabolites that can regulate osmotic homeostasis. These metabolites can also protect membrane and photosynthetic tissues, and detoxify reactive oxygen species. Some of these solutes may also be exogenously applied to improve plant resistance to salt stress. This chapter will deal with the mechanisms of organic solutes in maintaining osmotic balance in plants growing under salt stress. It will also discuss approaches to increase these osmolytes in plants under salt stress conditions, which may be applied to ameliorate salt stress in plants.
