Salinity In Plants

Salinity is a most critical abiotic stress eliminating growth and crop yield of plants in many regions in the world because of increasing use of poor quality of water for irrigation and soil salinization (Gupta and Huang 2014). High salt soil leads to hyperosmotic stress and hyperionic stress(Tuteja 2007). Hyperosmotic stress is considered the initial stage of salinity stress which is the reduction of water absorption capacity of root systems and acceleration of water loss from leaves. As sequences, various physiological changes will happen such as disturbance of membranes, nutrient imbalance, reduction the ability of reactive oxygen species (ROS) detoxification, alteration in the antioxidant enzymes and decreased photosynthetic activity. The

In addition, ROS formation such as superoxide, singlet oxygen, hydroxyl radical and hydrogen peroxide, is enhanced as a response to salinity stress. ROS production can lead to oxidative damages in several cellular constituents such as lipids, proteins, and DNA which cause the interruption of essential cellular functions in plants(Gupta and Huang 2014). Some Plants can withstand salinity and are known as halophytes (salt tolerant). While, the majority of plants are glycophytes (salt sensitive) that cannot withstand salinity and eventually die (Tuteja 2007).

Strategies to obtain tolerance under high salinity are:

1- Ion homeostasis: The accumulation of sodium ions in cytoplasm is toxic to the cytosolic enzymes, inhibits the uptake of other nutrients such as potassium, phosphorous, nitrogen and calcium which have an important function in plant metabolism. Additionally, the resemblance of the chemical nature and hydration energy between sodium and potassium ions results in a competitive uptake of sodium ions through

These osmolytes are low molecular weight organic compounds, uncharged, polar, soluble in nature and do not interfere with routine biochemical reactions. They consist of simple sugars such as glucose and fructose, sugar alcohols (glycerol and methylated inositols), complex sugars (trehalose and raffinose) , sulfonium compounds ( dimethyl sulfonium, choline-o-sulfate and propironate) and quaternary amino acid derivatives (putrescine ,alanine betaine, proline, proline betaine diamine, glycine betaine, polyamines, spermidine and spermine) .Their functions are the adjustment of the osmotic potential in plants based on the external osmolarity and promotion of water influx. Also, they play an important role in prevention of plant cell dehydration, shrinking and plasmolysis or cytorrhesis . Furthermore, osmoprotectants is dependable in the scavenging of reactive oxygen species (ROS) that are byproducts of hyperosmotic and ionic stresses that may cause membrane dysfunction and cell death (Yokoi, Bressan, and Hasegawa 2002; Kosová et al. 2013; Maurya and Gothandam