Physiology and molecular biology of salinity stress tolerance in plants

The productivity of plants is greatly affected by various environmental stresses. Soil salinity affects plant growth and development by way of osmotic stress, injurious effects of toxic Na+ and Cl- ions and to some extent Cl- and SO42- of Mg2+ and nutrient imbalance caused by excess of Na+ and Cl- ions. Salinity stress response is multigenic, as a number of processes involved in the tolerance mechanism are affected, such as various compatible solutes/osmolytes, polyamines, reactive oxygen species and antidoxidant defence mechanism, ion transport and compartmentalization of injurious ions. Various genes/cDNAs encoding proteins involved in the above-mentioned processes have been identified and isolated. The role of genes/cDNAs encoding proteins involved in regulating other genes/proteins, signal transduction process involving hormones like ABA, JA and polyamines, and strategies to improve salinity stress tolerance have also been discussed.