Physiological Role of Gamma-Aminobutyric Acid in Salt Stress Tolerance

Extreme salt environments are destructive to several plant and limiting the crop productivity. The effect of salt stress involves modifications in different metabolic and physiological processes. Salinity stress inhibits plant growth, to inhibit photosynthesis, to alter metabolism of reactive oxygen species, and to cause cell death that finally obstructs the production of crops. Plants synthesized various compounds that involve in signaling and play important role in stress tolerance. Gamma-aminobutyric acid (GABA) is a four-carbon, ubiquitous, non-protein amino acid. The synthesis of GABA occurs in the cytosol by an irreversible alpha-decarboxylation of L-glutamate by L-glutamate decarboxylase. During salt stress condition, the accumulation of GABA increases that helps in to stabilizing the intracellular pH of cell and carbon/nitrogen metabolism for the Krebs cycle. Exogenic GABA treatment enhanced plant growth, improved stress tolerance via scavenges free radicals, regulating enzyme activities and stabilization in plant against salinity stress. In this chapter, we highlight on the physiological and metabolic role of GABA in relation to salt stress tolerance.