Physiological role of gamma aminobutyric acid (GABA) in salt stress tolerance

Abstract

High salt concentrations in soils have been reported to be harmful to several plants which thereby play a limiting role in the crop productivity. The effect of salt stress involves modifications in different metabolic and physiological processes. Salt stress inhibits plant growth, inhibits photosynthesis, alters metabolism of reactive oxygen species, and causes cell death that finally obstructs the production of crops. Plants synthesize various compounds that involve in signaling and play an important role in stress tolerance. Gamma-aminobutyric acid (GABA) is a four-carbon, ubiquitous, nonprotein amino acid. The synthesis of GABA occurs in the cytosol by an irreversible alpha-decarboxylation of l-glutamate by l-glutamate decarboxylase (GAD). During salt stress condition, the accumulation of GABA increases that helps in stabilizing the intracellular pH of cell and carbon/nitrogen metabolism for the Krebs cycle. Exogenic GABA treatment enhanced plant growth and improved stress tolerance via scavenging free radicals, regulating enzyme activities, and stabilizing plants against increased salt stresses. In this chapter, we have tried to highlight the physiological and metabolic role of GABA in relation to salt stress tolerance.