Gamma Aminobutyric Acid (GABA) and Plant Responses to Stress

Abstract

4-aminobutyrate (GABA) is a non-protein amino acid that is widely distributed throughout the biological world. In animals, GABA functions as the predominant inhibitory neurotransmitter in the central nervous system by acting through the GABA receptors. The neuromuscular system enables animals to escape from environmental stresses. Being nonmotile, plants have evolved chemical responses to mitigate stress. Mechanisms by which GABA may facilitate these responses are discussed in this review. Environmental stresses increase GABA accumulation through two different mechanisms. Stresses causing metabolic and/or mechanical disruptions, resulting in cytosolic acidification, induce an acidic pH-dependent activation of glutamate decarboxylase and GABA synthesis. Extremely marked declines in cytosolic pH occur under oxygen deprivation, which is the primary stress factor in flooded soils, and this stress induces the greatest accumulation of GABA. Other stresses, including cold, heat, salt, and mild or transient envir...