GABA and Drought Stress

In plants, GABA is synthesized and catabolized through three enzymatic reactions, collectively known as the GABA shunt, which bypass two steps of the TCA cycle. Its accumulation provides anaplerotic precursors to the cycle and supports various physiological functions, particularly under biotic and abiotic stress conditions. During drought stress, GABA levels increase in numerous plant species, driven by the upregulation of glutamate decarboxylase (GAD) through Ca 2+ /calmodulin signalling and cytosol acidification, alongside enhanced transcription of GAD genes. This accumulation enhances drought tolerance. GABA mitigates drought stress primarily through its antioxidant role, directly scavenging ROS and upregulating ROS-detoxifying enzymes. Additionally, it promotes the accumulation of protective metabolites such as disaccharides, amino acids, and organic acids. Emerging evidence highlights GABA's role as a signal molecule, particularly in regulating stomatal opening via interactions with aluminum-activated malate transporters (ALMTs), which act as receptors. These findings suggest a broader regulatory network involving GABA and other molecular components.