The role of gamma amino butyric acid (GABA) in signal transduction processes in relation to drought responses

Plants encounter different environmental stresses such as; biotic stress, drought, salt and high temperature during their lifespan. Gamma aminobutyric acid (GABA), is an non-protein amino acid. It is found in several unicellular and multicellular organisms. Up to date its role on several proccesses in plants have been elucidated and in literature there are hypothesis about its role as a signalling molecule. In our research we aimed to analyse GABA and GABA shunt components in diurnal rythym (day-night cycles) of tobacco plants under the effect of drought stress. Drought stress was induced by 20 % PEG in tobacco plants and the differences in GABA, glutamate and prolin contents, and glutamate dehydrogenase (GDH) and glutamate decarboxylase (GAD) enzyme activities were analyzed in plant leaf samples taken during diurnal rythym. According to our findings, GABA, glutamate and prolin act in collaboration for adressing stress induced responses in tobacco plants during the shifts from day to night cycles.