Comparative effects of drought, salt, heavy metal and heat stresses on gamma-aminobutryric acid levels of sesame (Sesamum indicum L.)

Gamma-aminobutryric acid (GABA) accumulation in response to diverse stresses is well known in plants; however, the comparative effects of different environmental stresses on GABA accumulation was not addressed in the same plant system. Here, we investigated GABA accumulation comparatively in sesame (Sesamum indicum L. cv. Cumhuriyet) plant under drought, salt, heavy metal (Se) and high-temperature stresses. Plants were stressed by application of 5% PEG-6000, 150 mM NaCl, 100 mu g g(-1) Se and high temperature (50A degrees C for 2 h). Root and shoot growth reduced after PEG, NaCl, Se and high-temperature treatments. Among these, heavy metal treatment had the highest and earliest effect on growth. GABA accumulation could be related to stress perception rather than protection in sesame plant if we consider that the adverse effects of different abiotic stresses on growth were not elevated by GABA.