GABA metabolism and ROS accumulation in barley (Hordeum vulgare L.) seedlings under the effect of salt and osmotic stress

GABA is a secondary metabolite that protects against oxidative damage, regulates nitrogen metabolism, and controls cytosolic pH in response to abiotic and biotic stress. This study examines the role of GABA shunt pathway response to salt and osmotic stress in three barley genotypes ("Acsad 176", "Athroh", and "Rum") interm of oxidative damage, seed germination and seedling growth as measured by glutamate decarboxylase gene (GAD) expression malondialdehyde accumulation (MDA), total proteins, total carbohydrates level, and GABA accumulation level. As Mannitol, NaCl, and sorbitol concentrations increased, seed germination decreased for all genotypes. All genotypes seedling MDA concentrations increased with increasing NaCl, mannitol, and sorbitol concentrations. Acsad 176 showed high GABA accumulation under NaCl treatment. Rum's GABA accumulation under mannitol testament increased significantly. All salt and osmotic treatments decreased chlorophyll a and b and carbohydrate content. At the same time it increased GAD transcription in all barley genotypes. Salt and osmotic stresses affected protein content in all genotypes. Acsad 176 may adapt to NaCl stress by accumulating carbohydrates more than Athroh and Rum. GABA shunt is a crucial signaling and metabolic pathway that facilitates barley's adaptation to salt and osmotic stress. In high salt and osmotic soil, Acsad 176 is the recommended genotype.