Determination of genetic and metabolic markers related to GABA shunt pathway in chickpea (Cicer arietinum L.) under cold stress

The Gamma aminobutyric acid (GABA) content as a free amino acid which is involved in reduction of oxidative stress damage and stress adaptation in the cell is adjusted by various routes, including the GABA shunt pathway. In this experiment, Gama -aminobutyric acid (GABA), Hydrogen Peroxide (H2O2), activity of GABA transaminase (GABA-T) and relative expression of Glutamate Gecarboxylase1 (GAD1) gene in cold-tolerant (Sel96th11439) and cold-sensitive (ILC533) chickpea (Cicer arietinum L.) genotypes under cold stress (4◦C) as a factorial experiment in a Completely Randomized Design were studied. In tolerant genotype H2O2 content after a significant increase on the first day of cold stress decreased significantly on the sixth day of cold stress compared to control conditions (up to 4.7%) while its accumulation was observed in sensitive genotype (up to 50%). Based on H2O2 adjustment as a damage index, these results indicated a relative acclimation to cold stress in tolerant genotype. Under cold stress, GABA content in tolerant genotype was higher compared to sensitive genotype (up to 14%). In this experiment, under cold stress, in tolerant genotype increasing GABA content was accompanied with an increase in GABA-T activity and relative expression of GAD1 gene as regulatory routes of this metabolite (up to 3- and 17-fold, respectively). The maximum and minimum activities of catabolic and anabolic pathways was observed in tolerant genotype on the sixth day of cold stress, respectively. Therefore, under cold stress, the accumulation of GABA in tolerant genotype led to reduced cell damage (H2O2 results) and improved cold tolerance.