Role of GABA transaminase in the regulation of development and senescence in Arabidopsis thaliana

GABA (gamma amino butyric acid) transaminase (GABA-T) shows significant regulatory function during plant developmental process. It is involved in the reduction of GABA to succinic semialdehyde and participates in GABA shunt pathway, which critically contributes to nitrogen metabolism during senescence stage of plant's life cycle. Thus, to study the function of GABA-T gene in the development and senescence processes, Arabidopsis thaliana GABA-T knock out mutants (pop2-1 and pop2-3) were characterized by the assays of leaf senescence parameters (survival efficacy, total chlorophyll content, electrolyte leakage of membrane, and lipid peroxidation) and GABA shunt components in different developmental stages. GABA-T gene mutants (pop2-1 and pop2-3) impact the overall plant morphology, leaf development, flowering time and display early onset of senescence. It was observed that pop2 mutants declined the leaf survival efficacy, total chlorophyll, GABA, GABA-T as well as glutamate decarboxylase (GAD) enzymes activities. Knockout mutation in GABA-T gene adversely elevated the electrolyte leakage of membrane, lipid peroxidation at S3 stage (30 days old plant) rather than S5 stage (50 days old plant). ROS generation and cell death was also increased in pop2 mutant leaf earlier. Taken together, our results suggest a prominent role of GABA-T gene in leaf senescence and development processes in Arabidopsis thaliana.