Gamma-amino butyric acid effect in the alleviation of saline–alkaline stress conditions in rice

The present study was conducted in order to determine the effect of GABA on 2 rice cultivars, i.e., CSR 43 (tolerant) and Pusa 44 (susceptible) at seedling stage under 200 mM saline–alkaline stress (SAS) (molar ratio of 1:9:9:1 of NaCl/Na2SO4/Na2CO3/Na2HCO3) with and without GABA (1.5 mM) supplementation. Exogenous GABA application enhanced the protein content along with the activities of glutamate decarboxylase (GAD) and diamine oxidase (DAO) in cultivar CSR 43. Under SAS, the activities of GAD, DAO and contents of protein were found higher in CSR 43 as compared to Pusa 44 while reverse was observed under GABA + SAS. As compared to sole application of GABA/SAS, CSR 43 possessed higher proline content under GABA + SAS. Endogenous GABA contents were found to increase under SAS in both cultivars, whereas the levels remained higher in CSR 43. Thus, it is elucidated that the increased endogenous GABA by exogenous GABA treatment could improve stress tolerance of rice seedlings associated with GABA regulation in improving DAO activity along with proline content.