Application of GABA (γ-aminobutyric acid) to improve saline stress tolerance of chufa (Cyperus esculentus L. var. sativus Boeck) plants by regulating their antioxidant potential and nitrogen assimilation

Abstract

The chufa is a perennial plant known for its almond-like underground tubers that have several health benefits for humans. GABA (γ-amino butyric acid) can regulate plants’ tolerance to stress including tolerance to salinity. However, it is unknown how chufa plants respond to GABA application and salinity. Here, we analysed the impact of GABA (2 mM) on growth features and physio-biochemical changes in chufa seedlings subjected to different saline stress levels (SS; 0, 100 and 200 mM NaCl and Na 2 SO 4 , 1:1 molar ratio). Our findings show that increasing SS levels negatively affected growth and metabolism. Increased SS reduced growth (root and shoot length, and their fresh and dry weights) and photosynthetic pigments, and significantly increased hydrogen peroxide (H 2 O 2 ), malondialdehyde (MDA) and osmolytes (i.e. soluble sugars, proline, soluble protein and superoxide dismutase (SOD). Peroxidase (POD) significantly declined at 50 mM and catalase (CAT) decreased under both stress levels. SS significantly enhanced salt ions (Na + and Cl – ) in roots and leaves but decreased root K + and increased Mg 2+ at 100 mM, levels that then declined under 200 mM SS. However, foliar K + and Mg 2+ remained unchanged. As well, NO 3 – and NH 4 + concentrations and nitrate reductase (NR) and glutamine oxoglutarate aminotransferase (GOGAT) declined significantly, while glutamine synthetase (GS) remained unaffected. However, exogenous GABA significantly reduced Na + and Cl – ions, H 2 O 2 and MDA and improved chlorophyll pigments, osmolytes, Mg 2+ and K + , antioxidant enzymes and N metabolism compared to untreated GABA peers. GABA might thus be able to improve the salinity stress tolerance of chufa by improving its cellular metabolism and preventing the build-up of harmful substances. Hence, exogenous GABA could be an effective approach for increasing salinity tolerance in chufa plants in salt-affected regions. Future studies should aim to elucidate the molecular mechanisms that operate when GABA regulates saline stress tolerance in chufa plants. • Increased saline stress levels negatively affect the growth of chufa seedlings. • Exogenous GABA mitigated negative effects of salinity on chufa seedlings. • GABA improved morpho-physio-biochemical attributes of seedlings.