Hypoxia treatment on germinating faba bean (Vicia faba L.) seeds enhances GABA-related protection against salt stress

Abstract

The γ-aminobutyric acid (GABA) is a non-protein amino acid with some functional properties for human health. Its content is usually lower in plant seeds. Hypoxia or salt (NaCl) stress is an effective way for accumulating GABA during seed germination. However, NaCl stress on GABA accumulation under hypoxia is currently infrequent. The effect of NaCl on GABA accumulation in germinating faba bean (Vicia faba L.) under hypoxia was therefore investigated in this study. Faba bean seeds were steeped in citric acid buffer (pH 3.5) containing NaCl with a final O2 concentration of 5.5 mg L -1 and germinated for 5 d. Results showed that 60 mmol L -1 NaCl was the optimum concentration for GABA accumulation in germinating faba beans under hypoxia. Germination for 5 d under hypoxia-NaCl stress was less beneficial for GABA accumulation than only hypoxia (control). Polyamine degradation pathway played a more important role for accumulating GABA in germinating faba bean as an adaptive response to NaCl stress. Removing NaCl significantly increased GABA content, while it decreased glutamate decarboxylase (GAD) activity. Simultaneously, polyamine was accumulated, which might be related to the enhancement of physiological activity after recovery. When treated with aminoguanidine (AG) for 3 d, GABA content decreased by 29.82%. These results indicated that the tolerance ability of GABA shunt to NaCl stress was weaker than that of polyamine degradation pathway. The NaCl treatment for 3 d under hypoxia could raise the contribution ratio of polyamine degradation pathway for GABA accumulation. The contribution ratio of polyamine degradation pathway for GABA formation was 29.82% when treated for at least 3 d.

Effect of γ-aminobutyric Acid on Phenolics Metabolism in Barley Seedlings under Low NaCl Treatment

“…As a signal molecule, GABA plays a key role in the response of plants to external stimuli. Under salt stress, GABA accumulated in germinated soybean [ 4 ], faba bean [ 26 ], and brown rice [ 27 ]. At the same time, GABA promoted the synthesis of phenolics under NaCl stress (60 mmol L −1 ) in barley seedlings [ 13 ].…”

Recent advances in γ‐aminobutyric acid (GABA) properties in pulses: an overview

“…salt stress) can increase the level of GABA in plants . Yang et al . reported that this phenomenon depends on stress intensity and duration.…”

“…These authors suggested that the longer stress treatment may have destroyed the activity of the enzymes responsible for GABA production (e.g. GAD and DAO) . The addition of a second stressor modified the level of GABA production in the faba beans.…”

Growth Performance and Nitrogen Fixing Efficiency of Faba Bean (Vicia faba L.) Genotypes in Symbiosis with Rhizobia under Combined Salinity and Hypoxia Stresses

“…In faba beans, the effects of hypoxia and salinity were analyzed separately, on root development for hypoxia [23] and on the physiological and biochemical response of the whole plant for salinity [24]. Few studies analysed the double hypoxia-NaCl stress on γ-aminobutyric acid accumulation [25,26], but no study has analyzed the effects of the double constraint on growth parameters. The selection of legume genotypes with better tolerance to hypoxia and salinity is therefore an important agronomic objective to allow more efficient use of legumes either alone or in rotation with other crops.…”