Exogenous gamma aminobutyric acid mitigates physiological and transcriptomic responses of Prunus mongolica under combined alkali salt and cadmium stress

Alkali-salt, cadmium, and combined alkali-salt and cadmium stress markedly inhibited seed germination and seedling growth, with the combined stress causing the most severe damage. Stress treatments promoted reactive oxygen species accumulation, lipid peroxidation, photosynthetic inhibition, and reductions in water status and root activity. Exogenous GABA alleviated these stress-induced effects by improving germination performance, seedling growth, chlorophyll accumulation, root activity, and relative water content, while reducing oxidative damage.

GABA also enhanced osmotic adjustment by increasing proline and soluble sugar contents and strengthened antioxidant defense through the activation of superoxide dismutase, peroxidase, catalase, ascorbate peroxidase, and glutathione reductase. Transcriptome analysis showed that GABA modulated stress-responsive genes associated with MAPK signaling, plant hormone signal transduction, plant-pathogen interaction, peroxisome, glutathione metabolism, photosynthesis, carbon metabolism, and other primary metabolic processes.

These results suggest that exogenous GABA enhances stress tolerance in Prunus mongolica by coordinating redox homeostasis, osmotic regulation, stress signaling, photosynthetic recovery, and metabolic reprogramming under single and combined alkali-salt and cadmium stresses.