γ-
Aminobutyric acid (
GABA) acts as an important regulator involved in the mediation of cell signal transduction and stress tolerance in plants. However, the function of
GABA in transcriptional regulation is not fully understood in plants under
water stress. The creeping bentgrass (Agrostis stolonifera) was pretreated with or without
GABA (0.5 mM) for 24 hours before being exposed to 5 days of
water stress. Physiological analysis showed that
GABA-treated plants maintained significantly higher endogenous
GABA content, leaf relative water content, net photosynthetic rate, and lower osmotic potential than untreated plants under
water stress. The
GABA application also significantly alleviated stress-induced increases in
superoxide anion (O2.-) content,
hydrogen peroxide (H2O2) content, and
electrolyte leakage through enhancing total
antioxidant capacity,
superoxide dismutase (SOD) activity, and
peroxidase (POD) activity in response to
water stress. The transcriptomic analysis demonstrated that the
GABA-induced changes in differentially expressed genes (DEGs) involved in
carbohydrates,
amino acids, and secondary metabolism helped to maintain better osmotic adjustment, energy supply, and metabolic homeostasis when creeping bentgrass suffers from
water stress. The
GABA triggered Ca2+-dependent
protein kinase (CDPK) signaling and improved transcript levels of DREB1/2 and WRKY1/24/41 that could be associated with the upregulation of stress-related functional genes such as POD, DHNs, and HSP70 largely contributing to improved tolerance to
water stress in relation to the
antioxidant, prevention of cell
dehydration, and
protein protection in leaves.