Exogenous gamma amino butyric acid (GABA) enhanced salinity tolerance in wheat by modulating morphological and anatomical traits

Gamma amino butyric acid (GABA) is crucial four carbons, non-protein amino acid that plays a key role in regulating plant growth under stress conditions. This study explored the impact of exogenous GABA on morpho-anatomical traits and growth of wheat cultivars, FSD-08 and ANAJ-17 under salinity stress. The experimental setup included two salinity levels, 0 and 120 mM NaCl and four GABA concentrations (0, 1, 2 and 3 mM). Results demonstrated that GABA application enhanced various growth parameters, such as plant height (3.22%, 6.58%), shoot fresh weight (17.4%, 18.5%), shoot dry weight (15.2%, 22.6%), root dry weight (3.67%, 3.79%), root length (9.18%, 4.76%), shoot length (2.80%, 8.46%), leaf area (26.6%, 3.01%), awn length (14.7%, 6.7%), number of leaves and roots (5.89%, 13.6% and 8.1%, 2.32%) for ANAJ-17 and FSD-08, respectively. Anatomical modifications induced by GABA included increases in stem radius, epidermal thickness, sclerenchyma thickness, phloem cell area, root cortical thickness, cortical cell area, endodermal thickness, endodermal cell area, and pith radius were increased (7.53%, 21.1%, 63.3%, 61.4%, 9.30%, 7.30%, 7.69%, 7.31% and 11.7%) for ANAJ-17 at 2 mM and (14.6%, 18.5%, 26.7%, 62.1%, 25.9%, 37.4%, 33.1%, 45.5% and 41.7%) for FSD-08 at 3 mM under saline conditions. Exogenous GABA also reduces the reactive oxygen species (ROS), regulated stomatal aperture, enhanced photosynthesis, and activated antioxidant enzymes and up regulated genes in wheat under salt stress. Overall, the exogenous GABA effectively modulated ion homeostasis, improving the performance of wheat plants under saline conditions.