Mitigating the harmful consequences of arsenic on celosia plants via the use of GABA

Arsenic (As) is a highly toxic metalloid that severely disrupts plant growth, metabolic function, and productivity by inducing oxidative stress and disturbing nutrient homeostasis. Soil contamination with arsenic severely limits plant growth and reduces the ornamental value of many species. In the present study, Celosia argentea var. spicata was grown in soil containing different arsenic levels (0, 30, 50, and 70 mg kg⁻¹ soil) to examine the ability of γ-aminobutyric acid (GABA) to mitigate arsenic-induced stress in both seasons (2023 and 2024). Our results revealed that exposure to As markedly reduced vegetative and reproductive growth characteristics—such as plant height, branch number, leaf area, and both fresh and dry biomass—and that these inhibitory effects intensified with increasing As levels. In contrast, exogenous GABA individually had significantly improved all growth and flowering parameters, at interaction conditions 1 mM treatment producing the greatest increase even under severe arsenic stress. At the physiological level, GABA application increased photosynthetic pigment concentrations (chlorophyll a, chlorophyll b, and carotenoids), total soluble sugars, and flavonoids while decreasing the accumulation of proline and phenolic compounds. GABA also reduced the As content in shoots and soil while promoting its retention within root tissues, suggesting a protective mechanism of immobilization. Biochemically, GABA alleviated oxidative damage by substantially lowering malondialdehyde (MDA) and hydrogen peroxide (H₂O₂) levels, with the strongest effects observed at 1 mM GABA. Exogenous γ-aminobutyric acid (GABA) application significantly enhanced superoxide dismutase (SOD) isoenzyme activity under arsenic-induced stress conditions. The results demonstrate that exogenous GABA at 0.5 or 1 mM can play a meaningful role in restricting arsenic movement from roots to shoots inside plants and reducing the oxidative damage associated with arsenic stress in C. argentea var. spicata.