Carnitine Regulates Water Status and Glutathione Pool Regulation under Salt and Drought Stress in Arabidopsis

Abiotic stresses such as salinity and drought severely affect plant growth and productivity. Plants employ various defence strategies, including antioxidant responses and osmotic adjustment, to cope with these stresses. Carnitine, a compound found in many organisms, has been linked to osmoprotection and stress mitigation. In this study, the effects of exogenous carnitine (5 μM) on antioxidant responses in Arabidopsis thaliana Col-0 under short-term salt (80 mM NaCl) and drought (150 mM mannitol) stress were evaluated. Carnitine application mitigated reductions in relative water content, shoot fresh weight, and rosette diameter. It also alleviated stress-induced damage, as indicated by decreased lipid peroxidation and H₂O₂ levels. Interestingly, enzyme activity responses differed between stress types: Catalase (CAT) and Ascorbate Peroxidase (APX) were predominantly upregulated under salt stress, while Peroxidase (POX) and APX increased under drought. In addition, total glutathione content was enhanced, suggesting support for redox homeostasis. While limited in scope, the findings indicate that carnitine may contribute to short-term stress tolerance through modulation of antioxidant metabolism. These results support the potential role of carnitine as a bioregulator under abiotic stress, though further studies are required to clarify its mechanisms and broader applicability.