Hydrogen Sulfide's Role in Enhancing Antioxidant Defense and Biochemical Resilience in Salt-Stressed Lavender (Lavandulaangustifolia) Plants

Hydrogen sulfide (H2S) has emerged as a critical signaling molecule in plants, particularly under stress conditions. This study investigates the role of exogenous H2S at two levels of 100 and 200 mu M, supplied as sodium hydrosulfide (NaHS), in enhancing the antioxidant defense and biochemical resilience of Lavandula angustifolia Miller subjected to 0, 150 and 300 mM NaCl stress for 7 and 14 days. The experiments were designed to evaluate key physiological parameters including malondialdehyde (MDA)and Hydrogen peroxide (H2O2) contents as well as antioxidant enzymes activity, ionic balance (Na+, Cl-, and K+ content), hydrogen sulfide (H2S) and protein levels across different treatments. Results demonstrated that NaHS treatment could effectively alleviate oxidative damage caused by salt stress and reduce the accumulation of MDA and H2O2 through enhancing the activities of antioxidant enzymes. The highest antioxidant activity was observed in plants treated with either 0 mM NaCl + 200 mu M NaHS or 300 mM salt stress with 100 mu M NaHS, highlighting the dual role of H2S in modulating the plant's response to varying stress levels. Additionally, the treatment of 150 mM NaCl combined with NaHS application significantly increased H2S content, which in turn enhanced antioxidant capacity and helped maintaining ionic homeostasis. Conversely, excessive NaHS application under 0 or 150 mM salt stress conditions were found to inhibit protein synthesis, suggesting a complex interaction between stress intensity and H2S signaling. This study underscores the potential of H2S as a modulator of plant stress responses, with implications to improve lavender resilience in saline environments.