Exogenous H2S regulates growth, and antioxidative defense in tomato seedings in a concentration dependent manner under salt stress
摘要
H2S is a lipophilic gaseous molecule with the characteristic pungent “rotten egg” odour. Studies have shown that H2S at lower concentrations acts as a gasotransmitter, providing evidence for its crucial role in plant growth, development and stress responses. The present work underlies the effects of moderate and high concentrations of NaCl stress and two concentrations of NaHS (H2S donor) on certain metabolic signatures of tomato seedlings. In this study, tomato seedlings were grown under different NaCl concentrations (0 mM, 40 mM, 80 mM and 120 mM) and three concentrations of H2S, i.e. T0 (0 µM), T1 (25 µM) and T2 (100 µM) were applied exogenously. The results showed a reduction in MDA content, electrolytic leakage, Na+/K+ ratio, and proline content in tomato seedlings with exogenous application of H2S under NaCl stress. On the contrary, exogenous H2S application at T2 concentration increased chlorophyll content, RWC, endogenous H2S content, L-DES activity and ascorbate content under 80 mM NaCl stress. Concomitantly, exogenous H2S treatment, particularly at T2 concentration, upregulated the antioxidative enzyme activity like glutathione reductase (GR), catalase (CAT), ascorbate peroxidase (APOD), peroxidase (POD) and superoxide dismutase (SOD) in NaCl-treated tomato seedlings. These results indicate that exogenous H2S application, especially at T2 concentration, imparts a higher amount of alleviation in salt-stressed tomato seedlings grown under 80 mM NaCl. Thus, a concentration-dependent interaction of NaCl stress and H2S signaling appears to be mediated through long-distance signaling in tomato seedlings.