Exogenous NaHS treatment alleviated Cd-induced stress in Ocimum basilicum plants through modulation of antioxidant defense system

Hydrogen sulfide (H2S) regulates many critical processes of plants. The effect of sodium hydrogen sulfide as H2S agent was investigated in basil plants under cadmium stress. A completely randomized design with three different concentrations (0, 50 and 100 μM) of CdCl2 and two levels of NaHS (0 and 100 μM) was used in this study. Cadmium exposure reduced growth parameters and relative water content. Cd also caused a significant increase in ion leakage and higher oxidative stress in terms of lipid peroxidation and H2O2 production. Although exogenous NaHS used in non-stressed control plants negatively affected growth and physiological parameters, it improved the root/shoot length ratio and fresh weight in basil plants under Cd 50 μM exposure. Moreover, NaHS alleviated deleterious effects of cadmium on ion leakage, relative water content and photosynthetic pigments of leaves. The activity of antioxidant enzymes like catalase, peroxidase and ascorbate peroxidase were also enhanced by NaHS in plants under moderate cadmium stress. Our results show that NaHS 50 μM ameliorates growth retardation induced by cadmium 50 μM stress in basil plants, probably through regulating physiological parameters such as photosynthetic pigments content, relative water content and the activity of antioxidant enzymes.