Hydrogen sulfide negatively regulates cd-induced cell death in cucumber (Cucumis sativus L) root tip cells

BACKGROUND: Hydrogen sulfide (H(2)S) is a gas signal molecule involved in regulating plants tolerance to heavy metals stress. In this study, we investigated the role of H(2)S in cadmium-(Cd-) induced cell death of root tips of cucumber seedlings. RESULTS: The results showed that the application of 200 μM Cd caused cell death, increased the content of reactive oxygen species (ROS), chromatin condensation, the release of Cytochrome c (Cyt c) from mitochondria and activated caspase-3-like protease. Pretreatment of seedlings with 100 μM sodium hydrogen sulfide (NaHS, a H(2)S donor) effectively alleviated the growth inhibition and reduced cell death of root tips caused by Cd stress. Additionally, NaHS + Cd treatment could decrease the ROS level and enhanced antioxidant enzyme activity. Pretreatment with NaHS also inhibited the release of Cyt c from the mitochondria, the opening of the mitochondrial permeability transition pore (MPTP), and the activity of caspase-3-like protease in the root tips of cucumber seedling under Cd stress. CONCLUSION: H(2)S inhibited Cd-induced cell death in cucumber root tips by reducing ROS accumulation, activating the antioxidant system, inhibiting mitochondrial Cyt c release and reducing the opening of the MPTP. The results suggest that H(2)S is a negative regulator of Cd-induced cell death in the root tips of cucumber seedling.