Hydrogen sulfide protects coriander seedlings against copper stress by regulating the ascorbate-glutathione cycle, in leaves

  Heavy metals are the cause of major abiotic stresses in plants and a principal contributor to environmental pollution in recent decades. This study investigated the effects of exogenous hydrogen sulfide on the ascorbate-glutathione cycle in the leaves of coriander seedlings under copper stress. Results showed that copper stress not only reduced APX and GR activities but also decreased leaf AsA, DHA, and GSH contents. Pretreatment with sodium hydrosulfide (NaHS), a hydrogen sulfide (H2S) donor, was observed to enhance both GR activity and AsA, GSH, and DHA contents under copper stress. Moreover, the pretreatment decreased the malondialdehyde content and electrolyte leakage induced by copper stress in plants. Based on the results obtained, it was hypothesized that exogenous hydrogen sulfide alleviates oxidative damage under copper stress by regulating the ascorbate-glutathione cycle and, further, that H2S plays an important role in the acquisition of copper stress tolerance in coriander seedlings. Exogenous hydrogen sulfide is, therefore, identified as an agent with the potential to be used as a regulator to improve crop tolerance under copper stress.   Keywords: Copper stress, Coriander, Hydrogen sulfide, Ascorbate, Glutathione.