Exogenous Hydrogen Sulfide Alleviates the Toxicity of Cu2+ Stress on the Growth Physiology and Quality Components in Camellia sinensis L.

Cu2+ stress impairs the growth and metabolism of tea plants, further reducing the quality of tea leaves. As a gas signaling molecule, H2S participates in various physiological processes and improves the stress resistance of plants. Here, the role of H2S in the response of tea plants to Cu2+ stress was investigated by analyzing the effects of Cu2+ stress on phenotypes, photosynthetic parameters, physiological indicators, and quality component contents with H2S or PAG (H2S synthase inhibitor) pretreatment. It was indicated that exogenous H2S reduced Cu accumulation and alleviated the inhibition of growth physiology mediated by Cu2+ stress in tea plants, mitigated the leaf cell ultrastructure damage, and increased the biomass, root activity, chlorophyll content, and photosynthetic capacity of tea plants under Cu2+ stress. Additionally, exogenous H2S activated the antioxidant system by increasing antioxidant enzyme activities and non-enzymatic antioxidant contents and enhanced the production of endogenous H2S by promoting LCD activity, thereby improving the antioxidant capacity of tea plants under Cu2+ stress. Meanwhile, the application of H2S effectively alleviated the reduction in the quality components of tea leaves under Cu2+ stress. Above all, exogenous H2S can enhanced tea plants’ tolerance to Cu2+ stress, providing a technical reference for the management of tea plants.