Hydrogen sulfide counteract copper induced inhibition of photosynthetic performance through altered proline metabolism and enhanced antioxidants in Cucumis sativus

It has been recently discovered that hydrogen sulfide (H₂S) is a gaseous substance responsible for controlling the growth and metabolism of plants. The present study was designed to explore the ameliorative effect of H₂S on Cucumis sativus plants under increasing levels of copper. This study revealed that varying concentrations of H₂S improved seed germination in a concentration-dependent manner. Furthermore, exogenous application of H₂S to copper stressed plants accelerated photosynthetic performance, antioxidant system, proline accumulation, and maintained copper uptake that was reflected in improved growth parameters. In addition to this, H₂S also curbed oxidative stress by lowering lipid peroxidation, H₂O₂ content, and electrolyte leakage. H₂S enhanced activities of the antioxidant system, and proline metabolism leading to decontamination of cucumber plants under lethal dose of copper. This work offers an understanding that exogenously sourced H₂S could be engaged as a significant biochemical approach in alleviating copper-induced toxicity in cucumber plants.