Hydrogen Sulfide Improves the Cold Stress Resistance through the CsARF5-CsDREB3 Module in Cucumber

Abstract

As an important gas signaling molecule, hydrogen sulfide (H₂S) plays a crucial role in regulating cold tolerance. H₂S cooperates with phytohormones such as abscisic acid, ethylene, and salicylic acid to regulate the plant stress response. However, the synergistic regulation of H₂S and auxin in the plant response to cold stress has not been reported. This study showed that sodium hydrosulfide (NaHS, an H₂S donor) treatment enhanced the cold stress tolerance of cucumber seedlings and increased the level of auxin. <i>CsARF5</i>, a cucumber auxin response factor (ARF) gene, was isolated, and its role in regulating H₂S-mediated cold stress tolerance was described. Transgenic cucumber leaves overexpressing <i>CsARF5</i> were obtained. Physiological analysis indicated that overexpression of <i>CsARF5</i> enhanced the cold stress tolerance of cucumber and the regulation of the cold stress response by <i>CsARF5</i> depends on H₂S. In addition, molecular assays showed that <i>CsARF5</i> modulated cold stress response by directly activating the expression of the dehydration-responsive element-binding (DREB)/C-repeat binding factor (CBF) gene <i>CsDREB3</i>, which was identified as a positive regulator of cold stress. Taken together, the above results suggest that CsARF5 plays an important role in H₂S-mediated cold stress in cucumber. These results shed light on the molecular mechanism by which H₂S regulates cold stress response by mediating auxin signaling; this will provide insights for further studies on the molecular mechanism by which H₂S regulates cold stress. The aim of this study was to explore the molecular mechanism of H₂S regulating cold tolerance of cucumber seedlings and provide a theoretical basis for the further study of cucumber cultivation and environmental adaptability technology in winter.