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

Abstract Hydrogen sulfide (H 2 S) plays a crucial role in regulating cold tolerance. But the synergistic regulation of H 2 S and auxin in the plant response to cold stress has not been reported. In the study, we found that sodium hydrosulfide (NaHS, an H 2 S donor) treatment enhanced the cold tolerance of cucumber seedlings and increased the level of auxin. CsARF5 , a cucumber auxin response factor (ARF) gene was isolated and its role in regulating H 2 S-mediated cold stress tolerance was described. Transgenic cucumber leaves overexpressing CsARF5 were obtained. Physiological analysis indicated that overexpression of CsARF5 enhanced the cold stress tolerance of cucumber and the regulation of the cold stress response by CsARF5 depends on H 2 S. In addition, molecular assays showed that CsARF5 modulated cold stress response by directly activating the expression of the dehydration-responsive element-binding (DREB)/C-repeat binding factor (CBF) gene CsDREB3 , which was identified as a positive regulator of cold stress. Taken together, our results suggest that CsARF5 plays an important role in H 2 S-mediated cold stress in cucumber. These results shed light on the molecular mechanism by which H 2 S regulates cold stress response by mediating auxin signaling, and will provide insights for further studies on the molecular mechanism by which H 2 S regulates cold stress. Highlight Auxin signaling participates in H 2 S-mediated cold stress through the CsARF5-CsDREB3 module in cucumber.