CsWRKY46 Is Involved in the Regulation of Cucumber Salt Stress by Regulating Abscisic Acid and Modulating Cellular Reactive Oxygen Species

Soil salinity significantly restricts the growth, development, and productivity of vegetables. Cucumber, a crucial greenhouse vegetable, is helpful for understanding how plants perceive, signal, and respond to salt stress. The WRKY family plays an important role in regulating stress responses. This study utilized the cucumber variety ‘Zhongnong 26’ to investigate the effects of salt stress on morphological changes, physiological and biochemical indices, and molecular regulations. CsWRKY46 was up-regulated in both salt stress and ABA response conditions in the leaves, roots, and fruits of cucumber. Transgenic Arabidopsis lines overexpressing CsWRKY46 (CsWRK46-OE1 and CsWRK46-OE5) showed higher proline accumulation and reduced electrolyte leakage compared to the wild type (WT). These overexpression lines demonstrated higher peroxidase (POD) and glutathione reductase (GR) activity, along with lower ascorbate peroxidase (APX) and catalase (CAT) activity. qRT-PCR analysis revealed elevated expression levels of ABI5 and ABF4 in CsWRKY46-OE lines compared to the WT. Additionally, the overexpression of CsWRKY46 increased the expression of stress-inducible genes such as PSCS1, PY19, and RD19. These findings suggest that CsWRKY46 enhances plant tolerance to salt stress, potentially through ABA regulation and modulation of cellular reactive oxygen species (ROS), and provide a foundation for the identification of new sources of salt stress tolerance for breeding programs.