Plant-specific BTB-TAZ domain (BT) proteins play key roles in stress responses, while their functions in cucumber remain largely unclear. In this study, we investigated the role of the CsBT2 gene under abiotic stress conditions. Tissue-specific expression analysis showed that CsBT2 is predominantly expressed in roots. qRT-PCR results indicated that its expression is regulated by salt stress, drought, and exogenous abscisic acid (ABA). To further explore its function, we generated CsBT2-overexpressing Arabidopsis transgenic plants and found that they exhibited enhanced sensitivity to salt and drought stress, manifested as reduced seed germination rates and inhibited root growth, with lower SOD activity and increased electrolyte leakage and MDA content. qRT-PCR analysis revealed that several stress-related genes, including AtRbohF, AtRD22, and AtRD29A, were downregulated in transgenic plants compared to wild-type (WT) plants under normal conditions. Additionally, the overexpression plants showed resistance to exogenous ABA-mediated root growth inhibition. CsBT2 acts as a negative regulator in cucumber responses to abiotic stress, likely by antagonizing ABA signaling and suppressing the expression of stress-related genes, thereby appears to negatively influence stress tolerance.
Huang et al. (Mon,) studied this question.