RsCAMTA11 positively regulates salt tolerance by repressing transcription of two RsRbohs in radish (Raphanus sativus...

Radish (Raphanus sativus L.) is one of the economically significant crops globally, yet salt stress severely hinders taproot formation and development. Calmodulin binding transcription activators (CAMTAs) contribute importantly to hormone signal transduction, plant growth and development, together with abiotic and biological stress tolerance by sensing calcium signals. Nevertheless, the regulatory network through which CAMTA transcription factors mediate salt stress responses in radish remains elusive. In this study, we identified 12 CAMTA genes from the radish genome, among which RsCAMTA11 showed significantly upregulated expression in the salt-tolerant cultivar 'NAU-TR17' under salt stress, indicating a positive correlation between its expression level and salt tolerance. Subcellular localization analysis confirmed that RsCAMTA11 is localized to the nucleus. Transient overexpression of RsCAMTA11 in radish cotyledons mitigated salt stress-induced detriment by reducing reactive oxygen species (ROS) accumulation and enhancing the activities of antioxidant enzymes. Intriguingly, molecular assays indicated that RsCAMTA11 directly binds to the promoters of RsRbohC and RsRbohF and represses their expression, thereby reducing ROS accumulation and oxidative damage. Collectively, our findings uncover a novel RsCAMTA11-RsRbohs regulatory module that enhances salt tolerance in radish. These results advance our comprehension of the molecular mechanisms underpinning RsCAMTA11-mediated salt stress responses in radish, providing insights for genetic improvement of stress-resistant root crops.