Drought stress is a major abiotic constraint that severely restricts the growth of Medicago falcata L. by inducing the accumulation of reactive oxygen species (ROS) in plants. WRKY transcription factors (TFs) play a key role in regulating plant responses to drought stress. In this study, we investigated the role of the MfWRKY40 gene in drought tolerance. Under mannitol and ABA stress treatments, MfWRKY40-overexpressing lines (OEs) showed significantly longer primary roots, increased lateral roots, and higher fresh weight compared to wild-type (Col) lines, indicating significantly enhanced growth and drought tolerance. Similarly, under soil drought conditions, transgenic Arabidopsis thaliana exhibited enhanced drought tolerance. NBT staining demonstrated decreased ROS accumulation in transgenic lines after stress treatment. Correspondingly, the MfWRKY40-overexpressing lines displayed significantly lower levels of hydrogen peroxide (H2O2), superoxide anion (O2−), and malondialdehyde (MDA) compared to Col, along with elevated activities of superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD), as well as increased proline (Pro) content. Furthermore, MfWRKY40 upregulated the expression of antioxidant enzyme genes (AtPOD3, AtSOD4, and AtCAT1) and modulated the expression of other drought-related genes. In summary, our results demonstrate that MfWRKY40 enhances drought tolerance in A. thaliana by improving ROS scavenging capacity. This study provides a theoretical foundation for further exploration of MfWRKY40’s functional mechanisms in drought stress adaptation.
Zhang et al. (2025) studied this question.