Dioscorea composita WRKY12 is involved in the regulation of salt tolerance by directly activating the promoter of AtRCI2A

Dioscorea composita (D. composita) is an important medicinal plant worldwide with high economic value. However, its large-scale cultivation was limited by soil salinization. Identification of genes and their mechanisms of action in response to salt stress are critically important. In the present study, we isolated a classical WRKY transcription factor from D. composita, namely DcWRKY12, and analyzed its function in salt tolerance. Expression pattern analysis showed DcWRKY12 is mainly expressed in roots and significantly induced by NaCl, polyethylene glycol-6000 (PEG-6000), and abscisic acid (ABA). Phenotypic and physiological analyses revealed that heterologous expression of DcWRKY12 enhanced salt and osmotic stress tolerance by increasing antioxidant enzyme activity, osmoregulatory substance content, maintaining relative water content and ion homeostasis, decreasing reactive oxygen species and malondialdehyde content. Correspondingly, the overexpression of DcWRKY12 modulated the expression of salt stress-responsive and ion transport-related genes. Dual luciferase assay and Y1H were further confirmed that DcWRKY12 activates the promoter of AtRCI2A through directly binding to the specific W-box cis-acting elements. These results suggest that DcWRKY12 is a positive regulator of salt tolerance in D. composita and has potential applications in salt stress.