Enhanced tolerance to drought stress resulting from Caragana korshinskii CkWRKY33 in transgenic Arabidopsis thaliana.

BACKGROUND: It is well known that WRKY transcription factors play important roles in plant growth and development, defense regulation and stress responses. RESULTS: In this study, a WRKY transcription factor, WRKY33, was cloned from Caragana korshinskii. A sequence structure analysis showed that it belonged to the Group-I type. Subcellular localization experiments in tobacco epidermal cells showed the presence of CkWRKY33 in the nucleus. Additionally, CkWRKY33 was overexpressed in Arabidopsis thaliana. A phenotypic investigation revealed that compared with wild-type plants, CkWRKY33-overexpressing transgenic plants had higher survival rates, as well as relative soluble sugar, proline and peroxidase contents, but lower malondialdehyde contents, following a drought stress treatment. CONCLUSIONS: This suggested that the overexpression of CkWRKY33 led to an enhanced drought-stress tolerance in transgenic A. thaliana. Thus, CkWRKY33 may act as a positive regulator involved in the drought-stress responses in Caragana korshinskii.