The tea plant <i>CsWRKY26</i> promotes drought tolerance in transgenic Arabidopsis plants

WRKY proteins participate in various plant physiological processes, especially in response to stress. However, limited information is available for WRKY proteins in tea plants. Camellia sinensis WRKY26 (CsWRKY26), a group I WRKY member, was characterized in this study. Tissue specificity of CsWRKY26 expression revealed that its transcripts are abundant in leaves and roots. Moreover, CsWRKY26 transcripts were markedly induced by treatments with sodium chloride (NaCl), polyethylene glycol (PEG), drought and different hormones. Ectopic expression of CsWRKY26 conferred ABA insensitivity and tolerance to transgenic Arabidopsis plants subjected to PEG treatments. When exposed to 15% PEG, the expression levels of some stress-tolerant genes, such as responsive to dehydration 22 (RD22), 9-cis-epoxycarotenoid dioxygenase 3 (NCED3), and Δ¹-pyrroline-5-carboxylate synthetase 1 (P5CS1), were up-regulated in transgenic plants compared to wild-type (WT) plants. Under natural drought stress, the growth performance of transgenic lines was better than those of WT plants, consistent with their significantly lower relative electrolyte leakage (REL) and higher proline content. These findings indicate that CsWRKY26 could enhance drought tolerance in Arabidopsis. This study provides a potential strategy for future crop improvement research.