CsWRKY2, a novel WRKY gene from Camellia sinensis, is involved in cold and drought stress responses

One of the largest families of transcriptional regulators contains WRKY proteins. They play important roles in plant defense responses. In this study, a novel WRKY gene, CsWRKY2, was isolated from the tea [Camellia sinensis (L.) O. Kuntze] plant. The full-length cDNA of CsWRKY2 was 2 050 bp in length and encoded a 522-amino acid peptide chain containing two typical WRKY domains and two zinc finger motifs, suggesting that CsWRKY2 was member of the WRKY group I family. A subcellular localization assay shows that CsWRKY2 was localized to the nucleus. Real time qPCR analysis shows that CsWRKY2 expression was higher in leaves than in other organs and was induced by cold (4 °C), drought stress, and exogenous abscisic acid (ABA). Additionally, ABA content was enhanced after the cold or drought stress and the effects were relieved by an ABA biosynthesis inhibitor. Furthermore, the expression of CsWRKY2 was up-regulated by exogenous ABA under the cold and drought stresses and down-regulated by an ABA biosynthesis inhibitor. Our findings indicate that CsWRKY2 played an important role in plant defense responses to the cold and drought stresses by participating in the ABA signaling pathway, downstream to ABA.