*Article* **Isolation and Characterization of CsWRKY7, a Subgroup IId WRKY Transcription Factor from** *Camellia sinensis***, Linked to Development in Arabidopsis**

#### **Wei Chen 1,2, Wan-Jun Hao <sup>1</sup> , Yan-Xia Xu <sup>1</sup> , Chao Zheng <sup>1</sup> , De-Jiang Ni <sup>2</sup> , Ming-Zhe Yao 1,\* and Liang Chen 1,\***


Received: 27 April 2019; Accepted: 6 June 2019; Published: 9 June 2019

**Abstract:** WRKY transcription factors (TFs) containing one or two WRKY domains are a class of plant TFs that respond to diverse abiotic stresses and are associated with developmental processes. However, little has been known about the function of *WRKY* gene in tea plant. In this study, a subgroup IId *WRKY* gene *CsWRKY7* was isolated from *Camellia sinensis*, which displayed amino acid sequence homology with Arabidopsis *AtWRKY7* and *AtWRKY15*. Subcellular localization prediction indicated that CsWRKY7 localized to nucleus. Cis-acting elements detected in the promotor region of *CsWRKY7* are mainly involved in plant response to environmental stress and growth. Consistently, expression analysis showed that *CsWRKY7* transcripts responded to NaCl, mannitol, PEG, and diverse hormones treatments. Additionally, *CsWRKY7* exhibited a higher accumulation both in old leaves and roots compared to bud. Seed germination and root growth assay indicated that overexpressed *CsWRKY7* in transgenic Arabidopsis was not sensitive to NaCl, mannitol, PEG, and low concentration of ABA treatments. *CsWRKY7* overexpressing Arabidopsis showed a late-flowering phenotype under normal conditions compared to wild type. Furthermore, gene expression analysis showed that the transcription levels of the flowering time integrator gene *FLOWERING LOCUS T* (*FT*) and the floral meristem identity genes *APETALA1* (*AP1*) and *LEAFY* (*LFY*) were lower in *WRKY7*-OE than in the WT. Taken together, these findings indicate that CsWRKY7 TF may participate in plant growth. This study provides a potential strategy to breed late-blooming tea cultivar.

**Keywords:** subgroup IId; CsWRKY7; flowering; Arabidopsis; *Camellia sinensis*
