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

Wei Chen,Wan-Jun Hao,Liang Chen,Chao Zheng,Ming-Zhe Yao,De-Jiang Ni,Yan-Xia Xu

doi:10.3390/ijms20112815

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.

Highlights

Plants suffering from diverse abiotic stresses in the developmental process have evolved and obtained a series of mechanisms to combat with these environmental stresses
CsWRKY7, one WRKY gene, was amplified from tea leaves cDNA by RT-PCR
CsWRKY7 was found to have a nuclear localization signal (NLS) at 227–230 amino acid region, and have two motifs, namely, HARF structure and a shorter conserved structural motif (C-region which is known as a Ca2+-dependent calmodulin-binding domain) (Figure 1A)

Summary

Introduction

Plants suffering from diverse abiotic stresses in the developmental process have evolved and obtained a series of mechanisms to combat with these environmental stresses. Majority of transcription factors (TFs) participate in these adaptive mechanisms [1]. WRKY transcription factor is named after the WRKY domain, which contains one or two highly conserved WRKYGQK motifs and one zinc-finger motif [5,6]. According to the number of WRKY domains and the type of zinc finger motif, WRKY TFs can be divided into three types: Group I, containing two WRKY domains and one C2H2 zinc-finger structure. Group II, containing one WRKY domain, and sharing the same zinc finger structure with group I. Based on the amino acid sequence of the DNA-binding domain, Group II can be further divided into IIa, IIb, IIc, IId, and IIe subgroups; Group III contains one WRKY domain, but its zinc finger structure is C2HC [4,7]

Methods

Results

Conclusion