CpWRKY71, a WRKY Transcription Factor Gene of Wintersweet (Chimonanthus praecox), Promotes Flowering and Leaf Senescence in Arabidopsis

Abstract

The WRKY transcription factors are one of the most important plant-specific transcription factors and play vital roles in various biological processes. However, the functions of <i>WRKY</i> genes in wintersweet (<i>Chimonanthus praecox</i>) are still unknown. In this report, a group IIc <i>WRKY</i> gene, <i>CpWRKY71</i>, was isolated from wintersweet. CpWRKY71 was localized to the nucleus and possessed transcriptional activation activity. qRT-PCR (quantitative real-time PCR) analysis showed that <i>CpWRKY71</i> was expressed in all tissues tested, with higher expression in flowers and senescing leaves. During the flower development, the highest expression was detected in the early-withering stage, an obvious expression of <i>CpWRKY71</i> was also observed in the flower primordia differentiation and the bloom stage. Meanwhile, the expression of <i>CpWRKY71</i> was influenced by various abiotic stress and hormone treatments. The expression patterns of the <i>CpWRKY71</i> gene were further confirmed in <i>CpWRKY71pro</i>:<i>GUS</i> (<i>β-glucuronidase</i>) plants. Heterologous overexpression of <i>CpWRKY71</i> in <i>Arabidopsis</i> caused early flowering. Consistent with the early flowering phenotype, the expression of floral pathway integrators and floral meristem identity (FMI) genes were significantly up-regulated in transgenic plants. In addition, we also observed that the transgenic plants of <i>CpWRKY71</i> exhibited precocious leaf senescence. In conclusion, our results suggested that <i>CpWRKY71</i> may be involved in the regulation of flowering and leaf senescence in <i>Arabidopsis</i>. Our study provides a foundation for further characterization of <i>CpWRKY</i> genes function in wintersweet, and also enrich our knowledge of molecular mechanism about flowering and senescence in wintersweet.