Functional analysis of a new WRKY gene isolated from pepper (capsicum annuum)

WRKY transcription factor family were widespreaded in plants. Previous studies have suggested that WRKY genes play key roles in modulating plant defense against different biotic and abiotic stresses. To study its function of a new WRKY transcription factor cloned from capsicum annuum, methods including Real-time PCR, transformation, cell localization, transient expression and VIGS were used. The results indicated that consistent with its role as a transcriptional regulator, CaWRKY is localized to nuclei of cells and binds specifically to functionally defined TGAC-containing W boxes of the 35s promoter in vivo. Overexpression of WRKY was sufficient to decrease pepper resistance to bacterial wilt compared with wild-type. Nevertheless, virus-induced gene silencing of WRKY in chili pepper leaves resulted in be sensitive to bacterial wilt. The result of Real-time PCR showed that WRKY transcriptional level decreased in leaves infected with Phytophthora capsici and lower levels gene induction were observed in plants following salicylic acid (SA) treatments, while WRKY is strongly induced by the signal molecule JA. These findings suggest that WRKY encodes a transcriptional repressor of biotic defense signaling.