CaWRKY01-10 and CaWRKY08-4 Confer Pepper’s Resistance to <i>Phytophthora capsici</i> Infection by Directly Activating a Cluster of Defense-Related Genes
Wei Cheng, Nan Wang, Yuan Li, Zhou Xianjun, Xueyi Bai, Li Liu, Xinjie Ma, Shuai Wang, Xueqi Li, Beibei Gong, Yan Jiang, Muhammad Azeem, Liyun Zhu, Lin Chen, Hui Wang, Moli Chu
Abstract
Phytophthora blight of pepper, which is caused by the notorious oomycete pathogen Phytophthora capsici, is a serious disease in global pepper production regions. Our previous study had identified two WRKY transcription factors (TFs), CaWRKY01-10 and CaWRKY08-4, which are prominent modulators in the resistant pepper line CM334 against P. capsici infection. However, their functional mechanisms and underlying signaling networks remain unknown. Herein, we determined that CaWRKY01-10 and CaWRKY08-4 are localized in plant nuclei. Transient overexpression assays indicated that both CaWRKY01-10 and CaWRKY08-4 act as positive regulators in pepper resistance to P. capsici . Besides, the stable overexpression of CaWRKY 01-10 and CaWRKY 08-4 in transgenic Nicotiana benthamiana plants also significantly enhanced the resistance to P. capsici . Using comprehensive approaches including RNA-seq, CUT&RUN-qPCR, and dual-luciferase reporter assays, we revealed that overexpression of CaWRKY01-10 and CaWRKY08-4 can activate the expressions of the same four Capsicum annuum defense-related genes (one PR 1, two PR 4, and one pathogen-related gene) by directly binding to their promoters. However, we did not observe protein–protein interactions and transcriptional amplification/inhibition effects of their shared target genes when coexpressing these two WRKY TFs. In conclusion, these data suggest that both of the resistant line specific upregulated WRKY TFs (CaWRKY01-10 and CaWRKY08-4) can confer pepper’s resistance to P. capsici infection by directly activating a cluster of defense-related genes and are potentially useful for genetic improvement against Phytophthora blight of pepper and other crops.