CaWRKY01-10 and CaWRKY08-4 Confer Pepper's Resistance to Infection by Directly Activating a Cluster of Defense-Related Genes.

Phytophthora blight of pepper, which is caused by the notorious oomycete pathogen , 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 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 . Besides, the stable overexpression of 01-10 and 08-4 in transgenic plants also significantly enhanced the resistance to . 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 defense-related genes (one 1, two 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 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.