CaWRKY22b Plays a Positive Role in the Regulation of Pepper Resistance to in a Manner Associated with Jasmonic Acid Signaling.

As important transcription factors, WRKYs play a vital role in the defense response of plants against the invasion of multiple pathogens. Though some WRKY members have been reported to participate in pepper immunity in response to infection, the functions of the majority of WRKY members are still unknown. Herein, was cloned from the pepper genome and its function against was analyzed. The transcript abundance of was significantly increased in response to the infection of and the application of exogenous methyl jasmonate (MeJA). Subcellular localization assay in the leaves of showed that CaWRKY22b protein was targeted to the nuclei. -mediated transient expression in pepper leaves indicated that overexpression triggered intensive hypersensitive response-like cell death, HO accumulation, and the up-regulation of defense- and JA-responsive genes, including , , , and . Virus-induced gene silencing assay revealed that knock-down of attenuated pepper's resistance against and the up-regulation of the tested defense- and jasmonic acid (JA)-responsive genes. We further assessed the role of CaWRKY22b in modulating the expression of JA-responsive , and the result demonstrated that CaWRKY22b trans-activated expression by directly binding to its upstream promoter. Collectively, our results suggest that CaWRKY22b positively regulated pepper immunity against in a manner associated with JA signaling, probably by modulating the expression of JA-responsive .