CaWRKY7 enhances pepper resistance to Phytophthora blight by modulating ROS homeostasis

Pepper blight caused by Phytophthora capsici severely reduces pepper yield and quality. WRKY transcription factors are critical components of plant immunity, but their functions in pepper blight resistance remain largely unexplored. Here, we isolated a group II WRKY gene CaWRKY7 , which encodes a protein of 350 amino acid residues containing a single WRKY domain and a C2H2-type zinc finger motif. Bioinformatics analysis revealed that it comprises three exons and two introns, and its promoter region harbors multiple stress-responsive cis -elements. Phylogenetic analysis indicated that CaWRKY7 possesses closely related orthologs in various plant species, including Arabidopsis thaliana , tomato, and tobacco. RT-qPCR assays demonstrated that CaWRKY7 is constitutively expressed in all tested pepper tissues and is significantly induced by P. capsici infection. Subcellular localization analysis showed that the CaWRKY7 is a nucleus‑localized protein. Furthermore, silencing CaWRKY7 via VIGS increased disease index and lesion area, decreased H₂O₂ accumulation, suppressed transcript levels and activities of antioxidant enzymes, whereas transient overexpression of CaWRKY7 produced opposite effects. Our results demonstrate that CaWRKY7 acts as a positive regulator of pepper resistance to P. capsici via ROS pathway, offering new insights into WRKY‑mediated defense against pepper blight.