Genome-wide analysis of WRKY gene family in Cucurbita moschata and involvement of CmWRKY22/63/84 in powdery mildew resistance

Powdery mildew (PM), mainly caused by Podosphaera xanthii , is a severe biotrophic pathogen disease of global Cucurbitaceae vegetables. However, Cucurbita moschata (pumpkin) strongly resists PM and shows wide adaptability. WRKY transcription factors participate in plant response to pathogen stresses, but the function of WRKY genes under PM stress in pumpkins is largely unknown. In this study, 98 members of the CmWRKYs family were identified in the genome of C. moschata and categorized into three groups. CmWRKY promoter regions contained many cis -regulatory elements closely related to light, hormone, and stress responses. A segmental duplication event drove the expansion of the pumpkin CmWRKY genes, and the WRKY genes were highly conserved in pumpkin and cucumber. Additionally, the expression of 13 CmWRKY genes was altered following PM infection, of which five CmWRKY genes were induced, while CmWRKY84 and 92 simultaneously responded to salicylic acid and hydrogen peroxide (H 2 O 2 ) treatments. Furthermore, transient overexpression of CmWRKY22/63/84 in pumpkin plants inhibited the hyphal growth of P. xanthii while enhancing the accumulation of H 2 O 2 . A genome-wide analysis of the WRKY family in C. moschata identified the involvement of CmWRKY22/63/84 in the PM resistance. Our results contribute to research on the function of CmWRKY genes in the pumpkin resistance to PM.