Increasing forms overexpression of CpVQ30 increases susceptibility of Cucurbita pepo to powdery mildew via oxidative stress and callose degradation

• This study achieved the breakthrough of Cucurbita pepo transgenic was realized. • Transient overexpression of CpVQ30 heightened the susceptibility of Cucurbita pepo to powdery mildew. • CpVQ30 increases susceptibility of Cucurbita pepo to powdery mildew via oxidative stress and callose degradation. • This study made a significant contribution to the subsequent disease resistance breeding of Cucurbita pepo by gene silencing. Powdery mildew (PM), caused by Podosphaera xanthii , poses a substantial menace to the worldwide Cucurbita pepo yield. The VQ family plays a broad role in plant growth, development, responses to biotic and abiotic stresses, and environmental signaling. To investigate the responsiveness of the CpVQ30 gene to powdery mildew infection in Cucurbita pepo L., CpVQ30 was transiently overexpressed in virus-susceptible and powdery mildew-susceptible material, YF. Results from GFP fluorescence assay, viral disease phenotyping, and qPCR confirmed the successful acquisition of Cucurbita pepo plants transiently overexpressing CpVQ30 . Compared to the control (empty vector), following powdery mildew infection, the transient overexpression of CpVQ30 exacerbated the powdery mildew symptoms, leading to the complete leaf coverage with white powder. There was an elevation in reactive oxygen species (ROS) accumulation and malondialdehyde (MDA) content, alongside reduced antioxidant enzyme activities, relative chlorophyll content, and callose content. Furthermore, powdery mildew mycelium grew faster and accumulated more. Moreover, the expression levels of callose synthase gene and defense-related genes were diminished. CpVQ30 heightened the susceptibility of Cucurbita pepo to powdery mildew. The study establishes a theoretical foundation for future gene silencing and genetic breeding, with the ultimate aim of developing powdery mildew-resistant Cucurbita pepo germplasm to improve both nutritional quality and yield.