Comprehensive analysis of the GeBP gene family in cucumber highlights functional divergence in fruit development and stress tolerance

GeBP genes play important roles in plant development and stress responses; however, they have not yet been systematically characterized in cucumber (Cucumis sativus). In this study, six GeBP genes were identified in the cucumber genome. All CsGeBP proteins possess conserved basic regions and leucine zipper–like domain and are predominantly localized in the nucleus. Phylogenetic and synteny analyses revealed that the GeBP gene family is highly conserved among cucurbit species and has expanded mainly through segmental duplication events. Expression analyses demonstrated clear functional divergence among CsGeBP genes. CsGeBP5 showed consistently high expression in reproductive tissues and was upregulated in long-fruit cucumber lines, suggesting a potential role in fruit development. In contrast, CsGeBP6 was strongly induced under salt stress, and its expression was further enhanced by silicon treatment. Moreover, it was markedly upregulated in the resistant cucumber line SSL508-28 after powdery mildew inoculation, suggesting a role in both abiotic stress tolerance and disease resistance. Overall, this study provides the first comprehensive analysis of the GeBP gene family in cucumber and identifies key potential genes associated with fruit development (CsGeBP5) and stress responses (CsGeBP6), laying a foundation for future functional studies and molecular breeding.