The systemic expressions of certain defense-related genes in cucumber plants induced by culture filtrate (CF) of the plant growth-promoting fungus (PGPF), Penicillium simplicissimum GP17-2, and challenging with Sio 2 nanoparticles against Papaya ring spot virus (PRSV) and its vector the green peach aphid Myzus persicae were investigated. CF and Sio 2 were topically applied to cucumber plants by soil drench method. Results showed that the severity of PRSV and its accumulation in cucumber leaves were significantly reduced in all treated cucumber plants compared with the control. The expression of pathogenesis-related genes showed strong activations of peroxidases (POX) and phenylalanineammonia lyase (PAL) genes and moderate expression of PR-1 one day after inoculation, while, six days after inoculation a high activation of PAL and PR-1 genes and moderate activation of POX gene were detected. No expression was detected in plants infected with PRSV alone without any treatments. These results suggested that CF and Sio 2 treatments mediated the expression of the majority of various pathogen-related genes, which may contribute to the increased defense mechanism against PRSV infection in cucumber.