Solanum torvum has broad resistance to wilt-causing bacteria and fungi and nematodes. Here, we applied virus-induced gene silencing (VIGS) in S. torvum and optimized the experimental conditions to suppress a carotenoid biosynthesis gene with high efficiency. Using this optimized method, we suppressed the StPsbO and StPsbP genes, which encode components of the oxygen-evolving complex, in S. torvum. Silencing of StPsbO and StPsbP impaired defense response in S. torvum, making it more susceptible to Ralstonia solanacearum. These results indicate that the optimized VIGS method can be used to identify genes required for plant immunity in S. torvum.