Spray-induced gene silencing as a potential tool to control rubber tree powdery mildew disease

Powdery mildew of rubber tree, caused by the obligate biotrophic fungus Erysiphe quercicola, is a serious disease that occurs in all rubber tree growing regions. The disease is mainly controlled by fungicides. Here, an alternative means for powdery mildew control by spraying double-stranded RNAs (dsRNA), which target E. quercicola genes, was investigated. First, we demonstrated that the conidia of E. quercicola can take-up environmental dsRNA. Furthermore, the spraying of dsRNA targeting E. quercicola genes can effectively reduce both the expression of the target gene of the pathogen and the rubber tree powdery mildew severity. The reduction in disease severity was up to 50 % compared to water-treated leaves. These results suggest that Spray-induced gene silencing (SIGS) of the pathogen genes will provide an additional tool to control rubber tree powdery mildew as well as a method to study the function of genes of E. quercicola.