Silencing of ATP Synthase β Impairs Egg Development in the Leafhopper Scaphoideus titanus, Vector of the Phytoplasma Associated with Grapevine Flavescence Doree

Scaphoideus titanus (Hemiptera: Cicadellidae) is the natural vector of Flavescence doree phytoplasma, a quarantine pest of grapevine with severe impact on European viticulture. RNA interference (RNAi) machinery components are present in S. titanus transcriptome and injection of ATP synthase beta dsRNAs into adults caused gene silencing, starting three days post injection (dpi) up to 20 dpi, leading to decrease cognate protein. Silencing of this gene in the closely related leafhopper Euscelidius variegatus previously showed female sterility and lack of mature eggs in ovaries. Here, alteration of developing egg morphology in S. titanus ovaries as well as overexpression of hexamerin transcript (amino acid storage protein) and cathepsin L protein (lysosome proteinase) were observed in dsATP-injected females. To evaluate RNAi-specificity, E. variegatus was used as dsRNA-receiving model-species. Different doses of two sets of dsRNA-constructs targeting distinct portions of ATP synthase beta gene of both species induced silencing, lack of egg development, and female sterility in E. variegatus, indicating that off-target effects must be evaluated case by case. The effectiveness of RNAi in S. titanus provides a powerful tool for functional genomics of this non-model species and paves the way toward RNAi-based strategies to limit vector population, despite several technical and regulatory constraints that still need to be overcome to allow open field application.

Automated summary

This study discovered the presence of RNA interference (RNAi) machinery in the insect species Scaphoideus titanus, which is the natural vector of a plant disease. Injection of dsRNA targeting a specific gene in S. titanus led to gene silencing and observed changes in egg development and protein expression.