Evidence of a Functional RNAi Gene Silencing Mechanism in the Corn Leafhopper, D. maidis
Tara-Kay L. Jones, Julio S. Bernal and Raul F. Medina
Corn leafhopper, Dalbulus maidis (DeLong & Wolcott), is the most efficient vector of corn stunting pathogens (Spiroplasma kunkelii, Maize bushy stunt phytoplasma and Maize rayado fino virus) in the Americas. Studies involving gene editing in insects are rapidly providing information that can potentially be used towards insect vector and plant disease control. RNA interference (RNAi), a sequence-specific way to silence target genes, is one of the most widely used molecular tools in functional genetics studies. RNAi uses exogenous double-stranded RNA (dsRNA) or small interfering RNA (siRNA) to prevent the production of proteins by inhibiting the expression of corresponding messenger RNA. In this study we measured the efficiency of gene silencing and its effects on corn leafhopper mortality as a means of demonstrating that the RNAi mechanism is viable in this insect. Oral delivery of dsRNA using an artificial diet was used to induce silencing of two key insect genes, vacuolar ATP synthase subunit B (V-ATPase-B) and subunit D (V-ATPase-D). Results showed higher mortality after oral delivery of dsRNA-V-ATPases, compared to control. Consistently, qRT-PCR analysis of gene expression indicated positive effects of V-ATPases gene silencing in corn leafhopper. The evidence of successful RNAi-based inhibition of gene expression in corn leafhopper is encouraging, and opens the way for further functional genetics studies, such as identification of vital genes, and genes involved in the transmission cycle of corn stunting pathogens. Identifying such genes will allow the development of population suppression or population replacement genetic control strategies for pests in the future.