Silencing of Decapentaplegic (Dpp) gene inhibited the wing expansion in the white-backed planthopper, Sogatella furcifera (Horvath) (Hemiptera: Delphacidae)

The Decapentaplegic gene controls wing patterning and spreading by regulating downstream genes in many insect species. However, the molecular characteristics, expression, and biological function of Dpp in Sogatella furcifera remain poorly understood. In this study, we cloned the Dpp gene from S. furcifera and examined its expression levels in different development stages, wing typed adults, and tissues. Then, the function of SfDpp gene was analyzed using an RNA interference (RNAi)-based approach. The results showed that the full-length complementary DNA of the SfDpp gene consists of 1034 bp and contains a 954-bp open reading frame encoding 317 amino acids. SfDpp has a transforming growth factor-beta (TGF-beta) propeptide superfamily domain and a TGF-beta superfamily domain, typical of members of the TGF-beta superfamily. Quantitative real-time polymerase chain reaction showed that the expression of SfDpp reached its highest expression level 40 min after eclosion. RNAi-based gene silencing inhibited transcript levels of the corresponding messenger RNA in S. furcifera nymphs injected with double-stranded RNA of SfDpp and resulted in death of 29.17% and 26.67% of 4th and 5th instar nymphs, respectively. The wing deformity rate of the adults was 74.12% and 3.41% after SfDpp gene silencing in 4th and 5th instar nymphs, respectively. Examining wing development-associated genes showed that two target genes of Dpp (Vestigial and Spalt) were both dramatically downregulated after SfDpp was silenced. Our results demonstrate that downregulated SfDpp in early development causes wing expansion failure in S. furcifera. Thus, Dpp may be a target gene for restricting the migration of rice-damaging planthoppers.