Vigilancia Tecnológica

The rice leaffolder Cnaphalocrocis medinalis is one of the most important pests of rice. Double-stranded RNA-degrading enzyme (dsRNase) is one of key factors affecting the stability of dsRNA in insects, thus restricting the application of RNA interference (RNAi) technology in pest control. In this study, a dsRNase gene from C. medinalis, designated CmdsRNase2, was cloned by using reverse transcription-polymerase chain reaction (RT-PCR). The open reading frame (ORF) of CmdsRNase2 is 1,335 bp in length, encoding 444 amino acids. The CmdsRNase2 protein contains a signal peptide and an Endounuclease_NS domain that includes six active sites, one Mg2+ binding site, and three substrate binding sites. Homology comparison showed that CmdsRNase2 was most closely related to dsRNase2 from Ostrinia nubilalis, with 66.96% similarity. Spatiotemporal expression pattern analyses indicated that CmdsRNase2 was expressed throughout developmental stages with the highest expression level in the fifth-instar larvae and all seven tissues tested in adults with the highest level in the hemolymph. On the third day after RNA interference (RNAi), silencing CmCHS (C. medinalis chitin synthase) alone had a RNAi efficiency of 56.84%, while co-sliencing both CmCHS and CmdsRNase2 caused a RNAi efficiency of 83.44%, an increase of 26.60%. The results showed that the efficiency of RNAi in C. medinalis was greatly improved by simultaneously interfering with expressions of both CmCHS and CmdsRNase2. This study is very helpful for understanding the mechanism of dsRNase involved in the RNAi process and for eco-friendly pest control by using RNAi strategies.