RNAi-based transgenic maize to control double-spotted leaf beetle (Monolepta hieroglyphica).

Background: The double-spotted leaf beetle (DLB), Monolepta hieroglyphica, is becoming a significant corn pest in China. It mainly attacks corn silk and developing kernels during the adult stage and is causing significant corn yield loss in north-eastern China. The damage caused by DLB is expected to worsen as pesticide usage is likely to decrease along with the upcoming commercial planting of transgenic lepidopteran-resistant maize in China. Therefore, it is highly desirable to develop transgenic corn for DLB resistance.

Results: Three target genes, MhSsj1, MhSnf7 and MhSec23A were cloned from DLB by their sequence similarity to their corresponding homologous genes known for their effectiveness as RNA interference (RNAi) targets in western corn rootworm (WCR, Diabrotica virgifera virgifera). Injection of the double-stranded RNAs (dsRNAs) of MhSsj1, MhSnf7 and MhSec23A to DLB adults was highly effective to suppress the messenger RNAs (mRNAs) of these genes and resulted in high mortality. Furthermore, a synergistic effect was observed among the dsRNAs of these three target genes. Transgenic maize plants simultaneously transcribing dsRNAs of any two of the three target genes were found to be highly resistant to DLB adults, showcasing the potential of utilizing RNAi-based strategy for transgenic DLB control.

Conclusion: MhSsj1, MhSnf7 and MhSec23A are effective RNAi target genes and transgenic corn based on suppression of these genes by RNAi are effective for controlling adult DLB. © 2024 Society of Chemical Industry.