Fusion dsRNA in targeting salivary protein genes enhance the RNAi-based aphid control.

RNA interference (RNAi) is a promising tool for pest control and relies on sequence-specific gene silencing. Salivary proteins are cooperatively secreted into plants to guarantee the feeding of aphids; thus they have potential to develop as selective targets for RNAi-based pest control strategy. For this purpose, we firstly analyzed 18 salivary proteomes of various aphid species, and these salivary proteins can be mainly categorized into seven functional groups. Secondly, we created a work-flow for fusion dsRNA design that can target multiple genes but were selectively safe to beneficial insects. Based on this approach, seven fusion dsRNAs were designed to feed the green peach aphid, which induced a significant reduction in aphid fitness. Among them, ingestion of dsperoxidase induced the highest mortality in aphids, which was also significantly higher than that of traditional dsRNAs in targeting three peroxidases separately. In addition, dsperoxidase-fed green peach aphids triggered the highest H2O2 content of host plants as well as the attraction to natural enemies (ladybeetle and parasitic wasp) but repellent to other control aphids. Our results indicate that the fusion dsRNA design approach can improve aphid control capacity, and the fusion dsRNA targeting salivary protein-encoding genes can enhance the direct and indirect defenses of host plants, thus providing a new strategy for RNAi-based aphid control.

Fusion dsRNA designs incorporating multiple target sequences can enhance the aphid control capacity of an RNAi-based strategy.

BACKGROUND: RNA interference (RNAi) is the sequence-dependent suppression of gene expression by double-stranded RNA (dsRNA). This is a promising strategy for the control of insect pests because dsRNA can be rationally designed to maximize efficacy and biosafety, the latter by using sequences that are found in target pests but are safe for non-target insects. However, this has yet to be optimized in aphids, destructive sap-sucking pests that also transmit plant viruses. We used the green peach aphid (Myzus persicae) as a case study to optimize the efficiency of RNAi by applying a novel fusion dsRNA design. RESULTS: Comparative transcriptomics revealed a number of genes that are induced in feeding aphids, and eight candidate genes were chosen as RNAi targets. To improve RNAi efficiency, our fusion dsRNA design approach combined optimal gene fragments (highly conserved in several aphid species but with less homology in beneficial insects such as the predator ladybeetle Propylea japonica) from three candidate genes. We compared this RNAi-based biological control approach with conventional chemical control using imidacloprid. We found that the fusion dsRNA strategy inhibited the aphid population to a significantly greater extent than single-target RNAi and did not affect ladybeetle fitness, allowing an additive effect between RNAi and natural predation, whereas imidacloprid was harmful to aphids and ladybeetles. CONCLUSION: Our fusion dsRNA design approach enhances the ability of RNAi to control aphids without harming natural predators. © 2024 Society of Chemical Industry.