ilvE as a potential RNAi target to inhibit amino acid synthesis to control the wheat aphid Sitobion miscanthi

Aphids form a tight and mutually beneficial symbiosis with their primary symbiont Buchnera aphidicola, which plays a prominent role in aphid nutrition metabolism. Here, we sequenced the genome of B. aphidicola from the wheat aphid Sitobion miscanthi and performed KEGG analysis of amino acid synthesis pathways based on our previously pub- lished S. miscanthi genome. The genome of B. aphidicola from S. miscanthi contained almost all genes of the valine (Val), leucine (Leu) and isoleucine (Ile) synthesis pathways; however, it lacked a branched-chain amino acid aminotransferase (ilvE) required in the pathways, but this gene was present in the S. miscanthi genome. Sequence analysis showed that the ilvE gene was highly conserved in aphids. ilvE was highly expressed in the 3rd and 4th instars of S. miscanthi and showed higher expression in the bacteriocyte than in other parts. After RNAi-mediated ilvE knockdown, the result showed a signifi- cant mortality and body weight losses. Meanwhile, the B. aphidicola relative abundance and the Val, Leu and Ile production decreased significantly after ilvE gene interference. These results indicate that ilvE is a bridge gene in the aphid genome, linking the metabolic relay between aphids and B. aphidicola and significantly affecting the vital life parameters of aphids, potentially by affecting Val, Ile and Leu production. Our study may provide a future direction for using key junctions of the metabolic relay between insects and endosymbionts as RNAi target loci to develop new strategies for agricultural pest control.

Automated summary

Buchnera aphidicola plays a crucial role in aphid nutrition metabolism, while the gene ilvE acts as a bridge gene in the aphid genome, affecting vital life parameters and Val, Ile, and Leu production. Knocking down the ilvE gene using RNAi significantly impacts aphid survival and body weight.