Odorant-Binding Protein 17 Mediates the Recognition of Soybean Volatiles in Adult Riptortus pedestris

RpedOBP17, an odorant-binding protein highly expressed in adult Riptortus pedestris antennae, was systematically investigated using prokaryotic expression, fluorescence competitive binding, molecular docking, site-directed mutagenesis, and RNA interference. Binding assays revealed affinity to six soybean volatile compounds. Molecular docking and mutagenesis identified Ile46 and Phe129 as critical residues for ligand recognition, since alanine substitutions markedly reduced binding. RNAi-mediated knockdown significantly impaired olfactory chemotaxis, with electroantennogram recordings showing attenuated responses to (Z)-3-hexenyl acetate, (E)-2-hexenyl acetate, and 4-ethylbenzaldehyde in both sexes, along with sex-specific changes to 2-methyl-1-butanol (females) and (Z)-3-hexenyl propionate (males). Y-tube olfactometer tests further confirmed decreased attraction to (E)-2-hexenyl acetate. These results elucidate the molecular interaction mechanism and provide a theoretical foundation for developing novel olfactory disruption-based control agents targeting RpedOBP17.