Binding Characteristics and Functional Analysis of Odorant-Binding Protein 17 in the Rice Water Weevil ( <i>Lissorhoptrus oryzophilus</i> ) with Host Volatiles

Odorant binding proteins (OBPs) are essential for insect olfaction. <i>Lissorhoptrus oryzophilus</i> (Coleoptera: Curculionidae), known as the rice water weevil, is a destructive pest of rice. In this study, rice volatiles were analyzed by gas chromatography-mass spectrometry (GC-MS), and ten rice volatiles were identified. Quantitative real-time PCR (<i>q</i>RT-PCR) analysis revealed that <i>LoryOBP17</i> is highly expressed in the antennae. Fluorescence competitive binding assays demonstrated that LoryOBP17 exhibits strong binding affinity to 1-penten-3-ol and (<i>E</i>)-2-hexenal among the identified volatiles. 1-Penten-3-ol and (<i>E</i>)-2-hexenal (0.1 μg/μL) elicited strong EAG responses and significant behavioral attraction. After RNA interference (RNAi), EAG responses and behavioral attraction to 1-penten-3-ol and (<i>E</i>)-2-hexenal were significantly reduced. These results indicate that LoryOBP17 recognizes and binds these two host plant volatiles, suggesting its involvement in host odorant perception in RWW.