Odorant binding proteins (OBPs) play an important role in insect peripheral olfactory systems and exploring the physiological function of OBPs could facilitate the understanding of insects' chemical communication. Here, the functional analysis of an antenna-based NlugOBP8 from brown planthopper (BPH) Nilaparvata lugens (Stål) was performed both in vitro and in vivo. Recombinant NlugOBP8 exhibited strong binding affinity to 13 out of 26 rice plant volatiles and could form a stable complex with 9 of them according to the fluorescence binding and fluorescence quenching experiments. Circular dichroism spectra demonstrated that six volatiles could give rise to significant conformational change of recombinant NlugOBP8. H-tube olfactometer bioassay confirmed that BPHs were significantly attracted by nerolidol and significantly repelled by linalool, caryophyllene oxide, and terpinolene, respectively. Antennae of dsNlugOBP8-injected BPHs exhibited significantly lower electrophysiological response to linalool and caryophyllene oxide. Moreover, the repellent responses of BPHs to these two volatiles were also impaired upon silencing NlugOBP8. These data suggest that NlugOBP8 is involved in recognizing linalool and caryophyllene oxide and provide additional target for the sustainable control of BPHs.
Keywords: EAG; H-tube olfactometer; Nilaparvata lugens; RNAi; odorant-binding proteins.