Three odorant-binding proteins are involved in the behavioral response of Sogatella furcifera to rice plant volatiles

Plant volatiles play an important role in regulating insect behavior. Odorant binding proteins (OBPs) are involved in the first step of the olfactory signal transduction pathway and plant volatiles recognition. Sogatella furcifera is one of the most destructive pests of rice crops. Understanding the functions of S. furcifera OBPs (SfurOBPs) in the host plant location and the behavioral responses of S. furcifera to rice plant volatiles could lead to improved, more environmentally-friendly, methods for controlling this pest. We found that SfurOBP1 displayed only weak binding with all the tested volatiles. SfurOBP2, SfurOBP3 and SfurOBP11 had different binding affinities to β-ionone. SfurOBP2 and SfurOBP11 had strong binding affinities to β-caryophyllene (K(i) = 2.23 µM) and plant alcohol (K(i) = 2.98 µM), respectively. The results of Y-olfactometer experiments indicate that S. furcifera was significantly repelled by octanal and n-octane but strongly attracted by (+)-limonene, acetophenone, 2-heptanone, n-hendecane, α-farnesene and β-ionone. Furthermore, the dsRNA-mediated gene silencing of SfurOBP2, SfurOBP3 and SfurOBP11 shifted the olfactory behavior of S. furcifera for β-ionone, α-farnesene and plant alcohol, respectively. These results suggest that the SfurOBPs are involved in the recognition of rice plant volatiles, and several potential repellants and lures for controlling this pest.