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

Abstract

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. <i>Sogatella furcifera</i> is one of the most destructive pests of rice crops. Understanding the functions of <i>S. furcifera</i> OBPs (<i>Sfur</i>OBPs) in the host plant location and the behavioral responses of <i>S. furcifera</i> to rice plant volatiles could lead to improved, more environmentally-friendly, methods for controlling this pest. We found that <i>Sfur</i>OBP1 displayed only weak binding with all the tested volatiles. <i>Sfur</i>OBP2, <i>Sfur</i>OBP3 and <i>Sfur</i>OBP11 had different binding affinities to β-ionone. <i>Sfur</i>OBP2 and <i>Sfur</i>OBP11 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 <i>S. furcifera</i> was significantly repelled by octanal and n-octane but strongly attracted by (+)-limonene, acetophenone, 2-heptanone, n-hendecane, <i>α</i>-farnesene and β-ionone. Furthermore, the dsRNA-mediated gene silencing of <i>SfurOBP2</i>, <i>SfurOBP3</i> and <i>SfurOBP11</i> shifted the olfactory behavior of <i>S. furcifera</i> for β-ionone, α-farnesene and plant alcohol, respectively. These results suggest that the <i>Sfur</i>OBPs are involved in the recognition of rice plant volatiles, and several potential repellants and lures for controlling this pest.