Odorant-Binding Protein 1 Plays a Crucial Role in the Olfactory Response of <i>Bemisia tabaci</i> to <i>R</i> -Curcumene

Abstract

The cultivated tomato <i>Solanum lycopersicum</i> suffered a severe attack by the whitefly <i>Bemisia tabaci</i> (Gennadius), causing damage to leaves by feeding as well as transmitting the tomato yellow leaf curl virus (TYLCV), while the wild tomato <i>S. habrochaites</i> is considerably less appealing to this insect species. It is reported that <i>B. tabaci</i> shows innate avoidance to <i>R</i>-curcumene, which is produced naturally by <i>S. habrochaites</i>. However, the mechanisms involved in the avoidance behavior of <i>B. tabaci</i> in response to this chiral compound are still unclear yet. In this study, the functional and binding characterization of odorant-binding protein 1 of <i>B. tabaci</i> (BtOBP1) were examined <i>in vivo</i> and <i>in vitro</i> against <i>R</i>-curcumene. The obtained results showed that BtOBP1 exhibits specific binding activity to <i>R</i>-curcumene, which acts as repellents to <i>B. tabaci</i>. By using a fluorescence-based binding assay, the difference of binding-affinity for <i>R</i>-curcumene between wild type BtOBP1 and the mutant BtOBP1 to <i>R</i>-curcumene was performed, which resulted in a single amino acid mutation (ASN108 > SER); moreover, BtOBP1-N108 displays significantly decreased binding affinities to <i>R</i>-curcumene. Most interestingly, a knock-down experiment with the BtOBP1 showed that the whitefly responses to <i>R</i>-curcumene are impaired. This study illustrated that BtOBP1 is a crucial protein involved in the perception and discrimination of <i>R</i>-curcumene. Our findings may provide an excellent chance of finding a suitable antagonist of eco-friendly features that can block the perception of chemosensory signals in insects, preventing behaviors like food-finding.