Molecular characterization and ligand-binding properties of six odorant-binding proteins (OBPs) from Aphis gossypii

Abstract Odorant-binding proteins (OBPs) play a significant role in the olfactory signal transduction of insects and help them locate hosts, oviposition sites, and mating partners. The sap-sucking insect, Aphis gossypii Glover (Homoptera: Aphididae), is a destructive cosmopolitan pest and yet the molecular mechanisms by which A. gossypii perceives pheromones and host volatiles remain unknown. In this study, we identified and characterized 6 OBPs, using the A. gossypii RNA-seq transcriptome dataset previously constructed in our laboratory. Real-time PCR indicated specific expression patterns of the 6 genes, which had different levels of expression based on development stage, tissue, morph, and life cycle. In addition, binding specificities of the 6 proteins investigated using the ligand-binding assays showed that all 6 OBPs exhibited high binding affinities towards Phlorizin dehydrate while AgosOBP3 and AgosOBP4 had strong affinity to beta-ionone and AgosOBP8 displayed higher binding affinities for Nerolidol and Cis-3-hexenyl acetate compared to other OBPs.