Abstract: 【Aim】 Odorant-binding proteins (OBPs) play a fundamental role in insect olfaction. The Colorado potato beetle (CPB), Leptinotarsa decemlineata (Say), is one of the most notorious insect pests of potato. The sequence properties and tissue expression profiles of 26 putative OBP genes of L. decemlineata were identified to clarify the molecular mechanisms of its olfactory perception. 【Methods】 Based on antennal transcriptome sequencing data of L. decemlineata, the phylogeny and tissue-specific gene expression profiles of 26 LdecOBPs (LdecOBP1-LdecOBP26) in L. decemlineata were analyzed by bioinformatic methods and qRT-PCR, respectively. 【Results】 Except LdecOBP26, the genes of the other 25 LdecOBPs have the full-length open reading frames, encoding 120-255 amino acid residues with the predicted molecular weights of 13.66-29.38 kD and isoelectric points of 4.12-8.42. The 25 LdecOBPs belong to two subfamilies, with 13 Classical-C OBPs and 12 Minus-C OBPs. Except LdecOBP3 and LdecOBP26, each of the other 24 LdecOBPs contains a signal peptide at the N-terminus consisting of 16-23 amino acid residues. These OBPs in each subfamily have their own typical conservative Cys residues. LdecOBPs are highly divergent and their amino acid sequence identities range from 3.20% to 41.91%. Phylogenetic analysis showed that LdecOBPs and GdauOBPs of Galeruca daurica are most closely related. Gene expression profiling showed the 26 LdecOBPs genes were expressed in different adult tissues of L. decemlineata, with 12 LdecOBPs genes (LdecOBP2, LdecOBP4, LdecOBP6, LdecOBP9, LdecOBP10, LdecOBP12, LdecOBP13, LdecOBP16, LdecOBP20-22 and LdecOBP24) highly expressed in antennae, two genes (LdecOBP5 and LdecOBP17) highly expressed in legs, and the other 12 (LdecOBP1, LdecOBP3, LdecOBP7, LdecOBP8, LdecOBP11, LdecOBP14, LdecOBP15, LdecOBP18, LdecOBP19, LdecOBP23, LdecOBP25 and LdecOBP26) expressed in tissues antennae, head (with antennae removed), thorax, abdomen, legs and wings. 【Conclusion】 These results establish a foundation for further research on the molecular mechanisms of chemical communications in L. decemlineata.

Key words: Leptinotarsa decemlineata, odorant-binding protein, sequence analysis, tissue expression profile, phylogeny