Abstract:

 【Aim】This study aims to clone and identify odorant-binding protein (OBP) genes in the adzuki bean seed weevil, Callosobruchus chinensis and to assay their tissue-specific expression profiles in C. chinensis adults, so as to to lay a foundation for studying the function of OBPs in olfactory perception in C. chinensis. 【Methods】Based on the antenna transcriptome data of C. chinensis, six OBP genes in C. chinensis were cloned by RT-PCR and analyzed by bioinformatics. The expression levels of OBP genes in tissues including head (excluding antennae), antennae, abdomen, legs and wings of female and male adults of C. chinensis were analyzed by qRT-PCR. 【Results】 The open reading frames of six OBP genes from C. chinensis were obtained, and named as CchiOBP1-CchiOBP6 (GenBank accession number: MN832700-MN832703, MN901841-MN901842). CchiOBP5 is a segment of Minus-C OBP with incomplete C-terminus, and the others belong to complete classical OBPs. It was predicted that all the six CchiOBPs contain signal peptides. Phylogenetic analysis showed that CchiOBP1, CchiOBP2 and CchiOBP5 were closely related to OBPs of Chrysomelidae, and CchiOBP3, CchiOBP4 and CchiOBP6 were closely related to OBPs of Cerambycidae. The qRT-PCR results showed that six CchiOBP genes were differentially expressed in the antennae, head (excluding antennae), abdomen, wings and legs of C. chinensis adults. CchiOBP1-4 and CchiOBP6 were highly expressed in antennae of female and male adults of C. chinensis, and their expression levels in antennae were extremely significantly higher than those in the other adult tissues. CchiOBP5 was highly expressed in female antennae and head (excluding antennae), but in males it showed significantly higher expression level in legs than in other adult tissues, with the lowest expression level in antennae. 【Conclusion】 The nucleotide and amino acid sequences of six CchiOBP genes of C. chinensis have been determined, among which five CchiOBP genes are highly expressed in the antennae of female and male adults of C. chinensis, suggesting their important roles in olfactory recognition of host plants.

Key words: Callosobruchus chinensis, olfactory system, odorant-binding protein, gene cloning, tissue-specific expression