Abstract: 【Aim】 The study aims to explore the structure and distribution of odorant binding proteins of Harmonia axyridis, so as to provide a basis for further understanding the functions of odorant binding proteins in the olfactory system of H. axyridis. 【Methods】 Two odorant binding protein genes were cloned from H. axyridis, and their protein structures were analyzed by bioinformatics methods. The expression levels of the two genes in different developmental stages and adult tissues of H. axyridis were analyzed by qRT-PCR. 【Results】 Two odorant binding proteins genes of H.axyridis, HaxyOBP1 and HaxyOBP6 (GenBank accession numbers: MG757923 and MG757927, respectively), were successfully cloned and sequenced. The open reading frame of HaxyOBP1 is 447 bp in length. It encodes 148 amino acids with six conserved cysteines, indicating that HaxyOBP1 belongs to Classical OBPs subfamily. HaxyOBP1 was expressed in various developmental stages of H. axyridis and had the highest expression level in male adults. Tissue expression profiles showed that HaxyOBP1 had the highest expression level in the head of male adult. The open reading frame of HaxyOBP6 is 414 bp in length. It encodes 137 amino acids with four conserved cysteines, indicating that HaxyOBP6 belongs to Minus-C OBPs subfamily. The expression level of HaxyOBP6 in adults was higher than that in larvae, and the expression level in male adults was significantly higher than that in female adults. Tissue expression profiles showed that HaxyOBP6 had the highest expression levels in the head of male adult and the wing of female adult. 【Conclusion】 In this study, two odorant binding protein genes were cloned from H. axyridis. The expression profiles showed that HaxyOBP1 and HaxyOBP6 were highly expressed in the head and the wing of adults, respectively, suggesting that the OBPs of H. axyridis may also play important roles in non-olfactory tissues. The results of this study lay a foundation for further study on the structure and function of OBPs of H. axyridis.

Key words: Harmonia axyridis; odorant binding protein, gene cloning, expression profiling, qRT-PCR