Abstract:  【Aim】The peach fruit moth, Carposina sasakii, is one of the most damaging borers of fruit trees in northern China. Once the larvae of this insect bore into fruits, they deteriorate the quality of the fruits. The adult stage is the key period to control the occurrence of this pest. Odorant binding proteins (OBPs), as important odor transport proteins binding to odor molecules in insect olfactory sensing system, play an important role in insect host localization and mating behaviors. In this study, the OBP genes in C. sasakii were cloned and identified, and their tissue-specific expression profiles in adults were assayed in order to lay a foundation for studying the function of OBPs in olfactory perception in C. sasakii. 【Methods】 Based on the transcriptome sequencing data of C. sasakii obtained previously, five OBP genes of C. sasakii (CsasOBP7, CsasOBP12, CsasOBP15, CsasOBP19 and CsasOBP21) highly expressed in the antennae of female and male adults were selected. The full-length cDNA sequences of the five OBP genes screened were cloned by RACE, and analyzed by bioinformatics. The expression levels of the five OBP genes in different developmental stages (1 and 5-day-old egg, newly hatched larva, mature larva, and pupa) of C. sasakii and different tissues (antenna, head without antenna, thorax, abdomen, leg and wing) of its newly emerged adults and female and male adults at the mating peak stage and 6 h after mating were detected by qRT-PCR. 【Results】 The fulllength cDNA sequences of the five OBP genes CsasOBP7, CsasOBP12, CsasOBP15, CsasOBP19 and CsasOBP21 (GenBank accession no.: MZ476786-MZ476790) of C. sasakii were obtained. CsasOBP19 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 five CsasOBPs contain signal peptides. Phylogenetic analysis showed that CsasOBP7 and CsasOBP19 have the closest relationship among the five CsasOBPs of C. sasakii. qRT-PCR results showed that CsasOBP7 and CsasOBP19 were highly expressed in the pupal stage of C. sasakii whereas CsasOBP12, CsasOBP15 and CsasOBP21 were highly expressed in the egg stage. The expression pattern of the five CsasOBP genes totally showed a decreasing trend from adult eclosion to mating peak, till 6 h after mating. In the newly emerged adults, the five CsasOBP genes were ubiquitously expressed in various tissues, and highly expressed mainly in male tissues. During the mating peak of adult, the five CsasOBP genes were highly expressed in the male antennae, and especially, CsasOBP7 and CsasOBP15 were specifically expressed in the male antennae. At 6 h after mating, each CsasOBP gene was only highly expressed in one or two tissues. 【Conclusion】 The high expression of the five CsasOBP genes in the male antennae of C. sasakii during the mating peak of adult suggests that these CsasOBP genes may play an important role in the process of males searching for females.

Key words: Carposina sasakii, odorant binding protein, gene cloning, expression profile, bioinformatics analysis