关键词: 梨小食心虫, 嗅觉, 气味受体, 性信息素, 触角电位反应

Abstract: 【Aim】To identify the odorant receptor (OR) GmolOR genes involved in recognizing sex pheromone in the antennae of Grapholita molesta, verify GmolORs that recognize female sex pheromone using RNAi, so as to lay the basis of understanding the molecular mechanisms of female and male communication based on sex pheromone in G. molesta. 【Methods】After full-length sequencing of the antennae transcriptome of the 3-day-old female and male adults of G. molesta using PacBio sequencing platform, the candidate GmolOR genes that are potentially involved in recognizing sex pheromone were identified through gene functional annotation and phylogenetic analysis. The expression levels of GmolOR genes in the antennae, head (removed antennae), thorax, abdomen, legs and wings in the 3-day-old female and male adults were determined by RT-qPCR. The synthesized dsGmolORs were injected into the 4-day-old male pupae of G. molesta to knock down the expression levels of GmolOR genes in the adult antennae, and electroantennogram (EAG) assay and a wind tunnel experiment were used to verify the recognition of GmolORs to female sex pheromones Z8-12∶OAc, E8-12∶OAc, Z8-12∶OH and 12∶OH. 【Results】 Eight GmolOR genes potentially involved in recognizing sex pheromones of G. molesta were identified, and named GmolOR1/2/6/7/9/11/21/22, respectively. The expression levels of GmolOR1, GmolOR2, GmolOR6 and GmolOR7 in male adult antennae were significantly higher than those in female adult antennae, while the expression levels of GmolOR9, GmolOR21 and GmolOR22 in female adult antennae were significantly higher than those in male adult antennae. GmolOR11 was the most abundantly expressed GmolOR gene in adult antennae without sex-bias expression. The expression levels of the target genes in male adult antennae of G. molesta injected with dsGmolOR decreased by 47.55%-56.39% as compared with those in the control group injected with dsGFP. Knockdown of the expression of GmolOR6 and GmolOR7 significantly decreased the EAG responses of male adults to Z8-12∶OH, and knockdown of the expression of GmolOR1 significantly reduced the EAG responses of male adults to E8-12∶OAc, Z8-12∶OH and 12∶OH compared with the control group injected with dsGFP. GmolOR2 was found to be the primary receptor in male adults recognizing the major sex pheromone Z8-12∶OAc in female adults. 【Conclusion】Eight odorant receptor genes as potential participants in recognizing sex pheromones in male adult antennae of G. molesta were identified. RNAi combined with EAG and behavioral assays confirmed that GmolOR2 is the primary odorant receptor in male adult of G. molesta recognizing the major sex pheromone Z8-12∶OAc in female adult. GmolOR2 is the important target gene for G. molesta control based on disrupting sex pheromone communication between female and male adults.

Key words: Grapholita molesta, olfaction, odorant receptor (OR), sex pheromone, electroantennogram response