Identification Of Sex Pheromone Receptors And Preliminary Functional Study Of CmedPR1/CmedOR27 In Cnaphalocrocis Medinalis

Insect sex pheromones are a group of trace odor compounds that are secreted by individuals and released outside the body to attract the opposite sex to produce behavioral responses such as mate seeking and mating.Insects often rely on pheromone receptors（PRs）for the perception of sex pheromones.Therefore,the resolution of sex pheromone receptors is important for the development of improved sex pheromone trapping techniques.The rice leaf roller（Cnaphalocrocis medinalis,Lepidoptera）,as a class of crop pests in China,poses a great threat to the safe production of rice.In order to reduce the use of chemical pesticides in the control of Cnaphalocrocis medinalis,sex pheromone of Cnaphalocrocis medinalis has been developed as a sex attractant and widely used for field monitoring and control.Currently,it is known that sex pheromone of Cnaphalocrocis medinalis are composed of six components Z13-18:Ac,Z11-16:Ac,Z11-18:Ald,Z11-18:OH,Z13-18:OH and Z13-18:Ald in certain proportions.However,the molecular mechanisms by which these sex pheromones bind to sex pheromone receptors to lure the male moths of Cnaphalocrocis medinalis are not clear.In view of this,the following studies were carried out in this thesis.Three families of chemosensory receptor genes,including 21 Ionotropic receptors（IRs）,8 Gustatory receptors（GRs）and 60 Olfactory receptors（ORs）,were systematically identified by sequencing the tentacle transcriptome of males and females of Cnaphalocrocis medinalis.Following that,a phylogenetic evolutionary free was built with 60 ORs of Cnaphalocrocis medinalis and found that CmedPR1,CmedPR2,CmedPR3,CmedPR4 and CmedOR27 clustered in the sex pheromone receptor branch.Based on transcriptome expression profiles and quantitative real-time fluorescence PCR（qRT-PCR）data,we found that CmedPR1 and CmedOR27 were significantly expressed in male moth antennae compared to female moths.We hypothesize that both CmedPRl and CmedOR27 are sex pheromone receptors for Cnaphalocrocis medinalis.To investigate the functions of CmedPRl and CmedOR27 in sex pheromone recognition,the full lengths of the two genes were firstly amplified and the gene sequences were characterized.tissue expression profiles of CmedPRl and CmedOR27 1 to 2 days after plumage showed that both were specifically expressed in the antennae,and the expression was significantly higher in males than in females.Second,behavioral convergence assays showed that males of Cnaphalocrocis medinalis showed behavioral convergence responses to（Z）-13-octadecenal,（Z）-11-octadecen-1-ol,and（Z）-13-octadecen-l-ylacetate.However,two-electrode voltage-clamp experiments revealed no significant potentiation responses for either of the six known sex pheromone compounds,except for an extremely weak potentiation response of CmedPR1 to Z13-18:Ac.The above results suggest that CmedPR1 and CmedOR27 have the sequence and expression characteristics of sex pheromone receptors,yet show weak potentiation responses to sex pheromone compounds.In summary,this study systematically analyzed three chemosensory receptor families of Cnaphalocrocis medinalis,and identified the full-length sequences of the obtained sex pheromone receptors CmedPR1 and CmedOR27.The preliminary exploration of the mechanism of sex pheromone recognition by CmedPR1 and CmedOR27 revealed that CmedPR1 weakly recognized the sex pheromone Z13-18:Ac.This research result systematically identifies the sex pheromone receptors of Cnaphalocrocis medinalis and initially explores their functions,which provides a theoretical basis for the improvement and application of sex attractants for Cnaphalocrocis medinalis.