Pheromone-bindingproteins(PBPs)arethoughttobindandtransportsexpheromonesontotheolfactoryreceptorsonthedendritemembraneofolfactoryneurons,andthusplayavitalroleinsexpheromoneperception.However,thefunctionofPBPshasrarelybeendemonstratedinvivo.Inthisstudy,twoPBPs(PBP1andPBP3)ofChilosuppressalis,oneofthemostnotoriouspyralidpests,wereinvivofunctionallycharacterizedusinginsectswiththePBPgeneknockedoutbytheCRISPR/Cas9system.First,throughdirectinjectionofPBP-singleguideRNA(sgRNA)/Cas9messengerRNAintonewlylaideggs,ahighrateoftarget-geneediting(checkedwithpolledeggs)wasinducedat24hafterinjection,21.3%forPBPl-sgRNAinjectedeggsand19.5%forPBP3-sgRNAinjectedeggs.Second,byanin-crossingstrategy,insectswithmutantPBP1orPBP3(bothwithaprematurestopcodon)werescreenedandhomozygousmutantswereobtainedintheG3generation.Third,themutantinsectsweremeasuredforelectroantennogram(EAG)responsetofemalesexpheromones.Asaresult,bothPBPmutantmalesdisplayedsignificantreductioninEAGresponse,andthisreductioninPBP1mutantswashigherthanthatinPBP3mutants,indicatingamoreimportantroleofPBP1.Finally,therelativeimportanceoftwoPBPsandthepossibleofftargeteffectinducedbysgRNA-injectionarediscussed.Takentogether,ourstudyprovidesadeeperinsightintothefunctionofandinteractionbetweendifferentPBPgenesinsexpheromoneperceptionofC.suppressalis,aswellasavaluablereferenceinmethodologyforgenefunctionalstudyinothergenesandothermothspecies.
