許多植物病毒通過昆蟲的傳播在自然界持續(xù)的循環(huán)，在昆蟲體內(nèi)循環(huán)的過程中，病毒從腸腔輸送到血淋巴是一個非常重要的步驟。鑒定參與病毒傳輸過程中的重要組分可能為對抗病毒傳播提供新策略。課題組研究發(fā)現(xiàn)，植物雙生病毒在穿過其昆蟲媒介煙粉虱的腸道的過程中，可以利用上皮細(xì)胞的胞吞胞吐以及囊泡結(jié)構(gòu)進(jìn)行跨細(xì)胞運(yùn)輸，從而越過腸道上皮細(xì)胞對病毒的阻礙。研究首次報道了雙生病毒在昆蟲腸道上皮細(xì)胞細(xì)胞中的運(yùn)輸機(jī)制。這一發(fā)現(xiàn)進(jìn)一步闡明了煙粉虱傳播雙生病毒的機(jī)理，為阻斷煙粉虱在田間傳播雙生病毒提供了新的防控思路。

 

Abstract

 

Begomovirusesareexclusivelytransmittedbywhitefliesinapersistentcirculativemannerandcauseconsiderableeconomiclossestocropproductionworldwide.Previousstudieshaveshownthatbegomovirusesaccumulateinvesicle-likestructuresinwhiteflymidgutcellsandthatclathrin-mediatedendocytosisisresponsiblefortheirinternalization.However,theprocessbywhichbegomovirusesaretraffickedwithinwhiteflymidgutcellsremainslargelyunknown.Inthisstudy,weinvestigatedtherolesofvesicletraffickinginthetransportofTomatoyellowleafcurlvirus(TYLCV),abegomovirusthathasspreadtoover50countriesandcausedextensivedamagetoarangeofimportantcrops,withinmidgutcellsofwhitefly(Bemisiatabaci).BydisruptingvesicletraffickingusingRNAsilencingandinhibitors,wedemonstratedthattheearlystepsofendosomaltraffickingareimportantfortheintracellulartransportofTYLCVinthewhiteflymidgut.Inaddition,ourdatashowthat,unlikemanyanimalviruses,TYCLVistraffickedwithincellsinamannerindependentofrecyclingendosomes,lateendosomes,lysosomes,theGolgiapparatusandtheendoplasmicreticulum.Instead,ourresultssuggestthatTYLCVmightbetransporteddirectlyfromearlyendosomestothebasalplasmamembraneandreleasedintothehemolymph.SilencingofthesortingnexinSnx12,whichmaybeinvolvedinmembranetubulation,resultedinfewerviralparticlesinhemolymph;thissuggeststhatthetubularendosomalnetworkmaybeinvolvedinthetransportofTYLCV.Ourresultsalsosupportarolefortheendo-lysosomalsysteminviraldegradation.WefurthershowedthatthefunctionsofvectorearlyendosomesandsortingnexinSnx12areconservedinthetransmissionofseveralotherbegomoviruses.Overall,ourdataindicatetheimportanceofearlyendosomesandthetubularendosomalnetworkinbegomovirustransmission.

 

Authorsummary

 

Manyplantvirusesarevectoredbyinsectsinapersistentcirculativemanner.Inthisprocess,thetransportofvirusfromthegutlumenintothehemolymphofthevectorisanimportantstep.Identificationofvectorcomponentsinvolvedinthistransportprocesscouldleadtonewstrategiestocombatvirusspread.Here,wedemonstratethattheearlystepsofendosomaltraffickingareimportantforthetransportofbegomovirusesacrossepithelialcellsinthewhiteflymidgut.Afterinternalizationbymidgutepithelialcells,begomovirusesaretransporteddirectlyfromearlyendosomestothebasalplasmamembraneinafastrecyclingroute.Wealsoidentifiedseveralhostprocessesthatareinvolvedinbegomovirustransmission,includingvesicletransportandmembranefusioneventsthatpromotevirustrafficking.Toourknowledge,thisisthefirstreportonmechanismsgoverningtheintracellulartransportofbegomovirusesintheirinsectvector.Ourstudyprovidesnewinsightsintothetransmissionmechanismsofcirculativeplantvirusesandgivesdirectiontofutureresearchintobegomovirustransmissionblockingstrategies.