許多植物病毒通過(guò)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(guò)程中，病毒從腸腔輸送到血淋巴是一個(gè)非常重要的步驟。鑒定參與病毒傳輸過(guò)程中的重要組分可能為對(duì)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(guò)其昆蟲媒介煙粉虱的腸道的過(guò)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(guò)腸道上皮細(xì)胞對(duì)病毒的阻礙。研究首次報(bào)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.