The Role Of SNARE Proteins In Bemisia Tabaci Acquisition Of Tomato Yellow Leaf Curl Virus

The whitefly Bemisia tabaci(Hemiptera: Aleyrodidae)is a specie complex consisting of over 36 cryptic species.Whiteflies damage plants in many ways,of which the transmission of begomoviruses causes the most serious damage to crops.Tomato yellow leaf curl virus(TYLCY),a plant virus in the genus Begomovirus(family:Geminiviridae)causes serious damage to the production of tomato worldwide.TYLCV passes through the intestinal tract,hemolymph,and salivary gland of the whiteflies and eventually is secreted into plants along with saliva.At present,studies have shown that TYLCV cross transcellular transport in the whitefly via the epithelial cells,and clathrin-mediated endocytosis participates in this process.Transport of TYLCV virions in the midgut epithelial cells depends on the vesicular structure,and early endosomal tubular networks help transport viruses.Previous reports showed that viruses are transported intracellularly via vesicles,where vesicle fusion is the final stage of vesicle trafficking and SNARE protein plays a key role in vesicle fusion.At present,there is no report on how SNARE protein affects the virus transport in whiteflies cells.In this study,we firstly developed a RNAi technique to silence whitefly genes by microinjection.Secondly,we used RNAi to silence the SNARE genes of Bemisia tabaci and then quantify the ability of whitefly to acquire TYLCV to infer the transport pathways of TYLCV in whitefly.The results are as follows:Whitefly adults was treated by microinjection and feeding(membrane feeding)ds RNA respectively.The results showed that silencing efficiency by microinjection was higher than that by feeding,and the silencing efficiency of different genes in whitefly is also different.Through the silencing of the SNARE genes Syx1 A,Syx2 and VAMP2 associated with the plasma membrane and the early endosome,the amount of virus of whiteflies was significantly reduced and the acquisition of TYLCV in whiteflies was inhibited.It is speculated that transport of TYLCV in whiteflies may be related to early endosomes and may be involved in the process of exocytosis on the plasma membrane.By silencing the SNARE genes VAMP7 and Vti1 b associated with lateendosomes,the amount of virus of whiteflies was increased.It is speculated that late endosomes may be involved in vesicular transport of TYLCV and was involved in virus degradation.The amount of virus of whiteflies was significantly increased by silencing the SNARE genes Syx6,Syx16 and membrin related to the Golgi apparatus.The amount of virus of Bemisia tabaci was significantly reduced after silencing Syx5,while the silencing of Vti1 a,Sec22b,Ykt6 and Gos28 had no effect.It is speculated that the Golgi may be involved in vesicular transport of TYLCV.Rab5,Rab7 and Rab11 were used to mark the early endosome,late endosome and recycling endosome,and there was a clear co-localization between TYLCV and early endosome.There was no colocalization among TYLCV,late endosome and recycling endosome.It is speculated that the transport of TYLCV may be related to early endosome.In summary,the present study successfully constructed a set of RNAi system by microinjection in whitefly adluts,which could provide a new method for the subsequent study on the gene function of whiteflies.The transport pathways of TYLCV in whiteflies were complicated,and the plasma membrane,early endosome,late endosome and Golgi apparatus might be involved in vesicular transport of TYLCV.