Molecular Mechanism Of Tomato Spotted Wilt Virus Utilizing The Host Plant Arabinogalactan Protein To Faciliate Viral Infection

In comparison to animal cells,the plasmodesmata(PD)of plant cells is a complex microchannel.It is unique to plants and that establishes communication between adjacent cells.The movement protein of tomato spotted wilt virus(TSWV)requires intercellular movement through PD.To investigate how TSWV and its movement protein NSm remodel the cell wall structure using host plant proteins to promote better cell-to-plant mobility,we performed transcriptome sequencing analysis of Arabidopsis thaliana infected TSWV.The results showed that there were a large number of up-regulation of genes related to cell wall relaxation factor.These genes that can degrade the cell wall.Through subcellular localization studies of major genes,most of them can localize to the plasma membrane and colocalized with NSm.Some genes such as arabinogalactose protein AGP and ?-1-3 glucan hydrolase can be recruited.NSm protein can accumulate more in PD.Using Bimolecular fluorescence complementation(BiFC)technology,we screen the up-regulated candidate genes,Arabinogalactan protein 5(AGP5)can interact with NSm in vivo,and further verifed by Co-Immunoprecipitation(co-IP).The subcellular localization of AGP5 indicates that the protein can localize to the PD and colocalized with the NSm on the plasma membrane and PD.Interestingly,after statistical analysis,it was found that co-expression of AGP5 and NSm would allow more NSm protein to be recruited to PD.At the same time,overexpression of AGP5 enhances the intercellular movement of NSm protein.Overexpression of AGP5 also enhances the movement and replication of the TSWV by using the TSWV minireplicon and mobile reverse genetics systems.Due to the complex diversity of the AGP family,the redundancy of homologous genes cannot be verified by silencing or knockout,but the AGP family protein is an arabinogalactose-modified protein.Through the galactose interference experiment,it is found that the number of NSm localized to PD is significant reduced.These data indicate that AGP5 is the host factor of TSWV infection which can help the virus to infect better.Therefore,AGP5 is an important host protein that can interact with TSWV NSm protein and plays an important regulatory role in TSWV infection.