The host range of viruses is determined in part by their ability to move cell-to-cell and long distance. Potexvirus movement functions are provided by the Triple Gene Block (TGB) and Coat (CP) proteins; we have examined subcellular localization of these proteins of Alternanthera mosaic virus (AltMV) and observed differences between AltMV and PVX. When AltMV GFP:TGB2 and DsRed:TGB3 were co-expressed by agro-infiltration, no obvious interaction was detected; GFP:TGB2 was observed mainly in the epidermis, and DsRed:TGB3 accumulated primarily in the mesophyll. In contrast, the equivalent PVX proteins are reported to co-localize, and agro-infiltrated PVX DsRed:TGB3 localized to the periphery of epidermal cells. C-terminal deletions of AltMV DsRed:TGB3 still accumulated in the mesophyll, but N-terminal deletions of TGB3 localized to the periphery of epidermal cells. Infectious clones of AltMV with either TGB2 or CP expression disrupted were unable to spread beyond the initially infected cells, whereas a clone with TGB3 expression ablated spread to multiple epidermal cells, but not into the underlying mesophyll. Complementation with agro-infiltrated wild-type TGB3 restored the ability of TGB3-deleted AltMV to spread through the mesophyll to the opposite epidermis throughout the agro-infiltrated area. Over-expression of TGB3 from infectious AltMV caused veinal necrosis. These results suggest that TGB3 contributes to both cell-to-cell and long distance vascular movement.
Behavior of the Triple Gene Block proteins of Alternanthera mosaic virus differs from those of Potato Virus X
Vaira AM;
2009
Abstract
The host range of viruses is determined in part by their ability to move cell-to-cell and long distance. Potexvirus movement functions are provided by the Triple Gene Block (TGB) and Coat (CP) proteins; we have examined subcellular localization of these proteins of Alternanthera mosaic virus (AltMV) and observed differences between AltMV and PVX. When AltMV GFP:TGB2 and DsRed:TGB3 were co-expressed by agro-infiltration, no obvious interaction was detected; GFP:TGB2 was observed mainly in the epidermis, and DsRed:TGB3 accumulated primarily in the mesophyll. In contrast, the equivalent PVX proteins are reported to co-localize, and agro-infiltrated PVX DsRed:TGB3 localized to the periphery of epidermal cells. C-terminal deletions of AltMV DsRed:TGB3 still accumulated in the mesophyll, but N-terminal deletions of TGB3 localized to the periphery of epidermal cells. Infectious clones of AltMV with either TGB2 or CP expression disrupted were unable to spread beyond the initially infected cells, whereas a clone with TGB3 expression ablated spread to multiple epidermal cells, but not into the underlying mesophyll. Complementation with agro-infiltrated wild-type TGB3 restored the ability of TGB3-deleted AltMV to spread through the mesophyll to the opposite epidermis throughout the agro-infiltrated area. Over-expression of TGB3 from infectious AltMV caused veinal necrosis. These results suggest that TGB3 contributes to both cell-to-cell and long distance vascular movement.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
