Salicylic acid has cell-specific effects on tobacco mosaic virus replication and cell-to-cell movement.
Tobacco mosaic virus (TMV) and Cucumber mosaic virus expressing green fluorescent protein (GFP) were used to probe the effects of salicylic acid (SA) on the cell biology of viral infection. Treatment of tobacco with SA restricted TMV.GFP to single-epidermal cell infection sites for at least 6 d post inoculation but did not affect infection sites of Cucumber mosaic virus expressing GFP. Microinjection experiments, using size-specific dextrans, showed that SA cannot inhibit TMV movement by decreasing the plasmodesmatal size exclusion limit. In SA-treated transgenic plants expressing TMV movement protein, TMV.GFP infection sites were larger, but they still consisted overwhelmingly of epidermal cells. TMV replication was strongly inhibited in mesophyll protoplasts isolated from SA-treated nontransgenic tobacco plants. Therefore, it appears that SA has distinct cell type-specific effects on virus replication and movement in the mesophyll and epidermal cell layers, respectively. Thus, SA can have fundamentally different effects on the same pathogen in different cell types.
Murphy
Alex M
AM
Department of Plant Sciences, University of Cambridge, Cambridge CB2 3EA, United Kingdom.
Carr
John P
JP
D017799:Cucumovirus / Q000187:drug effects / Q000235:genetics / Q000254:growth & development; D049452:Green Fluorescent Proteins; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D010935:Plant Diseases / Q000821:virology; D019441:Plant Epidermis / Q000187:drug effects / Q000821:virology; D018515:Plant Leaves / Q000187:drug effects / Q000821:virology; D053830:Plant Viral Movement Proteins; D021381:Protein Transport / Q000187:drug effects; D012367:RNA, Viral / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D020156:Salicylic Acid / Q000494:pharmacology*; D015398:Signal Transduction; D014026:Nicotiana / Q000187:drug effects / Q000821:virology*; D014027:Tobacco Mosaic Virus / Q000187:drug effects* / Q000235:genetics / Q000254:growth & development; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism; D014779:Virus Replication / Q000187:drug effects
D008164:Luminescent Proteins; D053830:Plant Viral Movement Proteins; D012367:RNA, Viral; D014764:Viral Proteins; D049452:Green Fluorescent Proteins; D020156:Salicylic Acid