Salicylic Acid Has Cell-Specific Effects on Tobacco mosaic virus Replication and Cell-to-Cell Movement

• Published in: Plant physiology (Bethesda) 2002-02, Vol.128 (2), p.552-563
• Main Authors: Murphy, Alex M., Carr, John P.
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; Cucumber mosaic virus; Cucumber mosiac virus; Cucumovirus - drug effects; Cucumovirus - genetics; Cucumovirus - growth & development; Dextrans; Epidermal cells; Fundamental and applied biological sciences. Psychology; Green Fluorescent Proteins; Infections; Luminescent Proteins - genetics; Luminescent Proteins - metabolism; Mesophyll cells; Nicotiana - drug effects; Nicotiana - virology; Pathology. Damages, economic importance; Phytopathology. Animal pests. Plant and forest protection; Plant Diseases - virology; Plant Epidermis - drug effects; Plant Epidermis - virology; Plant Leaves - drug effects; Plant Leaves - virology; Plant Viral Movement Proteins; Plant viruses and viroids; Plants Interacting with Other Organisms; Protein Transport - drug effects; Protoplasts; Resistance movements; RNA; RNA, Viral - drug effects; RNA, Viral - genetics; RNA, Viral - metabolism; Salicylic Acid - pharmacology; Signal Transduction; Tobacco; Tobacco mosaic virus; Tobacco Mosaic Virus - drug effects; Tobacco Mosaic Virus - genetics; Tobacco Mosaic Virus - growth & development; Transgenic plants; Viral Proteins - genetics; Viral Proteins - metabolism; Virus Replication - drug effects; Viruses
• ISSN: 0032-0889; 1532-2548
• DOI: 10.1104/pp.010688

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.