Tobamovirus coat protein CPCg induces an HR-like response in sensitive tobacco plants.
When inoculated into sensitive tobacco Xanthi-nn plants, the crucifer and garlic-infecting Tobacco mosaic virus (TMV-Cg) induces local necrotic lesions that resemble those seen in the hypersensitive response (HR) of resistant tobacco plants. However, unlike these, tobacco Xanthi-nn plants do not become resistant to infection and the virus spreads systemically causing a severe disease characterized by necrotic lesions throughout the plant. To identify the viral protein that elicits this necrotic response, we used a set of hybrid viruses constructed by combination of TMV-Cg and the tobacco mosaic virus strain U1 (TMV-U1). In this study we present evidence that the coat protein of TMV-Cg (CPCg) is the elicitor of the necrotic response in tobacco Xanthi-nn plants. Local and systemic necrotic lesions induced by TMV-Cg and by the hybrid U1-CPCg -that carries CPCg in a TMV-U1 context- are characterized by cell death and by the presence of autoflorescent phenolic compounds and H2O2, just like the HR lesions. In addition, defense-related genes and detoxifying genes are induced in tobacco Xanthi-nn plants after TMV-Cg and U1-CPCg inoculation. We postulate that in our system, CPCg is recognized by sensitive tobacco plants that mount an incomplete defense response. We call this an HR-like since it is not enough to induce plant resistance.
Departamento de Genética Molecular y Microbiología, P. Universidad Católica de Chile, Santiago, Chile.
Nicole
N
Ehrenfeld
Paola
P
Cañón
Claudia
C
Stange
Consuelo
C
Medina
Patricio
P
Arce-Johnson
D036022:Capsid Proteins / Q000276:immunology*; D017343:Genes, Plant; D009336:Necrosis; D014026:Nicotiana / Q000276:immunology* / Q000821:virology*; D014027:Tobacco Mosaic Virus / Q000737:chemistry / Q000235:genetics / Q000276:immunology*
D036022:Capsid Proteins