RESUMO
Tobamovirus movement proteins play a determinant role in the establishment of infections in plants, allowing the local movement of viral RNA genome through plasmodesmatas. We expressed the movement protein (MP) of the crucifer- and garlic-infecting Tobacco Mosaic Virus strain Cg (TMV-Cg) in both resistant Xanthi NN and sensitive Xanthi nn Nicotiana tabacum plants. MP-Cg function was assayed by inoculating transgenic plants with a trafficking-deficient mutant of TMV strain U1. Following infection, local necrotic lesions were developed in resistant transgenic plants, and a systemic infection was produced in sensitive tobaccos. Thus, movement function of the mutant virus was complemented in trans by MP-Cg expressed in transgenic plants, causing the same symptoms as wild-type strain. We demonstrated that the function of MP-U1 could be replaced efficiently by MP-Cg, even though these proteins share only 36% of identity. Similar hydrophobic patterns of MP-Cg and MP-U1 suggests structure and function conservations of both proteins. This work is an example of how two tobamoviruses differing in their host range help to understand viral movement mechanism during the infection.
Assuntos
Mutação/genética , Doenças das Plantas/virologia , Proteínas do Movimento Viral em Plantas/genética , Plantas Geneticamente Modificadas/virologia , Vírus do Mosaico do Tabaco/genética , Expressão Gênica , Genótipo , Fatores de Tempo , /genéticaRESUMO
Tobamovirus movement proteins play a determinant role in the establishment of infections in plants, allowing the local movement of viral RNA genome through plasmodesmatas. We expressed the movement protein (MP) of the crucifer- and garlic-infecting Tobacco Mosaic Virus strain Cg (TMV-Cg) in both resistant Xanthi NN and sensitive Xanthi nn Nicotiana tabacum plants. MP-Cg function was assayed by inoculating transgenic plants with a trafficking-deficient mutant of TMV strain U1. Following infection, local necrotic lesions were developed in resistant transgenic plants, and a systemic infection was produced in sensitive tobaccos. Thus, movement function of the mutant virus was complemented in trans by MP-Cg expressed in transgenic plants, causing the same symptoms as wild-type strain. We demonstrated that the function of MP-U1 could be replaced efficiently by MP-Cg, even though these proteins share only 36% of identity. Similar hydrophobic patterns of MP-Cg and MP-U1 suggests structure and function conservations of both proteins. This work is an example of how two tobamoviruses differing in their host range help to understand viral movement mechanism during the infection.
Assuntos
Mutação/genética , Doenças das Plantas/virologia , Proteínas do Movimento Viral em Plantas/genética , Plantas Geneticamente Modificadas/virologia , Vírus do Mosaico do Tabaco/genética , Tabaco/virologia , Expressão Gênica , Genótipo , Fatores de Tempo , Tabaco/genéticaRESUMO
The microprojectile bombardment method was used to transfer DNA into embryogenic callus of asparagus (Asparagus officcinalis L.) and to produce stably transformed asparagus plants. Embryogenic callus, derived from UC 157 and UC72 asparagus cultivars, was bombarded with tungsten particles coated with plasmid DNA that contained genes encoding hygromycin phosphotransferase, phosphinothricin acetyl transferase and ß-glucuronidase. Putatively transformed calli were identified from the bombarded tissue after 4 months selection on 25 mg/L hygromycin B plus 4 mg/L phosphinothricin (PPT). By selecting embryogenic callus on hygromycin plus PPT the overall transformation and selection efficiencies were substantially improved over selection with hygromycin or PPT alone, where no transgenic clones were recovered. The transgenic nature of the selected material was demonstrated by GUS histochemical assays and Southern blot hybridization analysis. Transgenic asparagus plants were found to withstand the prescribed levels of the PPT-based herbicide BASTATM for weed control.
