RESUMO
A previous study showed that both Grapevine Algerian latent virus (GALV) and Tomato bushy stunt virus (TBSV) systemically infect Nicotiana benthamiana, but GALV causes systemic infection whereas TBSV causes only local lesions in Chenopodium quinoa (C. quinoa). We recently isolated GALV strain Naju (GALV-N) from Limonium sinense and TBSV strain Sacheon (TBSV-S) from tomato. Both viruses belong to the genus Tombusvirus and have a similar genome organization. To identify determinants of systemic infection of GALV-N in C. quinoa in the current study, we generated infectious clones and capsid protein (CP)-deletion clones for the two viruses and confirmed that CP of GALV-N is required for systemic infection of C. quinoa due to its primary structural role in virus assembly. Through the use of chimeras, we identified a viral factor in addition to CP that contributes to systemic infection by GALV-N. Inactivation of the p19 demonstrated that host-specific activities of p19 are necessary for efficient systemic infection of C. quinoa by GALV-N. Our study is the first report to determine the viral factors required for systemic infection of GALV in C. quinoa.
Assuntos
Chenopodium quinoa/virologia , Doenças das Plantas/virologia , Tombusvirus/metabolismo , Proteínas Virais/metabolismo , Especificidade de Hospedeiro , Tombusvirus/genética , Tombusvirus/patogenicidade , Proteínas Virais/genética , VirulênciaRESUMO
The complete genomes of 30 Soybean mosaic virus (SMV) isolates and strains were sequenced in this study. Together with fourteen previously reported sequences, we analyzed the genetic structure of the SMV population. Analyses of genetic diversity showed that different genomic regions of SMV are under different evolutionary constraints and that there was no significant genetic differentiation between East Asian and North American populations of SMV. Phylogenetic analyses revealed a significant correlation between phylogeny of the cylindrical inclusion (CI) gene of SMV and SMV resistance gene 3 (Rsv3)-relating pathogenicity of SMV, suggesting CI might be a pathogenic determinant in Rsv3-mediated disease response. Interestingly, recombination analyses identified 19 'clear' recombination events in the SMV population. Furthermore, as several resistance-breaking strains were identified as recombinants, it appears that recombination might contribute to overcome host resistance in SMV-soybean pathosystem. Our finding suggests that recombination as well as mutation is an important evolutionary process in the genetic diversification of SMV population.
Assuntos
Variação Genética , Genoma Viral , Glycine max/virologia , Doenças das Plantas/virologia , Potyvirus/classificação , Potyvirus/genética , Sequência de Aminoácidos , Análise por Conglomerados , Evolução Molecular , Coreia (Geográfico) , Epidemiologia Molecular , Dados de Sequência Molecular , Mutação de Sentido Incorreto , Filogenia , Potyvirus/isolamento & purificação , Recombinação Genética , Análise de Sequência de DNA , Homologia de Sequência , Proteínas Virais/genética , Fatores de Virulência/genéticaRESUMO
Plant virus-based vectors provide attractive and valuable tools for conventional transgenic technology and gene function studies in plants. In the present study, we established the infectivity of intact plasmid DNA of Soybean mosaic virus (SMV) cDNA upon simple rub-inoculation of soybean leaves by utilizing viral transcription and processing signals to produce infectious in vivo transcripts. Furthermore, we engineered this SMV cDNA clone as a gene delivery vector for systemic expression of foreign proteins in soybean. Using this SMV-based vector, several genes with different biological activities were successfully expressed and stably maintained following serial plant passage in soybean. Thus, DNA-mediated gene delivery using this SMV-based vector provides a rapid and cost-effective approach for the overproduction of valuable proteins and for the evaluation of new traits in soybean after simple rub-inoculation onto leaves.
