Caracterização de dois begomovírus (Tomato severe rugose virus e Tomato yellow vein streak virus) que infectam tomateiro e obtenção de clones infecciosos / Characterization of two begomoviruses (Tomato severe rugose virus and Tomato yellow vein streak virus) that infect tomato and production of infectious clones

AUTOR(ES)

Alison Talis Martins Lima

DATA DE PUBLICAÇÃO

2008

RESUMO

The genus Begomovirus (family Geminiviridae) includes viruses with a genome comprised of one or two molecules of circular, single-stranded DNA, transmitted to dicot species by the whitefly Bemisia tabaci. In Brazil, after the introduction of the B biotype of B. tabaci in the early 1990s, the incidence of begomoviruses in tomato has become frequent, with several reports of new viral species. Some of these species have become prevalent under field conditions, including Tomato severe rugose virus (ToSRV) and Tomato yellow vein streak virus (ToYVSV). The purpose of this study was to characterize two isolates of these species through the cloning of their whole genomes followed by molecular analysis, and the production of infectious clones for determination of their host ranges. Total DNA extracts of infected plants were used for whole genome amplification using the phi29 phage DNA polymerase. The amplification products were cloned into plasmids and completely sequenced. Sequence analysis indicated that the DNA-A and DNA-B of ToSRV-[BR:Pir1:05] and ToYVSV- [BR:Pda30:05] isolates had greater than 90% identities with other isolates of ToSRV and ToYVSV, respectively. The molecular analysis indicated that the DNA-A of the BR:Pir1:05 isolate may be the result of a recombination event, in which the virus acquired the rep ORF of Tomato rugose mosaic virus (ToRMV) and the cp ORF of an unidentified virus. Analysis of the DNA-B of the same isolate indicated the existence of a relationship with viruses that infect weed/wild hosts in Brazil, corroborating the hypothesis that viruses present in wild hosts led to the virus currently found in tomatoes. Additionally, because of the high identity observed between the DNA-B of ToSRV-[BR:Pir1:05] and ToRMV, it is possible that this genomic component is shared by the two viruses. In host range assays, plants showing latent infections were observed for both isolates. Such plants can act as natural reservoirs and serve as a primary source of inoculum for host plants of economic importance such as the tomato. The infectious clones of ToYVSV- [BR:Pda30:05] had low infectivity in the host range assays. It is possible that the inoculation method was not effective in the transmission of this isolate, or one or both clones could contain mutations that reduce the efficiency of their replication.

ASSUNTO(S)

molecular cloning tomato clonagem molecular pests and diseases begomovírus doenças e pragas geminivirus geminiviruses fitopatologia begomoviruses tomate

Documentos Relacionados

• Fontes de resistência em tomateiro aos begomovírus bissegmentados Tomato yellow spot virus e Tomato severe rugose virus
• Seleção de progênies de tomateiro resistentes a Tomato yellow vein streak vírus
• Dinâmica temporal e espacial da begomovirose causada por Tomato yellow vein streak virus em tomateiro na região de Campinas - SP
• Caracterização molecular e biológica de um isolado de tomato Yellow Vein Streak Virus
• Caracterização de um begomovírus obtido de maracujazeiro (Passiflora edulis f. flavicarpa) e produção de clones infecciosos