RESUMO
The stunting disease, incited by chrysanthemum stunt viroid (CSVd), has become a serious problem in chrysanthemum production areas worldwide. Here we identified 46 weed species from chrysanthemum fields in two producing regions of the State of São Paulo, Brazil. The mechanical inoculation of these weeds with a Brazilian CSVd isolate revealed that this viroid was able to infect 17 of these species, in addition to chrysanthemum, tomato and potato. Plants of Oxalis latifolia and chrysanthemum naturally infected with CSVd were found in chrysanthemum fields in Colombia, which is the first CSVd report in that country. Therefore, weeds have the potential to act as reservoirs of CSVd in the field. These results are the first reports of experimental CSVd infection in the following species: Amaranthus viridis, Cardamine bonariensis, Chamaesyce hirta, Conyza bonariensis, Digitaria sanguinalis, Gomphrena globosa, Helianthus annuus, Lupinus polyphyllus, Mirabilis jalapa, Oxalis latifolia, Portulaca oleracea and Catharanthus roseus. The phylogenetic analyses of the CSVd variants identified herein showed three groups with Brazilian CSVd variants distributed in them all, which suggests that Brazilian CSVd isolates may have different origins through successive introductions of infected germplasm of chrysanthemum in Brazil.
Assuntos
Chrysanthemum/virologia , Reservatórios de Doenças/virologia , Doenças das Plantas/virologia , Plantas Daninhas/virologia , Viroides/fisiologia , Animais , Brasil , Colômbia , Reservatórios de Doenças/classificação , Variação Genética , Especificidade de Hospedeiro , Solanum lycopersicum/virologia , Filogenia , Plantas Daninhas/classificação , RNA Viral/genética , Solanum tuberosum/virologia , Viroides/classificação , Viroides/genética , Viroides/isolamento & purificaçãoRESUMO
Background: Chrysanthemum plants are subject to serious viral diseases. The viruses cause severe losses of the quantity and quality of chrysanthemum. The most problematic pathogen of chrysanthemum is typically considered Chrysanthemum virus B (CVB). Thus, a method for the simultaneous detection of CVB is needed. Results: We used gene-specific primers, which were derived from the coat protein gene region of the virus, for reverse transcription to obtain cDNA. Nested amplification polymerase chain reaction (PCR) was employed to detect the viral gene. This method was sensitive enough to detect the virus at up to 10-9 dilution of the cDNA. Conclusion: A highly specific and sensitive nested PCR-based assay has been described for detecting CVB. This new method is highly specific and sensitive for the detection of CVB, which is known to infect chrysanthemum plants in the fields. Further, this protocol has an advantage over traditional methods as it is more cost-effective. This assay is ideal for an early stage diagnosis of the disease.