Caracterização de um isolado do Sugarcane mosaic virus que quebra a resistência de variedades comerciais de cana-de-açúcar
Carregando...
Data
2007-02-01
Autores
Gonçalves, Marcos C.
Santos, Amaury S.
Maia, Ivan de Godoy [UNESP]
Chagas, César M.
Harakava, Ricardo
Título da Revista
ISSN da Revista
Título de Volume
Editor
Sociedade Brasileira de Fitopatologia
Resumo
Os vírus pertencentes ao subgrupo do Sugarcane mosaic virus (SCMV, gênero Potyvirus, família Potyviridae) infectam e causam mosaico em diferentes espécies botânicas da subfamília Panicoideae (família Poaceae), porém apenas o SCMV e o Sorghum mosaic virus (SrMV) infectam naturalmente cana-de-açúcar. No Brasil, a espécie SCMV parece ser o único agente causal da doença. Embora a maioria das variedades comerciais de cana-de-açúcar seja considerada resistente ou tolerante ao SCMV, relatos de incidência de mosaico em tais variedades têm ocorrido no campo. Amostras com sintomas, de diversos clones e variedades, foram coletadas em campos experimentais e comerciais de cana-de-açúcar. Dentre as variedades, a RB72-454, uma das mais plantadas no país e considerada resistente à doença, também apresentou plantas com sintomas de mosaico. As amostras foram testadas por DAS-ELISA, com anti-soros policlonais para as espécies SCMV, Johnsongrass mosaic virus (JGMV) e Maize dwarf mosaic virus (MDMV), apresentando resultados negativos. Porém, sintomas de mosaico foram observados em mudas de sorgo Rio e TX2786 quando inoculadas mecanicamente com os isolados, indicando tratar-se de infecção pelo SCMV. RNA total foi extraído das folhas de cana e submetido a RT-PCR com oligonucleotídeos específicos para SCMV e SrMV. Fragmentos específicos de aproximadamente 880 pares de bases foram amplificados com os oligonucleotídeos para o SCMV, confirmando os resultados da inoculação mecânica. Os produtos de PCR foram clonados e seqüenciados. Um dos isolados de SCMV encontrado constitui uma nova estirpe, mais severa, capaz de infectar plantas da variedade RB72-454 e de outras variedades, consideradas tolerantes, no campo.
Viruses in the Sugarcane mosaic virus (SCMV, genus Potyvirus, family Potyviridae), subgroup cause mosaic in different botanical species in the subfamily Panicoideae (family Poaceae). However, only SCMV and Sorghum mosaic virus (SrMV) naturally infect sugarcane. In Brazil, SCMV seems to be the only causal agent of mosaic in sugarcane. Most sugarcane cultivars are believed to be resistant to mosaic, although new cases have been reported in the field. Symptomatic samples, from several clones and cultivars, were collected in sugarcane crops. Among these cultivars, RB72-454, one of the most grown in Brazil, and considered resistant, showed plants with mosaic symptoms. Samples were tested by DAS-ELISA with antisera to SCMV, Johnsongrass mosaic virus (JGMV) and Maize dwarf mosaic virus (MDMV), showing negative results. However, sorghum Rio and TX2786 showed mosaic symptoms when mechanically inoculated with the viral isolates, indicating infection by SCMV. Total RNA was extracted and submitted to amplification with specific primers to SCMV and SrMV in RT-PCR. Specific bands with ca. 880 bp were amplified with the SCMV-specific primer pair, corroborating results from mechanical inoculation. PCR products were cloned and sequenced. One of the SCMV isolates comprises a new and more severe strain capable of infecting RB72-454 and other tolerant cultivars in the field.
Viruses in the Sugarcane mosaic virus (SCMV, genus Potyvirus, family Potyviridae), subgroup cause mosaic in different botanical species in the subfamily Panicoideae (family Poaceae). However, only SCMV and Sorghum mosaic virus (SrMV) naturally infect sugarcane. In Brazil, SCMV seems to be the only causal agent of mosaic in sugarcane. Most sugarcane cultivars are believed to be resistant to mosaic, although new cases have been reported in the field. Symptomatic samples, from several clones and cultivars, were collected in sugarcane crops. Among these cultivars, RB72-454, one of the most grown in Brazil, and considered resistant, showed plants with mosaic symptoms. Samples were tested by DAS-ELISA with antisera to SCMV, Johnsongrass mosaic virus (JGMV) and Maize dwarf mosaic virus (MDMV), showing negative results. However, sorghum Rio and TX2786 showed mosaic symptoms when mechanically inoculated with the viral isolates, indicating infection by SCMV. Total RNA was extracted and submitted to amplification with specific primers to SCMV and SrMV in RT-PCR. Specific bands with ca. 880 bp were amplified with the SCMV-specific primer pair, corroborating results from mechanical inoculation. PCR products were cloned and sequenced. One of the SCMV isolates comprises a new and more severe strain capable of infecting RB72-454 and other tolerant cultivars in the field.
Descrição
Palavras-chave
Potyviridae, mosaico da cana, Sugarcane mosaic virus subgroup, Potyviridae, sugarcane mosaic, Sugarcane mosaic virus subgroup
Como citar
Fitopatologia Brasileira. Sociedade Brasileira de Fitopatologia, v. 32, n. 1, p. 32-39, 2007.