Identificação e caracterização de isolado de Bidens mosaic virus e triagem de alface para resistência
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Data
2006-01-27
Autores
Hasegawa, Jorge Massaki [UNESP]
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
O Bidens mosaic virus (BiMV) é um Potyvirus relatado pela primeira vez no Brasil, no Estado de São Paulo, onde foram realizados estudos através de microscopia eletrônica por Kitajima et al.(1961). É um vírus que causa sintomas em espécies de importância econômica como o girassol, a alface e a ervilha, além de algumas plantas ornamentais. Atualmente, embora se conheça o seu mecanismo de transmissão, a sua sintomatologia, as suas propriedades biológicas e físico-químicas e o seu círculo de hospedeiras, pouco se sabe sobre a importância do BiMV para a cultura da alface e a possíveis fontes de resistência em Lactuca sativa. O presente trabalho teve como objetivos a coleta de isolados de BiMV de diferentes regiões produtoras de alface no Estado de São Paulo, sua caracterização biológica, identificação por meio de técnicas moleculares e triagem de materiais de alface para resistência. Isolados virais coletados em plantas de picão-preto de regiões produtoras do Estado de São Paulo foram submetidos a diferentes metodologias de identificação e caracterização. Testes biológicos em hospedeiros diferenciais permitiram a diferenciação dos isolados de outros vírus de importância para a cultura da alface e a caracterização biológica de alguns isolados como BiMV. Foram vistas partículas flexuosas alongadas ao microscópio eletrônico de transmissão, sugerindo a participação de um Potyvirus na manifestação dos sintomas. O seqüenciamento direto de produtos de PCR de um isolado mostrou identidade de 96% com a seqüência de um isolado de BiMV coletado de ervilha. Isolados monolesionais multiplicados de BiMV foram inoculados em 89 cultivares de alface 2 de diferentes grupos varietais. A maioria das cultivares se mostrou resistente ao BiMV, exceto no caso das nacionais do tipo repolhuda lisa, que foram todas suscetíveis... .
Bidens mosaic virus (BiMV) belongs to the genus Potyvirus and was originally described in São Paulo, Brazil, under examinations by electron microscopy made on exudates obtained from infected plants by Kitajima et al.(1961). Some of the affected plants with economic importance are sunflower, lettuce, peas and bedding plants. Until now, transmission mechanisms, symptomatology on host plants, physical properties and host range had been reported, but few information are available about the importance of BiMV to commercial lettuce fields. At the present time there is no information on resistant cultivars in Lactuca sativa. The aims of this work was to collect isolates of BiMV from different commercial fields in São Paulo State; to determine their biological characterization and their identification by molecular methods and identify sources of resistance in lettuce by the screening of accessions for resistance. Virus isolates originated from different regions were submitted to various methods of detection and characterization. Tests on experimental host range provided data to differentiate one lettuce-infecting species to the others and the virus identification based upon symptom expression. Flexuous rods were observed in leaf extracts from infected plants, showing the presence of a Potyvirus as the causal agent of the symptoms. Direct nucleotide sequencing from amplified PCR products showed 96% of identity compared to an accession of BiMV at GenBank. Monolesional isolates of BiMV properly maintained and multiplied in propagational host were inoculated in 89 cultivars of lettuce of different horticultural types. The great number of them showed resistance to BiMV, except in the case 4 of the Brazilian butterhead types, all susceptible. At present, as the most important commercial lettuce cultivars exhibit high degrees of BiMV resistance, mainly in leafy and iceberg types, it is possible to affirm... (Complete abstract, click electronic address below)
Bidens mosaic virus (BiMV) belongs to the genus Potyvirus and was originally described in São Paulo, Brazil, under examinations by electron microscopy made on exudates obtained from infected plants by Kitajima et al.(1961). Some of the affected plants with economic importance are sunflower, lettuce, peas and bedding plants. Until now, transmission mechanisms, symptomatology on host plants, physical properties and host range had been reported, but few information are available about the importance of BiMV to commercial lettuce fields. At the present time there is no information on resistant cultivars in Lactuca sativa. The aims of this work was to collect isolates of BiMV from different commercial fields in São Paulo State; to determine their biological characterization and their identification by molecular methods and identify sources of resistance in lettuce by the screening of accessions for resistance. Virus isolates originated from different regions were submitted to various methods of detection and characterization. Tests on experimental host range provided data to differentiate one lettuce-infecting species to the others and the virus identification based upon symptom expression. Flexuous rods were observed in leaf extracts from infected plants, showing the presence of a Potyvirus as the causal agent of the symptoms. Direct nucleotide sequencing from amplified PCR products showed 96% of identity compared to an accession of BiMV at GenBank. Monolesional isolates of BiMV properly maintained and multiplied in propagational host were inoculated in 89 cultivars of lettuce of different horticultural types. The great number of them showed resistance to BiMV, except in the case 4 of the Brazilian butterhead types, all susceptible. At present, as the most important commercial lettuce cultivars exhibit high degrees of BiMV resistance, mainly in leafy and iceberg types, it is possible to affirm... (Complete abstract, click electronic address below)
Descrição
Palavras-chave
Alface, Plantas - Resistencia Resistência, Virus de planta, Hortaliças - Melhoramento genetico, Identificação, Bidens mosaic virus, Lettuce, Lactuca sativa
Como citar
HASEGAWA, Jorge Massaki. Identificação e caracterização de isolado de Bidens mosaic virus e triagem de alface para resistência. 2006. viii, 44 f. Dissertação (mestrado) - Universidade Estadual Paulista, Faculdade de Ciências Agronômicas, 2006.