Caracterização molecular e biológica do Lettuce big-vein associated vírus e Mirafiori lettuce big-vein vírus e estudo da ocorrência em relação à época e sintoma em plantas de alface no Estado de São Paulo
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Data
2006-01-31
Autores
Sanches, Márcio Martinello [UNESP]
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
Recentemente sintomas da doença conhecida como engrossamento das nervuras, ou big-vein, foram observados no Estado de São Paulo, principalmente no período de inverno. A doença foi historicamente associada ao Lettuce big-vein associated virus (LBVaV), porém a presença dos sintomas característicos foi atribuída ao Mirafiori lettuce big-vein virus (MLBVV). Tradicionamente ambos vírus vem sendo diagnosticados pelo teste de ELISA, de modo que resultados discrepantes quanto ao agente causal dos sintomas da doença foram obtidos na Europa, possivelmente devido à falta de sensibilidade do teste. Deste modo, o presente trabalho teve como finalidade utilizar a técnica de RT-PCR na detecção segura e específica do MLBVV e LBVaV. Foram coletadas 366 plantas sintomáticas nas regiões produtoras de Bauru, Campinas e Mogi das Cruzes no Estado de São Paulo nos meses de junho e setembro de 2004 e abril e julho de 2005, e 18 plantas assintomáticas na região de Mogi das Cruzes no mês de dezembro de 2004. Os oligonucleotídeos específicos foram altamente eficientes na detecção de ambos os vírus, sendo que a banda viral foi clonada e sequenciada para alguns dos isolados, comprovando a identidade viral de cada um dos vírus. Foi observado que 76,2% das plantas sintomáticas apresentaram infecção mista do LBVaV e MLBVV, em 11,5% somente o MLBVV e em 6,6% somente o LBVaV. Nas plantas assintomáticas foi detectada a presença de infecção mista por MLBVV e LBVaV em quatro amostras, infecção apenas por MLBVV em cinco amostras e apenas por LBVaV em três amostras, indicando que o desenvolvimento de sintomas depende de fatores abióticos, além da presenca dos vírus. A análise das sequencias de aminoácidos da região codificadora da proteína capsidial, revelou que os isolados de LBVaV possuem baixa variabilidade genética e mesma origem evolutiva entre isolados de diferentes partes do mundo...
Lettuce plants with big-vein symptons have been observed in the São Paulo State during the winter. The disease has been historically associated to Lettuce big-vein associated virus (LBVaV), however recently the development of symptoms was atributted to Mirafiori lettuce big-vein virus (MLBVV). Tradicionally both viruses were routinely detected by ELISA, but discrepants results about the main disease agent were obtained in the Europe possible by the low sensibility of the assay. The objective of this study was to detect MLBVV and LBVaV by RT-PCR, using specifics primers. A total of 366 samples from symptomatic plants of Bauru, Campinas and Mogi das Cruzes regions, from São Paulo State, were collected during june and september of 2004 and april and july of 2005, and 18 symptomless plants from the Mogi das Cruzes region during December 2004. The primers were highly efficient in the 4 detection of both viruses, and the fragment of some isolates were cloned and sequenced to confirm the RT-PCR. Mixed infection of LBVaV and MLBVV was observed on 76,2% symptomatic plants. MLBVV on 11,5% and LBVaV on 6,6%. In a total of 18 symptomless plants, four were infected with both viruses, five only with MLBVV and three plants with LBVaV. These results indicates that not only the presence of the viruses, but also abiotic factors are necessary for the occurrence of big-vein symptoms. Amino acid sequence identities of part of the coat protein gene of LBVaV isolates was high indicating a possible same evolutive origin. Genetic diversity among MLBVV isolates was higher when compared to LBVaV isolates. MLBVV brazilian isolates belongs to subgroup A, with one RsaI restriction site on the coat protein sequence. One plant with MLBVV and LBVaV (mixed infection) was sap inoculated on a host range (temperature and luminosity controled), indicating that MLBVV can be transmitted to Nicotiana tabacum TNN, N. rustica... (Complete abstract, click electronic address below).
Lettuce plants with big-vein symptons have been observed in the São Paulo State during the winter. The disease has been historically associated to Lettuce big-vein associated virus (LBVaV), however recently the development of symptoms was atributted to Mirafiori lettuce big-vein virus (MLBVV). Tradicionally both viruses were routinely detected by ELISA, but discrepants results about the main disease agent were obtained in the Europe possible by the low sensibility of the assay. The objective of this study was to detect MLBVV and LBVaV by RT-PCR, using specifics primers. A total of 366 samples from symptomatic plants of Bauru, Campinas and Mogi das Cruzes regions, from São Paulo State, were collected during june and september of 2004 and april and july of 2005, and 18 symptomless plants from the Mogi das Cruzes region during December 2004. The primers were highly efficient in the 4 detection of both viruses, and the fragment of some isolates were cloned and sequenced to confirm the RT-PCR. Mixed infection of LBVaV and MLBVV was observed on 76,2% symptomatic plants. MLBVV on 11,5% and LBVaV on 6,6%. In a total of 18 symptomless plants, four were infected with both viruses, five only with MLBVV and three plants with LBVaV. These results indicates that not only the presence of the viruses, but also abiotic factors are necessary for the occurrence of big-vein symptoms. Amino acid sequence identities of part of the coat protein gene of LBVaV isolates was high indicating a possible same evolutive origin. Genetic diversity among MLBVV isolates was higher when compared to LBVaV isolates. MLBVV brazilian isolates belongs to subgroup A, with one RsaI restriction site on the coat protein sequence. One plant with MLBVV and LBVaV (mixed infection) was sap inoculated on a host range (temperature and luminosity controled), indicating that MLBVV can be transmitted to Nicotiana tabacum TNN, N. rustica... (Complete abstract, click electronic address below).
Descrição
Palavras-chave
Reação em cadeia de polimerase - São Paulo, Viroses - São Paulo, Alface - Aspectos biológicos - São Paulo, Fitopatologia - São Paulo, RT-PCR, Biological characterization, MLBVV, LBVaV
Como citar
SANCHES, Márcio Martinello. Caracterização molecular e biológica do Lettuce big-vein associated vírus e Mirafiori lettuce big-vein vírus e estudo da ocorrência em relação à época e sintoma em plantas de alface no Estado de São Paulo. 2006. viii, 56 f. Dissertação (mestrado) - Universidade Estadual Paulista, Faculdade de Ciências Agronômicas, 2006.