Navegando por Autor "Gall, Olivier Le"
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Item Frequência de Lettuce big-vein associated virus e Mirafiori lettuce big-vein virus em Plantas de alface no Estado de São Paulo e transmissão através de extrato vegetal e solo(Summa Phytopathologica, 2007-10) Sanches, Márcio Martinello; Krause-Sakate, Renate; Zerbini, Francisco Murilo; Rosales, Marlene; Gall, Olivier Le; Pavan, Marcelo AgenorA presença de sintomas de 'big vein' ou engrossamento das nervuras em alface e a associação do Lettuce big-vein associated virus (LBVaV) e Mirafiori lettuce big-vein virus (MLBVV) foram verificadas por RT-PCR utilizando-se oligonucleotídeos específicos para ambos os vírus. Foram coletadas 366 plantas sintomáticas nas regiões 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. Infecção mista do LBVaV e MLBVV foi detectada em 76,2% das plantas sintomáticas, em 11,5% somente o MLBVV foi detectado e em 6,6% somente o LBVaV. Nas plantas assintomáticas coletadas em dezembro na região de Mogi das Cruzes, em áreas de alta incidência da doença durante o inverno, foi detectada a presença de MLBVV em 9 amostras e LBVaV em 7 amostras. Quatro dessas amostras apresentaram infecção mista, indicando que o desenvolvimento de sintomas depende de fatores abióticos, como temperatura. A inoculação via extrato vegetal a partir de plantas de alface com infecção mista pelo MLBVV e LBVaV foi realizada a 16°C/ 10°C (dia/noite) e fotoperíodo de 11 horas, verificando-se que o MLBVV foi transmitido para Nicotiana tabacum TNN, N. rustica, N. occidentalis, Chenopodium quinoa e para as cultivares de alface Trocadero e White Boston, enquanto o LBVaV foi transmitido apenas para a alface White Boston. Entretanto, nenhuma destas plantas apresentou sintomas da doença, com exceção de C. quinoa que apresentou sintomas de lesões locais. Plantio em solo proveniente de áreas com histórico da doença de Mogi das Cruzes permitiu a transmissão do LBVaV para alface cv. White Boston e do MLBVV para alface cv. Trocadero e White Boston, embora apenas a cv. White Boston tenha apresentado sintomas da doença. Em conjunto, estes resultados demonstram a dificuldade de transmissão de ambos os vírus, mesmo em condições de laboratório.Item Molecular characterization of two brazilian isolates of Lettuce mosaic virus with distinct biological properties(Fitopatologia Brasileira, 2001-06) Krause- Sakate, Renate; Mello, Raquel N.; Pavan, Marcelo A.; Zambolim, Eunize M.; Carvalho, Murilo G.; Gall, Olivier Le; Zerbini, F. Murilo; Krause-Sakate, RenateThe coat protein genes of two field isolates of Lettuce mosaic virus (LMV) from São Paulo State, previously characterized based on their virulence on lettuce (Lactuca sativa) differential cultivars as belonging to pathotypes II (isolate AF198, unable to infect cultivars possessing the genes mo11 or mo12) and IV (isolate AF199, which breaks the resistance conferred by mo11 or mo12), were cloned and sequenced. Comparisons of the nucleotide sequences from European, Middle-Eastern, North American, and the two Brazilian isolates did not distinguish strains, because homologies were always greater than 95%. However, phylogenetic analysis indicated that the Brazilian isolate AF198 clusters with isolates LMV-R and LMV-0 (pathotype II, from the United States and France, respectively). Isolate AF199 clustered with two isolates (LMV-Aud and LMV-13) from France. These isolates are also closely related to isolates from Chile, although a common origin is not proposed. Independent mutation events may be occurring in different parts of the world, leading to the emergence of distinct LMV strains capable of overcoming the resistance genes mo11 or mo12.Item Molecular mapping of the viral determinants of systemic wilting induced by a Lettuce mosaic virus (LMV) isolate in some lettuce cultivars(Virus Research, 2005-05) Zerbini, F. Murilo; Krause-Sakate, Renate; Redondo, Elise; Richard-Forget, Florence; Jadão, Adriana Salomão; German-Retana, Sylvie; Pavan, Marcelo Agenor; Candresse, Thierry; Gall, Olivier Le; Houvenaghel, Marie ChristineThe isolate AF199 of Lettuce mosaic virus (LMV, genus Potyvirus) causes local lesions followed by systemic wilting and plant death in the lettuce cultivars Ithaca and Vanguard 75. Analysis of the phenotype of virus chimeras revealed that a region within the P1 protein coding region (nucleotides 112–386 in the viral genome) and/or another one within the CI protein coding region (nucleotides 5496–5855) are sufficient together to cause the lethal wilting in Ithaca, but not in Vanguard 75. This indicates that the determinants of this particular symptom are different in these two lettuce cultivars. The wilting phenotype was not directly correlated with differences in the deduced amino acid sequence of these two regions. Furthermore, transient expression of the LMV-AF199 proteins, separately or in combination, did not induce local necrosis or any other visible reaction in the plants. Together, these results suggest that the systemic wilting reaction might be due to RNA rather than protein sequences.Item Quantitative control of Lettuce mosaic virus fitness and host defence inhibition by P1-HCPro(Summa Phytopathologica, 2007-04) Krause-Sakate, Renate; Richard-Forget, Florence; Redondo, Elise; Pavan, Marcelo Agenor; Zerbini, Francisco Murilo; Candresse, Thierry; Gall, Olivier LeTwo Lettuce mosaic virus isolates capable of overcoming the resistance afforded by the resistance gene mo12 in lettuce, LMV-AF199 from Brazil, and LMV-E, an European isolate, were evaluated for the rapidity and severity of symptoms induced on the lettuce variety Salinas 88 (mo12). The mosaic symptoms on Salinas 88 plants inoculated with LMV-AF199 appeared 7 days post-inoculation (dpi) and 15 dpi for LMV-E. The symptoms induced by LMV-AF199 in this cultivar were also more severe than those induced by LMV-E. In order to identify the region of the viral genome responsible for this phenotype, recombinant viruses were constructed between these isolates and the phenotype of each recombinant was analysed. The region encoding proteins P1 and HcPro from LMV-AF199 was associated with the increased virulence in Salinas 88.