Identificação e purificação de um vírus da poliedrose nuclear da lagarta Spodoptera frugiperda (J.E. Smith, 1797) (Lepidoptera Noctuidae).

A lagarta-do-cartucho e considerado uma das principais pragas da cultura do milho e seu controle tem sido feito basicamente pelo uso de inseticidas quimicos. O CNPMS/EMBRAPA considerando as possibilidades de um controle biologico desta praga, tem procurado um virus de granulose. Recentemente isolou-se , a partir de uma lagarta do campo, um virus de poliedrose nuclear (VPN), que tem sido mantido em larvas em condicoes de laboratorio, causando nestas sintomas identicos ao observado no campo. Poliedrose puderam ser purificados a partir de extratos de lagarta infectada atraves de centrifugacao diferencial em um gradiente de densidade de sacarose. Teste de infectividade mostraram que larvas de S. frugiperda, criadas artificialmente, de 3, 6 e 7 dias de idade,alimentadas com suspensoes poliedros, em concentracoes de 2 x 106 ml, tiveram alta taxa de mortalidade (praticamente 100%), exceto as de 7 dias, na menor dose cuja mortandade foi da ordem de 70%. Exames de extratos das lagartas infectadas mostraram a presenca de grande numero de poliedros, mas a identificacao adequada de que se tratava de um virus de poliedrose nuclear, do tipo "multi-enveloped", (MECPN) so pode ser feita atraves de exames de seccoes ultra finas ao microscopio eletronico: nucleos de ectoderma, tecido adiposo e traqueocitos continham grande numero de poliedros e, ocluidas nestes, particulas baciliformes, em geral varias delas envolvidas por um envoltorio comum.Suplemento

"Enfezamento pálido" e "enfezamento vermelho" na cultura do milho no Brasil Central.

Foi constatada alta incidencia de plantas com sintomas de "Enfezamento Palido" e de "Enfezamento vermelho" em lavouras de milho no Brasil Central. Na mesma area observou-se a presenca de cigarrinha Dalbulus maidis em alta densidade. A presenca de espiroplasma foi confirmada apenas em plantas com sintomas de "Enfezamento Palido", atraves de teste DAS-ELISA. Os resultados da analise por PCR indicaram a presenca de fitoplasma em algumas amostras de plantas com sintomas do "enfezamento Vermelho"

Ocorrência de um Potyvirus associado ao mosaico da açucena-gigante.

Plants of spider lily (Crinum sp) showing mosaic symptoms were found in Londrina, Paraná. Electron microscopy examinations revealed flexuous rod shaped particles and lamellar inclusion bodies in the cell cytoplasm. RT-PCR products of 2 kb were amplified by a pair of genus specific primers suggesting the association of a potyvirus, being this the first time a virus infection in this host is reported in Brazil

Inheritance of tolerance to Cowpea Mild Mottle Virus in soybean.

Soybean stem necrosis is caused by Cowpea mild mottle virus (CPMMV) and it has been recognized as an emerging and economically important disease in Brazil. No resistant, but only tolerant cultivars have been identified so far, and their genetic control is still unknown. To investigate the inheritance of soybean tolerance to CPMMV, two crosses between tolerant cultivars (BRS 133 x BRSMT Pintado), and between a susceptible (CD 206) and a tolerant cultivar (BRSMT Pintado) were carried out to obtain F2 and F2:3 generations. Quantitative and qualitative analyses applied to the data from greenhouse evaluations showed that there are at least two distinct major genes determining tolerance to CPMMV, one in the soybean cultivar BRS 133 and another in the cultivar BRSMT Pintado, with predominance of additive genetic effects and heritability levels that allow for efficient selection based on early generation means

Comparative morpho-anatomical studies of the lesions caused by citrus leprosis virus on sweet orange

The leprosis disease shows a viral etiology and the citrus leprosis virus is considered its etiologic agent. The disease may show two types of cytopatologic symptom caused by two virus: nuclear (CiLV-N) and cytoplasmic (CiLV-C) types. The aim of this study was to compare the morpho-anatomical differences in the lesions caused by leprosis virus-cytoplasmic and nuclear types in Citrus sinensis (L.) Osbeck ?Pêra?. Leaf and fruit lesions were collected in Piracicaba/São Paulo (cytoplasmic type) and Monte Alegre do Sul/São Paulo and Amparo/São Paulo (nuclear type). The lesions were photographed and then fixed in Karnovsky solution, dehydrated in a graded ethylic series, embedded in hydroxy-ethyl methacrylate resin (Leica Historesin), sectioned (5?m thick), stained and mounted in synthetic resin. The digital images were acquired in a microscope with digital video camera. Leaf and fruit lesions caused by the two viruses were morphologically distinct. Only the lesion caused by CiLV-N virus presented three well-defined regions. In both lesions there was the accumulation of lipidic substances in necrotic areas that were surrounded by cells with amorphous or droplets protein. Only leaf and fruit lesions caused by CiLV-N virus exhibited traumatic gum ducts in the vascular bundles.Disponivel em: .Acesso em: 18 out. 2010

Algumas propriedades do vírus do mosaico do picão.

O vírus do mosaico do picão (VMP) foi inativado no extrato foliar mantido entre 55_60ºC por 10 minutos e nas diluições acima de 10-3 ou ainda quando conservado após 5 e 21 dias a 24-26oC e a 4-50C, respectivamente. Nos exames ao microscópio eletrônico de preparações "leaf dip" sempre foram detectadas partículas alongadas e flexíveis, com comprimento normal de ca. 735 nm e, esporadicamente, formações lamelares. Em secções ultrafinas verificou- se a presença de inclusões citoplasmáticas lamelares do tipo catavento. Essas inclusões puderam ser observadas em células epidermais quando examinadas no microscópio de luz. O VMP foi parcialmente purificado pela clanficação do suco com n-butanol e pela precipitação do vírus por centrifugação em gradiente de densidade de sacarose. A partir deste preparado foi elaborado um antissoro. Entretanto, a detecção do vírus por meio de testes de dupla difusão em agar gel com sulfato dodecil de sódio foi inconsistente. (Fito patologia Brasileira 7:185-195.1982) Some properties of Bidens Mosaic Vírus Bidens mosaic virus (BMV) was inactived in leaf3extracts 55-600C for 10 minutes, was not recovered from leaf extracts diluited beyond 10- ,or when preserved for longer periods than 5 and 21 days respectively at roo,n temperature 24 - 260 and 4 -50 C. Electron microscopie examinations showed cytoplasmic lamellar and pinwheei inclusion bodies, which were also detected by light microscopy, in epidermal cells. Elongated particles with a normallength of ca. 735 nm ' were consistently seen in "leaf dip" preparations. The virus was partially purified by sap clarification with 8% n-butanol, concentration by differential centrifugation, followed by centrifugation in sucrose density gradient and recovery of the viral bando An antiserum to this vírus was prepared, however detection of BMV in double diffusion in agar gel containing sodium dodecyl sulfate gave inconsistent results. (Fito patologia Brasileira 7:185-195.1982

Ocorrência e estudos electrono-microscópicos do vírus do mosaico do trigo, transmitido pelo solo, no estado do Rio Grande do Sul.

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