186 resultados para wilt
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Pós-graduação em Agronomia (Proteção de Plantas) - FCA
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Pós-graduação em Agronomia (Horticultura) - FCA
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Pós-graduação em Agronomia (Proteção de Plantas) - FCA
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Pós-graduação em Agronomia (Proteção de Plantas) - FCA
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Pós-graduação em Agronomia (Horticultura) - FCA
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Background: Tospoviruses (Genus Tospovirus, Family Bunyaviridae) are phytopathogens responsible for significant worldwide crop losses. They have a tripartite negative and ambisense RNA genome segments, termed S (Small), M (Medium) and L (Large) RNA. The vector-transmission is mediated by thrips in a circulative-propagative manner. For new tospovirus species acceptance, several analyses are needed, e. g., the determination of the viral protein sequences for enlightenment of their evolutionary history. Methodology/Principal Findings: Biological (host range and symptomatology), serological, and molecular (S and M RNA sequencing and evolutionary studies) experiments were performed to characterize and differentiate a new tospovirus species, Bean necrotic mosaic virus (BeNMV), which naturally infects common beans in Brazil. Based upon the results, BeNMV can be classified as a novel species and, together with Soybean vein necrosis-associated virus (SVNaV), they represent members of a new evolutionary lineage within the genus Tospovirus. Conclusion/Significances: Taken together, these evidences suggest that two divergent lineages of tospoviruses are circulating in the American continent and, based on the main clades diversity (American and Eurasian lineages), new tospovirus species related to the BeNMV-SVNaV clade remain to be discovered. This possible greater diversity of tospoviruses may be reflected in a higher number of crops as natural hosts, increasing the economic impact on agriculture. This idea also is supported since BeNMV and SVNaV were discovered naturally infecting atypical hosts (common bean and soybean, respectively), indicating, in this case, a preference for leguminous species. Further studies, for instance a survey focusing on crops, specifically of leguminous plants, may reveal a greater tospovirus diversity not only in the Americas (where both viruses were reported), but throughout the world.
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The ornamental market is dynamic and demands constant novelties. The use of fruit crops as ornamental plants can be an interesting alternative with very differentiated and original products. The banana germplasm bank at Embrapa Cassava and Fruits has been primarily used in the breeding program for generating new cultivars as food. To diversify and expand the use of this collection, accessions with ornamental potential have been selected to obtain new hybrids. This work was aimed at characterizing the progeny of ornamental Musa L. spp. by grouping the hybrids according to the following uses: landscape plants, potted plants, cut flower, or minifruits. Forty-two hybrids were evaluated with 14 quantitative and 12 qualitative descriptors in three production cycles. In addition, assays for resistance to black and yellow Sigatoka and to Fusarium wilt were performed. Variability was observed for all the characteristics evaluated within progenies, especially with regard to leaf color, fruit, peduncle, rachis, and heart. All evaluated hybrids were resistant to yellow Sigatoka and to Fusarium wilt and were resistant or showed reduced symptoms of susceptibility to black Sigatoka. Most hybrids (82%) presented reduced plant height. After clustering by use category, the hybrids RM 09, RM 38, RM 37, and RM 33 were selected and recommended to be used as cut flowers, minifruits, or landscaping plants.
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A modern management of crop protection should be based on integrated control programmes, including the use of environmentally safe products. Antagonistic/beneficial bacteria and resistance inducers may have a great potential in the prophylaxis of diseases caused by common and quarantine pathogens. This work was carried out to confirm the ability of the known strain IPV-BO G19 (Pseudomonas fluorescens) against fire blight (Erwinia amylovora), as well as to evaluate their efficacy against southern bacterial wilt of tomato (Ralstonia solanacearum) and grapevine crown gall (Agrobacterium vitis). A virulent strain of R. solanacearum race 3 was inhibited by the antagonist on plate. When the pathogen was inoculated 48 h after their application to the root apparatus of tomato plants grown in a climatic chamber, bacterial wilt progression rate was clearly reduced. Moreover the defence response evoked by IPV-BO G19 was studied in tomato plants by monitoring the transcription of genes codifying for three PRs as PR-1a, PR-4, PR-5 and for an intracellular chitinase using multiplex RT-PCR and Real Time RT-PCR. In two field trials during 2005 and 2006, the strain IPV-BO G19 was compared with biofungicides and some abiotic elicitors to protect actively growing shoots of pear scions against fire blight. In both trials, IPV-BO G19 plus Na-alginate gave a high level of protection, three weeks after wound inoculation with E. amylovora. In pear leaf tissues treated with the antagonistic strain IPV-BO G19, catalase, superoxyde dismutase and peroxidise activity was evaluated as markers of induced resistance. The IPV-BO G19 strain was compared with other bioagents and resistance inducers to prevent grapevine crown gall under glasshouse and vineyard conditions.