Caracterização de Diaporthe citri em diferentes meios de cultura, condições de temperatura e luminosidade
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Data
2004-08-01
Autores
Nozaki, Márcia de H. [UNESP]
Camargo, Margarete [UNESP]
Barreto, Modesto [UNESP]
Título da Revista
ISSN da Revista
Título de Volume
Editor
Sociedade Brasileira de Fitopatologia
Resumo
Estudou-se o crescimento micelial de dez isolados de Diaporthe citri, utilizando-se seis meios de cultura (aveia-ágar, maltose-peptona-ágar, batata-dextrose-ágar, folha de laranja-dextrose-ágar, folha de limão-dextrose-ágar, milho-ágar) à temperatura de 22 ± 2 °C e fotoperíodo de 12 h claro/12 h escuro. O cultivo em meio de batata-dextrose-ágar (BDA) foi conduzido em cinco temperaturas diferentes (10, 15, 20, 25 e 30 °C). Três diferentes regimes de luminosidade (12 h claro/12 h escuro, claro contínuo, escuro contínuo) foram utilizados para verificar o crescimento do fungo. Foram observadas variações na produção de picnídios e de massa micelial nos diferentes meios de cultura, temperaturas e regimes de luminosidade testados, sendo que, para a maioria dos isolados, o meio de cultura de aveia-ágar, a faixa de 20 a 25 °C e o regime de claro contínuo induziram maior crescimento micelial. A produção de picnídios foi maior para o regime de luz contínua. O teste de patogenicidade foi feito por inoculação de discos de micélio de 5 mm de diâmetro em ferimentos em ramos e caule de limão 'Feminelo' (Citrus limon) enxertado em citrumelo 'Swingle'(Poncirus trifoliolata x Citrus paradisi) e plantas de limão 'Cravo' (C. limonia) enxertados com laranja 'Valência' (C. sinensis). Após sete dias, houve o aparecimento de exsudação de goma nas plantas inoculadas com os isolados, mas não na testemunha. Todos os isolados mostraram-se patogênicos, sendo os isolados PC2 e PC5, os que causaram comprimento de lesão maior nas plantas.
The mycelial growth of ten Diaporthe citri isolates was studied comparing six culture media (oatmeal-agar, malt-peptone-agar, potato-dextrose-agar, orange leaf-dextrose-agar, lemon leaf-dextrose-agar, corn-agar) under 22 ± 2 °C and 12 h light/12 h dark. The evaluation of the mycelial growth of the fungi was also compared under five different temperatures (10, 15, 20, 25 and 30 °C) and three different luminosity conditions (12 h light/12 h dark, continuous light and continuous dark) on potato-dextrose-agar media (PDA). Variations in pycnidial and mycelial mass production were observed in the different media, temperature and luminosity conditions tested. For most isolates, oatmeal-agar, 20-25 °C and continuous light promoted best sporulation. The pycnidial production was greater under continuous light. The pathogenicity test was made by inoculating mycelial discs of 5 mm on sores made in twigs and stem of citrus (Citrus spp.) cultivars. After seven days, gum exudation was observed in plants that were inoculated with the isolates, but not on control. All isolates were pathogenic, but PC2 and PC5 caused bigger lesions in plants.
The mycelial growth of ten Diaporthe citri isolates was studied comparing six culture media (oatmeal-agar, malt-peptone-agar, potato-dextrose-agar, orange leaf-dextrose-agar, lemon leaf-dextrose-agar, corn-agar) under 22 ± 2 °C and 12 h light/12 h dark. The evaluation of the mycelial growth of the fungi was also compared under five different temperatures (10, 15, 20, 25 and 30 °C) and three different luminosity conditions (12 h light/12 h dark, continuous light and continuous dark) on potato-dextrose-agar media (PDA). Variations in pycnidial and mycelial mass production were observed in the different media, temperature and luminosity conditions tested. For most isolates, oatmeal-agar, 20-25 °C and continuous light promoted best sporulation. The pycnidial production was greater under continuous light. The pathogenicity test was made by inoculating mycelial discs of 5 mm on sores made in twigs and stem of citrus (Citrus spp.) cultivars. After seven days, gum exudation was observed in plants that were inoculated with the isolates, but not on control. All isolates were pathogenic, but PC2 and PC5 caused bigger lesions in plants.
Descrição
Palavras-chave
Citros, melanose, Crescimento micelial, produção de picnídios
Como citar
Fitopatologia Brasileira. Sociedade Brasileira de Fitopatologia, v. 29, n. 4, p. 429-432, 2004.