Estudos preliminares sobre as invertases de cafeeiros atacados por Hemileia vastatrix

Carvalho, Paulo de Campos Torres de

doi:10.1590/S0071-12761972000100015

Resumos

No presente trabalho, que o autor considera exploratório, foram estudadas as invertases presentes em folhas de cafeeiros das variedades Geisha (SH1 SH5) e Kent (SH2 SH5), inoculados com as raças III (n1 n5) e XXIV (n2 n4) de Hemileia vastatrix. Devido ao genótipo do material utilizado as reações são opostas, ou seja, o cafeeiro Kent é resistente à raça III e suscetível à raça XXIV e o Geisha o contrário. Em cada par de folhas, uma foi inoculada e outra mantida como controle e a determinação das invertases foi feita aos 6 e 16 dias após a inoculação. Os resultados preliminares obtidos mostraram que, independente da variedade de cafeeiro ou da raça de Hemileia vastatrix, nas combinações suscetíveis não houve alteração das invertases presentes, iguais às de plantas sadias, com o máximo de atividade em pH 4,5. Já nas combinações resistentes no 6.º dia após a inoculação houve o aparecimento de uma "invertase ácida pH 4,0", ausente tanto nas plantas sadias como nas combinações suscetíveis das mesmas variedades. O aparecimento da "invertase ácida pH 4,0" está relacionado com a diminuição do teor de sacarose nas folhas. Quanto ao significado desta "invertase ácida pH 4,0" na patogenese da ferrugem do cafeeiro, o autor aventa 3 hipóteses que poderiam ocorrer isolada ou simultaneamente. 1. A sacarose seria desviada para a formação de defesa, tais como fenóis, fitoalexinas e outras. 2. A sacarose seria desviada para outras partes da planta, num processo fisiológico semelhante ao das folhas em senectude. 3. Haveria um aumento da respiração e metabolismo dos tecidos doentes, com o implícito consumo da energia armazenada.

The present research, considered exploratory by the Author, was dons in order to study leaf invertases of two coffee varieties, Geisha (SH1SH5) and Kent SH2SH5) inoculated with races III (v1v5) and XXIV (v2v4) of Hemileia vastatrix. The Geisha coffee is susceptible to race III and resistant to race XXIV, while Kent coffee has opposite reactions. In each pair of leaves, one was inoculated and the other was kept as control. Determinations of the invertases were made at 6 and 16 days after inoculation. The preliminary results showed that in the susceptible combinations there was no changes in the invertases, that were the same as in the healthy plants, with the maximum of activity at pH 4.5. In the resistant combinations, however, it was found an "acid invertase pH 4.0" on the 6th day after inoculations. This invertase was absent in both healthy and infected plants of the same varieties. The occurrence on the "acid invertase pH 4.0" is related to the decrease in the sucrose content of the leaves. The Author suggest three hipothesis that could explain a relation of this "acid invertase pH 4.0" with the coffee rust pathogenesis. These hipothesis, which could occur alone or simultaneously are: 1) The sucrose would be deviated to the formation of defense substances, such as phenols, phytoalexins and others. 2) The sucrose would be deviated to others parts of the plant, in 2l physiological process similar to that of the leaves in senescence. 3) There would be an increase in the respiration and metabolism of the infected tissues, with the implicit consumption of the stored energy.

Paulo de Campos Torres de Carvalho

Departamento de Fitopatologia da Escola Superior de Agricultura "Luiz de Queiroz" da Universidade de São Paulo

RESUMO

No presente trabalho, que o autor considera exploratório, foram estudadas as invertases presentes em folhas de cafeeiros das variedades Geisha (SH₁ SH₅) e Kent (SH₂ SH₅), inoculados com as raças III (n₁ n₅) e XXIV (n₂ n₄) de Hemileia vastatrix. Devido ao genótipo do material utilizado as reações são opostas, ou seja, o cafeeiro Kent é resistente à raça III e suscetível à raça XXIV e o Geisha o contrário. Em cada par de folhas, uma foi inoculada e outra mantida como controle e a determinação das invertases foi feita aos 6 e 16 dias após a inoculação.

Os resultados preliminares obtidos mostraram que, independente da variedade de cafeeiro ou da raça de Hemileia vastatrix, nas combinações suscetíveis não houve alteração das invertases presentes, iguais às de plantas sadias, com o máximo de atividade em pH 4,5. Já nas combinações resistentes no 6.º dia após a inoculação houve o aparecimento de uma "invertase ácida pH 4,0", ausente tanto nas plantas sadias como nas combinações suscetíveis das mesmas variedades. O aparecimento da "invertase ácida pH 4,0" está relacionado com a diminuição do teor de sacarose nas folhas. Quanto ao significado desta "invertase ácida pH 4,0" na patogenese da ferrugem do cafeeiro, o autor aventa 3 hipóteses que poderiam ocorrer isolada ou simultaneamente.

1. A sacarose seria desviada para a formação de defesa, tais como fenóis, fitoalexinas e outras.

2. A sacarose seria desviada para outras partes da planta, num processo fisiológico semelhante ao das folhas em senectude.

3. Haveria um aumento da respiração e metabolismo dos tecidos doentes, com o implícito consumo da energia armazenada.

SUMMARY

The present research, considered exploratory by the Author, was dons in order to study leaf invertases of two coffee varieties, Geisha (SH₁SH₅) and Kent SH₂SH₅) inoculated with races III (v1v5) and XXIV (v2v4) of Hemileia vastatrix. The Geisha coffee is susceptible to race III and resistant to race XXIV, while Kent coffee has opposite reactions. In each pair of leaves, one was inoculated and the other was kept as control. Determinations of the invertases were made at 6 and 16 days after inoculation.

The preliminary results showed that in the susceptible combinations there was no changes in the invertases, that were the same as in the healthy plants, with the maximum of activity at pH 4.5. In the resistant combinations, however, it was found an "acid invertase pH 4.0" on the 6th day after inoculations. This invertase was absent in both healthy and infected plants of the same varieties. The occurrence on the "acid invertase pH 4.0" is related to the decrease in the sucrose content of the leaves.

The Author suggest three hipothesis that could explain a relation of this "acid invertase pH 4.0" with the coffee rust pathogenesis. These hipothesis, which could occur alone or simultaneously are:

1) The sucrose would be deviated to the formation of defense substances, such as phenols, phytoalexins and others.

2) The sucrose would be deviated to others parts of the plant, in 2l physiological process similar to that of the leaves in senescence.

3) There would be an increase in the respiration and metabolism of the infected tissues, with the implicit consumption of the stored energy.

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LITERATURA CITADA

Entregue para publicação em 29/12/72.

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