Caracterização da resistência vertical e horizontal do cafeeiro à ferrugem (Hemileia vastatrix Berk. & Br) em acesso de Híbrido de Timor
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2005
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Resumo
A ferrugem alaranjada, causada por Hemileia vastatrix Berk. & Br, constitui um dos principais problemas para a cultura do café. O controle da doença geralmente é feito com o uso de fungicidas, os quais aumentam o custo de produção e os ricos ambientais e à saúde humana. O uso de variedades resistentes é uma alternativa para um controle eficiente, simples, barato e que reduz o uso de agrotóxicos na cafeicultura. Portanto, programas de melhoramento têm sido realizados visando obter variedades resistentes a esta doença. Para dar suporte a esses programas, no presente trabalho, foi realizado o estudo da herança da resistência do Híbrido de Timor UFV 440-22, importante fonte utilizada pelos melhoristas. O conhecimento da herança da resistência é essencial para o planejamento e uso eficiente das fontes no melhoramento genético do cafeeiro. O Híbrido de Timor foi cruzado com a cultivar suscetível Catuaí UFV 2143-193 e a planta F1 foi autofecundada formando a população segregante F2, com 113 indivíduos. Os genitores, a planta F1 e a população F2 foram inoculados com a raça II de H. vastatrix. A avaliação da doença foi realizada aos 50 dias após a inoculação, com base na reação de resistência ou suscetibilidade. A resistência horizontal também foi analisada utilizando-se sete componentes de resistência a doença: período de incubação (PI), período latente (PL), número de lesões (NL), número de lesões esporuladas (NLE), razão de infecção (RI), razão de esporulação (RE) e produção de uredosporos (PE). A fonte de resistência UFV440-22 e o híbrido F1 comportaram-se como resistentes, enquanto a cv. Catuaí UFV 2143-193 foi severamente atacada. Na geração segregante F2, das 113 plantas observadas, 101 foram resistentes e 12 suscetíveis, indicando que um gene dominante independente e dois recessivos complementares controlam a resistência deste Híbrido de Timor à raça II de H. vastatrix (X2 ; P>0,05%). Além da resistência vertical, indivíduos da população F2 apresentaram resistência horizontal, demonstrando que o Híbrido de Timor UFV 440-22 pode ser utilizado como fonte para resistência vertical ou horizontal nos programas de melhoramento que visam a obtenção de variedades resistente à ferrugem.
The coffee leaf rust caused by Hemileia vastatrix Berk & Br is the most important disease of Coffea arabica L. The control of the disease is based on the application of fungicides, which increase the production costs and the environmental and human health risks. The use of resistant varieties is the best alternative to control the disease, because it is simple and inexpensive; furthermore it decrease the use of agrochemicals in the coffee plantation. Therefore, breeding programs have been accomplished in order to obtain resistant varieties to this disease. To assist these programs, the inheritance resistance of Tymor Hybrid UFV 440-22, which is an important source used by plant breeders, was used. The knowledge about inheritance resistance is essential for both planning and efficient use of the sources in the coffee genetic breeding. The Tymor Hybrid was crossed with the susceptible cultivar Catuaí UFV 2143-193 and the F1 plant was self-fertilized, forming the F2 population, with 113 individuals. The genitors, the F1 plant and the F2 population were inoculated with the H. vastatrix race II. The evaluation of the disease was done 50 days after the inoculation, based on the resistance or susceptibility reaction. The horizontal resistance was also analyzed by the resistance components: incubation period (PI), latent period (PL), lesion number (NL), number of sporulated lesions (NLE), infection rate (RI), sporulation rate (RE) and uredospores production (PE). The resistance source UFV 440-22 and the F1 hybrid behaved as resistant, while the cultivar Catuaí UFV 2143-193 was severely attacked. On the F2 population, out of the 113 observed plants 101 were resistant and 12 were susceptible, indicating that one independent dominant and two complementary recessive genes control the Tymor Hybrid resistance to Hemileia vastatrix race II (X2; P>0,05%). Horizontal resistance was also observed in the F2 population, demonstrating that the Tymor Hybrid UFV 440-22 can be used as source to either vertical or horizontal resistance in the breeding programs aiming to develop resistant varieties to coffee leaf rust.
The coffee leaf rust caused by Hemileia vastatrix Berk & Br is the most important disease of Coffea arabica L. The control of the disease is based on the application of fungicides, which increase the production costs and the environmental and human health risks. The use of resistant varieties is the best alternative to control the disease, because it is simple and inexpensive; furthermore it decrease the use of agrochemicals in the coffee plantation. Therefore, breeding programs have been accomplished in order to obtain resistant varieties to this disease. To assist these programs, the inheritance resistance of Tymor Hybrid UFV 440-22, which is an important source used by plant breeders, was used. The knowledge about inheritance resistance is essential for both planning and efficient use of the sources in the coffee genetic breeding. The Tymor Hybrid was crossed with the susceptible cultivar Catuaí UFV 2143-193 and the F1 plant was self-fertilized, forming the F2 population, with 113 individuals. The genitors, the F1 plant and the F2 population were inoculated with the H. vastatrix race II. The evaluation of the disease was done 50 days after the inoculation, based on the resistance or susceptibility reaction. The horizontal resistance was also analyzed by the resistance components: incubation period (PI), latent period (PL), lesion number (NL), number of sporulated lesions (NLE), infection rate (RI), sporulation rate (RE) and uredospores production (PE). The resistance source UFV 440-22 and the F1 hybrid behaved as resistant, while the cultivar Catuaí UFV 2143-193 was severely attacked. On the F2 population, out of the 113 observed plants 101 were resistant and 12 were susceptible, indicating that one independent dominant and two complementary recessive genes control the Tymor Hybrid resistance to Hemileia vastatrix race II (X2; P>0,05%). Horizontal resistance was also observed in the F2 population, demonstrating that the Tymor Hybrid UFV 440-22 can be used as source to either vertical or horizontal resistance in the breeding programs aiming to develop resistant varieties to coffee leaf rust.
Descrição
Trabalho apresentado no Simpósio de Pesquisa dos Cafés do Brasil (4. : 2005 : Londrina, PR). Anais. Brasília, D.F. : Embrapa Café, 2005.
Palavras-chave
Hemileia vastatrix Herança da resistência Resistência vertical e horizontal Café Melhoramento genético, Hemileia vastatrix Resistance inheritance Vertical and horizontal resistance Coffee breeding
Citação
Barbosa, Júlio César; Caixeta, Eveline Teixeira; Zambolim, Eunize Maciel; Capucho, Alexandre Sandri; Rufino, Raphael Nascif; Alvarenga, Samuel Mazzinghy; Zambolim, Laércio; Sakiyama, Ney Sussumu. Caracterização da resistência vertical e horizontal do cafeeiro à ferrugem (Hemileia vastatrix Berk. & Br) em acesso de Híbrido de Timor. In: Simpósio de Pesquisa dos Cafés do Brasil (4. : Londrina, PR : 2005). Anais. Brasília, D.F. : Embrapa - Café, 2005. (1 CD-ROM), 5p.