Data/hora: 11/06/2024 20:44:15

Biblioteca(s): | Embrapa Soja.
Data corrente: | 06/04/2004
Data da última atualização: | 27/07/2007
Autoria: | ARIAS, C. A. A.; RIBEIRO, A. S.; KIIHL, R. A. de S.
Título: | A single gene determining high level of resistance to powdery mildew in soybean.
Ano de publicação: | 2004
Fonte/Imprenta: | In: WORLD SOYBEAN RESEARCH CONFERENCE, 7.; INTERNATIONAL SOYBEAN PROCESSING AND UTILIZATION CONFERENCE, 4.; CONGRESSO BRASILEIRO DE SOJA, 3., 2004, Foz do Iguassu. Abstracts of contributed papers and posters. Londrina: Embrapa Soybean, 2004.
Páginas: | p. 95-96.
Série: | (Embrapa Soja. Documentos, 228).
Idioma: | Inglês
Notas: | Editado por Flávio Moscardi, Clara Beatriz Hoffmann-Campo, Odilon Ferreira Saraiva, Paulo Roberto Galerani, Francisco Carlos Krzyzanowski, Mercedes Concordia Carrão-Panizzi.
Conteúdo: | Powdery mildew (Erysiphe diffusa - Braun & Takamatsu, 2000, Schlechtendalia 4:1-33) was considered a secondary soybean disease prior to 1996, causing some damage only in specific cases like in late sowing crops or winter season crops. However, its importance has increased since 1996/97 season, when soybean crops from the southern to the central Brazilian regions were heavily attacked, provoking significant losses. The presence of susceptible varieties to this disease contributed to increment the use of leaf fungicides, which were extensively applied to prevent losses in the following crop seasons. The fungus ability to quickly develop new physiologic races, increases the complexity around the arduous task to develop resistant varieties. The resistance level presented by the new varieties must be sufficient to avoid the chemical control or, at least, diminish the probability of multiple chemical applications. The use of new genes of resistance to this disease is a priority in the Brazilian breeding program conducted by Embrapa. A soybean line, named BRI98-641, derived from the breeding program for insect resistance, was classified as having a high resistance level. To study the inheritance of this powdery mildew resistant line, crosses were made with the varieties BRS 184, Chapadões, BRS 132, CD 202, Embrapa 48 and BRS 134, totaling six combinations. For each cross, six plants of each parental and three F2 lines derived from individual F1 plants (each one with 40 plants) were planted at greenhouse conditions arranged in a Completely Randomized Design. The plants were pulverized 20 days after sowing, with a suspension obtained after washing infected leaves. Two evaluations were made, determining the infection level on leaves according to a diagrammatic scale. The line BRI98-641 showed only traces of the disease, where the varieties showed different levels of susceptibility. The goodness of fit between the theoretical expected proportion and the observed proportion for resistant and susceptible F2 plants was performed by chi-square test. Segregation pattern of three resistant to one susceptible was accepted for all crosses, indicating that a single dominant gene determine the resistance. The presence of plants in the F2 generation more susceptible than the susceptible parental observed in all crosses, shows that the resistant gene from the line is placed in a different locus in relation to the genes expressing partial resistance for the varieties. Later assessments on the cross BRI98-641 x Embrapa 48, permitted to separate homozygous and heterozygous resistant genotypes, facilitating the breeding.
Categoria do assunto: | --
Registro original: | Embrapa Soja (CNPSO)
Exemplares: | CNPSO - (23702-1) - UMT - PL - -- - RF 633.34072 - W927a -  - DIS