Resistência de genótipos de alface ao míldio
Lettuce (Lactuca sativa L.) is among the leafy vegetables, the most important economically for Brazil. In winter, low temperatures and high humidity, the lettuce downy mildew, a disease caused by etiological agent Bremia lactucae Regel, occurs in all regions of the world where lettuce is grown, whic...
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| Tipo de recurso: | tesis de maestría |
| Estado: | Versión publicada |
| Fecha de publicación: | 2010 |
| País: | Brasil |
| Institución: | Universidade Federal de Lavras (UFLA) |
| Repositorio: | Repositório Institucional da UFLA |
| Idioma: | portugués |
| OAI Identifier: | oai:repositorio.ufla.br:1/4115 |
| Acceso en línea: | https://repositorio.ufla.br/handle/1/4115 |
| Access Level: | acceso abierto |
| Palabra clave: | CNPQ_NÃO_INFORMADO Lactuca sativa L. Bremia lactucae Regel Ambiente controlado Melhoramento de plantas Resistência genética |
| Sumario: | Lettuce (Lactuca sativa L.) is among the leafy vegetables, the most important economically for Brazil. In winter, low temperatures and high humidity, the lettuce downy mildew, a disease caused by etiological agent Bremia lactucae Regel, occurs in all regions of the world where lettuce is grown, which is considered one of the most severe foliar disease of lettuce . The acquisition of resistant cultivars is the main alternative to control the disease. To collect information which should assist in driving improvement program, were conducted two research activities. At first, the objective was to evaluate the resistance reaction to downy mildew (B. lactucae) in ten genotypes of lettuce. For this, nine genotypes were used as cultivars (‘Colorado’ ‘Raider Plus’, ‘Veronica’, ‘Rubete’, ‘Elisa’, ‘Salinas 88’, ‘Grand Rapids’, ‘Regina 71’ and ‘Hortência’) and one line (AFX-020A-06). The trial was conducted in a germination chamber BOD, and the genotypes sown in seedling boxes on blotting paper moistened with distilled water. Fifteen days after sowing the inoculation was made, using as inoculum sporangia washed from infected tissues of susceptible cultivar 'Solaris', at a concentration of 5x104 sporangium.mL1. Evaluation for resistance to downy mildew was recorded 15 days after inoculation, verifying the presence or absence of symptoms and sporulation of each seedling. The experimental design was completely randomized design with three replications. Seedlings of cultivars Colorado Raider Plus, Rubete and showed resistance to B. lactucae. The low percentage of healthy seedlings found in the cultivars Veronica, Elisa, Salinas 88, Grand Rapids, Regina 71 and Hortencia and the line AFX-020A-06 shows the susceptibility of these genotypes to the pathogen B. lactucae. In the second activity, the objective was to confirm the mode of inheritance of resistance to downy mildew (B. lactucae) isolated MGLA-01, derived from crosses between contrasting materials for this character, in order to select genotypes resistant and better adapted the soil and climatic conditions of southern Minas Gerais. It was used in the hybridization two contrasting parents, the resistant strain B. lactucae AFL-008 and the susceptible cultivar Salinas 88, both from American Type The trial was conducted in a germination chamber type "BOD", and in the greenhouse, and resistance tests performed on gerbox paper kills Blot dampened with distilled water. Fifteen days after inoculation were sown in the maternal and paternal parents, the F1, F2 and population control in tough, using as inoculums the sporangia washed from infected tissues at a concentration of 1x105 sporangium.mL-1. Evaluation for resistance to downy mildew was recorded 15 days after inoculation, verifying the presence or absence of symptoms and sporulation of each seedling. Was made an analysis of variance to test the data. The experimental design was completely randomized design with three replications. For data analysis, the response variable used was the number of healthy plants. For the study of inheritance, we performed a significance test Chi-square (χ2) in population F2. In genetic control of resistance to Bremia lactucae Regel, the causal agent of lettuce downy mildew, the gene shows allelic interaction of dominance. For the control of resistance are present one or a few closely linked genes, with dominant allele conferring resistance. |
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