Reação de resistência ao míldio e seleção de genótipos nacionais resistentes em população F2 de alface americana

Abstract

In this study, we tried to confirm the inheritance mode of resistance to downy mildew (B. lactucae) MGLA-01 isolated by crossing among contrasting materials for this character, in order to select resistant genotypes and better adapted ones to the ecological conditions of southern Minas Gerais. It was used in hybridization, two contrasting parents the lineage AFL-008 (resistant to B. lactucae) and cultivar Salinas 88 (susceptible to B. lactucae) both american-type materials. The trial was conducted in a germination chamber type BOD and in the greenhouse. Fifteen days after sowing, inoculation was made in the maternal and paternal parents, F1 generation, the F2 population and witness tough, using as inoculum the washed infected tissues sporangium at a concentration of 1x105 sporangium.mL-1. The evaluation for resistance to downy mildew was held 15 days after inoculation. The experimental design was completely random with three replications. For data analysis we used as a response variable the number of healthy plants. For the inheritance study, we made a significance test Chisquare in the F2 population. In genetic resistance control to Bremia lactucae Regel, the causal agent of lettuce downy mildew, the gene shows allelic interaction of dominance, with dominant allele which confers resistance mildew.