Desempenho de familias do cruzamento entre linhagens de feijões andinos e mesoamericanos em produtividade e resistência a Phaeoisariopsis griseola

Abstract

No Estado de Minas Gerais, tem sido constatado que as raças fisiológicas prevalecentes de Phaeiosariopsis griseola (Sacc.) Ferr. infectam predominantemente os feijões mesoamericanos. Os feijões andinos normalmente apresentam boa resistência. A introdução de alelos de resistência de cultivares andinas em cultivares mesoamericanas é uma boa estratégia na obtenção de cultivares adaptadas e resistentes a esse patógeno. Com esse objetivo foi realizado o cruzamento entre a linhagem ESAL 550 (grupo andino e resistente à mancha angular) x Carioca-MG (grupo mesoamericano e suscetível à mancha angular). Após a avaliação das famílias segregantes nas gerações F2:3, F2:4 e F2:5, foram selecionadas linhagens que associavam bom nível de resistência à P. griseola e grãos creme com rajas marrons porém, nenhum deles em condições de ter aceitação comercial.

Research Article Genetic diversity as an additional selection criterion in a carioca common bean recurrent selection program for resistance to common bacterial blight

“…Nevertheless, its causal agent has wide genetic variability, which can contribute to an increase in experimental coefficient of variation. Results of coefficient of variation for anthracnose and angular leaf spot similar to these were obtained in studies in field screening trials performed by Bruzi et al (2007), Couto et al (2008), and Pereira et al (2012). For resistance to CBB, there was predominance of experiments with coefficient of variation lower than 20%, similar to that found by Theodoro (2004).…”

Allele frequency and selection efficiency in cross populations of Andean x Mesoamerican common beans (Phaseolus vulgaris L. Fabales, Fabaceae)

“…These loci formed gene pools that persisted for a long time but when Andean and Mesoamerican P. vulgaris are crossed these favorable combinations are undone and, normally, the performance and the adaptation of the progenies are inferior to either one of the parents. This has been confirmed in some situations (Johnson and Gepts, 2002;Bruzi et al, 2007) and Moreto et al (2007) has reported that epistasis is a factor in the control of grain yield in populations of the cross BRS-Radiante x CMG, same cross as was used by us. These considerations explain why the success in the hybridizations involving Andean x Mesoamerican P. vulgaris has been so small, although the parents are normally very divergent.…”

“…Andean and Mesoamerican P. vulgaris crosses are normally incompatible (i.e., F 1 generation plants do not grow or produce no descendants), this being genetically controlled by two genes with double recessive epistasis (Shii et al, 1980). But even when crosses are viable, the performance of the segregating population is not good, with the progeny normally showing worse performance than either of the parents (Johnson and Gepts, 1999;Johnson and Gepts, 2002;Bruzi et al, 2007). A possible explanation for this is that during evolution P. vulgaris from these two domestication centers developed gene pools and/or epistatic combinations that are disrupted in crosses between P. vulgaris plants from these two regions, thus reducing the adaptation.…”

Non-parametric approach to the study of phenotypic stability

“…Ten genotypes were evaluated in 20 environments, and incomplete block trials with three replicates were used (Bruzi et al, 2007). All of the methods used to study phenotypic stability were implemented in the R program.…”