Navegando por Autor "Corrêa, Ronan Xavier"
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Item Caracterização de linhagens endogâmicas recombinantes e mapeamento de locos de características quantitativas associados a ciclo e produtividade do feijoeiro-comum(Pesquisa Agropecuária Brasileira, 2003-12) Ragagnin, Vilmar Antônio; Moreira, Maurílio Alves; Cruz, Cosme Damião; Corrêa, Ronan Xavier; Barros, Everaldo Gonçalves de; Faleiro, Fábio Gelape; Schuster, IvanO objetivo deste trabalho foi caracterizar 154 linhagens endogâmicas recombinantes por meio da avaliação de características quantitativas, morfológicas, moleculares e de resistência a doenças e mapear locos de características quantitativas associados a ciclo e produtividade do feijoeiro-comum. Adotando o valor do limite de detecção (LOD) de 4,0 e uma freqüência máxima de recombinação de 0,40, foram mapeados 43 marcadores em nove grupos de ligação cobrindo uma distância de recombinação total de 247,8 cM. A distância entre marcadores adjacentes variou entre 0 e 28 cM, com média de 7,3 cM. Os grupos de ligação variaram em tamanho de 2,3 a 61,2 cM. Os genes de resistência à ferrugem e à antracnose ficaram localizados no mesmo grupo de ligação. Foram mapeados locos associados às oito características quantitativas estudadas, e a explicação da variância fenotípica pelos marcadores variou de 14,03% a 40,14%. Os resultados encontrados lançam bases para o desenvolvimento de mapas específicos saturados e de utilidade em programas de melhoramento do feijoeiro-comum.Item Genetic distances in soybean based on RAPD markers(Bragantia, 1999) Corrêa, Ronan Xavier; Abdelnoor, Ricardo Vilela; Faleiro, Fábio Gelape; Cruz, Cosme Damião; Moreira, Maurilio Alves; Barros, Everaldo Gonçalves DeFour methods were applied to determine pairwise genetic distances among five soybean genotypes which are potential genitors for a mapping population. Additionally, individual plants from the most divergent pair of genotypes were evaluated by the RAPD technique to determine their degree of homozygosity. Genetic distances based on RAPD data were calculated by the modified Rogers' distance, and also by the following arithmetical complements of similarity: simple match, Nei and Li, and Gower. These genetic distances were similar, presenting a correlation coefficient ranging from 0.99 to 1.00. In all four methods lines UFV 91-717 and Ichigowase were the most divergent ones (4.53 to 21.43%). DNA samples from five plants from each of the two most divergent genotypes were amplified with 28 different primers. Among the amplified products, only five were polymorphic in each group (2.10%), demonstrating their high intragroup degree of homozygosity. These homozygosity were maintained when DNA samples from 12 plants from each of the two most divergent genotypes were amplified. These parameters were extremely useful for the confirmation of the chosen pair of genitors to generate a mapping population.Item Ligação gênica da resistência à ferrugem e à antracnose na variedade de feijão ouro negro(Revista Ceres, 2000-07) Moreira, Maurílio Alves; Ragagnin, Vilmar Antônio; Corrêa, Ronan Xavier; Vinhadelli, Wender Santos; Barros, Everaldo Gonçalves de; Faleiro, Fábio GelapeA variedade Ouro Negro tem sido utilizada no Programa de Melhoramento do Feijoeiro (Phaseolus vulgaris L.) da UFV/BIOAGRO/EPAMIG como fonte de genes de resistência à ferrugem e à antracnose. Para melhor entendimento da herança e da organização desses genes de resistência, foi analisada a segregação de 231 plantas RC3F2 com relação à resistência a essas duas doenças. As plantas RC3F2, com aproximadamente 10 dias, foram inoculadas com uma mistura de uredosporos de Uromyces appendiculatus var appendiculatus coletados em diferentes municípios de Minas Gerais Após a avaliação da resistência à ferrugem, as mesmas plantas RC3F2 foram inoculadas com a raça 89 de Colletotrichum lindemuthiamun. A análise dos sintomas evidenciou que tanto a resistência à ferrugem quanto à antracnose são controladas por fatores dominantes únicos. Foi também observado que os genes de resistência à ferrugem e à antracnose presentes Ouro Negro estão ligados entre si. Para melhor entendimento da organização genômica de tais genes, estão sendo realizados, nos laboratórios do BIOAGRO-UFV, trabalhos mais detalhados envolvendo marcadores moleculares e populações segregantes adequadas.Item RAPD markers linked to a block of genes conferring rust resistance to the common bean(Genetics and Molecular Biology, 1999-09-03) Faleiro, Fábio Gelape; Vinhadelli, Wender Santos; Ragagnin, Vilmar Antonio; Corrêa, Ronan Xavier; Moreira, Maurilio Alves; Barros, Everaldo Gonçalves deRust, caused by the fungus Uromyces appendiculatus, may cause a significant loss to common bean (Phaseolus vulgaris L.) yield. RAPD markers tightly linked to the resistance genes may be used in breeding programs to aid the development of rust-resistant bean cultivars. In this sense, the objective of the present work was to identify RAPD markers linked to a rust resistance gene block present in the cultivar Ouro Negro. Two hundred and fourteen F2 individuals from a cross between the resistant cultivar Ouro Negro and the susceptible cultivar US Pinto 111 were inoculated with a mixture of eight races of U. appendiculatus. The segregation ratio obtained suggested that resistance is monogenic and dominant. Bulked segregant analysis was used in conjunction with the RAPD technique to search for markers linked to rust resistance genes. Two molecular markers flanking the rust resistance gene block were identified, one at 5.8 ± 1.6 cM (OX11630) and the other at 7.7 ± 1.7 cM (OF101,050) of the gene. Simulated indirect selection efficiency in the F2 population using the two markers was 100%. The molecular markers identified in this work are currently being used for the selection of disease-resistant plants in the commom bean breeding program of the Federal University of Viçosa.Item Sequence characterized amplified regions linked to rust resistance genes in the common bean(Crop Science, 2000-05) Corrêa, Ronan Xavier; Costa, M. R.; Good- God, P. I.; Ragagnin, V. A.; Faleiro, F. G.; Moreira, M. A.; Barros, E. G. deUromyces appendiculatus (Pers.) Unger, the causative fungus of rust in common beans (Phaseolus vulgaris L.), consists of many pathotypes or pathogenic races. Cultivar Ouro Negro is resistant to most pathotypes detected in Brazil in the last few decades. We attempted to identify molecular markers linked to a rust resistance gene block present in Ouro Negro. DNA samples extracted from homozygous near isogenic BC3F2:3 lines derived from a cross between susceptible cultivar US Pinto 111 and Ouro Negro were grouped, following greenhouse inoculations, into two contrasting bulks, one containing only resistant and the other only susceptible plants. The bulks were amplified with 605 random primers and two of them amplified bands which were heteromorphic between the two bulks. These random amplified polymorphic DNA (RAPD) bands were transformed into sequence characterized amplified regions (SCARs) SCARBA08 and SCARF10. The rust resistance–susceptibility phenotypes and the molecular genotypes with the two SCAR markers of 303 F2:3 families from US Pinto 111 × Ouro Negro were determined. SCARBA08 and SCARF10 were determined to be 4.3 ± 1.2 and 6.0 ± 1.3 centimorgans (cM) from the rust resistance locus, respectively. These markers are being used in combination with other markers for resistance to rust, anthracnose, and angular leaf spot previously identified in our laboratory to aid the indirect selection of desirable plants in segregating populations in which Ouro Negro has been used as donor parent.