Correlações, análise de trilha e diversidade fenotípica e molecular em soja

• Ano de defesa: 2011
• Autor(a) principal: Nogueira, Ana Paula Oliveira
• Orientador(a): Sediyama, Tuneo
• Banca de defesa: Pereira, Derval Gomes , Sediyama, Maria Aparecida Nogueira
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Doutorado em Genética e Melhoramento
• Departamento: Genética animal; Genética molecular e de microrganismos; Genética quantitativa; Genética vegetal; Me
• País: BR
• Palavras-chave em Português: Glycine max L. Merrill; Fenótipo; Genótipo; Características agronômicas; Marcadores microssatélites
• Palavras-chave em Inglês: Glycine max L. Merrill; Phenotype; Genotype; Agronomic features; Microsatellite markers
• Área do conhecimento CNPq: CNPQ::CIENCIAS AGRARIAS::AGRONOMIA
• Link de acesso: http://locus.ufv.br/handle/123456789/1333

Soybean is one the economically most important grain producing plants. It is known that the genetic base of Brazilian soybeans is narrow and the study of genetic diversity provides important information for genetic breeding. During the selection process it is desirable to simultaneously improve several characters. Thus information about correlation and path analysis contribute for the elaboration of selection strategies. This study analyzed the correlations between traits, as well as its partitioning by path analysis considering as the principal character grain production; evaluated the genetic diversity in soybean based on phenotypical traits and microsatellite markers. Experiments were done in greenhouse and in the laboratory. The first one involved 90 soybean genotypes, grown in two sowing dates as randomized blocks with 3 repetitions. Qualitative and quantitative traits were evaluated. The laboratory experiment evaluated the 41 most productive soybean cultivars and mostly grown in different regions of Brazil, using 40 microsatellite markers. The studies of phenotypical and genotypical correlations, and the path analysis identified the total number of pods per plant, independently of sowing date, as the greatest favorable effect on soybean grain production. Sowing date affected the expression of agronomic traits and, consequently, the estimates of phenotypical, genotypical and environment correlations. Uni and multivariate analyses were used for the phenotypical traits. Significant differences were observed at 1% probability for all characters analyzed. Based on Mahalanobis' generalized distance (D2) high divergence among the genotypes studied was observed. In February sowing, D2 varied from 4.38 to 458.68, while smaller range was observed for December sowing, varying from 2.62 to 362.46. The traits with greatest contribution for genetic dissimilarity were number of days for maturity, plant height at maturity and above ground dry matter. The methods of Tocher and UPGMA presented similarity in the grouping pattern. Around 50% of the 90 genotypes analyzed constituted one single group belonging to the region of adaptation to the Middle West. The generated groupings allowed the identification of the diverging parents for the crossings. Among the 40 microsatellites loci, 2 were monomorphic and 38 markers amplified 131 alleles, oscillating between 2 and 5 alleles per locus, with an average of 3.45. The index weighted by the number of alleles was adopted to estimate the dissimilarity among the 41 cultivars. This, in turn, varied between 0.26 and 0.80 with average of 0.57. Dissimilarity distribution between the 41 genotype pairs comprehended 75% between the distances of 0.5 and 0.69. Making a cut at about 87% dissimilarity, the formation of 12 groups with distinct number of cultivars was observed. There were similarities between the methodologies of UPGMA and Tocher on the constitution of the groups. The use of microsatellite molecular markers allowed the detection of significant genetic variability in elite cultivars, indicating that there still is useful genetic variability for soybean breeding in Brazil.