Caracterização genética e morfoagronômica de germoplasma de Stylosanthes guianensis (Aubl.) Sw.

• Autor(a) principal: KARIA, Cláudio Takao
• Data de Publicação: 2008
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Repositório Institucional da UFG
• Texto Completo: http://repositorio.bc.ufg.br/tede/handle/tde/436
• topic: recursos genéticos; leguminosa; forrageira tropical; estilosantes; marcador SSR; microssatélite; 1. Genética vegetal Recurso de germoplasma 2. Plantas Me- lhoramento genético 3.Melhoramento genético vegetal 4. Germo- plasma vegetal Recursos Utilização 5. Leguminosa 6. Plantas forrageir; genetic resources; legume; tropical forage; stylo; SSR marker; microsatellite; CNPQ::CIENCIAS AGRARIAS::RECURSOS FLORESTAIS E ENGENHARIA FLORESTAL::SILVICULTURA::GENETICA E MELHORAMENTO FLORESTAL

Plant genetic resources maintained ex situ, in germplasm banks, are few used in agricultural systems and genetic plant breeding programs. One of the main reasons of this incipient use is the difficulty to obtain information about stored accessions, especially the characterization and preliminary evaluation data. Stylosanthes guianensis is a predominantly self-pollinated and diploid species, which has a great number of this stored accessions and potential for use in agricultural systems. There are approximately one thousand accessions of the S. guianensis in Embrapa‟s germplasm bank. Moreover, only one genotype of this species is now available to commercial growers in Brazil, the cultivar Mineirão. To promote the use of these resources, this study aimed to characterize accessions of S. guianensis, stored in the germplasm bank of Embrapa, using morpho-agronomic traits and microstellites markers (SSR). In morpho-agronomic characterization 535 accessions were evaluated using 23 quantitative traits. The data were analyzed by a principal component analysis (PCA), the Ward's agglomerative hierarchical clustering method, and by univariate analysis of variance, associated to a Tukey test for comparisons among means of the established groups. Thirteen similarity accession groups were established, five of them were considered the ones with the highest potential use in agricultural systems. Regarding these potential groups, it is possible to reduce from 535 to 126 accessions to be thoroughly evaluated. The molecular characterization was made in 437 accessions, using seven microsatellites fluorescent primers, and the detection of the DNA fragments generated by PCR (Polimerase Chain Reaction) was accomplished by a capillary electrophoresis. The seven loci provided 45 alleles (6.43 alleles/locus), of which four were private alleles. Both, principal coordinates analysis and cluster analysis, in this case, by UPGMA agglomerative method, showed a tendency to group accessions together by botanical varieties (canescens, guianensis and pauciflora), except for the microcephala variety. The correlation between the genetic and morpho-agronomic dissimilarities was highly significant, however, it was of low magnitude (r = 0.23, P ≤ 0.0001). This indicates that both evaluations are important and should be performed to achieve a more complete characterization of these accessions and, possibly, of the species. Taking account the germplasm accessions with agronomic potential, selected based on the morpho-agronomic evaluation, several of them presented significant genetic dissimilarities to the Mineirão cultivar. These accessions should be better assessed for agronomic traits, and crossed with this cultivar in breeding programs of the species. The results of this research will allow increasing the efficiency and effectiveness of the germplasm bank activities, helping the choice of genotypes to be tested in agronomic evaluations, and stimulating further researches with these genetic resources.