Caracterização genética de uma população base do programa de melhoramento de cana-de-açúcar da Ridesa/UFG

• Autor(a) principal: Carneiro, Karla da Silva
• Data de Publicação: 2017
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da UFG
• Texto Completo: http://repositorio.bc.ufg.br/tede/handle/tede/9028
• topic: Saccharum; Diversidade genética; Marcador molecular; Divergência genética; SNP; Saccharum; Genetic diversity; Molecular marker; SNP; GENETICA::GENETICA VEGETAL

In Brazil, the history of sugarcane is related to the social, economic and politic country development. Sugarcane cultivation is considered as the first organized economic activity in the country. The main purpose of sugarcane cultivation is for sugar and biofuel production, but in recent years the energy production from its biomass has also been explored, increasing the attention for this crop. Modern cultivated sugarcane varieties are hybrids from interspecific crosses between S. officinarum and S. spontaneum. The genetic breeding has given many contributions to sugarcane production and exploration, by the development of superior genotypes. The main sources of variability used in breeding programs are the germplasm banks. However, to explore these resources efficiently it is necessary to have basic information on the available levels of genetic diversity and on its structure, to support decisions on how they can be used in breeding programs. The purpose of this work was to characterize the genetic diversity and structure of a base population from the Ridesa/UFG sugarcane breeding program. A sample of 160 sugarcane clones were genotyped using 37,914 SNP markers. The population showed medium levels of genetic diversity. The average Nei’s gene diversity index was estimated to be 0,173, while the medium observed heterozygosity was a little higher (0,236). The genetic divergence, estimated by Roger’s modified distance varied from 0,20 to 0,30. SNP markers were efficient to identify individuals that are genetic divergent or similar, even without genealogy information. The population structure analysis, performed with the software Structure, suggested the existence of two clusters. Each clone had a fraction of its genome inside these two clusters, corroborating the fact that modern sugarcane cultivars are essentially hybrids. Our results suggest that, given the low level of genetic structure among clones, from the breeding programs standpoint, the evaluated population can be managed as weakly structured, although some small groups, including a small number of clones, had been detected. Among the evaluated clones, the least divergent pairs were those formed by the genotypes 023 and 011, and 066 and 036. The most divergent pairs were formed by the clones 131 and 084, and 131 and 063.