Diversidade genética, estrutura populacional e mapeamento associativo em Coffea canephora

• Autor(a) principal: Souza, Flávio de França
• Data de Publicação: 2011
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/1331
• topic: Café Robusta; Germoplasma; Desequilíbrio de ligação; Robusta coffee; Germplasm; Linkage disequilibrium; CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::FITOTECNIA::MELHORAMENTO VEGETAL

Marker-assisted selection (MAS) is a technique potentially able to aid in Coffea canephora breeding. However, its usefulness depends on the precise identification of molecular markers linked to agronomic traits. Nowadays, the search for these markers has been done through linkage mapping, which includes the development of controlled populations and, generally, results on low-resolution frames. Recently, association mapping methodology, based on linkage disequilibrium, emerged as an alternative to obtain linked markers through high-resolution mapping in natural populations. This work aimed to study the genetic diversity, population structure and linkage disequilibrium in Brazilian germplasm of C. canephora, in order to implement association mapping technique. We used accession collections representative of the germplasm either grown on commercial plantations or conserved in research institutions in São Paulo, Espírito Santo, Minas Gerais and Rondônia. Phenotypic evaluations were performed at the Experimental Station of Empresa Brasileira de Pesquisa Agropecuária (Embrapa), at Ouro Preto do Oeste, Rondônia. The accessions were genotyped at the Laboratório de Biotecnologia do Cafeeiro (Biocafé), in the Universidade Federal de Viçosa, at Viçosa, Minas Gerais. First genetic diversity analysis and population structure were performed using a set of 20 microsatellites. Subsequently, the collection with greater diversity, less structured and with smaller level of relatedness among individuals was genotyped with a set of 77 microsatellites. We evaluated the linkage disequilibrium and the occurrence of associations among molecular markers and phenotypic traits of interest for breeding. The germplasm showed a considerable genetic diversity. There was a strong structure, mainly due to evolutionary processes prior to domestication of the species. Evidence of sub-structure promoted by recent events was also observed. The varietal groups Robusta and Conilon presented quite divergent. Into Conilon cluster, remarkable differentiation was observed between the samples of Rondônia and Espírito Santo. In most populations, linkage disequilibrium was low. Evidences of association among some microsatellite and phenotypic traits were obtained. This study increased the knowledge about Brazilian C. canephora germplasm, providing to breeders and gene bank curators, subsidies for augmenting the efficiency of breeding programs and to a better management of genetic resources of the species. We also presented important considerations regarding the potential use of mapping association in this germplasm.