Mating system in a natural population of Theobroma grandiflorum (Willd. ex Spreng.) Schum., by microsatellite markers.

• Autor(a) principal: ALVES, R. M.
• Data de Publicação: 2003
• Outros Autores: ARTERO, A. S., SEBBENN, A. M., FIGUEIRA, A.
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Institucional da EMBRAPA (Repository Open Access to Scientific Information from EMBRAPA - Alice)
• Texto Completo: http://www.alice.cnptia.embrapa.br/alice/handle/doc/406930
• topic: População natural; Conservação de germoplasma; Nova Ipixuna; Pará; Brasil; Cupuaçu; Genética; Amazonia

The aim of this research was to study the mating system of a natural population of Theobroma grandiflorum (cupuassu) from Nova Ipixuna, Pará state, using microsatellite markers. Eight polymorphic microsatellite loci were analyzed in eight families, each represented by 10 six-month old seedlings derived from open-pollinated pods. The estimation for the multilocus outcrossing rate ($tm= 1.0) and individual outcrossing rate ($t= 1.0) for this population suggests that T. grandiflorum may be a perfect outbreeding (allogamous) species. Likewise, for the studied population the estimate for single locus outcrossing rate ($ts) was elevated (0.946), but lower than $tm, confirming the likely outcrossing character of the species and suggesting the occurrence of 5.4% biparental inbreeding rate ($tm-$ts). The estimation of genetic divergence ($FST) between allelic frequencies in ovules and pollen revealed a deviation from random mating in 75% of the evaluated loci. Likewise, the estimate of correlation of paternity ($rp= 0.930) and the mean coefficient of co-ancestrality within families ($?xy= 0.501) indicated that the outcrossings were predominantly correlated, and the offspring were full-sibs. These results suggested that for this particular population of T. grandiflorum, the sampling strategy for genetic conservation and breeding should adopt specific models for families derived from correlated outcrossing (full-sibs) and not the ones usually adopted in classic outcrossing species breeding programs (half-sibs).