Desenvolvimento de marcadores microssatélites e estrutura genética de Hancornia speciosa Gomes (Apocynaceae)

• Autor(a) principal: Rodrigues, Andreia Juliana Leite
• Data de Publicação: 2009
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Repositório Institucional da UFG
• Texto Completo: http://repositorio.bc.ufg.br/tede/handle/tede/8445
• topic: Mangaba; Microssatélite; Estrutura genética; Cerrado; Genetic structure; SILVICULTURA::GENETICA E MELHORAMENTO FLORESTAL

The objective of this work was to construct primers from the development of libraries enriched with microsatellite loci and to evaluate the magnitude and spatial distribution of genetic variability in natural populations of H. speciosa do Cerrado. Locals containing microsatellite regions were isolated and sequenced, which resulted in the design of 74 primer pairs. Of these, 35 were selected for synthesis and optimization of PCR amplification. All the synthesized primers amplified, with annealing temperature ranging from 48° C to 64° C. The primers were tested on 35 genotypes of mangabeira originating from different geographic areas. The 35 individuals were also grouped into four populations according to the botanical variety they belong to (H. s. Var. Speciosa, H. s.var. cuyabensis, H. s.var. gardneri, H. s.var. pubescens). Six pairs of primers were selected for analysis of 162 progenies belonging to the EA / UFG germplasm collection. The developed markers were considered highly informative, with high index of polymorphism and represent a suitable tool to be used in genetic structure studies of natural populations. A high number of alleles per locus were observed. The progenies evaluated had a high polymorphism index. The value obtained for ‘He’ was high, which is indicative of high genetic diversity. The value obtained for the fixation index (f) was positive and high and suggests a relatively high rate of inbreeding in the studied populations. The estimated value of FST, considering each geographical area as a subpopulation, was 0.19. This parameter is indicative of the genetic divergence among the subpopulations, which suggests a high level of differentiation and corroborates the hypothesis of restriction to the gene flow. The NST parameter, similar to the FST, but considering the size of the alleles, provided a considerably higher value, which reinforces the great diversity among the subpopulations of the Cerrado mangrove. Nei was also observed to group the populations in a random manner, regardless of the geographic distance, which indicates that there is no structuring in the geographic space of the genetic variability among the populations. An absence of correlation between genetic distances and geographic distances was observed, which confirms the random distribution of genotypes for this study, reinforcing the hypothesis of restriction to gene flow, even at short distances. When considering the botanical varieties as different populations, an estimate of 0.0583 was observed for the FST statistic and the estimated NST was 0.11738, which again indicates the greater sensitivity of this parameter to detect divergence between populations. A genetic structure analysis was carried out in pairs between the botanical varieties and from the genetic distances obtained, measured by the parameter NST, it was possible to observe a greater similarity between H. s. var. gardneri and H. s. var. pubescens which was expected to be sympatric in its occurrence. The H. s. var. cuyabensis was the most divergent in relation to the others. The fact that the population of Japonvar-MG did not cluster with H. s. var. speciosa, corroborates the hypothesis that this belongs to another botanical variety, which should be further investigated.