RESUMO
Eucalyptus urophylla is an important species in the Brazilian forest sector due to its rapid growth rates and resistance to disease. The aim of this study was to verify Mendelian inheritance, genetic linkage, and genotypic disequilibrium for 15 microsatellite loci, with the goal of producing a robust set of genetic markers. Mendelian inheritance and genetic linkage analyses were carried out using genotypes from maternal trees, and their open-pollinated seeds and genotypic disequilibrium were assessed using adult trees. By comparing heterozygous maternal genotypes and their seeds, we found no significant deviations from the expected 1:1 Mendelian segregation and the expected 1:1:1:1 segregation hypothesis for pairwise loci. For adult trees, we did not find strong evidence of genotypic imbalance for pairwise loci. Our results indicated that the analyzed set of microsatellite loci could be used to carry out analyses of genetic diversity, mating system, and parentage in E. urophylla.
Assuntos
Eucalyptus/genética , Desequilíbrio de Ligação , Repetições de Microssatélites , Frequência do Gene , Genótipo , Polimorfismo GenéticoRESUMO
Cariniana estrellensis is one of the largest trees found in Brazilian tropical forests. The species is typical of advanced stages of succession, characteristic of climax forests, and essential in genetic conservation and environmental restoration plans. In this study, we assessed Mendelian inheritance, genetic linkage, and genotypic disequilibrium in nine microsatellite loci for a C. estrellensis population. We sampled and genotyped 285 adult trees and collected seeds from 20 trees in a fragmented forest landscape in Brazil. Based on maternal genotypes and their seeds, we found no deviation from the expected 1:1 Mendelian segregation and no genetic linkage between pairwise loci. However, for adults, genotypic disequilibrium was detected for four pairs of loci, suggesting that this result was not caused by genetic linkage. Based on these results, we analyzed microsatellite loci that are suitable for use in population genetic studies assessing genetic diversity, mating system, and gene flow in C. estrellensis populations.
Assuntos
Lecythidaceae/genética , Desequilíbrio de Ligação , Repetições de Microssatélites , Brasil , Florestas , Fluxo Gênico , Genótipo , Sementes/genéticaRESUMO
Hymenaea stigonocarpa is a deciduous and monoecious Neotropical tree species pollinated by bats. Due to overexploitation and habitat destruction, the population size has drastically diminished in nature. No previous study has investigated Mendelian inheritance, linkage, and genotypic disequilibrium in the available microsatellite markers in this species. So, our aim was to estimate these parameters using six microsatellite loci in a sample of 470 adults and 219 juveniles from two populations of H. stigonocarpa. In addition, 30 seeds per tree from 35 seed-trees were collected. Each seed was kept record of the seed-trees and fruit origin. Based on the six microsatellite loci, we found that only 10.6% of the cases showed significant deviations from Mendelian segregation and 15.3% showed linkage. We detected no evidence of genotypic disequilibrium between the loci in the adult trees or juveniles. Thus, our results suggest that these loci can be used with great accuracy in future genetic analyses of H. stigonocarpa populations.
Assuntos
Fabaceae/genética , Repetições de Microssatélites , Evolução Molecular , Genes de Plantas , Loci Gênicos , Genótipo , Desequilíbrio de LigaçãoRESUMO
Genipa americana is a tropical tree species that is widely distributed in the humid tropical and subtropical regions of Central and South America. This study investigated Mendelian inheritance, genetic linkage, and genotypic disequilibrium at six microsatellite loci developed for G. americana. Adult trees (188) and regenerants (163) were sampled and genotyped in a fragmented population of the species. We also genotyped open-pollinated seeds from 12 seed-trees during reproductive events in 2010 and 2011. Significant deviations from the expected 1:1 Mendelian segregation were detected in 29.5% of the tests. Significant genetic linkage between pairwise loci was detected in 54.4% of the tests, but no genotypic disequilibrium was detected between pairwise loci for adult trees and regenerants. Overall, the results indicate that the six loci analyzed may be used in studies of G. americana's genetic diversity and structure, its mating system, and in parentage analyses.