Análise de diversidade genética em populações de Campomanesia adamantium (Cambess.) O. Berg (Myrtaceae) por meio de marcadores microssatélites transferíveis

Abstract

Campomanesia adamantium O. Berg (Myrtaceae), known as guavira or gabiroba, is an endemic plant of the Cerrado biome. It has potential of production due to the use of its fruits in culinary and its medicinal properties. Genetic diversity studies using molecular markers with this species are still scarce, but necessary to provide the basis for conservation and breeding programs. In this context, this work was carried out to investigate the genetic variability of five populations of C. adamantium through EST-derived microsatellite markers transferred from Eucalyptus. Leaf samples were collected from 167 individuals from five populations located in DouradosMS, Bonito-MS, Ponta Porã-MS, Jardim-MS, in Brazil and in Cerro Corá, Paraguay. The DNA was extracted and then PCR was performed with seven microsatellite markers (Embra1335, 1076, 1470, 1364, 1363, 1374, 1811). After genotyping on ABI3500 automatic sequencer, analysis of genetic diversity and population structure were carried out. All seven loci were polymorphic (9 alleles on average) and 61 alleles were detected with size ranging 197-396 bp. All populations showed high levels of allelic richness and genetic diversity. The population of Bonito showed greater genetic variability, while the population of Dourados showed less variability. Since populations had low level of inbreeding, the deviations from the HardyWeinberg equilibrium in the loci may have been caused by gene flow from other nearby populations, which also contributes to the high genetic diversity. The high heterozygosity found may be related to the greater vigor of heterozygotes, which provides adaptability to the environmental conditions of Cerrado. A low level of interpopulational differentiation was detected (FST=0.028) due to alleles being shared, and populations that were geographically closest were more similar genetically. This indicates occurrence of high gene flow possibly by stepping stone patterns or isolation by distance, supported by the wide distribution, density and frequency of the species and its stable dispersion patterns mediated by pollinators and animals. Thus, the conservation and collection of germplasm of guavira populations becomes important to preserve their high genetic variability, which in addition to being important for the survival of the species, can serve as a source for selection of superior genotypes in breeding programs.