Search Results (2)

Platonia insignis is a fruit tree native to Brazil of increasing economic importance, with its pulp trading among the highest market values. This study aimed to evaluate the structure and genomic diversity of P. insignis (bacurizeiro) accessions from six locations in the Brazilian States of Roraima, Amazonas, Pará (Amazon biome), and Maranhão (Cerrado biome). A total of 2031 SNP markers were obtained using genotyping-by-sequencing (GBS), from which 625 outlier SNPs were identified. High genetic structure was observed, with most of the genetic variability (59%) concentrated among locations, mainly between biomes (Amazon and Cerrado). A positive and significant correlation (r = 0.85; p < 0.005) was detected between genetic and geographic distances, indicating isolation by distance. The highest genetic diversity was observed for the location in the Cerrado biome (H_E = 0.1746; H_O = 0.2078). The locations in the Amazon biome showed low genetic diversity indexes with significant levels of inbreeding. The advance of urban areas, events of burning, and expansion of agricultural activities are most probably the main factors for the genetic diversity reduction of P. insignis. Approaches to functional analysis showed that most of the outlier loci found may be related to genes involved in cellular and metabolic processes. Full article

Molecular analyses are providing new elements to decipher the origin, domestication and dispersal of native Amazonian crops in an expanding archaeological context. Solid molecular data are available for manioc (Manihot esculenta), cacao (Theobroma cacao), pineapple (Ananas comosus), peach palm (Bactris gasipaes) and guaraná (Paullinia cupana), while hot peppers (Capsicum spp.), inga (Inga edulis), Brazil nut (Bertholletia excelsa) and cupuassu (Theobroma grandiflorum) are being studied. Emergent patterns include the relationships among domestication, antiquity (terminal Pleistocene to early Holocene), origin in the periphery, ample pre-Columbian dispersal and clear phylogeographic population structure for manioc, pineapple, peach palm and, perhaps, Capsicum peppers. Cacao represents the special case of an Amazonian species possibly brought into domestication in Mesoamerica, but close scrutiny of molecular data suggests that it may also have some incipiently domesticated populations in Amazonia. Another pattern includes the relationships among species with incipiently domesticated populations or very recently domesticated populations, rapid pre- or post-conquest dispersal and lack of phylogeographic population structure, e.g., Brazil nut, cupuassu and guaraná. These patterns contrast the peripheral origin of most species with domesticated populations with the subsequent concentration of their genetic resources in the center of the basin, along the major white water rivers where high pre-conquest population densities developed. Additional molecular genetic analyses on these and other species will allow better examination of these processes and will enable us to relate them to other historical ecological patterns in Amazonia. Full article