Genetic diversity of Brazil nut tree (Bertholletia excelsa Bonpl.) in southern Brazilian Amazon

Abstract

Understanding genetic diversity is the basis of the evolutionary process of any species, as there are mechanisms that increase or reduce genetic variation. Brazil nut (Bertholletia excelsa Bonpl.) occurs in the Amazon region, and is included in the list of endangered species, justifying the importance of this study for the species. This study hypothesized that genetic diversity among individuals collected at different locations in the Amazon (between groups) is greater than genetic diversity between individuals from the same location (within groups). We aimed to study the genetic diversity of four populations of B. excelsa, located in native forests in the Amazon region of the state of Mato Grosso. DNAs were collected from 50 adult trees at each four sites, which were evaluated by seven microsatellite molecular markers (loci Bex06, Bet15, Bet14, Bex09 and Bet16). Genetic diversity of four Brazil nut tree populations collected in the Amazon region were assessed by microsatellite molecular markers. Brazil nut tree revealed to have greater genetic diversity between population than within in individuals in each population, suggesting that seed collection considering a larger number of matrices between a population than within populations is a more effective strategy. The most genetically distant populations were Itaúba and Juína, and Itaúba and Cotriguaçu, showing a relationship with geographical distance and also with differences found in fruit and seed characteristics already reported in other studies evaluating such populations. The findings of this study contribute to the establishment of the species breeding strategies that, in turn, ensure the maintenance and preservation of the genetic diversity of Brazil nut tree in southern Brazilian Amazon.