GENETIC DIVERSITY AND STRUCTURE OF MACAW PALM: IMPLICATIONS FOR GENETIC VARIABILITY SAMPLING

ABSTRACT The macaw palm, Acrocomia aculeata (Jacq.) Lodd. ex Mart., is a Brazilian native species with great potential for biofuel production. The aim of this work was to analyze macaw palm genetic diversity to structure and assist in the definition of sampling strategies for germplasm banks. Forty-six microsatellite markers, from which seven polymorphic markers were used to evaluate 103 macaw palm individuals collected from different Brazilian locations. The polymorphic markers were used to generate a dissimilarity matrix by weighted index. The imaging of genetic variability was realized by 3D projection of matrix dissimilarity. Sixty-seven individuals had their ITS region sequenced and aligned, and the mutations found were used to generate a haplotype network. The average genetic distance identified between individuals was 76.2%, ranging from 3.7 to 100%. Genetic variability structure was not found. ITS region sequencing of the 67 individuals revealed four polymorphic sites, defining four haplotypes. The results of this study suggest that historically, macaw populations were strongly connected, indicating a recent population expansion of the species. The results indicate that macaw genetic variety sampling should focus on effective collection in selected locations. Areas such as Caatinga and Humid Chaco however, could present new sources of genetic variability, and should be studied.

摘要
金刚鹦鹉棕榈 (Acrocomia aculeata (Jacq.) Lodd. ex Mart.) 是巴西本土物种，具备极高的生物燃料生产潜力。本研究旨在分析金刚鹦鹉棕榈的遗传多样性，以构建种群遗传结构，并为种质资源库的采样策略制定提供依据。
本研究共使用46个微卫星标记 (microsatellite markers)，其中7个多态性标记 (polymorphic markers) 用于评估采自巴西不同地区的103株金刚鹦鹉棕榈个体。利用该组多态性标记，通过加权指数法构建相异矩阵 (dissimilarity matrix)，并通过对该相异矩阵进行三维投影实现遗传变异的可视化。
此外，本研究对67个个体的ITS序列 (Internal Transcribed Spacer) 进行了测序与序列比对，将检测到的变异位点用于构建单倍型网络 (haplotype network)。分析结果显示，个体间的平均遗传距离为76.2%，取值范围为3.7%至100%，且未检测到明显的遗传变异结构。
对67个个体的ITS序列测序结果显示存在4个多态性位点，共定义出4种单倍型。本研究结果表明，金刚鹦鹉棕榈种群在历史上具有较强的基因交流水平，暗示该物种近期发生过种群扩张事件。
研究结果提示，金刚鹦鹉棕榈的遗传多样性采样应优先在选定区域开展高效种质收集。不过，卡廷加 (Caatinga) 与湿润查科 (Humid Chaco) 等区域可能存在未被发掘的遗传变异资源，有待进一步研究。