Fast and novel botanical exploration of a 320-km transect in eastern Amazonia using DNA barcoding

ABSTRACT We explored a 320-km transect in the Tumucumaque mountain range along the border between southern French Guiana and Brazil, sampling all trees and lianas with DBH ≥ 10 cm in seven 25 x 25-m plots installed near seven boundary milestones. We isolated DNA from cambium tissue and sequenced two DNA barcodes (rbcLa and matK) to aid in species identification. We also collected fertile herbarium specimens from other species (trees/shrubs/herbs) inside and outside the plots. The selected DNA barcodes were useful at the family level but failed to identify specimens at the species level. Based on DNA barcoding identification, the most abundant families in the plots were Burseraceae, Fabaceae, Meliaceae, Moraceae, Myristicaceae and Sapotaceae. One third of the images of sampled plants posted on the iNaturalist website were identified by the community to species level. New approaches, including the sequencing of the ITS region and fast evolving DNA plastid regions, remain to be tested for their utility in the identification of specimens at lower taxonomic levels in floristic inventories in the Amazon region.

摘要
我们在法属圭亚那南部与巴西交界的图穆库马克山脉开展了一条总长320公里的样带调查，在7个设于界碑附近的25×25米样地内，对所有胸径(DBH)≥10厘米的乔木和藤本进行了系统采样。我们从形成层组织中提取脱氧核糖核酸（DNA），并对两个DNA条形码（DNA barcodes，rbcLa与matK）进行测序，以辅助物种鉴定。此外，我们还从样地内外的其他物种（乔木/灌木/草本）中采集了带有繁殖结构的蜡叶标本。
所选DNA条形码在科级分类阶元的识别中表现良好，但无法实现物种水平的标本鉴定。基于DNA条形码鉴定结果，样地内物种丰富度最高的科依次为橄榄科（Burseraceae）、豆科（Fabaceae）、楝科（Meliaceae）、桑科（Moraceae）、肉豆蔻科（Myristicaceae）以及山榄科（Sapotaceae）。
上传至iNaturalist平台的采样植物图像中，有三分之一被该社区用户鉴定至物种水平。包括内转录间隔区（ITS）测序和快速进化的DNA质体区域测序在内的新方法，其在亚马逊地区植物区系调查中用于低分类阶元标本鉴定的实用性仍有待验证。