The desiccation-tolerant shrub Myrothamnus flabellifolia has colonised a unique and harsh niche that provides little protection from the elements. It has a wide distribution range in southern Africa, occurring across an environmental gradient that is exceptionally arid in the southwest and highly mesic in the northeast. It is also harvested for use in medicinal preparations, both traditionally and commercially. However, the phytochemical variability of plants from different rainfall regions has not been assessed, nor have the intraspecific relationships been evaluated by means of a rigorously tested phylogeny. The aims of the present study were thus (1) to test a phylogenetic hypothesis for intraspecific relationships in M. flabellifolia; (2) to assess, based on the global metabolomic profiles, whether accessions collected from the three different geographic locations in southern Africa across a rainfall gradient can be differentiated, and if this corroborates the phylogenetic signature; and (3) with the aid of multivariate statistical analysis, identify and evaluate the most significant discriminatory metabolites between the three sampled regions that could act as potential barcodes. The results show that the phylogenetic and metabolomic signatures were congruent, and the metabolomic data were better able to discriminate the different populations collected from the three regions. Several potential barcodes for discriminating the material from the three regions are proposed. Quercetin-rhamnoside and 3-O-methylquercetin, both significant antioxidants, were present at significantly higher quantities in the material from the driest region in the west than from the more mesic regions in the south and east, whereas quercetin-3-O-glucuronide was significantly higher in the latter. A naringenin-like compound or arbutin derivative could discriminate the southern samples from the eastern samples, whereas digalloylglucose differentiated the eastern samples from the southern samples. In summary, the findings of this study imply that the origin of the material should be considered when used in medicinal and cosmetic preparations.

中文翻译：

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代谢组学作为系统发育学的补充，用于评估耐干燥药用灌木 Myrothamnus flabellifolia（Myrothamnaceae）的种内边界

耐干燥的灌木 Myrothamnus flabellifolia 已经定居在一个独特而严酷的生态位上，几乎没有提供任何保护。它在南部非洲有广泛的分布范围，跨越一个环境梯度，在西南地区异常干旱，在东北地区高度中等。它也被收获用于传统和商业上的药物制剂。然而，尚未评估来自不同降雨区域的植物的植物化学变异性，也没有通过严格测试的系统发育来评估种内关系。因此，本研究的目的是 (1) 检验 M. flabellifolia 种内关系的系统发育假设；(2) 根据全球代谢组学概况评估，是否可以区分从南部非洲三个不同地理位置收集的种质跨越降雨梯度，以及这是否证实了系统发育特征；(3) 在多变量统计分析的帮助下，识别和评估三个采样区域之间可以作为潜在条形码的最显着的区分代谢物。结果表明，系统发育和代谢组学特征是一致的，代谢组学数据能够更好地区分从三个区域收集的不同种群。提出了几种用于区分来自三个区域的材料的潜在条形码。槲皮素-鼠李糖苷和 3-O-甲基槲皮素，都是重要的抗氧化剂，来自西部最干燥地区的材料中存在的数量明显高于南部和东部较中等的地区，而后者的槲皮素-3-O-葡萄糖苷酸明显更高。柚皮素样化合物或熊果苷衍生物可以区分南部样品和东部样品，而二没食子糖可以区分东部样品和南部样品。总之，本研究的结果表明，在用于药物和化妆品制剂时应考虑该材料的来源。而二没食子糖将东部样品与南部样品区分开来。总之，本研究的结果表明，在用于药物和化妆品制剂时应考虑该材料的来源。而二没食子糖将东部样品与南部样品区分开来。总之，本研究的结果表明，在用于药物和化妆品制剂时应考虑该材料的来源。