Royal Botanic Gardens, Kew, TW9 3AE, UK.
Gothenburg Global Biodiversity Centre, Department of Biological and Environmental Sciences, University of Gothenburg, Gothenburg, 405 30, Sweden.
Am J Bot. 2021 Jul;108(7):1143-1165. doi: 10.1002/ajb2.1697. Epub 2021 Jul 13.
Comprising five families that vastly differ in species richness-ranging from Gelsemiaceae with 13 species to the Rubiaceae with 13,775 species-members of the Gentianales are often among the most species-rich and abundant plants in tropical forests. Despite considerable phylogenetic work within particular families and genera, several alternative topologies for family-level relationships within Gentianales have been presented in previous studies.
Here we present a phylogenomic analysis based on nuclear genes targeted by the Angiosperms353 probe set for approximately 150 species, representing all families and approximately 85% of the formally recognized tribes. We were able to retrieve partial plastomes from off-target reads for most taxa and infer phylogenetic trees for comparison with the nuclear-derived trees.
We recovered high support for over 80% of all nodes. The plastid and nuclear data are largely in agreement, except for some weakly to moderately supported relationships. We discuss the implications of our results for the order's classification, highlighting points of increased support for previously uncertain relationships. Rubiaceae is sister to a clade comprising (Gentianaceae + Gelsemiaceae) + (Apocynaceae + Loganiaceae).
The higher-level phylogenetic relationships within Gentianales are confidently resolved. In contrast to recent studies, our results support the division of Rubiaceae into two subfamilies: Cinchonoideae and Rubioideae. We do not formally recognize Coptosapelteae and Luculieae within any particular subfamily but treat them as incertae sedis. Our framework paves the way for further work on the phylogenetics, biogeography, morphological evolution, and macroecology of this important group of flowering plants.
包含五个在物种丰富度上差异极大的科，从包含 13 个物种的茄科到包含 13775 个物种的茜草科，玄参目植物通常是热带森林中物种最丰富和最多的植物之一。尽管在特定的科和属内进行了相当多的系统发育研究，但以前的研究提出了玄参目科级关系的几种替代拓扑结构。
在这里，我们基于针对被子植物 353 探针组靶向的核基因，对约 150 个物种进行了基因组分析，这些物种代表了所有科和大约 85%的正式承认的族。我们能够从大多数分类单元的非靶向读取中检索到部分质体基因组，并推断出系统发育树，以便与核衍生的树进行比较。
我们对超过 80%的所有节点都得到了高度支持。质体和核数据基本一致，除了一些支持较弱到中等的关系。我们讨论了我们的结果对该目分类的影响，强调了以前不确定关系的支持点增加。茜草科与一个分支（玄参科+茄科）+（夹竹桃科+萝藦科）相对。
玄参目内的高级系统发育关系得到了可靠的解决。与最近的研究相反，我们的结果支持将茜草科分为两个亚科：茜草亚科和Rubioideae。我们没有正式将 Coptosapelteae 和 Luculieae 归入任何特定的亚科，但将它们视为不确定的位置。我们的框架为进一步研究这个重要的开花植物类群的系统发育、生物地理学、形态进化和宏观生态学铺平了道路。
