Neves Susana S, Watson Mark F
Royal Botanic Garden Edinburgh, 20A Inverleith Row, Edinburgh EH3 5LR, UK.
Ann Bot. 2004 Apr;93(4):379-98. doi: 10.1093/aob/mch052. Epub 2004 Feb 23.
The genus Bupleurum has long been recognized as a natural group, but its infrageneric classification is controversial and has not yet been studied in the light of sequence data.
Phylogenetic relationships among 32 species (35 taxa) of the genus Bupleurum were investigated by comparative sequencing of the ITS region of the 18-26S nuclear ribosomal DNA repeat. Exemplar taxa from all currently accepted sections and subsections of the genus were included, along with outgroups from four other early branching Apioideae genera (Anginon, Heteromorpha, Physospermum and Pleurospermum).
Phylogenies generated by maximum parsimony, maximum likelihood, and neighbour-joining methods show similar topologies, demonstrating monophyly of Bupleurum and the division of the genus into two major clades. This division is also supported by analysis of the 5.8S coding sequence alone. The first branching clade is formed by all the species of the genus with pinnate-reticulate veined leaves and B. rigidum with a unique type of leaf venation. The other major clade includes the remaining species studied, all of which have more or less parallel-veined leaves.
These phylogenetic results do not agree with any previous classifications of the genus. Molecular data also suggest that the endemic Macaronesian species B. salicifolium is a neoendemic, as the sequence divergence between the populations in Madeira and Canary Islands, and closer mainland relatives in north-west Africa is small. All endemic north-west African taxa are included in a single unresolved but well-supported clade, and the low nucleotide variation of ITS suggests a recent radiation within this group. The only southern hemisphere species, B. mundii (southern Africa), is shown to be a neoendemic, apparently closely related to B. falcatum, a Eurasian species.
柴胡属长期以来被视为一个自然类群，但其属下分类存在争议，且尚未依据序列数据进行研究。
通过对18 - 26S核糖体DNA重复序列的ITS区域进行比较测序，研究了柴胡属32个物种（35个分类单元）之间的系统发育关系。纳入了该属目前所有被认可的组和亚组的代表性分类单元，以及其他四个早期分支的芹亚科属（Anginon、Heteromorpha、Physospermum和Pleurospermum）的外类群。
由最大简约法、最大似然法和邻接法生成的系统发育树显示出相似的拓扑结构，表明柴胡属为单系类群，且该属分为两个主要分支。这一划分也得到了单独对5.8S编码序列分析的支持。第一个分支由该属所有具羽状网脉叶的物种以及具独特叶脉类型的硬柴胡组成。另一个主要分支包括其余所研究的物种，它们都或多或少具平行叶脉。
这些系统发育结果与该属之前的任何分类都不一致。分子数据还表明，马卡罗尼西亚特有种柳叶柴胡是一个新特有种，因为马德拉群岛和加那利群岛的种群与西北非更近的大陆近缘种之间的序列差异很小。所有西北非特有分类单元都包含在一个未解决但得到有力支持的单分支中，ITS的低核苷酸变异表明该类群近期发生了辐射分化。唯一的南半球物种芒迪柴胡（南非）被证明是一个新特有种，显然与欧亚物种镰叶柴胡关系密切。
