Wei Lai, Xiang Xiao-Guo, Wang Yin-Zheng, Li Zhen-Yu
College of Life Sciences, Beijing Normal University, Xinjiekouwai Street, Beijing, China; State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Xiangshan, Beijing, China.
State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Xiangshan, Beijing, China.
PLoS One. 2015 Sep 2;10(9):e0137190. doi: 10.1371/journal.pone.0137190. eCollection 2015.
Ruta, which belongs to tribe Ruteae, is the type genus of the subfamily Rutoideae and the family Rutaceae. Molecular systematic studies have shown that the genera in Ruteae are closer related to Aurantioideae than to most other genera of Rutoideae, some of the genera traditionally placed in Ruteae have been shown to be nested within the Aurantioideae clade, but the diagnostic characters for determining new patterns in the relationship are poor. In this study, we investigated the floral development of Boenninghausenia in Ruteae (sensu stricto), Haplophyllum in the basal position of Aurantioideae and Murraya in traditional Aurantioideae using scanning electron microscopy. The androecium of Boenninghausenia is obdiplostemony. As androecia in other genera within Ruteae (s.s.) are also obdiplostemonous, reconstruction of the ancestral state indicates that obdiplostemony is an ancestral character in this clade. Because the androecia of Haplophyllum and Murraya are also obdiplostemonous, obdiplostemony is also an ancestral character in Aurantioideae clade. The ancestral state reconstruction indicates this character can serve as a synapomorphy of the Ruteae-Aurantioideae clade. The results of our work also shed light on the evolution of the androecium in Rutaceae, as the obdiplostemony of this group is clearly derived from haplostemony in the ancestral genera in Rutaceae and has develop into polyandry by increasing antepetalous stamens.
芸香属属于芸香族，是芸香亚科和芸香科的模式属。分子系统学研究表明，芸香族中的属与柑橘亚科的关系比与芸香亚科的大多数其他属更为密切，一些传统上置于芸香族的属已被证明嵌套在柑橘亚科分支内，但用于确定新关系模式的诊断特征并不明显。在本研究中，我们使用扫描电子显微镜研究了芸香族（狭义）中的石椒草属、柑橘亚科基部的单叶芸香属以及传统柑橘亚科中的九里香属的花发育情况。石椒草属的雄蕊群为双外轮雄蕊式。由于芸香族（狭义）内其他属的雄蕊群也是双外轮雄蕊式，祖先状态的重建表明双外轮雄蕊式是该分支的一个祖先特征。因为单叶芸香属和九里香属的雄蕊群也是双外轮雄蕊式，所以双外轮雄蕊式也是柑橘亚科分支的一个祖先特征。祖先状态重建表明这一特征可作为芸香族 - 柑橘亚科分支的一个共衍征。我们的研究结果也为芸香科雄蕊群的进化提供了线索，因为该类群的双外轮雄蕊式显然源自芸香科祖先属中的单轮雄蕊式，并通过增加对瓣雄蕊发展为多雄蕊。
