东亚鼠尾草属（唇形科，筋骨草亚科）的系统发育和雄蕊演化。
Phylogeny and staminal evolution of Salvia (Lamiaceae, Nepetoideae) in East Asia.
机构信息
Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, Yunnan, China.
College of Life Sciences, Guizhou University, Guiyang, Guizhou, China.
出版信息
Ann Bot. 2018 Sep 24;122(4):649-668. doi: 10.1093/aob/mcy104.
BACKGROUND AND AIMS
Salvia is the largest genus within Lamiaceae, with about 980 species currently recognized. East Asia, with approx. 100 species, is one of the three major biodiversity centres of Salvia. However, relationships within this lineage remain unclear, and the staminal lever mechanism, which may represent a key innovation within the genus, has been understudied. By using six genetic markers and nearly comprehensive taxon sampling, this study attempts to elucidate relationships and examine evolutionary trends of staminal development within the East Asia (EA) Salvia clade.
METHODS
Ninety-one taxa of EA Salvia were sampled and 34 taxa representing all other major lineages of Salvia were included for analysis. Two nuclear [internal transcribed spacer (ITS) and external transcribed spacer (ETS)] and four chloroplast (psbA-trnH, ycf1-rps15, trnL-trnF and rbcL) DNA markers were used for phylogenetic analysis employing maximum parsimony (MP), maximum likelihood (ML) and BEAST, with the latter also used to estimate divergence times.
KEY RESULTS
All Salvia species native to East Asia form a clade, and eight major subclades (A-G) were recognized. Subclade A, comprising two limestone endemics (S. sonchifolia and S. petrophila), is sister to the remainder of EA Salvia. Six distinct stamen types were observed within the EA clade. Stamen type A, with two fully fertile posterior thecae, only occurs in S. sonchifolia and may represent the ancestral stamen type within EA Salvia. Divergence time estimates showed that the crown of EA Salvia began to diversify approx. 17.4 million years ago.
CONCLUSIONS
This study supports the adoption of a broadly defined Salvia and treats EA Salvia as a subgenus, Glutinaria, recognizing eight sections within this subgenus. Stamen type A is ostensibly plesiomorphic within EA Salvia, and the other five types may have been derived from it. Staminal morphology has evolved in parallel within the EA Salvia, and staminal structure alone is inadequate to delimit infrageneric categories.
背景与目的
鼠尾草是唇形科中最大的属，目前约有 980 种。东亚拥有约 100 种，是鼠尾草的三个主要生物多样性中心之一。然而，该谱系内的关系仍不清楚，雄蕊杠杆机制可能是该属的一个关键创新，研究还不够充分。本研究通过使用 6 个遗传标记和近乎全面的分类群采样，试图阐明东亚（EA）鼠尾草分支内的关系，并研究雄蕊发育的进化趋势。
方法
本研究共采样了 91 种东亚鼠尾草，并包括代表鼠尾草所有其他主要谱系的 34 种进行分析。使用两个核（内转录间隔区（ITS）和外转录间隔区（ETS））和四个叶绿体（psbA-trnH、ycf1-rps15、trnL-trnF 和 rbcL）DNA 标记进行最大简约法（MP）、最大似然法（ML）和 BEAST 分析，后者也用于估计分歧时间。
主要结果
所有原产于东亚的鼠尾草形成一个分支，识别出 8 个主要的亚分支（A-G）。亚分支 A 由两种石灰岩特有种（S. sonchifolia 和 S. petrophila）组成，与东亚鼠尾草的其余部分形成姐妹关系。在东亚分支内观察到六种不同的雄蕊类型。只有在 S. sonchifolia 中才出现的 A 型雄蕊，具有两个完全可育的后药室，可能代表东亚鼠尾草内的祖始雄蕊类型。分歧时间估计表明，东亚鼠尾草的冠部约在 1740 万年前开始多样化。
结论
本研究支持采用广义的鼠尾草概念，并将东亚鼠尾草视为一个亚属，即 Glutinaria，在这个亚属中识别出 8 个节。A 型雄蕊在东亚鼠尾草中显然是原始的，其他五种类型可能是从它衍生而来的。雄蕊形态在东亚鼠尾草内平行进化，仅雄蕊结构不足以划分种下类别。
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