Nguyen Nhu H, Driscoll Heather E, Specht Chelsea D
Department of Plant and Microbial Biology, University of California, Berkeley, 111 Koshland Hall, MC 3102, Berkeley, CA 94720, USA.
Mol Phylogenet Evol. 2008 Jun;47(3):1157-72. doi: 10.1016/j.ympev.2007.12.006. Epub 2007 Dec 15.
Nuclear ribosomal DNA (ITS and ETS) sequences from 39 native Californian (USA) Allium species and congeners were combined with 154 ITS sequences available on GenBank to develop a global Allium phylogeny with the simultaneous goals of investigating the evolutionary history (monophyly) of Allium in the Californian center of diversity and exploring patterns of adaptation to serpentine soils. Phylogenies constructed with ITS alone or ITS in combination with ETS provided sufficient resolution for investigating evolutionary relationships among species. The ITS region alone was sufficient to resolve the deeper relationships in North American species. Addition of a second marker (ETS) further supports the phylogenetic placements of the North American species and adds resolution within subgenus Amerallium, a clade containing many Californian endemics. Within the global phylogeny, the native North American species were found to be monophyletic, with the exception of Allium tricoccum and Allium schoenoprasum. All native Californian species included in the analysis fell into a monophyletic subgenus Amerallium section Lophioprason, although endemic Californian species were not monophyletic due to the inclusion of species with ranges extending beyond the California Floristic Province. The molecular phylogeny strongly supports previous morphology-based taxonomic groupings. Based on our results, serpentine adaptation appears to have occurred multiple times within section Lophioprason, while the ancestor of the Californian center of diversity may not have been serpentine-adapted.
来自美国加利福尼亚州39种本土葱属植物及其同属植物的核糖体DNA（ITS和ETS）序列，与GenBank上可获得的154条ITS序列相结合，构建了一个全球葱属植物系统发育树，同时旨在研究加利福尼亚州多样性中心葱属植物的进化历史（单系性），并探索对蛇纹岩土的适应模式。单独使用ITS或ITS与ETS组合构建的系统发育树，为研究物种间的进化关系提供了足够的分辨率。仅ITS区域就足以解析北美物种之间更深层次的关系。添加第二个标记（ETS）进一步支持了北美物种的系统发育定位，并增加了美洲葱亚属（包含许多加利福尼亚特有种的一个分支）内的分辨率。在全球系统发育树中，发现北美本土物种是单系的，但葱和细香葱除外。分析中纳入的所有加利福尼亚本土物种都属于美洲葱亚属的Lophioprason组，尽管由于纳入了分布范围超出加利福尼亚植物区系省的物种，加利福尼亚特有物种并非单系。分子系统发育强烈支持先前基于形态学的分类分组。根据我们的结果，蛇纹岩适应似乎在Lophioprason组内多次发生，而加利福尼亚多样性中心的祖先可能并未适应蛇纹岩环境。
