Nedelcu Aurora M, Borza Tudor, Lee Robert W
Mol Biol Evol. 2006 May;23(5):1011-5. doi: 10.1093/molbev/msj108. Epub 2006 Feb 13.
The search for the unicellular relative of Streptophyta (i.e., land plants and their closest green algal relatives, the charophytes) started many years ago and remained centered around the scaly green flagellate, Mesostigma viride. To date, despite numerous studies, the phylogenetic position of Mesostigma is still debated and the nature of the unicellular ancestor of Streptophyta remains unknown. As molecular phylogenetic studies have produced conflicting results, we constructed a M. viride expressed sequence tags library and searched for sequences that are shared between M. viride and the Streptophyta (to the exclusion of the other green algal lineages--the Chlorophyta). Here, we report a multigene family that is restricted to Streptophyta and M. viride. The phylogenetic distribution of this complex character and its potential involvement in the evolution of an important land plant adaptive trait (i.e., three-dimensional tissues) argue that Mesostigma is a close unicellular relative of Streptophyta.
对链形植物（即陆地植物及其最亲近的绿藻亲属轮藻）单细胞近亲的探寻始于多年前，且一直围绕着有鳞片的绿色鞭毛虫——绿中缢虫展开。时至今日，尽管已有大量研究，但中缢虫的系统发育位置仍存在争议，链形植物单细胞祖先的本质也依然未知。由于分子系统发育研究得出了相互矛盾的结果，我们构建了一个绿中缢虫表达序列标签文库，并寻找绿中缢虫与链形植物（不包括其他绿藻谱系——绿藻纲）共有的序列。在此，我们报告了一个仅限于链形植物和绿中缢虫的多基因家族。这一复杂特征的系统发育分布及其在一种重要陆地植物适应性性状（即三维组织）进化中的潜在作用表明，中缢虫是链形植物的单细胞近亲。
