A Molecular Analysis of Origin and Early Evolution of Angiosperms

为了阐明被子植物的系统发育和早期进化，本文基于atpB和rbcL基因序列进行了系统发育分析。作为被子植物中具有代表性的分支，本文选取了厚朴属、波斯属、山茱萸属、烟叶属和稻谷属。在最近的分子研究中被认为是被子植物中最原始的谱系（Chase et al. 1993）的角藻门也在研究范围内。对于一个外群，选择松来生根。基于rbcL序列得到的系统发育树与基于atpB序列得到的系统发育树拓扑结构不同。在这两棵树中，角藻叶都没有长到基部。这些树也不同于基于rbcL基因的被子植物系统发育全局分析的结果（Chase et al.）。为了阐明置信限，对两个数据集进行了自举分析。因此，这些树的置信度相当低，表明缺乏足够的信息。为了获得更多的信息，我们将rbcL和atpB两个数据集连接起来进行分析。结果得到拓扑结构为(((（Nymphaea, Ceratophyllum, Nicotiana, Magnolia, Persea, Oryza）的树。然而，对这棵树的信心还不够，需要更多的其他基因的信息来阐明系统发育。

To clarify a phylogeny and early evolution of angiosperms, phylogenetic analysis based on atpB and rbcL gene sequence was done. For representative of some clades in angiopserms, Magnolia, Persea, Nymphaea, Nicotian and Oryza were selected for the study. Ceratophyllum which was considered as most primitive lineage of angiosperms in recet molecular study (Chase et al. 1993) is also included in the study. For an outgroup Pinus thunbergii was sclccted for rooting a tree.The phylogenetic tree obtained based on rbcL sequences and that based on atpB have different topology each other. In both tree, Ceratophyllum did not come to a basal position. These trees are also different from the result of global analysis of angiosperm phylogeny based on rbcL gene (Chase et al.). For elucidate confidence limit, bootstrap alaysis was performed in both data set. As a result confidence of these trees were rather low, indicating lack of enough information. For using more information, two data sets, rbcL and atpB,were connected and analysis. As a result the tree with a topology ((((Nymphaea, Ceratophyllum) , Nicotiana), (Magnolia, Persea)) , Oryza) was obtained. However, confidence of this tree is also not enough and need more information of other genes to clarify the phylogeny.