基于18S rDNA、rbcL和atpB序列的轮藻科植物的系统发育研究

Phylogeny of characeae based on 18S rDNA, rbcL and atpB gene sequences

为找到适宜用于轮藻科植物系统发育研究的分子片段,对本研究所选轮藻进行18S rDNA、rbcL、atpB及18S rDNA-rbcL-atpB三基因联合序列的多样性分析,并通过构建系统进化树的方法,开展系统发育研究.结果表明,18S rDNA序列较适宜用于研究轮藻科下两个族和各属间的分类问题,但进一步对属内轮藻进行分类需要借助变异程度更高的序列;rbcL、atpB序列变异程度高于18S rDNA序列,但两者不适宜单独用于轮藻科植物的系统发育研究;三基因联合序列的种间、种内遗传距离有一定差异,种间遗传距离(0.002~0.097)大于种内遗传距离(0~0.001),且所得进化树的拓扑结构与传统形态学分类结构一致,属内轮藻分类不再混乱,进化树呈现良好的拓扑结构.综上所述,18S rDNA-rbcL-atpB三基因联合分析后可将形态近似的轮藻分开,解决本研究选取的轮藻科植物的分类问题.

In order to find a suitable molecular marker for the classification of Charophytes, some of the Charophytes were used as material to make a phylogenetic study by analyzing the diversity of 18 S rDNA、rbcL、atpB and 18 S rDNA-rbcL-atpB three-gene combination and constructing the phylogenetic tree. The results showed that 18 S rDNA gene was more suitable for the study of the classification between the genus and tribus, but further classification requires a more mutated sequences;though the rbcL and atpB sequences were more mutated than the 18 S rDNA, they were not suitable for phylogenetic study of Characeae alone. There were some gaps in the interspecific and intraspecific genetic distance of the three gene combination analysis, and the interspecific genetic distance(0.002~0.097) was greater than intraspecific genetic distance(0~0.001). Meanwhile, the topological structure of the phylogenetic tree analyzed by three gene combination sequences was consistent with the traditional morphological classification structure, and the ambiguity of Chara classification was resolved in genus and tribus, the phylogenetic tree appeared a good topologic structure. In the summary, the 18 S rDNA-rbcL-atpB three-gene combination sequences analysis can separate some similar species of the Charophytes, and solve the classification problem of the Charophytes species selected in this study.