16SrRNA及rpoC1基因用于螺旋藻、节旋藻系统发育的比较

Phylogenetic comparison between Spirulina and Arthrospira based on 16S rRNA and rpoC1 gene

摘要:

[目的] 利用16S rRNA和rpoC1基因分子标记研究螺旋藻、节旋藻的系统发育关系,并对其区分能力进行比较。[方法] 以84株螺旋藻、节旋藻为研究对象,对其进行16S rRNA、rpoC1基因序列的扩增、测序及分析,并对构建的系统发育树进行对比。[结果] rpoC1基因序列保守位点所占比例49.7%、平均G+C百分含量47.7%和序列相似度76%-100%明显低于16S rRNA基因序列的79.4%、55.6%和91%- 100%,其变异程度高于16S rRNA基因;基于16S rRNA、rpoC1基因构建的系统发育NJ树拓扑结构基本一致,84株实验藻株分为2个属3个类群,其中仅F-351、F-904-2、F-1070和TJBC14-1藻株为螺旋藻,其余均为节旋藻;虽然2个基因都不能区分形态种和地理种,但rpoC1基因NJ树的置信度(100%)高于16S rRNA基因(99%),属内分群效果也明显优于16S rRNA基因。[结论] 支持了螺旋藻、节旋藻为两个不同属的结论,且在属内分类时rpoC1基因比16S rRNA基因具有更高的区分度。

Abstract:

[Objective] Based on 16S rRNA and rpoC1 gene sequences, the phylogenetic relationship between Spirulina and Arthrospira were studied and compared. [Methods] We amplified, sequenced and analyzed 16S rRNA and rpoC1 of 84 strains. Then the phylogenetic trees were constructed and compared. [Results] The conserved sites percentage, average G+C content and sequence identity of rpoC1 were 49.7%, 47.7%, 76%-100% respectively, significantly lower than 79.4%, 55.6% and 91%-100% of 16S rRNA, and the heterogeneity degree was higher. The trees generated with two different genes showed similar topologies and thus inferred consistent phylogenetic relationships. Eighty-four experimental strains were divided into 3 groups belonging to 2 genera: F-351, F-904-2, F-1070 and TJBC14 were Spirulina and the rest were Arthrospira. Although morphospecies and geographical species could not be distinguished based on 16S rRNA and rpoC1 gene sequences, the bootstrap value of rpoC1 (100%) was higher than that of 16S rRNA (99%). Moreover, clustering effect of rpoC1 for Spirulina and Arthrospirai was better than 16S rRNA. [Conclusion] Spirulina and Arthrospira were different genera, rpoC1 gene has more advantage to distinguish the strains in the same genus than that of 16S rRNA gene.