基于rpoC1基因的微囊藻属分子系统学研究

测定了广东省9个水库4株铜绿微囊藻Microcystis aeruginosa、5株水华微囊藻M.flos-aquae和4株未定种微囊藻rpoC1基因部分序列,结合GenBank下载的日本5个水体11株铜绿微囊藻、5株绿色微囊藻M.viridis和5株惠氏微囊藻M.wesenbergii间源序列,进行序列分析.结果显示,34株微囊藻存在21种基因型,序列相似性达97.6%～100%.在邻接树上不同形态种和不同地理来源的藻株混杂在一起,没有形成明显的谱系结构和地理结构:同一形态种藻株可能具有不同的基因型,而相同基因型的藻株可能是不同的形态种;从同一水体中分离的微囊藻具有不同的形态种和不同的基因型,而不同水体分离的微囊藻有时又具有相同基因型,表明rpoC1基因序列无法区分形态种和地理株,支持Kondo和Otsuka提出的暂将铜绿微囊藻、水华微囊藻、惠氏微囊藻和绿色微囊藻等归为铜绿微囊藻复合种的分类处理.

Phylogenetic relationships of Microcystis based on rpoC1 gene sequences in China

Partial rpoC1 gene sequences of 4 strains of Microcystis aeruginosa, 5 strains of M.flos-aquae and 4 strains of M.sp. collected from 9 reservoirs in Guangdong province, China were determined and subjected to phylogenetic analysis by a combination of homologous GenBank sequences of 11 strains of M.aeruginosa, 5 strains of M.viridis and 5 strains of M.wesenbergii in 5 Japanese water bodies. In total, 21 genotype were found and the sequence similarities ranged from 97.6% to 100% in 34 Microcystis strains. The strains of different 'morphospecies' and geographic origins were intertwined together in the derived neighbor-joining tree, indicating no obvious lineages or geographic clusters. The same 'morphospecies' included different genotypes, and the same genotype exhibited different phenotypes. The strains isolated from the same water body had various genotypes or phenotypes, and strains from different water body shared the same genotype or genotype. These results demonstrated that different 'morphospecies' and geographic strains couldn't be differentiated by partial rpoC1 gene sequences, temporally support Kondo and Otsuka's proposal to treat M.aeruginosa, Mflos-aquae, Mwesenbergii and M.viridus icrocystis as M.aerugnose complex.