Phenotypic variability and phylogenetic relationships of the genera Tolypothrix and Calothrix (Nostocales, Cyanobacteria) from running water
Phenotypic variability and phylogenetic relationships of the genera Tolypothrix and Calothrix (Nostocales, Cyanobacteria) from running water
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DOI：
10.1099/ijs.0.027581-0
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发表时间：
2011-12-01
影响因子：
2.8
通讯作者：
Mateo, Pilar
中科院分区：
文献类型：
--
作者：
Berrendero, Esther;Perona, Elvira;Mateo, Pilar
异囊蓝藻属（Calothrix属和toolypothrix属）的分类问题一直存在争议，但它们的系统发育关系仍未得到很好的理解。我们的目的是比较这些属的成员的系统发育和形态，它们表现出基部-顶端极性。基于16S rRNA基因序列重建了系统发育，并与新分离株和环境样本的形态特征进行了比较。从几条河流和溪流中分离出来的菌株在富营养培养基中培养时显示出高度的锥形。然而，当他们转移到营养不良的培养基时，明显的差异是明显的。部分菌株表现出较低的变细程度和假分枝等形态特征，而其他菌株则保持了牛刺属的形态特征。系统发育分析结果与表型特征一致，可以明显地将毒株与环境样品分离开来。低锥度的分离株和自然样本被归为同一聚类，而牛角蓟马属的菌株则被划分为很好的分支。本研究结果表明，红毛蓟属的代表具有大部分形态和发育特征，并且具有高度的16S rRNA基因序列相似性。然而，尽管相似的，有时重叠的形态可能发生在葛蓟属的分离物，这些形态类型可以根据其明确的遗传分化来区分。
The taxonomy of heterocystous cyanobacteria belonging to the genera Calothrix and Tolypothrix has long been a matter of debate, but their phylogenetic relationships are still not well understood. Our aim was to compare the phylogeny and morphology of members of these genera, which exhibit basal-apical polarity. A phylogeny was reconstructed on the basis of 16S rRNA gene sequences and compared with the morphological characterization of new isolates and environmental samples. Strains isolated from several rivers and streams showed a high degree of tapering when they were cultured in a nutrient-rich medium. However, clear differences were apparent when they were transferred to a nutrient-poor medium. Some strains showed a low degree of tapering and other morphological features corresponding to the genus Tolypothrix, such as false branching, whereas others maintained the morphological characteristics of the genus Calothrix. Phylogenetic analysis was congruent with the phenotypic characterization, in which the strains and environmental samples of the Tolypothrix and Calothrix morphotypes could be clearly separated. Isolates with a low degree of tapering and natural samples of Tolypothrix distorta were grouped in the same cluster, but strains of the genus Calothrix fell into well separated clades. Results from this study showed that representatives of the genus Tolypothrix share most morphological and developmental properties and a high degree of 16S rRNA gene sequence similarity. However, although similar and sometimes overlapping morphologies may occur in isolates of the genus Calothrix, these morphotypes may be distinguished on the basis of their clear genetic divergence.