Phycoerythrin evolution and diversification of spectral phenotype in marine Synechococcus and related picocyanobacteria
Phycoerythrin evolution and diversification of spectral phenotype in marine Synechococcus and related picocyanobacteria
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DOI：
10.1016/j.ympev.2012.04.013
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发表时间：
2012-09-01
影响因子：
4.1
通讯作者：
Wood, A. Michelle
中科院分区：
文献类型：
--
作者：
Everroad, R. Craig;Wood, A. Michelle
在海洋聚球藻中，有证据表明主要捕光色素藻红蛋白(PE)的光谱不同形式的适应性进化。最近的研究表明，这些谱型的PE具有与核心基因组不同的进化历史。然而，由于缺乏对可供选择的假说或这些基因的选择的明确的统计检验，使得很难评估PE谱型之间的进化关系或水平基因转移(HGT)在海洋聚球藻色素系统的适应性表型进化中所起的作用。在这项工作中，构建了具有已知光谱表型的微囊藻的PE系统发育，包括来自墨西哥湾的新分离的海洋聚球藻，以更全面地探索这一群体的光谱表型多样性和PE进化。首次对匹克蓝细菌PE基因座的竞争性进化假说和正选择检验进行了统计评估。与特定PE光谱表型相关的PE基因在PE树中形成了强有力的单系支系，正向选择驱动进化向更高的植物香豆素(PUB)含量进化。经鉴定为蓝藻的蓝藻谱系中含有PE的海洋微囊藻中存在缺乏pub的表型，这可以用HGT从海洋聚球藻归入这一组来解释。综上所述，这些数据提供了通过突变、正向选择和水平基因转移在细菌中对单一表型性状进行适应性进化的强有力的例子。(C)2012 Elsevier Inc.保留所有权利。
In marine Synechococcus there is evidence for the adaptive evolution of spectrally distinct forms of the major light harvesting pigment phycoerythrin (PE). Recent research has suggested that these spectral forms of PE have a different evolutionary history than the core genome. However, a lack of explicit statistical testing of alternative hypotheses or for selection on these genes has made it difficult to evaluate the evolutionary relationships between spectral forms of PE or the role horizontal gene transfer (HGT) may have had in the adaptive phenotypic evolution of the pigment system in marine Synechococcus. In this work, PE phylogenies of picocyanobacteria with known spectral phenotypes, including newly co-isolated strains of marine Synechococcus from the Gulf of Mexico, were constructed to explore the diversification of spectral phenotype and PE evolution in this group more completely. For the first time, statistical evaluation of competing evolutionary hypotheses and tests for positive selection on the PE locus in picocyanobacteria were performed. Genes for PEs associated with specific PE spectral phenotypes formed strongly supported monophyletic clades within the PE tree with positive directional selection driving evolution towards higher phycourobilin (PUB) content. The presence of the PUB-lacking phenotype in PE-containing marine picocyanobacteria from cyanobacterial lineages identified as Cyanobium is best explained by HGT into this group from marine Synechococcus. Taken together, these data provide strong examples of adaptive evolution of a single phenotypic trait in bacteria via mutation, positive directional selection and horizontal gene transfer. (C) 2012 Elsevier Inc. All rights reserved.