Molecular and ecological evidence for species specificity and coevolution in a group of marine algal-bacterial symbioses
Molecular and ecological evidence for species specificity and coevolution in a group of marine algal-bacterial symbioses
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DOI：
10.1128/aem.66.7.3024-3030.2000
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发表时间：
2000-07-01
影响因子：
4.4
通讯作者：
Goff, LJ
中科院分区：
文献类型：
--
作者：
Ashen, JB;Goff, LJ
从16 S rDNA序列分析推断的细菌共生体的系统发育关系的海洋红藻属Prionitis（红藻）的三个胆轴承种，并与主机的系统发育也推断从序列比较（核核糖体内部转录间隔区）。先前已经在两种Prionitis，P. lanceolata（来自加州中部）和P. decipiens（来自秘鲁）上描述了瘿的形成。本次调查报告的第三个相关的主机，Prionitis filiformis虫瘿形成。基于序列比较的系统发育分析将该细菌作为变形菌门（Proteobacteria）或变形菌门（Proteobacteria）亚类的Roseobacterium分组内的单一谱系（在变形菌门类型之间的序列同一性为99.4%至98.25%）。共生体和宿主分子的同源性比较证实了三个胆轴承藻类谱系的存在，并与这些红色海藻和它们的细菌共生体共同进化的假设是一致的。这些协会的物种特异性进行了研究，在自然界中的全细胞杂交的瘿菌和在实验室中使用交叉接种试验。全细胞原位杂交证实，一个单一的细菌共生菌的类型是存在于每一个主机的虫瘿。在实验室试验中，细菌共生体不能在替代宿主（包括两种不含虫瘿的物种）上诱导虫瘿。Prionitis胆汁形成中的共生体-宿主特异性表明这些密切相关的共生体之间的有效生态分离，并提供了一个生物背景下考虑16 S rDNA序列变异的器官意义的例子。
The phylogenetic relationships of bacterial symbionts from three gall-bearing species in the marine red algal genus Prionitis (Rhodophyta) were inferred from 16S rDNA sequence analysis and compared to host phylogeny also inferred from sequence comparisons (nuclear ribosomal internal-transcribed-spacer region). Gall formation has been described previously on two species of Prionitis, P. lanceolata (from central California) and P. decipiens (from Peru). This investigation reports gall formation on a third related host, Prionitis filiformis. Phylogenetic analyses based on sequence comparisons place the bacteria as a single lineage within the Roseobacter grouping of the or subclass of the division Proteobacteria (99.4 to 98.25% sequence identity among phylotypes). Comparison of symbiont and host molecular phylogenies confirms the presence of three gall-bearing algal lineages and is consistent with the hypothesis that these red seaweeds and their bacterial symbionts are coevolving. The species specificity of these associations was investigated in nature by whole-cell hybridization of gall bacteria and in the laboratory by using cross-inoculation trials. Whole-cell in situ hybridization confirmed that a single bacterial symbiont phylotype is present in galls on each host. In laboratory trials, bacterial symbionts were incapable of inducing galls on alternate hosts (including two non-gall-bearing species). Symbiont-host specificity in Prionitis gall formation indicates an effective ecological separation between these closely related symbiont phylotypes and provides an example of a biological context in which to consider the organismic significance of 16S rDNA sequence variation.