Endosymbiotic Gene Transfer in Tertiary Plastid-Containing Dinoflagellates
Endosymbiotic Gene Transfer in Tertiary Plastid-Containing Dinoflagellates
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DOI：
10.1128/ec.00299-13
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发表时间：
2014-02-01
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影响因子：
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通讯作者：
Keeling, Patrick J.
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文献类型：
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作者：
Burki, Fabien;Imanian, Behzad;Keeling, Patrick J.
质体建立涉及内共生基因转移到宿主细胞核，这一过程称为内共生基因转移（EGT）。大量的EGT不仅存在于几种光合谱系中，而且存在于当今缺乏质体的生物体中，这支持了内共生基因在宿主细胞核中留下大量遗传足迹的观点。然而，这种基因重新定位的程度仍然存在争议，主要是因为自大多数质体起源以来已经过去了很长一段时间，已经抹去了有关这一过程如何展开的许多线索。然而，在甲藻中，含有多甲素的祖先质体在最近几次被第三级质体取代，为我们提供了一个不太古老的窗口来检查质体起源。在这项研究中，我们评估了具有三级质体的两个甲藻谱系中内共生对宿主基因组的贡献。我们为含有硅藻衍生质体的“恐龙”生成了第一个核转录组数据集，并将这些数据与卡氏动物的可用转录组结合起来分析，其中卡伦亚门含有来自附着体的质体。我们发现在两个甲藻谱系中可检测到的EGT水平都很低，在甲藻和卡氏动物中分别只有9个基因和90个可能的三级内共生起源基因，这表明三级内共生并没有严重影响宿主甲藻基因组。
Plastid establishment involves the transfer of endosymbiotic genes to the host nucleus, a process known as endosymbiotic gene transfer (EGT). Large amounts of EGT have been shown in several photosynthetic lineages but also in present-day plastid-lacking organisms, supporting the notion that endosymbiotic genes leave a substantial genetic footprint in the host nucleus. Yet the extent of this genetic relocation remains debated, largely because the long period that has passed since most plastids originated has erased many of the clues to how this process unfolded. Among the dinoflagellates, however, the ancestral peridinin-containing plastid has been replaced by tertiary plastids on several more recent occasions, giving us a less ancient window to examine plastid origins. In this study, we evaluated the endosymbiotic contribution to the host genome in two dinoflagellate lineages with tertiary plastids. We generated the first nuclear transcriptome data sets for the "dinotoms," which harbor diatom-derived plastids, and analyzed these data in combination with the available transcriptomes for kareniaceans, which harbor haptophyte-derived plastids. We found low level of detectable EGT in both dinoflagellate lineages, with only 9 genes and 90 genes of possible tertiary endosymbiotic origin in dinotoms and kareniaceans, respectively, suggesting that tertiary endosymbioses did not heavily impact the host dinoflagellate genomes.