Most eukaryotic microbial diversity is uncultivated, under-studied and lacks nuclear genome data. Mitochondrial genome sampling is more comprehensive, but many phylogenetically important groups remain unsampled. Here, using a single-cell sorting approach combining tubulin-specific labelling with photopigment exclusion, we sorted flagellated heterotrophic unicellular eukaryotes from Pacific Ocean samples. We recovered 206 single amplified genomes, predominantly from underrepresented branches on the tree of life. Seventy single amplified genomes contained unique mitochondrial contigs, including 21 complete or near-complete mitochondrial genomes from formerly under-sampled phylogenetic branches, including telonemids, katablepharids, cercozoans and marine stramenopiles, effectively doubling the number of available samples of heterotrophic flagellate mitochondrial genomes. Collectively, these data identify a dynamic history of mitochondrial genome evolution including intron gain and loss, extensive patterns of genetic code variation and complex patterns of gene loss. Surprisingly, we found that stramenopile mitochondrial content is highly plastic, resembling patterns of variation previously observed only in plants.

中文翻译：

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异养鞭毛原生生物的靶向单细胞基因组学揭示了意外的线粒体基因组多样性。

大多数真核微生物多样性未得到培养、研究不足且缺乏核基因组数据。线粒体基因组采样更全面，但许多系统发育重要的群体仍未采样。在这里，我们使用单细胞分选方法将微管蛋白特异性标记与光色素排除相结合，从太平洋样本中分选了鞭毛异养单细胞真核生物。我们回收了 206 个单一扩增的基因组，主要来自生命之树上代表性不足的分支。70 个单扩增基因组包含独特的线粒体重叠群，包括 21 个完整或接近完整的线粒体基因组，这些基因组来自以前采样不足的系统发育分支，包括端粒纲动物、katablepharids、尾尾动物和海洋原生藻菌，有效地将异养鞭毛虫线粒体基因组的可用样本数量加倍。总的来说，这些数据确定了线粒体基因组进化的动态历史，包括内含子的获得和丢失、遗传密码变异的广泛模式和基因丢失的复杂模式。令人惊讶的是，我们发现原生藻菌线粒体含量具有高度可塑性，类似于以前仅在植物中观察到的变异模式。