A study of 22 different types of lichens revealed 10 included fungi that had lost a gene for energy production, making them completely dependent on their algal partner.
对22种不同类型的地衣进行的一项研究发现，有10种真菌丢失了用于产生能量的基因，（这一丢失）使得它们完全依赖于它们的藻类伙伴。
撰文/播音凯伦·霍普金（Karen Hopkin）
翻译 张心茹
校对 杨枭
“Lichens are really cool successful organisms that are composed of at least two symbiotic partners: a fungal partner that provides structure and protection and a photosynthetic partner that likely provides energy in the form of sugar.”
“地衣是很成功、也很奇特的生物，至少由两个共生物组成：一个提供结构和保护的真菌伴侣以及一个可能以糖的形式提供能量的光合作用伴侣。”
Cloe Pogoda, a graduate researcher at the University of Colorado. She led research that found that this partnership extends to the genetic level. The fungal partner in many lichen jettison a gene that’s critical for energy production—making them completely dependent on their algal associates.
科罗拉多大学研究生研究员蔻依·普古达（Cloe Pogoda）领导了一项研究，发现这种伙伴关系延伸到了基因层面。许多地衣的真菌伙伴抛弃了一个对能源生产至关重要的基因——使它们完全依赖于它们的藻类伴侣。
Although scientists have long appreciated that general division of labor, what’s been less clear is whether the relationship was entirely obligatory. In other words, are the cohorts changed by their evolutionary association in such a way that they can no longer make it alone?
尽管科学家们长期以来一直认识到分工的普遍性，但不清楚的是这种关系是否完全是强制性的。换句话说，这些群体是否被他们的进化联系改变了，以至于他们不能再独自生存呢？
To find out, the team sequenced the genomes of 22 lichen species collected in the southern Appalachian Mountains. And they concentrated on the participants’ mitochondria, which contain genomes of their own.
为了找到答案，该小组对在南部阿巴拉契亚山脉采集的22种地衣物种的基因组进行了测序。他们重点关注了研究对象的线粒体，这些线粒体含有自己的基因组。
“Because there are so many copies of these genomes in each cell, and because they’re so conserved across all domains of life the mitochondrial genomes were the focus of our study.” Kyle Keepers, also at the University of Colorado.
“由于这些基因组在每个细胞中有很多副本，并且因为它们在各个生命进程中都保存完好，所以线粒体基因组是我们研究的重点。”同在科罗拉多大学的凯尔·基普斯（Kyle Keepers）说。
What the researchers found is that a key mitochondrial gene was missing from the fungal partner in 10 of the lichen species they examined. These species hailed from three different evolutionary lineages.
研究人员发现，他们检查的10种地衣属真菌伴侣中缺少一个关键的线粒体基因。这些物种来自三种不同的进化谱系。
CP: “This is a really cool result because it demonstrates that this lichen relationship is obligate. And that the same strategy for genome streamlining was employed three different times over evolution.” The findings appear in the journal Molecular Ecology. [Cloe S. Pogoda et al., Reductions in Complexity of Mitochondrial Genomes in Lichen-Forming Fungi Shed Light on Genome Architecture of Obligate Symbioses]
蔻依·普古达说：“这是一个非常棒的结果，因为它证明了这种地衣关系是必需性的。而且，在进化过程中的三个不同时间都采用了相同的基因组精简策略。“研究结果出现在”分子生态学“杂志上。
“Think of it like two partners moving in together. And they each have their own printer. Who needs two printers?” Erin Tripp, the study’s principal investigator, is the curator of botany at the university’s Museum of Natural History.
“把这个过程想象成两个伴侣搬到一起住。他们每个人都有自己的打印机。谁会需要两台打印机呢？“艾林·特里普（Erin Tripp）说，她是该研究的首席研究员，也是该大学自然历史博物馆植物部门的馆长。
Letting the algae provide the cellular energy likely makes the fungal partner more efficient, perhaps allowing it to focus on building a stable structure and reproducing. Tripp wonders whether some of the bacteria living in our guts might have developed similar molecular co-dependencies.
让藻类提供细胞能量可能会使真菌伙伴更有效率，也许可以让它专注于建立稳定的结构以及繁殖。特里普想知道生活在我们肠道中的某些细菌是否也发展出了类似的分子共依赖性。
ET: “What this data analysis pipeline, moreover, creates is motivation to look for similar forms of gene loss in other types of symbioses, such as that between humans and their gut microbiomes. It may very well be that some bacteria are completely dependent on their human hosts and thus co-evolving with us, whereas others can come and go.”
艾林·特里普说：“此外，数据分析流程还使人们开始渴望寻找其他类型共生关系中类似形式的基因丢失现象，例如人类与其肠道微生物群之间的共生关系。很可能有些细菌完全依赖于他们的人类宿主，并因此与我们共同进化，而其他细菌可以自由来去。”
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