Evolutionary genomics of the cold-adapted diatom Fragilariopsis cylindrus
Evolutionary genomics of the cold-adapted diatom Fragilariopsis cylindrus
复制标题
DOI：
10.1038/nature20803
复制
发表时间：
2017-01-26
期刊：
影响因子：
64.8
通讯作者：
Grigoriev, Igor V.
中科院分区：
文献类型：
--
作者：
Mock, Thomas;Otillar, Robert P.;Grigoriev, Igor V.
南大洋拥有一个多样化和多产的生物群落（1，2）。单细胞真核硅藻是这种环境中的主要初级生产者，其中光合作用受到低浓度溶解铁和光照，温度和海冰范围的季节性波动的限制（3-7）。硅藻如何适应这种极端环境在很大程度上是未知的。在这里，我们提出的见解冷适应硅藻从南大洋，Fragilariopsis cylindrus（8，9）的基因组进化的基础上与温带硅藻的比较。我们发现，约24.7%的二倍体F。柱孢属的基因组由具有高度分化的等位基因的遗传基因座组成（总基因组大小61.1兆碱基中的15.1兆碱基）。这些不同的等位基因在不同的环境条件下差异表达，包括黑暗，低铁，冷冻，高温和增加CO2。具有最大比率的非同义与同义核苷酸替换的等位基因也显示出最明显的条件依赖性表达，这表明多样化选择与等位基因分化之间的相关性。不同的等位基因可能参与适应南大洋的环境波动。
The Southern Ocean houses a diverse and productive community of organisms(1,2). Unicellular eukaryotic diatoms are the main primary producers in this environment, where photosynthesis is limited by low concentrations of dissolved iron and large seasonal fluctuations in light, temperature and the extent of sea ice(3-7). How diatoms have adapted to this extreme environment is largely unknown. Here we present insights into the genome evolution of a cold-adapted diatom from the Southern Ocean, Fragilariopsis cylindrus(8,9), based on a comparison with temperate diatoms. We find that approximately 24.7 per cent of the diploid F. cylindrus genome consists of genetic loci with alleles that are highly divergent (15.1 megabases of the total genome size of 61.1 megabases). These divergent alleles were differentially expressed across environmental conditions, including darkness, low iron, freezing, elevated temperature and increased CO2. Alleles with the largest ratio of non-synonymous to synonymous nucleotide substitutions also show the most pronounced condition-dependent expression, suggesting a correlation between diversifying selection and allelic differentiation. Divergent alleles may be involved in adaptation to environmental fluctuations in the Southern Ocean.