Genome evolution of ferns: evidence for relative stasis of genome size across the fern phylogeny
Genome evolution of ferns: evidence for relative stasis of genome size across the fern phylogeny
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DOI：
10.1111/nph.13833
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发表时间：
2016-05-01
期刊：
影响因子：
9.4
通讯作者：
Schneider, Harald
中科院分区：
文献类型：
--
作者：
Clark, James;Hidalgo, Oriane;Schneider, Harald
与被子植物相比，蕨类植物的基因组进化被认为相对静态。在本研究中，我们在系统发育框架中分析基因组大小数据和染色体数量，以探索三个假设：基因组大小和染色体数量的相关性、现代蕨类植物起源于具有高染色体数量的祖先，以及蕨类植物进化过程中发生的几次全基因组重复。为了实现这一目标，我们生成了新的基因组大小数据，将基因组大小估计为现有多样性的 2.8% 的蕨类物种百分比增加，并确保全面的系统发育覆盖，包括每个蕨类植物目中至少三个物种。尽管所有蕨类植物的基因组大小与染色体数量存在显着差异，但这两个性状都存在相关性。我们观察到每条染色体 DNA 数量保持不变的趋势，尽管紫萁科和松柏科的染色体要大得多。祖先基因组性状的重建表明，最早的蕨类植物已经具有高染色体数量的特征，并且蕨类植物中最早的分化与显着的核学变化相关。在整个系统发育过程中发现了重复的全基因组重复的证据。蕨类植物基因组往往进化缓慢，尽管某些进化枝中会发生基因组重排。
The genome evolution of ferns has been considered to be relatively static compared with angiosperms. In this study, we analyse genome size data and chromosome numbers in a phylogenetic framework to explore three hypotheses: the correlation of genome size and chromosome number, the origin of modern ferns from ancestors with high chromosome numbers, and the occurrence of several whole-genome duplications during the evolution of ferns. To achieve this, we generated new genome size data, increasing the percentage of fern species with genome sizes estimated to 2.8% of extant diversity, and ensuring a comprehensive phylogenetic coverage including at least three species from each fern order. Genome size was correlated with chromosome number across all ferns despite some substantial variation in both traits. We observed a trend towards conservation of the amount of DNA per chromosome, although Osmundaceae and Psilotaceae have substantially larger chromosomes. Reconstruction of the ancestral genome traits suggested that the earliest ferns were already characterized by possessing high chromosome numbers and that the earliest divergences in ferns were correlated with substantial karyological changes. Evidence for repeated whole-genome duplications was found across the phylogeny. Fern genomes tend to evolve slowly, albeit genome rearrangements occur in some clades.