Kerguelen Islands harbor a unique, probably very ancient flora with a high rate of endemism. However, the evolutionary history and characteristics of this flora still require investigation. This concerns in particular genome size and ploidy level variation, despite the evolutionary and ecological significance of those traits. Here we report the first assessment of genome size, using flow cytometry, for eight plant species of which two are endemics of Kerguelen Islands and four of the South Indian Ocean Province. The 2C DNA value ranged from 1.08 pg for Pringlea antiscorbutica to 11.88 pg for Ranunculus biternatus. The chromosome numbers of Colobanthus kerguelensis (2n = 80), Lyallia kerguelensis (2n = 96) and Poa kerguelensis (2n = 28) were also reported in this study for the first time. Overall, our data allowed to infer that all Kerguelen studied species are polyploid (from tetra- to octopolyploid). Intra-genus comparisons showed significant differences of 2C DNA values among Poa and among Ranunculus species, despite their identical ploidy level. In addition, our data highlight the existence of an intraspecific variability of genome size for the two octoploid species Colobanthus kerguelensis and Lyallia kerguelensis. Finally, our data also support the hypothesis regarding which polyploidy may have played a major role in the adaptation of flowering plants to high latitudes, as it has been suggested for arctic species.

中文翻译：

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凯尔盖朗群岛十种植物的基因组大小和染色体数目

凯尔盖朗群岛拥有一种独特的、可能非常古老的植物群，并且具有很高的地方性。然而，该植物群的进化历史和特征仍有待调查。这尤其涉及基因组大小和倍性水平变异，尽管这些性状具有进化和生态意义。在这里，我们报告了使用流式细胞术对八种植物物种的基因组大小的首次评估，其中两种是凯尔盖朗群岛的特有物种和南印度洋省的四种植物。2C DNA 值的范围从 Pringlea antiscorbutica 的 1.08 pg 到 Ranunculus biternatus 的 11.88 pg。Colobanthus kerguelensis (2n = 80)、Lyallia kerguelensis (2n = 96)和Poa kerguelensis (2n = 28)的染色体数目也是本研究首次报道。全面的，我们的数据允许推断所有 Kerguelen 研究的物种都是多倍体（从四倍体到八倍体）。属内比较显示早熟禾和毛茛属物种之间的 2C DNA 值存在显着差异，尽管它们的倍性水平相同。此外，我们的数据强调了两种八倍体物种 Colobanthus kerguelensis 和 Lyallia kerguelensis 基因组大小的种内变异性的存在。最后，我们的数据还支持关于哪种多倍体可能在开花植物适应高纬度地区发挥主要作用的假设，正如它对北极物种所提出的那样。我们的数据强调了两种八倍体物种 Colobanthus kerguelensis 和 Lyallia kerguelensis 基因组大小的种内变异性的存在。最后，我们的数据还支持了关于哪种多倍体可能在开花植物适应高纬度地区发挥主要作用的假设，正如对北极物种提出的那样。我们的数据强调了两种八倍体物种 Colobanthus kerguelensis 和 Lyallia kerguelensis 基因组大小的种内变异性的存在。最后，我们的数据还支持关于哪种多倍体可能在开花植物适应高纬度地区发挥主要作用的假设，正如它对北极物种所提出的那样。