Genome size and chromosome number of ten plant species from Kerguelen Islands
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ORIGINAL PAPER
Genome size and chromosome number of ten plant species from Kerguelen Islands Sonja Siljak‑Yakovlev1 · Françoise Lamy1,2 · Najat Takvorian1,3 · Nicolas Valentin4 · Valérie Gouesbet5 · Françoise Hennion5 · Thierry Robert1,3 Received: 13 February 2020 / Revised: 16 September 2020 / Accepted: 25 September 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract 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. Keywords 2C DNA value · Endemic species · Flow cytometry · Genome size · Ploidy level · Sub-Antarctic flora
Introduction
Françoise Hennion and Thierry Robert both contributed as senior authors. * Sonja Siljak‑Yakovlev sonia.yakovlev@u‑psud.fr; sonia.yakovlev@universite‑paris‑saclay.fr 1
Université Paris-Saclay, CNRS, AgroParisTech, Ecologie Systématique Evolution, 91405 Orsay, France
2
Département de Biologie, 45 bd des Etats‑Unis, Université Versailles-Saint-Quentin, 78035 Versailles, France
3
Sorbonne Université, UFR 927, 4 Place Jussieu, 75252 Paris Cedex 05, France
4
Institute of Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Saclay, 91198 Gif‑sur‑Yvette, France
5
Ecosystèmes, Biodiversité, Evolution, UMR 6553 ECOBIO, Université de Rennes 1, OSUR, CNRS, 35042 Rennes, France
The sub-Antarctic islands (sensu Smith 1984; Van der Putten et al. 2010) host a depauperate angiosperm flora of about 58 taxa. These islands were very early suggested to be important in the floristic history of the Southern Hemisphere as possible stepping-stones for dispersal or refuges for plant species during glacial times (e.g., Hooker 1847; Werth 1911; Hennion and Walton 1997; Chown et al.
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