Ploidy Level and Genome Size of Vincetoxicum nigrum and V.rossicum (Apocynaceae), Two Invasive Vines in North Americ

Bon Marie-Claude, Guermache Fathia, Rodier-Goud Marguerite, Bakry Frédéric, Bourge Mickael, Dolgovskaya M., Volkovitsh Mark, Sforza René, Darbyshire S., Milbrath L.. 2011. Ploidy Level and Genome Size of Vincetoxicum nigrum and V.rossicum (Apocynaceae), Two Invasive Vines in North Americ. In : Proceedings of the XIII International Symposium on Biological Control of Weeds, September 11- 16, 2011, Waikoloa, USA. Wu Yun (ed.), Johnson Tracy (ed.), Sing Sharlene (ed.), Raghu S. (ed.), Wheeler Greg (ed.), Pratt Paul (ed.), Warner Keith (ed.), Center Ted (ed.), Goolsby John (ed.), Reardon Richard (ed.). Hawaii : FHTET, 325. International Symposium on Biological Control of Weeds. 13, Hawaï, États-Unis, 11 Septembre 2011/16 Septembre 2011.

Résumé : Vincetoxicum nigrum (L.) Moench (black swallow-wort) and V. rossicum (Kleopow) Barbarich (pale swallow-wort) (Apocynaceae) are perennial vines that are targeted for classical biological control as a result of their massive invasion in natural areas and horticultural nurseries in the U.S. and Canada. Native ranges of V. nigrum and V. rossicum are limited to southwestern Europe and to Ukraine-southwestern Russia, respectively. The evolutionary mechanisms that have facilitated the range expansion since their introduction 150 years ago into North America have yet to be understood. In this study we examine two characteristics of the genome organization, i) the most frequently assessed ploidy level and ii) the variation in genome size, i.e., variation in the amount of DNA per monoploid set of chromosomes through loss or gain of repeated DNA sequences. Both can allow rapid changes in key phenotypic traits that enhance invasive ability. Flow cytometry using propidium iodide for the analysis of genome size variation and chromosome counting using DAPI were conducted on plants sampled from the introduced and native ranges of both species. In V. nigrum, accessions from Southern France and North America were all tetraploid (2n = 4x = 44). In V. rossicum, accessions from Russia and North America were all diploid (2n = 2x = 22). The mean 2C value (±STD) of V. nigrum and V. rossicum is 1.44±0.03pg and 0.71±0.02pg, respectively. This is the first report of genome size for the genus. At the species level, no evidence for genome size variation was found between the two ranges. Our data indicate that the invasive spread of both species was not triggered by differences in ploidy level or genome size between native and introduced populations. Alternative explanations should be sought.

Auteurs et affiliations

• Bon Marie-Claude, USDA (FRA)
• Guermache Fathia, USDA (FRA)
• Rodier-Goud Marguerite, CIRAD-BIOS-UMR AGAP (FRA)
• Bakry Frédéric, CIRAD-BIOS-UMR AGAP (FRA)
• Bourge Mickael, CNRS (FRA)
• Dolgovskaya M., Russian Academy of Sciences (RUS)
• Volkovitsh Mark, Russian Academy of Sciences (RUS)
• Sforza René, USDA (FRA)
• Darbyshire S., Agriculture and Agri-Food Canada (CAN)
• Milbrath L., USDA (FRA)

Source : Cirad-Agritrop (https://agritrop.cirad.fr/593379/)

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