A study of the genetic variation of the aquatic fern Marsilea quadrifolia L. preserved in botanical collections in Poland and originated from natural populations in Europe

Aim of the present study was to evaluate the genetic diversity of selected European populations of Marsilea quadrifolia L. and to assess the applicability of those genetic resources of Marsilea quadrifolia L. that have been preserved in Polish botanical gardens, for the reintroduction of this species into its historical range in Poland. Three Polish populations that originated from botanical collections (Zabrze, Żarów and Puławy) and four natural populations (two from Slovakia (Slovakia I and Slovakia II), one from France and one from Germany) were analyzed using Amplified Fragment Length Polymorphism (AFLP) markers. A very low level of genetic variation was found both within and between the populations in the study, which likely resulted from a genetic bottleneck probably caused by human activities. Plants with the same AFLP fingerprint were found across several populations; however, singleton samples with a unique AFLP band pattern were also present within all of the populations. The presence of singletons led to relatively high values of Simpson's diversity index, which may suggest a considerable effect of mutations and some possibility of sexual reproduction as sources of the observed variation. The partitioning of molecular variance was calculated using hierarchical AMOVA, which showed that a negligible value of only 0.81% of the variation was explained by the category of population, i.e. plants originating from the botanical collections or from the natural habitats. This result indicates that M. quadrifolia populations from botanical collections resemble natural populations in terms of the level of their genetic variation and that the populations that were obtained from the Polish collections could be used for the successful reintroduction of this species into its historical range in Poland, and a similar situation may be given also in other areas of occurrence of this plant that is under threat throughout its area of occurrence in Europe.