Manipulation of cytosine methylation does not remove latitudinal clines in two invasive goldenrod species in Central Europe

Abstract

Invasive species frequently differentiate phenotypically in novel environments within a few generations, often even with limited genetic variation. For the invasive plants Solidago canadensis and S. gigantea, we tested whether such differentiation might have occurred through heritable epigenetic changes in cytosine methylation. In a 2-year common-garden experiment, we grew plants from seeds collected along a latitudinal gradient in their non-native Central European range to test for trait differentiation and whether differentiation disappeared when seeds were treated with the demethylation agent zebularine. Microsatellite markers revealed no population structure along the latitudinal gradient in S. canadensis, but three genetic clusters in S. gigantea. Solidago canadensis showed latitudinal clines in flowering phenology and growth. In S. gigantea, the number of clonal offspring decreased with latitude. Although zebularine had a significant effect on early growth, probably through effects on cytosine methylation, latitudinal clines remained (or even got stronger) in plants raised from seeds treated with zebularine. Thus, our experiment provides no evidence that epigenetic mechanisms by selective cytosine methylation contribute to the observed phenotypic differentiation in invasive goldenrods in Central Europe. K E Y W O R D S common-garden experiment, epigenetic variation, microsatellites, Solidago canadensis, Solidago gigantea, zebularine This is an open access article under the terms of the Creative Commons Attribution-NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.

Traces of Genetic but Not Epigenetic Adaptation in the Invasive Goldenrod Solidago canadensis Despite the Absence of Population Structure

“…Several studies have shown that variation in cytosine methylation might be associated with differentiation between local habitat conditions or along climatic gradients: for example in the clonal invasive species Reynoutria japonica (Richards et al, 2012) and the poleward range-expanding apomictic plant species Taraxacum officinale (Preite et al, 2015). Since variation in cytosine methylation was suggested as a response to changing environments (Münzbergová et al, 2019), it could also be involved in the formation of altitudinal (Alexander et al, 2009;Moran et al, 2017) and latitudinal clines across the invasive range (Kollmann and Bañuelos, 2004;Eckert et al, 2021), or related to invasion dynamics due to landscape heterogeneity (Deutschewitz et al, 2003;Eschtruth and Battles, 2009). Invasive plant species are exposed to novel environmental conditions often combined with high disturbance levels in their new range (Theoharides and Dukes, 2007).…”

“…For this purpose, we focused on Solidago canadensis s.l., a perennial Asteraceae, which is invasive in Central Europe, as well as in many other parts of the world, and which has formed latitudinal clines that persist even when plants are grown in common-garden environments (Weber and Schmid, 1998;Li et al, 2016;Eckert et al, 2021). Eckert et al (2021) found that in Central Europe these clines persisted in offspring that have been treated with the cytosine demethylation agent zebularine.…”

“…For this purpose, we focused on Solidago canadensis s.l., a perennial Asteraceae, which is invasive in Central Europe, as well as in many other parts of the world, and which has formed latitudinal clines that persist even when plants are grown in common-garden environments (Weber and Schmid, 1998;Li et al, 2016;Eckert et al, 2021). Eckert et al (2021) found that in Central Europe these clines persisted in offspring that have been treated with the cytosine demethylation agent zebularine. Although this suggests that variation in cytosine methylation does not play a role in generating adaptive variation along geographic clines, it might still reflect fine-scale spatial separation between populations as has been found, for example, for Helleborus foetidus (Herrera et al, 2016) and Fragaria vesca (De Kort et al, 2020).…”

“…Therefore, a reasonable period of time might have passed for S. canadensis populations in Central Europe to develop epigenetic and genetic signatures at varying spatial scales that are reflected in phenotypic variation. Because the effect of clinal variation in S. canadensis related to climatic and latitudinal gradients has been analyzed before (Weber and Schmid, 1998;Eckert et al, 2021), we focused on possible associations between (epi)genetic variation and phenotypic variation, and to what extent these associations might have been affected by the zebularine treatment. For this purpose, we incorporated the effect of spatial structure in the invasive range.…”

The Genomic Processes of Biological Invasions: From Invasive Species to Cancer Metastases and Back Again

“…In addition to using transcriptomics approaches, several authors have argued that epigenetic mechanisms could be particularly important for invasive species (Ardura et al, 2017;Hawes et al, 2018;Marin et al, 2020;Mounger et al, 2021a; but see Eckert et al, 2021). The case has been made particularly for those invasive species that are clonal or have low genetic diversity.…”