Data from: Natural epigenetic variation contributes to heritable flowering divergence in a widespread asexual dandelion lineage

Epigenetic variation has been proposed to contribute to the success of asexual plants, either as a contributor to phenotypic plasticity or by enabling transient adaptation via selection on transgenerationally stable, but reversible, epialleles. While recent studies in experimental plant populations have shown the potential for epigenetic mechanisms to contribute to adaptive phenotypes, it remains unknown if heritable variation in ecologically relevant traits is at least partially epigenetically determined in natural populations. Here, we tested the hypothesis that DNA methylation variation contributes to heritable differences in flowering time within a single widespread apomictic clonal lineage of the common dandelion (Taraxacum officinale s. lat.). Apomictic clone members of the same apomictic lineage collected from different field sites showed heritable differences in flowering time, which was correlated with inherited differences in methylation-sensitive AFLP marker profiles. Differences in flowering between apomictic clone members were significantly reduced after in vivo de-methylation using the DNA methyltransferase inhibitor zebularine. This synchronization of flowering times suggests that flowering time divergence within an apomictic lineage was mediated by differences in DNA methylation. While the underlying basis of the methylation polymorphism at functional flowering time-affecting loci remains to be demonstrated, our study shows that epigenetic variation contributes to heritable phenotypic divergence in ecologically relevant traits in natural plant populations. This result also suggests that epigenetic mechanisms can facilitate adaptive divergence within genetically uniform asexual lineages.

表观遗传变异（epigenetic variation）已被提出可助力无性植物的适应性成功：既可为表型可塑性（phenotypic plasticity）提供基础，也可通过对跨代稳定但可逆的表观等位基因（epialleles）的选择，实现临时性适应。尽管近期针对实验植物种群的研究已证实，表观遗传机制具备促成适应性表型的潜力，但自然种群中生态相关性状的可遗传变异是否至少部分由表观遗传决定，目前仍无定论。
本研究以广布的普通蒲公英（Taraxacum officinale 广义类群）的单一无融合生殖克隆谱系为研究对象，检验了“DNA甲基化（DNA methylation）变异可导致开花时间（flowering time）产生可遗传差异”这一假说。从不同野外生境采集的同一无融合生殖谱系的克隆个体，其开花时间存在可遗传差异，且该差异与甲基化敏感扩增片段长度多态性（AFLP）标记谱的遗传差异显著相关。
使用DNA甲基转移酶抑制剂泽布拉林（zebularine）进行体内去甲基化处理后，不同克隆个体间的开花时间差异显著缩小。这种开花时间的同步化现象表明，无融合生殖谱系内的开花时间分化，是由DNA甲基化差异介导的。尽管影响开花时间的功能位点上的甲基化多态性的分子基础仍有待验证，但本研究证实，表观遗传变异可促成自然植物种群中生态相关性状的可遗传表型分化。
该结果同时表明，表观遗传机制可推动遗传一致的无性谱系内产生适应性分化。