Hybridization has been widely used in breeding of cultivated species showing low genetic variability, such as peach (Prunus persica). The merging of two different genomes in a hybrid often triggers a so-called “genomic shock” with changes in DNA methylation and in the induction of transposable element expression and mobilization. Here, we analysed the DNA methylation and transcription levels of transposable elements and genes in leaves of Prunus persica and Prunus dulcis and in their F1 hybrid using high-throughput sequencing technologies. Contrary to the “genomic shock” expectations, we found that the overall levels of DNA methylation in the transposable elements in the hybrid are not significantly altered compared with those of the parental genomes. We also observed that the levels of transcription of the transposable elements in the hybrid are in most cases intermediate as compared with that of the parental species and we have not detected cases of higher transcription in the hybrid. We also found that the proportion of genes whose expression is altered in the hybrid compared with the parental species is low. The expression of genes potentially involved in the regulation of the activity of the transposable elements is not altered. We can conclude that the merging of the two parental genomes in the P. persica x P. dulcis hybrid does not result in a “genomic shock” with significant changes in the DNA methylation or in the transcription. The absence of major changes may facilitate using this interspecific cross for peach improvement.

中文翻译：

---

桃和杏仁之间的种间杂交不存在主要的表观遗传和转录组变化

杂交已广泛用于培育显示低遗传变异性的栽培物种，例如桃（Prunus persica）。杂交中两个不同基因组的合并通常会引发所谓的“基因组冲击”，即 DNA 甲基化的变化以及转座因子表达和动员的诱导。在这里，我们使用高通量测序技术分析了 Prunus persica 和 Prunus dulcis 及其 F1 杂种叶片中转座因子和基因的 DNA 甲基化和转录水平。与“基因组冲击”的预期相反，我们发现与亲本基因组相比，杂种中转座因子中 DNA 甲基化的总体水平没有显着改变。我们还观察到，在大多数情况下，与亲本物种相比，杂种中转座因子的转录水平处于中间水平，我们没有检测到杂种中转录水平较高的情况。我们还发现，与亲本物种相比，杂种中表达改变的基因比例很低。可能参与调节转座因子活性的基因的表达没有改变。我们可以得出结论，在 P. persica x P. dulcis 杂种中两个亲本基因组的合并不会导致 DNA 甲基化或转录发生显着变化的“基因组冲击”。没有重大变化可能有助于使用这种种间杂交进行桃改良。