Parasitism is a successful life strategy that has evolved independently in several families of vascular plants. The genera Cuscuta and Orobanche represent examples of the two profoundly different groups of parasites: one parasitizing host shoots and the other infecting host roots. In this study, we sequenced and described the overall repertoire of small RNAs from Cuscuta campestris and Orobanche aegyptiaca. We showed that C. campestris contains a number of novel microRNAs (miRNAs) in addition to a conspicuous retention of miRNAs that are typically lacking in other Solanales, while several typically conserved miRNAs seem to have become obsolete in the parasite. One new miRNA appears to be derived from a horizontal gene transfer event. The exploratory analysis of the miRNA population (exploratory due to the absence of a full genomic sequence for reference) from the root parasitic O. aegyptiaca also revealed a loss of a number of miRNAs compared to photosynthetic species from the same order. In summary, our study shows partly similar evolutionary signatures in the RNA silencing machinery in both parasites. Our data bear proof for the dynamism of this regulatory mechanism in parasitic plants.

中文翻译：

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寄生植物小 RNA 分析揭示了 microRNA 保留、丢失和获得的寄生虫特异性特征。

寄生是一种成功的生活策略，在几个维管植物科中独立进化。Cuscuta 和 Orobanche 属代表了两种截然不同的寄生虫群的例子：一种寄生于寄主枝条，另一种感染寄主根部。在这项研究中，我们对来自 Cuscuta campestris 和 Orobanche aegyptiaca 的小 RNA 的全部组成部分进行了测序和描述。我们发现 C. campestris 除了明显保留其他茄目中通常缺乏的 miRNA 外，还含有许多新的 microRNA (miRNA)，而几种通常保守的 miRNA 在寄生虫中似乎已经过时。一种新的 miRNA 似乎来自水平基因转移事件。对来自埃及伊蚊根寄生的 miRNA 群体的探索性分析（由于缺乏完整的基因组序列供参考而进行探索性分析）也揭示了与来自同一目的光合物种相比，一些 miRNA 的损失。总之，我们的研究表明，两种寄生虫的 RNA 沉默机制具有部分相似的进化特征。我们的数据证明了寄生植物中这种调节机制的活力。