A plant parasite obligately parasitizing another plant parasite is referred to as epiparasite, which is extremely rare in angiosperms, and their complete plastome sequences have not been characterized to date. In this study, the complete plastomes of two flowering epiparasites: Phacellaria compressa and P. glomerata (Amphorogynaceae, Santalales) were sequenced. The plastomes of both species are of similar size, structure, gene content, and arrangement of genes to other hemiparasites in Santalales. Their plastomes were characterized by the functional loss of plastid-encoded NAD(P)H-dehydrogenase and infA genes, which strongly coincides with the general pattern of plastome degradation observed in Santalales hemiparasites. Our study demonstrates that the relatively higher level of nutritional reliance on the host plants and the reduced vegetative bodies of P. compressa and P. glomerata do not appear to cause any unique plastome degradation compared with their closely related hemiparasites.

专性寄生于另一种植物寄生虫的植物寄生虫被称为外寄生虫，这在被子植物中极为罕见，迄今为止尚未对其完整的质体序列进行表征。在这项研究中，对两种开花外寄生虫的完整质体进行了测序：Phacellaria compressa和P. glomerata（Amphorogynaceae，Santalales）。这两个物种的质体在大小、结构、基因含量和基因排列方面与桑塔拉目中的其他半寄生虫相似。他们的质体以质体编码的NAD( P )H-脱氢酶和infA的功能丧失为特征基因，这与在桑塔拉目半寄生虫中观察到的一般质体降解模式非常吻合。我们的研究表明，与其密切相关的半寄生虫相比，对寄主植物的相对较高水平的营养依赖以及P. compressa和P. glomerata的营养体减少似乎不会导致任何独特的质体降解。