Parasitic plants have evolved to have reduced or completely lost ability to conduct photosynthesis and are usually characterized by sweeping morphological, physiological and genomic changes. The plastid genome (or plastome) is highly conserved in autotrophic plants and houses many key photosynthesis genes. This molecule is thus a useful system for documenting the genomic effects of a loss of autotrophy. Cuscuta (dodders) represents one of 12 independent transitions to a parasitic lifestyle in angiosperms. This near-cosmopolitan genus contains > 200 obligate parasitic species circumscribed in four subgenera: Grammica, Pachystigma, Cuscuta and Monogynella. With respect to photosynthesis, Cuscuta is a heterogeneous group, containing both hemi- and holoparasitic members that are, respectively, partially or entirely reliant on parasitism to meet their carbon budget. Plastomes in this genus have been reported to show a substantial degree of diversification in terms of length and gene composition. Considered together with well-understood phylogenetic relationships, this genus presents an opportunity for fine-scale comparisons among closely related species of heterotrophic plants. This research documents changes in sequence composition and structure that occurred as these plants evolved along the trophic spectrum by using multiple whole-plastome assemblies from each of the four subgenera. By ‘triangulating’ the positions of genomic changes, we construct a step-by-s’tep model of plastome evolution across the phylogenetic backbone of Cuscuta and highlight the remarkable retention of most photosynthetic genes in these parasitic plants.

中文翻译：

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整个寄生属植物的系统发育重建骨干演变质体菟丝子（旋）

寄生植物已经进化为具有降低的或完全丧失的进行光合作用的能力，并且通常特征在于形态，生理和基因组的全面变化。质体基因组（或质体组）在自养植物中高度保守，并具有许多关键的光合作用基因。因此，该分子是用于证明自养丧失的基因组效应的有用系统。s丝（（丝）代表被子植物向寄生虫生活方式的12种独立转变之一。这个近世界化的属包含在四个亚属中限定的200多个专性寄生种：革兰氏菌属，Pachystigma，Cuscuta和Monogynella。关于光合作用，Cu丝是一个异质族，包含半寄生和全寄生成员，分别部分或完全依靠寄生来满足其碳预算。据报道，该属的质粒在长度和基因组成方面显示出很大程度的多样化。与公认的系统发育关系一起考虑，该属为密切相关的异养植物物种之间的精细比较提供了机会。这项研究记录了这些植物通过使用来自四个亚属的多个全质体组装体沿营养谱进化而发生的序列组成和结构的变化。通过“划分”基因组变化的位置，我们构建了跨整个系统发生主干的质体组进化的逐步模型。s和突出显示这些寄生植物中大多数光合基因的显着保留。