Plastid genomes (plastomes) of land plants have a conserved quadripartite structure in a gene-dense unit genome consisting of a large inverted repeat that separates two single copy regions. Recently, alternative plastome structures were suggested in Geraniaceae and in some conifers and Medicago the coexistence of inversion isomers has been noted. In this study, plastome sequences of two Cyperaceae, Eleocharis dulcis (water chestnut) and Eleocharis cellulosa (gulf coast spikerush), were completed. Unlike the conserved plastomes in basal groups of Poales, these Eleocharis plastomes have remarkably divergent features, including large plastome sizes, high rates of sequence rearrangements, low GC content and gene density, gene duplications and losses, and increased repetitive DNA sequences. A novel finding among these features was the unprecedented level of heteroplasmy with the presence of multiple plastome structural types within a single individual. Illumina paired-end assemblies combined with PacBio single-molecule real-time sequencing, long-range polymerase chain reaction, and Sanger sequencing data identified at least four different plastome structural types in both Eleocharis species. PacBio long read data suggested that one of the four E. dulcis plastome types predominates.

中文翻译：

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Eleocharis（莎草科，Poales）质膜空前的个体内结构异质性。

陆地植物的质体基因组（质体组）在基因密集的单位基因组中具有保守的四方结构，该基因组由将两个单拷贝区域分开的大反向重复组成。最近，有人建议在草菊科和一些针叶树和紫花苜蓿中存在其他的塑性组结构，并存在倒位异构体的共存。在这项研究中，完成了两个莎草科（Eleocharis dulcis（water）和Eleocharis cellulosa（海湾沿岸棘）的塑性组序列。不同于Poales基群中保守的质体组，这些Eleocharis质体组具有显着不同的特征，包括较大的质体组大小，高序列重排率，低GC含量和基因密度，基因重复和丢失以及重复DNA序列增加。这些特征中的一个新发现是，在单个个体中存在多种质体组结构类型的情况下，异质性水平达到了前所未有的水平。Illumina的配对末端组件与PacBio单分子实时测序，远程聚合酶链反应和Sanger测序数据相结合，确定了两种Eleocharis物种中至少四种不同的质体结构类型。PacBio的长期阅读数据表明，四种E. dulcis质体组中的一种占主导地位。