Xu Xiaodong, Wang Dong
School of Life Sciences, Central China Normal University, Key Laboratory for Geographical Process Analysis and Simulation, Wuhan, China.
Bio-Resources Key Laboratory of Shaanxi Province, Shaanxi University of Technology, Hanzhong, China.
Front Plant Sci. 2021 Jan 27;11:600354. doi: 10.3389/fpls.2020.600354. eCollection 2020.
The chloroplast genome (plastome) of angiosperms (particularly photosynthetic members) is generally highly conserved, although structural rearrangements have been reported in a few lineages. In this study, we revealed to be another unusual lineage with extensive large-scale plastome rearrangements. In the four newly sequenced plastomes that represent all the three subgenera of , we detected (1) two independent relocations of the same five genes (-) from the typically posterior part of the large single-copy (LSC) region to the front, downstream of either the gene in or the gene in both and ; (2) relocation of the gene from the LSC region to the inverted repeat (IR) region in ; (3) uniform inversion of an 11-14 kb segment (-) in the IR region of all the four Corydalis species (the same below); (4) expansions (>10 kb) of IR into the small single-copy (SSC) region and corresponding contractions of SSC region; and (5) extensive pseudogenizations or losses of 13 genes (, , and 11 genes). In addition, we also found that the four plastomes exhibited elevated GC content in both gene and intergenic regions and high number of dispersed repeats. Phylogenomic analyses generated a well-supported topology that was consistent with the result of previous studies based on a few DNA markers but contradicted with the morphological character-based taxonomy to some extent. This study provided insights into the evolution of plastomes throughout the three subgenera and will be of value for further study on taxonomy, phylogeny, and evolution of .
被子植物（尤其是光合成员）的叶绿体基因组（质体基因组）通常高度保守，尽管在一些谱系中已报道有结构重排。在本研究中，我们发现 是另一个具有广泛大规模质体基因组重排的异常谱系。在代表 的所有三个亚属的四个新测序的质体基因组中，我们检测到：（1）同一五个基因（-）从大单拷贝（LSC）区域的典型后部独立重新定位到前部，位于 中的 基因或 和 中的 基因下游；（2） 中的 基因从LSC区域重新定位到反向重复（IR）区域；（3）所有四种紫堇属植物的IR区域中一个11 - 14 kb片段（-）的一致倒位（以下相同）；（4）IR扩展（>10 kb）进入小单拷贝（SSC）区域以及SSC区域相应收缩；以及（5）13个基因（ 、 和11个 基因）的广泛假基因化或丢失。此外，我们还发现这四个 质体基因组在基因和基因间区域均表现出较高的GC含量以及大量分散重复序列。系统基因组分析产生了一个得到充分支持的拓扑结构，该结构与先前基于少数DNA标记的研究结果一致，但在一定程度上与基于形态特征的分类法相矛盾。本研究为整个 三个亚属的质体基因组进化提供了见解，并将对 的分类学、系统发育和进化的进一步研究具有价值。
