Han Shiyun, Ding Hengwu, Bi De, Zhang Sijia, Yi Ran, Gao Jinming, Yang Jianke, Ye Yuanxin, Wu Longhua, Kan Xianzhao
Anhui Provincial Key Laboratory of the Conservation and Exploitation of Biological Resources, College of Life Sciences, Anhui Normal University, Wuhu 241000, China.
College of Landscape Engineering, Suzhou Polytechnic Institute of Agriculture, Suzhou 215000, China.
Plants (Basel). 2022 Dec 15;11(24):3544. doi: 10.3390/plants11243544.
As representative of the early-divergent groups of angiosperms, Saxifragales is extremely divergent in morphology, comprising 15 families. Within this order, our previous case studies observed significant structural diversities among the plastomes of several lineages, suggesting a possible role in elucidating their deep phylogenetic relationships. Here, we collected 208 available plastomes from 11 constituent families to explore the evolutionary patterns among Saxifragales. With thorough comparisons, the losses of two genes and three introns were found in several groups. Notably, 432 indel events have been observed from the introns of all 17 plastomic intron-containing genes, which could well play an important role in family barcoding. Moreover, numerous heterogeneities and strong intrafamilial phylogenetic implications were revealed in pttRNA (plastomic tRNA) structures, and the unique structural patterns were also determined for five families. Most importantly, based on the well-supported phylogenetic trees, evident phylogenetic signals were detected in combinations with the identified pttRNAs features and intron indels, demonstrating abundant lineage-specific characteristics for Saxifragales. Collectively, the results reported here could not only provide a deeper understanding into the evolutionary patterns of Saxifragales, but also provide a case study for exploring the plastome evolution at a high taxonomic level of angiosperms.
作为被子植物早期分化类群的代表，虎耳草目在形态上极为多样，包含15个科。在这个目内，我们之前的案例研究观察到几个谱系的质体基因组之间存在显著的结构差异，这表明质体基因组在阐明它们的深层系统发育关系中可能发挥作用。在这里，我们从11个组成科收集了208个可用的质体基因组，以探索虎耳草目的进化模式。通过全面比较，发现几个类群中存在两个基因和三个内含子的丢失。值得注意的是，在所有17个含有质体基因组内含子的基因的内含子中观察到432个插入缺失事件，这很可能在科级条形码中发挥重要作用。此外，在质体基因组tRNA（pttRNA）结构中揭示了许多异质性和强烈的科内系统发育意义，并且还确定了五个科的独特结构模式。最重要的是，基于得到充分支持的系统发育树，结合已鉴定的pttRNA特征和内含子插入缺失检测到明显的系统发育信号，表明虎耳草目具有丰富的谱系特异性特征。总体而言，这里报道的结果不仅可以提供对虎耳草目进化模式的更深入理解，还可以为在被子植物高分类水平上探索质体基因组进化提供一个案例研究。
