Liu Lu-Xian, Du Ying-Xue, Folk Ryan A, Wang Shen-Yi, Soltis Douglas E, Shang Fu-De, Li Pan
Key Laboratory of Plant Stress Biology, School of Life Sciences, Henan University, Kaifeng, China.
Department of Biological Sciences, Mississippi State University, Starkville, MS, United States.
Front Plant Sci. 2020 Apr 24;11:361. doi: 10.3389/fpls.2020.00361. eCollection 2020.
Saxifragaceae, a family of over 600 species and approximately 30 genera of herbaceous perennials, is well-known for intergeneric hybridization. Of the main lineages in this family, the group represents a valuable model for the analysis of plastid capture and its impact on phylogeny reconstruction. In this study, we investigated plastome evolution across the family, reconstructed the phylogeny of the group and examined putative plastid capture between and . Seven species (11 individuals) representing , as well as and , were selected for genome skimming. We assembled the plastomes, and then compared these to six others published for Saxifragaceae; the plastomes were found to be highly similar in overall size, structure, gene order and content. Moreover, 15 was lost due to pseudogenization and 2 lost its only intron for all the analyzed plastomes. Comparative plastome analysis revealed that size variations of the plastomes are purely ascribed to the length differences of LSC, SSC, and IRs regions. Using nuclear ITS + ETS and the complete plastome, we fully resolved the species relationships of , finding that the genus is monophyletic and the Asian species is most closely related to the western North American species. However, the position of the species was highly incongruent between nuclear and plastid data. Comparisons of nuclear and plastid phylogenies revealed that multiple plastid capture events have occurred between and , through putative ancient hybridization. Moreover, we developed numerous molecular markers for (e.g., plastid hotspot and polymorphic nuclear SSRs), which will be useful for future studies on the population genetics and phylogeography of this disjunct genus.
虎耳草科是一个拥有600多种、约30属多年生草本植物的科，以属间杂交而闻名。在该科的主要谱系中，[具体类群名称]代表了一个分析质体捕获及其对系统发育重建影响的宝贵模型。在本研究中，我们研究了整个科的质体基因组进化，重建了[具体类群名称]的系统发育，并研究了[两个相关类群名称]之间假定的质体捕获。选择了代表[具体类群名称]以及[另外两个相关类群名称]的7个物种（11个个体）进行基因组浅层测序。我们组装了质体基因组，然后将其与已发表的另外6个虎耳草科质体基因组进行比较；发现这些质体基因组在总体大小、结构、基因顺序和内容上高度相似。此外，在所有分析的质体基因组中，有15个基因因假基因化而丢失，2个基因失去了其唯一的内含子。比较质体基因组分析表明，质体基因组的大小变化完全归因于LSC、SSC和IRs区域的长度差异。使用核ITS + ETS和完整的质体基因组，我们完全解析了[具体类群名称]的物种关系，发现该属是单系的，亚洲物种与北美西部物种关系最为密切。然而，[某个物种名称]的位置在核数据和质体数据之间存在高度不一致。核系统发育和质体系统发育的比较表明，通过假定的古代杂交，[两个相关类群名称]之间发生了多次质体捕获事件。此外，我们为[具体类群名称]开发了许多分子标记（如质体热点和多态性核SSR），这将有助于未来对这个间断分布属的群体遗传学和系统地理学的研究。
