Tian Chunyu, Li Xiansong, Wu Zinian, Li Zhiyong, Hou Xiangyang, Li Frank Yonghong
Institute of Grassland Research, Chinese Academy of Agricultural Sciences, Hohhot, China.
School of Ecology and Environment, Inner Mongolia University, Hohhot, China.
Front Genet. 2021 Aug 5;12:705482. doi: 10.3389/fgene.2021.705482. eCollection 2021.
Astragalus is the largest genus in Leguminosae. Several molecular studies have investigated the potential adulterants of the species within this genus; nonetheless, the evolutionary relationships among these species remain unclear. Herein, we sequenced and annotated the complete chloroplast genomes of three species-, var. , and using next-generation sequencing technology and plastid genome annotator (PGA) tool. All species belonged to the inverted repeat lacking clade (IRLC) and had similar sequences concerning gene contents and characteristics. Abundant simple sequence repeat (SSR) loci were detected, with single-nucleotide repeats accounting for the highest proportion of SSRs, most of which were A/T homopolymers. Using var. as reference, the divergence was evident in most non-coding regions of the complete chloroplast genomes of these species. Seven genes (, , , , , , and ) showed high nucleotide variability (Pi), and could be used as DNA barcodes for sp. and were found undergoing positive selection by the section patterns in the coded protein. Phylogenetic analysis showed that is a monophyletic group closely related to the genus within the tribe Galegeae. The newly sequenced chloroplast genomes provide insight into the unresolved evolutionary relationships within spp. and are expected to contribute to species identification.
黄芪属是豆科中最大的属。一些分子研究调查了该属内物种的潜在掺假物；然而，这些物种之间的进化关系仍不清楚。在此，我们使用下一代测序技术和质体基因组注释工具（PGA）对三种物种——[物种名称1]、[物种名称2]变种和[物种名称3]的完整叶绿体基因组进行了测序和注释。所有物种都属于缺乏反向重复序列的分支（IRLC），并且在基因内容和特征方面具有相似的序列。检测到丰富的简单序列重复（SSR）位点，其中单核苷酸重复占SSR的比例最高，大多数是A/T同聚物。以[物种名称2]变种为参考，这些物种完整叶绿体基因组的大多数非编码区域存在明显差异。七个基因（[基因名称1]、[基因名称2]、[基因名称3]、[基因名称4]、[基因名称5]、[基因名称6]和[基因名称7]）显示出高核苷酸变异性（Pi），可作为[物种名称1]和[物种名称3]的DNA条形码，并且发现[物种名称3]在编码蛋白中通过区段模式经历正选择。系统发育分析表明，[物种名称1]是一个单系类群，与山羊豆族内的[属名]属密切相关。新测序的叶绿体基因组为黄芪属物种中尚未解决的进化关系提供了见解，并有望有助于物种鉴定。
