Ha Young-Ho, Kim Changkyun, Choi Kyung, Kim Joo-Hwan
Department of Life Science, Gachon University, Seongnam, South Korea.
Korea National Arboretum, Pocheon, South Korea.
Front Plant Sci. 2018 Feb 5;9:99. doi: 10.3389/fpls.2018.00099. eCollection 2018.
Tribe Forsythieae (Oleaceae), containing two genera ( and ) and 13 species, is economically important plants used as ornamentals and in traditional medicine. This tribe species occur primarily in mountainous regions of Eurasia with the highest species diversity in East Asia. Here, we examine 11 complete chloroplast genome and nuclear () DNA sequences of 10 species and using Illumina platform to provide the phylogeny and biogeographic history of the tribe. The chloroplast genomes of the 11 Forsythieae species are highly conserved, except for a deletion of about 400 bp in the - region detected only in . Within Forsythieae species, analysis of repetitive sequences revealed a total of 51 repeats comprising 26 forward repeats, 22 palindromic repeats, and 3 reverse repeats. Of those, 19 repeats were common and 32 were unique to one or more Forsythieae species. Our phylogenetic analyses supported the monophyly of and its sister group is using the concatenated dataset of 78 chloroplast genes. Within , and were basal lineages followed by ; the three species are characterized by minutely serrate or entire leaf margins. The remaining species, which are distributed in East Asia, formed two major clades. One clade included , , and ; they are morphologically supported by broadly ovate leaves. Another clade of , , , and characterized by lanceolate leaves (except which have broad ovate leaves). Although phylogeny is largely congruent to chloroplast genome phylogeny, we find the discordance between two phylogenies in the position of suggesting that introgression of the chloroplast genome from one species into the nuclear background of another by interspecific hybridization in East Asian species. Molecular dating and biogeographic reconstructions suggest an origin of the Forsythieae species in East China in the Miocene. Distribution patterns in indicated that the species were radially differentiated from East China, and the speciation of the European was the result of both vicariance and dispersal in the late Miocene to Pliocene.
连翘族（木犀科）包含两个属（连翘属和素馨属）以及13个物种，是具有重要经济价值的植物，可用于观赏和传统医学。该族物种主要分布在欧亚大陆的山区，东亚地区的物种多样性最高。在此，我们使用Illumina平台检测了10个连翘属物种和1个素馨属物种的11个完整叶绿体基因组以及核（核糖体DNA）DNA序列，以提供该族的系统发育和生物地理历史。11个连翘族物种的叶绿体基因组高度保守，仅在金钟连翘中检测到在trnL-F区域有大约400 bp的缺失。在连翘族物种中，对重复序列的分析共发现51个重复序列，包括26个正向重复序列、22个回文重复序列和3个反向重复序列。其中，19个重复序列是常见的，32个是一个或多个连翘族物种特有的。我们的系统发育分析支持连翘属的单系性，其姊妹群是素馨属，使用78个叶绿体基因的串联数据集得出此结果。在连翘属内，金钟连翘和秦连翘是基部支系，随后是连翘；这三个物种的特征是叶片边缘有细锯齿或全缘。其余分布在东亚的物种形成了两个主要分支。一个分支包括丽江连翘、川滇连翘和东北连翘；它们在形态上的支持特征是叶片宽卵形。另一个分支包括金钟连翘、连翘、奇异连翘和毛连翘，其特征是叶片披针形（除金钟连翘具有宽卵形叶片外）。尽管核糖体DNA系统发育在很大程度上与叶绿体基因组系统发育一致，但我们发现在金钟连翘的位置上两个系统发育之间存在不一致，这表明在东亚连翘属物种中通过种间杂交，叶绿体基因组从一个物种渗入到另一个物种的核背景中。分子年代测定和生物地理重建表明，连翘族物种起源于中新世的中国东部。连翘属的分布模式表明，这些物种从中国东部呈放射状分化，欧洲连翘的物种形成是中新世晚期至上新世期间地理隔离和扩散的结果。
