Park Inkyu, Yang Sungyu, Song Jun-Ho, Moon Byeong Cheol
Herbal Medicine Resources Research Center, Korea Institute of Oriental Medicine, Naju, South Korea.
Front Plant Sci. 2020 Dec 4;11:606463. doi: 10.3389/fpls.2020.606463. eCollection 2020.
The genera and (Lithospermeae-Boraginaceae) comprise 25-30 and 50-60 species, respectively. Some of them are economically valuable, as their roots frequently contain a purple-red dye used in the cosmetic industry. Furthermore, dried roots of , , and , which have been designated Lithospermi Radix, are used as traditional Korean herbal medicine. This study is the first report on the floral micromorphology and complete chloroplast (cp) genome sequences of (including ), , and . We reveal great diversity in floral epidermal cell patterns, gynoecium, and structure of trichomes. The cp genomes were 149,361-150,465 bp in length, with conserved quadripartite structures. In total, 112 genes were identified, including 78 protein-coding regions, 30 tRNA genes, and four rRNA genes. Gene order, content, and orientation were highly conserved and were consistent with the general structure of angiosperm cp genomes. Comparison of the four cp genomes revealed locally divergent regions, mainly within intergenic spacer regions (, , , , , and ). To facilitate species identification, we developed molecular markers - (PSY), (TCY), and - (NCTV) based on divergence hotspots. High-resolution phylogenetic analysis revealed clear clustering and a close relationship of to its sister group, which was supported by strong bootstrap values and posterior probabilities. Overall, gynoecium characteristics and genetic distance of cp genomes suggest that , might be recognized as an independent species rather than a synonym of . The present morphological and cp genomic results provide useful information for future studies, such as taxonomic, phylogenetic, and evolutionary analysis of Boraginaceae.
紫草属（紫草科）和假紫草属分别包含25 - 30种和50 - 60种植物。它们中的一些具有经济价值，因为其根部通常含有一种用于化妆品行业的紫红色染料。此外，紫草、新疆紫草和内蒙紫草的干燥根被用作韩国传统草药，已被指定为紫草。本研究首次报道了紫草（包括假紫草）、新疆紫草和内蒙紫草的花部微形态以及完整叶绿体（cp）基因组序列。我们揭示了花表皮细胞模式、雌蕊和毛状体结构的巨大差异。cp基因组长度为149,361 - 150,465 bp，具有保守的四分体结构。总共鉴定出112个基因，包括78个蛋白质编码区、30个tRNA基因和4个rRNA基因。基因顺序、含量和方向高度保守，与被子植物cp基因组的一般结构一致。对这四个cp基因组的比较揭示了局部差异区域，主要存在于基因间隔区（如trnH-psbA、trnL-F、rpl32-trnL、rps16-trnQ、trnC-ycf6和psbK-psbI）。为便于物种鉴定，我们基于差异热点开发了分子标记——八氢番茄红素合成酶（PSY）、番茄红素环化酶（TCY）和核酮糖-1,5-二磷酸羧化酶大亚基（NCTV）。高分辨率系统发育分析揭示了明显的聚类以及紫草与其近缘姐妹群的密切关系，这得到了较高的自展值和后验概率的支持。总体而言，雌蕊特征和cp基因组的遗传距离表明，内蒙紫草可能应被视为一个独立的物种，而非新疆紫草的同义词。目前的形态学和cp基因组学结果为紫草科未来的研究，如分类学、系统发育和进化分析，提供了有用的信息。
