The Complete Mitochondrial Genome of Thymus mongolicus and I

The Complete Mitochondrial Genome of Thymus mongolicus and Its Phylogenetic Relationship with Lamiaceae Species

 https://doi.org/10.3390/biom15030343


Thymus mongolicus (Lamiaceae) is a plant commonly found throughout China, in which it is widely used in chemical products for daily use, traditional medicinal preparations, ecological management, and cooking. In this study, we have assembled and annotated for the first time the entire mitochondrial genome (mitogenome) of T. mongolicus. The mitochondrial genome of T. mongolicus is composed in a monocyclic structure, with an overall size of 450,543 base pairs (bp) and a GC composition of 45.63%. It contains 32 unique protein-encoding genes. The repetitive sequences of the T. mongolicus mitogenome include 165 forward repetitive sequences and 200 palindromic repetitive sequences, in addition to 88 simple sequence repeats, of which tetramers accounted for the highest proportion (40.91%). An analysis of the mitogenome codons revealed that synonymous codons generally end with A/U. With the exception of nad4L, which uses ACG/ATG as an initiation codon, all other genes begin with the ATG start codon. Codon analysis of the mitogenome also showed that leucine (909) are the most abundant amino acid, while tryptophan (134) are the least prevalent. In total, 374 RNA editing sites were detected. Moreover, 180 homologous segments totaling 105,901 bp were found when the mitochondrial and chloroplast genomes of T. mongolicus were compared. Phylogenetic analysis further indicated that T. mongolicus is most closely related to Prunella vulgaris in the Lamiaceae family. Our findings offer important genetic insights for further research on this Lamiaceae species. To the best of our knowledge, this study is the first description of the entire mitogenome of T. mongolicus.
百里香（Thymus mongolicus，唇形科）广布中国，是日用化工、传统医药、生态治理及烹调领域的重要植物。本研究首次完成其线粒体基因组（mitogenome）的组装与注释。该基因组呈单环结构，全长 450,543 bp，GC 含量 45.63%，编码 32 个独特蛋白基因。重复序列包括 165 个正向重复、200 个回文重复及 88 个简单序列重复（SSR），其中四核苷酸 SSR 占比最高（40.91%）。密码子分析显示，同义密码子多以 A/U 结尾；除 nad4L 使用 ACG/ATG 双起始密码子外，其余基因均以 ATG 起始。氨基酸组成方面，亮氨酸（909 个）最丰富，色氨酸（134 个）最少。共鉴定 374 个 RNA 编辑位点。线粒体与叶绿体基因组比对发现 180 个同源片段，总长 105,901 bp。系统发育分析表明，蒙古百里香与唇形科夏枯草（Prunella vulgaris）亲缘关系最近。本研究为深入挖掘该唇形科植物遗传资源提供关键数据，亦为首次报道百里香完整线粒体基因组。


The complete mitochondrial genome of Thymus mongolicus is represented in a circular diagram. In the figure, the genes of the outer ring showed positive transcription, while the genes of the inner ring showed reverse transcription. In the inner ring of the figure, the GC content was highlighted in an intuitive carbon gray tone, and different functional gene categories were color-coded.