Chen Lang, Yan Rong-Rong, Yang Chong-Yi, Ling Li-Zhen, Bai Xin-Xiang, Ren Qi-Fei, Hu Guo-Xiong
College of Life Sciences, Guizhou University, Guiyang, 550025, Guizhou, China.
Key Laboratory of Plant Resource Conservation and Germplasm Innovation in Mountainous Region (Ministry of Education), Guizhou University, Guiyang, 550025, Guizhou, China.
BMC Plant Biol. 2025 Jul 2;25(1):827. doi: 10.1186/s12870-025-06838-7.
H. Lév., a member of the Gesneriaceae family with an actinomorphic corolla, is evaluated as vulnerable and classified as a National Grade I Protected Plant. The species is endemic to Guizhou Province in southwestern China, restricted to the Longtoudashan Nature Reserve. Current research on mitochondrial genomes (mitogenomes) in Gesneriaceae plants is limited to only three species. Given the crucial role of mitochondria in plant energy metabolism and stress responses, mitogenome analyses may offer novel insights into the genetic basis of adaptive traits and contribute to understanding evolutionary processes. Therefore, in this study, we assembled and annotated the mitogenome of , and performed comparative analyses to investigate structural features and variation across mitogenomes.
The mitogenome of exhibited a linear structure, consisting of 36 protein-coding genes (PCGs), 23 tRNA genes, three rRNA genes, and one pseudogene. A total of 158 repeat sequences were identified, with the majority located in intergenic regions, while a smaller fraction appeared in coding regions. Homology analysis revealed 58 plastid-derived fragments, spanning 52,103 bp and accounting for 11.45% of the mitogenome. Collinearity analysis demonstrated extensive genomic rearrangements between and its close relatives, implying structural divergence during evolution. Positive selection signals were detected in seven coding genes of the mitogenome, with a potential impact on environmental adaptation. Phylogenetic analysis inferred from shared mitochondrial genes presented a well-supported topology, in which was closely related with K. M. Liu & X. Z. Cai.
Overall, this study presents the first report of the complete mitogenome of , revealing a linear structure, extensive genomic rearrangements, and frequent plastid-derived DNA insertions. Despite structural variation, the mitogenomes of remains relatively conserved at the sequence level, particularly in terms of gene content, GC content, and codon usage bias. These findings highlight dynamic genomic evolution and provide critical molecular resources for future studies on plant adaptation and species conservation.
The online version contains supplementary material available at 10.1186/s12870-025-06838-7.
半边莲（H. Lév.）是苦苣苔科的一员，具有辐射对称花冠，被评估为易危物种，列为国家一级保护植物。该物种是中国西南部贵州省的特有种，仅分布于龙头大山自然保护区。目前对苦苣苔科植物线粒体基因组（mitogenomes）的研究仅限于三个物种。鉴于线粒体在植物能量代谢和应激反应中的关键作用，线粒体基因组分析可能为适应性性状的遗传基础提供新的见解，并有助于理解进化过程。因此，在本研究中，我们组装并注释了半边莲的线粒体基因组，并进行了比较分析，以研究线粒体基因组的结构特征和变异。
半边莲的线粒体基因组呈现线性结构，由36个蛋白质编码基因（PCGs）、23个tRNA基因、3个rRNA基因和1个假基因组成。共鉴定出158个重复序列，大多数位于基因间区域，而较小一部分出现在编码区域。同源性分析揭示了58个来自质体的片段，跨度为52,103 bp，占线粒体基因组的11.45%。共线性分析表明半边莲与其近缘种之间存在广泛的基因组重排，这意味着在进化过程中结构发生了分化。在半边莲线粒体基因组的7个编码基因中检测到正选择信号，这可能对环境适应有潜在影响。基于共享线粒体基因推断的系统发育分析呈现出一个得到充分支持的拓扑结构，其中半边莲与刘氏苦苣苔（K. M. Liu & X. Z. Cai）关系密切。
总体而言，本研究首次报道了半边莲完整的线粒体基因组，揭示了其线性结构、广泛的基因组重排以及频繁的质体来源DNA插入。尽管存在结构变异，但半边莲的线粒体基因组在序列水平上仍相对保守，特别是在基因含量、GC含量和密码子使用偏好方面。这些发现突出了动态的基因组进化，并为未来植物适应性和物种保护研究提供了关键的分子资源。
在线版本包含可在10.1186/s12870-025-06838-7获取的补充材料。
