First Mitochondrial Genomes Tie Endangered Hansenia Speciation to Plateau Uplift

Researchers have assembled the first complete mitochondrial genomes of Hansenia, a genus of perennial medicinal herbaceous plants native to the Qinghai-Tibet Plateau and surrounding regions whose species are valued for antioxidant, antiviral, and antitumor properties. The open-access study, published in BMC Plant Biology, characterised the organelle genomes of eight individuals representing four endangered Hansenia species using a hybrid sequencing strategy that integrated Illumina, HiFi, and Oxford Nanopore Technologies (ONT) data. Until this work, no complete mitochondrial genome of any Hansenia species had been characterised, leaving the mitochondrial side of this high-altitude lineage’s genetics unexplored.

The assemblies revealed varied genome architectures. For most of the eight individuals, the mitochondrial genome was represented by a single master circle model, but the two individuals of H. forbesii differed from one another: one showed a circular configuration while the other assembled into a branched structure. The finished mitochondrial genomes ranged in size from 284,004 to 339,028 base pairs and contained 36 to 40 annotated protein-coding sequence copies, 24 to 30 transfer RNA genes, and three ribosomal RNA genes. Guanine-cytosine content varied narrowly across the genomes, from 44.1 to 45.1 percent.

The team also predicted RNA editing, a post-transcriptional process in plant mitochondria, across 35 protein-coding genes in each genome. The analysis identified 535 to 538 editing sites per genome, with species-level variation: 535 sites in H. weberbaueriana, 538 in H. forrestii, 536 to 538 in H. forbesii, and 535 to 537 in H. oviformis. These counts document the editing landscape of the genus’s mitochondrial transcripts at fine resolution for the first time.

The study also quantified DNA sequences of chloroplast origin embedded within the mitochondrial genomes. Such chloroplast-derived fragments ranged from as little as 29 base pairs to as much as 8,931 base pairs, and their transfer frequency was significantly higher in H. forbesii and H. oviformis than in the other species examined. This uneven distribution of organellar sequences across closely related species provides a molecular record of how differently each lineage’s mitochondrial genome has incorporated chloroplast material.

Phylogenetic reconstruction based on the mitochondrial genomes recovered interspecific relationships consistent with those previously inferred from plastid and nuclear data, giving the genus a coherent evolutionary picture across three genomes. Molecular dating added a geological dimension: the divergence times of the Hansenia species closely correspond with the second uplift event of the Qinghai-Tibet Plateau, dated to 13 to 15 million years ago, and the third uplift event, dated to 7 to 8 million years ago. The authors suggest that geographic isolation driven by the plateau’s uplift served as a major evolutionary driver for speciation in the genus.

As the first mitochondrial genomes reported for Hansenia, the assemblies provide a genomic foundation for future research on the genus. According to the study’s conclusions, the resource offers crucial biological insights into the evolutionary history, adaptive mechanisms, and phylogenetic relationships of these endangered plateau plants, whose speciation history appears written by the same tectonic forces that raised their habitat.

Subject of Research: Comparative mitochondrial genome analysis of endangered Hansenia species on the Qinghai-Tibet Plateau

Article Title: Comparative analysis of mitochondrial genomes of the endangered Hansenia species in the qinghai-tibet plateau

Article References: Luo, C., Zhao, W., Wu, X., Mao, N., Zhao, H., Liu, R., Guo, M., Wang, H., Fang, X., Chen, W., Liu, M., & Li, Z. (2026). Comparative analysis of mitochondrial genomes of the endangered Hansenia species in the qinghai-tibet plateau. BMC Plant Biology. https://doi.org/10.1186/s12870-026-10131-6

Image Credits: AI Generated

DOI: 10.1186/s12870-026-10131-6

Keywords: mitochondrial genome, Hansenia, Qinghai-Tibet Plateau, organelle genome assembly, RNA editing, chloroplast DNA transfer, phylogenetics, molecular dating, speciation, endangered medicinal plants, Comparative, analysis