The research team, led by Yusheng Wang and Cunyu Zhou of Yangtze University together with colleagues at Huazhong University of Science and Technology, the Wuhan Botanical Garden of the Chinese Academy of Sciences, and Southwest Minzu University, assembled complete mitochondrial genomes from nine accessions of D. fruticosa and one accession of D. glabra. Rather than relying on short-read sequencing, which often struggles with the repetitive architecture of plant mitogenomes, the team used PacBio HiFi long reads, a technology that produces highly accurate reads long enough to span the complex repeats that make plant mitochondrial DNA notoriously difficult to assemble. When combined with two previously published accessions, the dataset encompassed twelve complete mitogenomes, providing an unusually rich comparative resource for a single plant genus.

The assembled genomes ranged in size from 263,889 to 294,600 base pairs, a span of roughly thirty thousand base pairs that underscores how variable mitochondrial genomes can be even among closely related individuals of the same species. Despite this size variation, the overall architecture proved remarkably stable. Guanine-cytosine content was conserved across all twelve accessions, and the core gene set remained essentially unchanged: thirty protein-coding genes, three ribosomal RNA genes, and between seventeen and eighteen transfer RNA genes. This combination of a stable functional core with a fluctuating genome size is a hallmark of plant mitochondrial evolution, where most of the size differences arise not from changes in gene content but from the gain and loss of non-coding sequence, repeats, and foreign DNA.

Codon usage analysis added another layer to the picture. Across all twelve mitogenomes, the researchers detected a clear preference for codons ending in A or U, a pattern consistent with the nucleotide composition biases that characterize many plant mitochondrial genomes. Such preferences matter beyond mere bookkeeping: they influence translational efficiency, the evolution of synonymous sites, and the choice of markers for phylogenetic reconstruction. For researchers hoping to use mitochondrial genes to untangle relationships within Dasiphora and among its relatives in the Rosaceae, knowing which codons and which genes carry the strongest compositional signals is essential groundwork.

Perhaps the most visually striking findings came from the repeat analysis. The team catalogued abundant simple sequence repeats and dispersed repeats scattered throughout the genomes, including a set of reverse repeats that appear to be specific to the D. glabra lineage. In plant mitochondria, large repeats are not passive passengers; pairs of repeats can recombine with one another, flipping genome segments, generating alternative genomic conformations, and occasionally triggering structural rearrangements. The presence of lineage-specific reverse repeats in D. glabra suggests that this species may harbor distinct recombination dynamics, potentially shaping its mitochondrial genome architecture in ways that differ from D. fruticosa even though the two species share a recent common ancestor.

The study also documented extensive traffic of DNA between the cell’s three genome-containing compartments, a phenomenon that has fascinated plant genomicists for decades. The researchers identified multiple chloroplast-derived fragments embedded within the mitochondrial genomes, evidence of DNA flowing from the plastid into the mitochondrion over evolutionary time. They also detected large nuclear mitochondrial DNA segments, known as NUMTs, in which mitochondrial sequence has been transferred into the nucleus. Strikingly, D. glabra harbored especially large mitochondrial-derived segments, indicating that the scale of inter-compartmental DNA transfer can differ substantially even between sister species. These transfers are more than curiosities; they can disrupt genes at insertion sites, inflate genome size, and complicate phylogenetic analyses by mixing signals from different compartments.

To gauge how much raw evolutionary variation the mitogenomes contain, the team measured nucleotide diversity across the genomes. The analysis pinpointed several highly variable mitochondrial genes as well as a set of hypervariable intergenic regions in the plastid genomes. Such variable loci are exactly what population geneticists and conservation biologists need: they serve as fine-grained markers for tracking gene flow, identifying population structure, and reconstructing the demographic history of species that colonized high-altitude habitats. For a genus like Dasiphora, whose members occupy fragmented alpine landscapes sensitive to climate change, a menu of variable markers is a practical tool for future monitoring and conservation work.

Phylogenetic trees built from the mitochondrial genomes and, separately, from the plastid genomes told a consistent and intriguing story: D. glabra was consistently placed within the D. fruticosa clade rather than as a clearly diverged sister lineage. This result echoes the reticulate, or network-like, evolutionary history that nuclear data had previously suggested for the pair, and it raises questions about how species boundaries are maintained, or blurred, in this group. Whether the pattern reflects recent divergence, incomplete lineage sorting, or historical hybridization cannot be settled by organellar genomes alone, but the congruence between mitochondrial and plastid signals strengthens the case that the two species are separated by a very shallow evolutionary divide.

Collinearity analysis, which aligns the genomes to one another to detect shared blocks of sequence, revealed high structural conservation across the twelve mitogenomes, punctuated by localized rearrangements. In other words, the overall gene order and large-scale architecture have been preserved, but specific regions have been shuffled, inverted, or repositioned, likely through the repeat-mediated recombination described above. This mosaic of conservation and local disruption is characteristic of plant mitochondrial genomes, which evolve slowly at the sequence level yet can reorganize their structure abruptly. Documenting where those breakpoints occur in Dasiphora provides a baseline for future comparisons with other Rosaceae genera and for studying the mechanisms that drive mitochondrial genome rearrangement in plants.

The significance of this work extends well beyond two shrubs. Dasiphora fruticosa is an ecologically important species across vast tracts of the Northern Hemisphere’s mountainous terrain, and it serves as a model for studying adaptation to cold, high-radiation environments. By delivering the first complete mitogenomic dataset for the genus, the study fills a conspicuous gap in the genomic resources available to plant scientists and lays a foundation for research into how organellar genomes contribute, or fail to contribute, to high-altitude adaptation. The work was supported by China’s National Key Research and Development Program, the Chinese Academy of Sciences’ Light of West China Program, the Second Tibetan Plateau Scientific Expedition and Research program, and the China Postdoctoral Science Foundation, reflecting the strategic importance of alpine ecosystem research in the region. As long-read sequencing becomes routine, studies of this kind are transforming plant mitochondria from genomic backwaters into front-line systems for exploring how genomes move, merge, and evolve inside the cell, and the shrubby cinquefoils of the world’s mountains have now joined that conversation.

Subject of Research: Comparative mitochondrial genomics of the alpine shrubs Dasiphora fruticosa and D. glabra

Article Title: Comparative mitogenomics of Dasiphora fruticosa and D. glabra: insights into genome structure, inter-organellar DNA transfer, and evolutionary dynamics

Article References: Wang, Y., Zhou, H., Jiang, Z., Wang, M., Wang, H., Zhang, H., & Zhou, C. (2026). Comparative mitogenomics of Dasiphora fruticosa and D. glabra: insights into genome structure, inter-organellar DNA transfer, and evolutionary dynamics. BMC Plant Biology. https://doi.org/10.1186/s12870-026-09452-3

Image Credits: AI Generated

DOI: 10.1186/s12870-026-09452-3

Keywords: Dasiphora, mitochondrial genome, mitogenomics, DNA transfer, chloroplast, NUMTs, repeats, phylogeny, nucleotide diversity, alpine plants, Rosaceae, PacBio HiFi