Research Background
Study Overview
Biological invasions can disrupt native ecosystems, reduce biodiversity, and alter habitat function. Yet the cellular and genomic mechanisms that enable introduced plant populations to establish and spread successfully remain incompletely understood.
Phragmites australis, commonly known as common reed, is widely distributed across wetland ecosystems. Populations introduced from Europe have become highly invasive in North America, where they often display stronger regenerative capacity and other traits associated with successful establishment.
A study published in Genome Biology investigated how gene regulation in the regenerating shoot system differs between European source populations and invasive North American populations. The researchers focused particularly on B chromosomes—supernumerary chromosomes that occur in addition to the standard chromosome set—and examined whether their copy number and gene activity are associated with plant invasiveness.
Study Design
An Integrated Cellular and Genomic Strategy
The study analyzed newly regenerated shoots from six allotetraploid P. australis individuals grown under common-garden conditions: three from a European source population and three from a North American invasive population. Single-cell RNA sequencing was used to characterize transcriptionally distinct cell populations, while spatial transcriptomics mapped these expression profiles back to their anatomical locations within the shoot.
The researchers then integrated these cell-resolved datasets with bulk RNA sequencing, comparative genomics, phylogenetic analysis, and selective-sweep analysis. Population-level RAD sequencing of 88 individuals and whole-genome sequencing of nine individuals were also used to assess B-chromosome copy-number variation across lineages.
This multi-layered approach enabled the team to connect differences in chromosome dosage with gene expression patterns across individual cell types and explore how these genomic features may relate to the invasive phenotype.
Research Highlights
Key Findings
A High-Resolution Cell Atlas of the Regenerating Shoot
After quality control, the single-cell dataset contained 57,217 cells and resolved 19 transcriptionally distinct cell types, including meristematic, parenchyma, mesophyll, epidermal, and vascular populations. Spatial transcriptomics further identified 17 spatial clusters and localized cell-type expression programs within the anatomical structure of the shoot.
Together, these datasets established a cell type-resolved molecular atlas of a non-model invasive plant and provided the framework needed to compare gene regulation between invasive and non-invasive populations.
B Chromosomes Are Expanded in Invasive Populations
Population genomic analyses showed consistently higher B-chromosome copy numbers in invasive North American individuals than in other lineages. Whole-genome sequencing indicated an average of approximately four B-chromosome copies in the invasive population, whereas B chromosomes were nearly absent from the European source population examined in the study.
The marked difference in chromosome dosage provides genomic evidence of B-chromosome expansion in the invasive lineage and offers a basis for investigating how these additional chromosomes may influence gene regulation and environmental adaptation.
B-Chromosome Genes Show Broad Expression Differences
A substantial proportion of the genes upregulated in invasive plants were located on B chromosomes. Four B-chromosome loci—PaChr24B.43 (IMP-α3), PaChr24B.82 (GATA2), and two SCC3-related loci, PaChr24B.218 and PaChr24B.240—were consistently differentially expressed across nearly all cell types.
The invasive population also displayed cell type-specific transcriptional responses associated with sugar starvation, light deprivation, hypoxia, cell-wall organization, and defense. These patterns suggest that increased B-chromosome dosage may contribute to regulatory differences relevant to growth and adaptation, although direct functional validation is still required.
Research Significance
New Insights into the Genomic Basis of Plant Invasion
This study extends the investigation of plant invasiveness from whole-tissue comparisons to individual cell types and their spatial organization. By combining a high-resolution molecular atlas with population and comparative genomic analyses, it reveals a clear association among B-chromosome expansion, B-linked gene expression, and transcriptional characteristics of invasive P. australis.
The findings provide a valuable resource for studying shoot regeneration, environmental adaptation, and the genomic features associated with biological invasion. Importantly, the authors note that the current evidence establishes correlation rather than causation. Functional experiments targeting key B-chromosome genes, together with broader population studies, will be needed to determine whether and how these genes directly influence invasive traits.
BMKGENE Contribution
Supporting Spatially Resolved Analysis of Common Reed Shoots
BMKGENE provided BMKMANU S3000 spatial transcriptomics sequencing services for this study. The spatially resolved transcriptomic data supported the localization of cell populations and gene expression programs across regenerating shoot sections.
By combining molecular information with tissue context, the analysis contributed to the construction of the high-resolution shoot atlas and enabled detailed comparison of cell type-specific expression patterns between European source and North American invasive populations.
BMKMANU S3000 Spatial Transcriptomics
Original Publication
Wang, C., Ord, J., Yan, M., et al. Single-cell and spatial transcriptomics in Phragmites australis reveal the association of B chromosomes with plant invasiveness. Genome Biology 27, 184 (2026). DOI: 10.1186/s13059-026-04079-x.
Post time: Sep-11-2026
