A near chromosome-level assembly of the serpentine endemic columbine, Aquilegia eximia

Our plain-English summary of A near chromosome-level assembly of the serpentine endemic columbine, Aquilegia eximia, by J. Johns, M. Escalona, C. Miller, et al (The Journal of Heredity, 2026).

The study

• Authors: J. Johns, M. Escalona, C. Miller, N. Chumchim, O. Nguyen, M.P.A. Marimuthu, S. Sacco, C. Fairbairn, E. Beraut, E. Toffelmier, H.B. Shaffer, S. Hodges
• Journal: The Journal of Heredity
• Published: 2026;117(1):85-95
• Cited by: 1 article, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

The flowering plant genus Aquilegia (columbine) is an important contributor to biodiversity and an example of both biotic and abiotic niche adaptation across much of the Northern Hemisphere, especially in California. Here we report a near-chromosome level draft genome assembly for A. eximia, a California endemic species. A. eximia is a serpentine-soil specialist and is very closely related to 2 columbine species also being studied for the California Conservation Genomics Project (CCGP), A. formosa (widespread) and A. pubescens (high alpine). Utilizing high throughput, long reads (PacBio) and chromatin capture (Omni-C), the A. eximia genome makes marked contiguity improvements compared to the existing reference genome for another North American columbine, A. coerulea "Goldsmith." The A. eximia genome will also be more useful for aligning whole genome resequencing data from California columbines than the genomes for more distantly related columbine species, the Asian A. oxysepala var. kansuensis and the European A. vulgaris. Notably, we found evidence that A. eximia, A. coerulea "Goldsmith," and A. vulgaris all share the same overall genome structure and differ from A. oxysepala var. kansuensis by the same reciprocal translocation. The A. eximia reference genome will be a valuable tool for identifying patterns of plant biodiversity across California for the CCGP, as well as for future population genomic and trait mapping studies.

© The American Genetic Association. 2025.

In plain English

This article reported a new genome assembly for Aquilegia eximia, a California columbine plant found almost only in seeps on serpentine soil. It does not discuss asbestos or human health. The authors sequenced DNA from one plant grown from seed collected at Prefumo Canyon in San Luis Obispo County, using PacBio long reads and Omni-C data. They estimated the genome size at 367 Mb. The primary assembled copy spanned 363.4 Mb in 265 scaffolds, with a BUSCO completeness score of 97.8%, and 95.6% of the genome sat in 8 major scaffolds. Two of these matched chromosome 4 of other columbines. The authors could not tell whether that chromosome is split in A. eximia or whether their data were insufficient to join the two scaffolds. A. eximia shared its overall genome structure with A. coerulea and A. vulgaris. It differed from the Asian A. kansuensis by the same reciprocal translocation between chromosomes 1 and 4. The authors concluded the genome will be an excellent reference for population genetic and genetic mapping studies.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Genome assembly (genome resource report) of a plant species, with comparison to other published Aquilegia genomes
• Who was studied: A single Aquilegia eximia (columbine) plant grown from seed collected at Prefumo Canyon, San Luis Obispo County, California
• Main results:
  • From the PacBio HiFi data, the estimated genome size was 367 Mb, with a 0.559% heterozygosity rate
  • The primary haplotype assembly had 265 scaffolds spanning 363.4 Mb, with a contig N50 of 6.09 Mb and a scaffold N50 of 47.38 Mb
  • The primary haplotype had a BUSCO completeness score of 97.8% for the Embryophyta gene set
  • The genome was organized in 8 major scaffolds, corresponding to 95.6% of the genome size
  • The authors found no convincing evidence to merge scaffolds 4.1 and 4.2, which align with chromosome 4 of A. coerulea and A. vulgaris
  • A. eximia, A. coerulea and A. vulgaris shared overall similar chromosome structures without large translocations
  • Compared with A. kansuensis, A. eximia showed the same reciprocal translocation between chromosomes 1 and 4 previously seen between A. coerulea and A. kansuensis
  • The A. eximia genome (363 Mb) was larger than the genomes of A. coerulea, A. kansuensis and A. vulgaris (292 to 296 Mb)
  • The comparisons suggested that scaffold order and orientation in pericentromeric regions of the A. coerulea genome may be somewhat misplaced
• The authors' conclusion: The authors concluded that the A. eximia genome will be an excellent reference genome for population genetic and genetic mapping studies, especially for closely related North American taxa
• Limitations the authors state:
  • The authors could not determine whether chromosome 4 has split into 2 chromosomes in A. eximia or whether their data were insufficient to merge the two scaffolds, and said future studies would be needed

Topics

The National Library of Medicine indexes this study under subjects our site covers: Chrysotile.

Medical terms in this study, explained in our Lexicon: Serpentine Group, Endemic, Translocation.

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