Rare Korean Shrub Genome Mapped to Reveal Hidden Plant Evolution Secrets

A rare flowering shrub native exclusively to the limestone forest slopes of Korea has finally had its complete genetic blueprint mapped. The deciduous plant, known scientifically as Zabelia densipila, is celebrated for its dense hairs on leaves and flowers, and researchers have now sequenced its entire chloroplast genome to better understand how it fits into the broader plant family tree.

Chloroplasts are specialized structures inside plant cells that handle photosynthesis and possess their own distinct DNA, which scientists frequently use to trace evolutionary history. Before this analysis, complete chloroplast genomes, or plastomes, had been cataloged for seven other species within the genus Zabelia, but Z. densipila remained unmapped since its initial discovery in Gangwon-do back in 2012. The fresh leaf samples used for this latest sequencing effort were gathered in Jeongseon-gun in April 2020 by researchers Hee-Young Gil, Sa Bum Jang, and Ye-Rim Choi.

How the Rare Korean Shrub Was Sequenced in Detail

To decode the plant’s genetic material, the research team extracted total genomic DNA from silica-dried leaves and ran it through high-throughput sequencing technology. They generated millions of paired-end reads, which were cleaned and assembled into a single continuous sequence. The findings are published in Mitochondrial DNA Part B, Resources by authors Tae-Soo Kim, Seung-Chul Kim, Young-Chan Ha, Ye-Rim Choi, Hee-Young Gil, and Byoung-Yoon Lee.

The resulting plastome spans 156,361 base pairs in length and displays the classic quadripartite structure seen in most flowering plants. This layout includes a large single-copy region of 87,094 base pairs, a small single-copy region of 17,845 base pairs, and a pair of identical inverted repeat regions measuring 25,711 base pairs each. The overall guanine-cytosine content, which measures the stability of the DNA strands, sits at 37.8 percent.

What the Genetic Map Reveals About Plant Evolution

In total, the chloroplast genome houses 130 genes, including 85 protein-coding genes, 37 transfer RNA genes, and 8 ribosomal RNA genes. The team also mapped out complex gene-splicing features, identifying 11 unique cis-splicing genes along with one trans-spliced gene. Across the entire circular genome, sequencing depth averaged over 704 times coverage, ensuring high accuracy with no gaps.

To determine evolutionary relationships, the authors constructed a maximum-likelihood phylogenetic tree using 79 concatenated protein-coding genes from Z. densipila and 17 related taxa. The analysis strongly supported the monophyly, or single common ancestry, of the genus Zabelia. Interestingly, Z. densipila formed a distinct clade alongside Zabelia biflora and Zabelia dielsii, a species found in China. Meanwhile, the genus Morina emerged as a sister group to Zabelia, while traditional relatives like Abelia grouped further away.

Because Z. densipila has a very restricted geographic range in Korea, having this complete genetic reference provides a crucial tool for future conservation efforts and population genetics. The authors note that while the plastome clarifies evolutionary branches within the family Caprifoliaceae, broader sampling of nuclear markers will still be required to fully map out the complex history of these woody plants.

The research was published in Mitochondrial DNA. Part B, Resources on October 27, 2026.