The genome of a new fern species from New Caledonia is the largest among all organisms

Tumecipteris oblancorata is a rare fern species known as the wolf lark, found in New Caledonia, a French overseas territory in the southwest Pacific Ocean. It has recently broken the world record with its genome size of 160.45 billion base pairs (Gbp), challenging current understanding and paving the way for further exploration of genome gigantism.

Tomesypteris is a small and relatively understudied genus consisting of 15 species, mostly found in Oceania and some Pacific islands.

Scientists have previously estimated the genome sizes of two Tomesypteris species – Tumecipteris tannensis and Tomesypteris obliqua – with large genomes of 73.19 Gbp and 147.29 Gbp, respectively.

In 2023, Dr. Jaume Pellicer and his colleagues from the Royal Botanic Gardens, Kew, traveled to New Caledonia to analyze the genome size of Tumecipteris oblancorata.

The analysis revealed a record-breaking genome size of 160.45 Gbp for Tumecipteris oblancorata, also known as Tumecipteris truncata, surpassing the genome size of the Japanese flower plant species Paris Japonica (148.89 Gbp). For comparison, the human genome contains approximately 3.1 Gbp across 23 chromosomes.

Tomesypteris is a unique fern genus whose ancestors date back around 350 million years, characterized by primarily being epiphytes with a distribution limited to Oceania and a few Pacific islands.

Dr. Ilia Reich of the Royal Botanic Gardens, Kew, expressed surprise at the world record held by the inconspicuous Tumecipteris oblancorata, highlighting the diversity of plants at the DNA level and their importance in Earth’s biodiversity.

The team’s findings were published in the journal iScience.

Genome size diversity in eukaryotes: (A) Current distribution of genome sizes in the major lineages of plants, animals, and fungi. (B) Top 10 largest genome sizes recorded in eukaryotes. Image courtesy of Pol Fernández et al., doi: 10.1016/j.isci.2024.109889.

This remarkable discovery raises questions about the biological limits and complexities of plant genomes, inspiring further exploration into the mysteries of genome gigantism.

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Pol Fernandez othersThe 160 Gbp fork fern genome breaks eukaryotic size record. iSciencePublished online May 31, 2024, doi: 10.1016/j.isci.2024.109889