New research has revealed that a small fern species named Tmesipteris oblanceolata (pronounced: teh-meh-SIP-teh-ris ob-lan-see-oh-LAH-tuh), found in New Caledonia, has the largest genome of any living organism. This genome is 7% larger than that of the previous record-holder, the Japanese plant Paris japonica, and over 50 times the size of the human genome. The fern’s DNA, if stretched out, would extend nearly 350 feet, which is taller than iconic structures like the Statue of Liberty. Tmesipteris oblanceolata grows primarily on the ground or atop fallen tree trunks in New Caledonia and nearby islands such as Vanuatu. Despite its small size of 10-15 centimeters, it has a remarkably large genome, which has puzzled scientists. The large genome does not seem to offer any evolutionary advantage and may be due to the plant’s inability to remove non-functional DNA sequences over time.

The study, published in the journal iScience, highlights the implications of having such a large genome. Larger genomes require more resources for DNA replication, repair, and transcription, which can strain the plant’s energy and nutrient resources, potentially affecting growth, reproduction, and stress responses. Additionally, larger genomes necessitate larger cells, slowing down cellular division and growth, which could limit the plant’s ecological competitiveness. This phenomenon raises questions about why some organisms have large genomes while others do not, as there is no clear relationship between genome size and organism complexity. The little fern’s genome is significantly larger than those of much larger animals and plants, such as the blue whale, African elephant, and giant redwood tree. Researchers continue to study genome sizes across various organisms to understand their role in biodiversity and ecological adaptation.