In a groundbreaking discovery, scientists have identified a small fern species with the largest known genome in the world. The findings, published in the journal iScience, reveal that this unassuming plant carries a genetic blueprint that dwarfs those of most other living organisms.
The fork fern Tmesipteris oblanceolata, native to the South Pacific islands of New Caledonia, boasts a genome size of approximately 160 billion nucleobases, the largest ever genome discovered till now. This genetic behemoth outstrips the human genome by more than 50 times and surpasses the previous record-holder by about 7 percent.
Lead researcher Jaume Pellicer, an evolutionary biologist from the Botanical Institute of Barcelona, expressed amazement at the fern’s genomic proportions. “Despite its modest size of just 15 centimeters, this plant carries an astounding amount of genetic information,” Pellicer noted.
The team’s investigation involved a meticulous survey of six fork fern species found in New Caledonia. Using fluorescent dye techniques to measure DNA content in leaf cells, they were able to calculate the genome sizes of each species.
This discovery raises intriguing questions about the biological limits of genome size and the evolutionary processes that lead to such extremes. Pellicer highlighted the energetic demands of maintaining such a large genome, pointing out that cell division requires the replication of over 100 meters of DNA.
Plant genomes are known for their variability, with the largest being thousands of times larger than the smallest. Scientists attribute this variation to processes such as chromosome duplication and the accumulation of repetitive DNA sequences.
Liming Cai, a plant evolutionary scientist from the University of Texas at Austin who was not involved in the study, suggested that repeated genetic bottlenecks might play a role in the development of such enormous genomes. These events could lead to the accumulation of non-functional DNA over time.
The research underscores the importance of studying less prominent species in biodiversity research. As Pellicer remarked, “This unassuming fern might easily be overlooked, but it conceals an extraordinary genetic treasure within its cells.”
Further analysis of the T. oblanceolata genome could provide valuable insights into the mechanisms of genome expansion and the functional implications of extreme genome sizes in plants. This discovery not only sets a new record but also opens up exciting avenues for future research in plant genetics and evolution.