The researchers identified Tmesipteris oblanceolataa fern from New Caledonia, as having the largest recorded genome, surpassing the previous record holder Paris japonica. This discovery, detailed in the iScience journal, reveals that this fern contains more than 50 times more DNA than humans and highlights the significant implications of larger genomes on plant biology and adaptation. Credit: SciTechDaily.com
THE Tmesipteris oblanceolata Fern sets new record for largest genome, impacting plant growth and adaptation.
- A fern from New Caledonia
speciesA species is a group of living organisms that share a common set of characteristics and are capable of reproducing and producing fertile offspring. The species concept is important in biology because it is used to classify and organize the diversity of life. There are different ways to define a species, but the most widely accepted is the biological species concept, which defines a species as a group of organisms capable of interbreeding and producing viable offspring in nature. This definition is widely used in evolutionary biology and ecology to identify and classify living organisms.
” data-gt-translate-attributes=”({“attribute”:”data-cmtooltip”, “format”:”html”})” tabindex=”0″ role=”link”>species received 3 Guinness World Records titles; The largest plant genome, the largest genome and the largest fern genome for the amount of
DNADNA, or deoxyribonucleic acid, is a molecule composed of two long strands of nucleotides that wrap around each other to form a double helix. It is the hereditary material in humans and almost all other organisms that contains the genetic instructions necessary for development, function, growth and reproduction. Almost all cells in the human body have the same DNA. Most DNA is found in the cell nucleus (where it is called nuclear DNA), but a small amount of DNA can also be found in the mitochondria (where it is called mitochondrial DNA or mtDNA).” data-gt-translate-attributes=”({“attribute”:”data-cmtooltip”, “format”:”html”})” tabindex=”0″ role=”link”>DNA in the core
- Lying down, the Tmesipteris oblanceolata the genome is taller than the tower of Big Ben in London
- Discovery raises new questions about how much DNA can be stored in cells
- Study will help scientists understand the impact of genome size on species facing biodiversity loss and climate change
A record genome
A new record holder for the largest amount of DNA stored in the nucleus of all living organisms on the planet has been discovered. The details were presented in a new study published in the journal iScience on May 31 by researchers from the Royal Botanic Gardens of Kew and the Institut Botànic de Barcelona (IBB-CSIC) in Spain.
With more than 100 meters of DNA discovered, the New Caledonian fork fern, Tmesipteris obblancolata, contains more than 50 times more DNA than humans and has dethroned the Japanese flowering plant species Paris japonica, which held this record since 2010. In addition, the plant has obtained three Guinness World Records titles for the largest plant genome, the largest genome and the largest fern genome for the amount of DNA in the core.
Study reveals Tmesipteris obblancolata has the largest genome, providing new insights into plant evolution and challenges. Credit: Kew
The natural habitat of the fern and the study methodology
T. oblanceolata is a rare species of fern found on the island nation of New Caledonia, a French overseas territory located in the southwest Pacific, about 750 miles east of Australia, and on some islands neighbors such as Vanuatu. The genus Tmesipteris is a little-studied group of plants consisting of approximately 15 species, most of which occur across a range of islands in the Pacific and Oceania.
So far, scientists have only estimated the genome sizes of two Tmesipteris species: T. tannensis And T. oblique – both of which contain gigantic genomes, at 73.19 and 147.29 gigabase pairs (Gbp), respectively.
In 2023, lead authors Dr Jaume Pellicer and Dr Oriane Hidalgo, from IBB and formerly of RBG Kew, traveled to New Caledonia to collect samples of Tmesipteris, which were then analyzed to estimate the size of their genome. This involved isolating the nuclei of thousands of cells, staining them with a dye, and then measuring how much of the dye was bound to the DNA in each nucleus: the more dye, the bigger the genome.
Groundbreaking results and comparisons
The analysis revealed the species T. oblanceolata have a record genome size of 160.45 Gbp, about seven percent larger than that of P. japonica (148.89 GB).
Once unraveled, the DNA of each cell of this fern would be taller than the Elizabeth Tower of Westminster, London, which is 96m high and houses the famous Big Ben bell. For comparison, the human genome contains about 3.1 Gbp spread across 23 chromosomes and when stretched like a ball of wool, the length of DNA in each cell is only about 2 m.
Implications of genome size for plant biology
Evolutionary biology researcher Dr Pellicer said: “Tmesipteris is a unique and fascinating small genus of ferns, whose ancestors evolved around 350 million years ago – long before dinosaurs set foot on Earth – and it is distinguished by its mainly epiphytic habit. (it grows mainly on the trunks and branches of trees) and restricted distribution in Oceania and several Pacific islands. For a long time we thought that beating the previous Paris japonica size record would be an impossible mission, but once again the limits of biology have exceeded our most optimistic predictions.
“Based on our previous research, we anticipated the existence of giant genomes in Tmesipteris. That said, the discovery of the greatest genome of all is not just a feat of scientific exploration, but the result of a nearly fourteen-year journey into the limitless complexity and diversity of plant genomes.
To date, scientists around the world have estimated the genome sizes of more than 20,000 eukaryotic organisms, revealing a wide range of genome sizes across the tree of life. These, in turn, have a profound impact not only on their anatomy, as larger genomes need larger cells to house them and take longer to replicate, but also on their functioning, evolution, as well as where and how they live.
In animals, some of the largest genomes include the marbled lungfish (Protopterus aethiopicus) at 129.90 Gbp and the Neuse water dog (Necturus lewisi) at 117.47 Gbp. In contrast, six of the largest known eukaryotic genomes are held by plants, including European mistletoe (Viscum album) at 100.84 Gbp.
Surprisingly, having a larger genome is generally not an advantage. In the case of plants, species with large amounts of DNA are limited to slow-growing perennials and are less effective at
” data-gt-translate-attributes=”({“attribute”:”data-cmtooltip”, “format”:”html”})” tabindex=”0″ role=”link”>photosynthesis (the process by which plants convert solar energy into sugars) and need more nutrients (especially nitrogen and phosphates) to grow and compete with their neighbors with smaller genomes. In turn, these effects can influence a plant’s ability to adapt to climate change and its risk of extinction.
Thoughts on genomic diversity and future research
Dr Ilia Leitch, Senior Research Manager – Trait Evolution, at RBG Kew, said: “Who would have thought that this unassuming little plant that most people would probably walk past without realizing it could carry a world record in terms of genome size. Compared to other organisms, plants are incredibly diverse at the DNA level, which should prompt us to think about their intrinsic value within the broader framework of global biodiversity. This discovery also raises many new and exciting questions about the upper limits of what is biologically possible, and we hope to solve these mysteries one day.
Adam Millward, editor-in-chief of Guinness World Records, said: “To think that this seemingly harmless fern has 50 times more DNA than humans has is a humbling reminder that there is still so much we don’t know. on the plant kingdom and that the record holders are not always the most visible on the outside.
Reference: “A 160 Gbp forked fern genome breaks the size record for eukaryotes” by Pol Fernández, Rémy Amice, David Bruy, Maarten JM Christenhusz, Ilia J. Leitch, Andrew L. Leitch, Lisa Pokorny, Oriane Hidalgo and Jaume Pellicer, May 31, 2024, iScience.
DOI: 10.1016/j.isci.2024.109889
The study identifying the genome size of Tmesipteris obblancolata was carried out by an international team of researchers from the Royal Botanic Gardens Kew, Queen Mary University of London, the New Caledonia Herbarium and the Spanish Research Council (CSIC).