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(16,245 posts)
Fri May 31, 2024, 04:32 PM May 2024

Biggest genome ever found belongs to this odd little plant

https://www.nature.com/articles/d41586-024-01567-7

NEWS
31 May 2024

Biggest genome ever found belongs to this odd little plant

The gigantic genome of a type of fork fern smashes the human one in terms of size.

By Max Kozlov



The record-breaking species Tmesipteris oblanceolata is easy to miss on the forest floor.Credit: Pol Fernandez

A small, unassuming fern-like plant has something massive lurking within: the largest genome ever discovered, outstripping the human genome by more than 50 times1.

The plant (Tmesipteris oblanceolata) contains a whopping 160 billion base pairs, the units that make up a strand of DNA. That’s 11 billion more than the previous record holder, the flowering plant Paris japonica, and 30 billion more than the marbled lungfish (Protopterus aethiopicus), which has the largest animal genome. The findings were published today in iScience.

Study co-author Jaume Pellicer, an evolutionary biologist at the Botanical Institute of Barcelona in Spain who also co-discovered P. japonica’s gargantuan genome2, had thought that the earlier discovery was close to the genome size limit. “But the evidence has once again surpassed our expectations,” he says.

Genomic giants
The world’s genomic champion, which is native to New Caledonia and neighbouring archipelagos in the South Pacific, is a species of plant called a fork fern. Its colossal number of base pairs raises questions as to how the plant manages its genetic material. Only a small proportion of DNA is made of protein-coding genes, leading study co-author Ilia Leitch, an evolutionary biologist at London’s Royal Botanic Gardens, Kew, to wonder how the plant’s cellular machinery accesses those bits of the genome “amongst this huge morass of DNA. It’s like trying to find a few books with the instructions for how to survive in a library of millions of books — it’s just ridiculous.”

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https://doi.org/10.1016/j.isci.2024.109889

ARTICLE | ONLINE NOW, 109889

A 160 Gbp fork fern genome shatters size record for eukaryotes

Pol Fernández, Rémy Amice, David Bruy, Lisa Pokorny, Oriane Hidalgo 10, Jaume Pellicer 10, 11
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Show footnotes Open Access Published:May 31, 2024
DOI:https://doi.org/10.1016/j.isci.2024.109889

Highlights

• Giant genomes are restricted across the eukaryotic Tree of Life

• The genome of T. oblanceolata is over 50 times larger than the human genome

• Genome size variation among eukaryotes expands over 61,000-fold


Summary

Vascular plants are exceptional among eukaryotes due to their outstanding genome size diversity which ranges ?2,400-fold, including the largest genome so far recorded in the angiosperm Paris japonica (148.89 Gbp/1C). Despite available data showing that giant genomes are restricted across the Tree of Life, the biological limits to genome size expansion remain to be established. Here, we report the discovery of an even larger eukaryotic genome in Tmesipteris oblanceolata, a New Caledonian fork fern. At 160.45 Gbp/1C, this record-breaking genome challenges current understanding and opens new avenues to explore the evolutionary dynamics of genomic gigantism.

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