The tiny fern contains the largest genome of any known species on Earth

In a new study published in the journal iScience, Scientists from the Royal Botanic Gardens, Kew The Barcelona Botanical Institute (IBB-CSIC) presents the new record holder for the largest number of DNA stored in the nucleus of any living organism on the planet.

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Temsepteris oblansulata It is an endemic species of fern that contains 50 times more DNA than humans, and has displaced the previous record holder, an ornamental plant. Paris Japonica, which has held that title since 2010. Why does a baby fern need so much genetic material? The answer to this question is not clear.

This fern broke three records

The genome is the complete set of DNA instructions in a cell that contains all the information necessary for the development and growth of an organism. Many plants have large genomes, and scientists want to know why. They hope to understand how this affects function and may have an impact on extinction risk.

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Fern, commonly known as Tmesipteris oblanceolateIt belongs to a primitive group of plants that evolved long before dinosaurs appeared on Earth. It is found only in New Caledonia in the Pacific Ocean and several neighboring islands (including Vanuatu), where it grows on the trunks and branches of rainforest trees.

Until now, scientists have estimated the size of the genomes of only two species tmcptr – T. tanensis I T. oblique Both were found to have giant genomes of 73.19 and 147.29 billion nitrogenous base pairs (Gbp), respectively. The previous record holder for the largest genome in the world was a flowering plant – Paris Japonica – From 148.89 GB. For comparison, the human genome is about 3.1 Gb in size and spans about 2 m in length.

Scientists extracted genetic material from the samples Tmesipteris oblanceolata They met in New Caledonia.
They measured the amount of dye binding to DNA: the more dye, the larger the genome. They found that the fern has a record genome size of 160.45 billion nitrogenous base pairs, which, if unpacked, would be about 100 meters long.

Adam Millward of Guinness World Records said:

The belief that this inconspicuous-looking fern contains 50 times more DNA than humans is a humbling reminder that there’s still a lot about the plant kingdom we don’t know, and that record holders aren’t always the most glamorous on the outside.

To date, scientists around the world have estimated the genome sizes of more than 20,000 eukaryotic organisms, revealing in the process a wide range of genome sizes across the tree of life. In turn, it was found to have a profound impact not only on their anatomy, as larger genomes need larger cells to house them and take longer to reproduce, but also on how they function and develop and where and how they live. . In the animal kingdom, some of the largest genomes include some lungfishes and salamanders, with about 120 billion base pairs. In contrast, the great oak tree has a relatively small genome – if you extended all the DNA from one cell, it would be 66 cm long.

It is worth noting that the six largest known eukaryotic genomes are found in plants, including common mistletoe (Viscos album) with a size of 100.84 GB. Surprisingly, having a larger genome is usually not an advantage. In plants, species with large amounts of DNA are restricted to slow-growing perennials, are less efficient at photosynthesis (the process by which plants convert sunlight into sugars), and require more nutrients (particularly nitrogen and phosphate) to grow It competes successfully with plants. Neighboring plants with smaller genomes. In turn, these effects may affect the plant’s ability to adapt to climate change and the risk of extinction.