The tiny fern breaks the world record for the size of the genome of any organism!

The saying goes that good things come in small packages, and although the discovery of the world's largest genome of any organism is an incredible find, the reality is a little more complicated. The New Caledonian species of fork fern Tmesipteris oblanceolata has a genome that would be above the Big Ben tower when stretched, and is now a three-fold world record holder.

With more than 100 meters of DNA (328 feet), the tiny modest fork fern has the largest amount of DNA stored in the core of any living organism on the planet. For comparison: the human genome has 3.1 pairs of giganucleotides, which corresponds to a length of about 2 meters (6.5 feet), and T. oblanceolata has 160.45. Thus, the fern established the largest genome of the fern, the largest genome of the plant and set the largest world records of the genome.

Although it may seem surprising for such a small plant, six of the 10 largest genomes belong to plants. The previous holder of the title Paris japonica, a Japanese flowering plant, has a genome of 148.89 pairs of gigabases, while in the animal world they were joined by a marble double-breathing fish (Protopterus aethiopicus) with a size of 129.90 Gbp, and the salamander was joined by the water dog of the river Noise (Necturus lewisi). ) at a frequency of 117.47 gigabases. These species have some of the largest genomes among animals, but they are much smaller than these plants.

Despite the fact that T. oblanceolata is a world record holder, in fact it is at a more disadvantage than its fellows with a smaller genome. The presence of a large genome and a large amount of DNA requires large cells, which means that species with a larger genome are likely to grow more slowly and photosynthesize less efficiently.

"In most cases, this is a negative fact. If you have a large genome, you need a large cell to accommodate it. So, we see that plants with large genomes are limited, so photosynthesis is less effective than species with small genomes, where you get a number of photosynthetic efficiency and, of course, photosynthesis produces sugar, which makes it possible to accumulate biomass. This means that these plants with larger genomes are less effective or less capable of rapid growth," Dr. Ilia Leitch, senior head of character evolution research at RBG Kew, told IFLScience.

In addition to less effective photosynthesis, the giant genome T. oblanceolata means that it is less able to compete with other, faster-growing species. The genome is so large that the team believes that the fern is octoploid, that is, it has eight sets of chromosomes. Humans are diploid and have only two sets.

"The larger your genomes, the more restrictions you have on environmental opportunities and your ability to grow and successfully compete with other plants. Thus, species with the largest genomes, such as Paris japonica or Tmesipteris, this fork fern, are usually found in a very stable environment in which there is no competition," Leitch continued.