Usually plants have small genomes sequences, but some of them are exceptional diverse and can posses very large genomes. Those genomes were discovered to be the biggest yet in the plant and in the eukaryotic world. The record goes to a tiny but mighty little fern that has a genome 50 times bigger than the size of the human genome. The little fork fern discovered in New Caledonia (Tmesipteris oblanceolata) have a genome that measure 160.45 Gbp/1C. This record was before held from another plant, an angiosperm called Japanese flower or Paris japonica with the whopping 148.89 Gbp/1C. The discovery of the genome of this new fern was suggested by previous works on fork fern (T.mesipteris) that had already a big genome. A team led by Jaume Pellicer, an evolutionary biologist from the Botanical Institute of Barcelona started to study more accurately the six fork fern species found in the South Pacific Island of New Caledonia. The researches collected cells from the fern’s leaves and isolated the nuclei of the cells. The nuclei were then stained with a fluorescent dye to highlight the DNA and the fluorescent glow was compared to other plants with smaller genome to calculate the size of the genome.
It is extremely fascinating to me how a fern T. Oblanceolata that survives in the large forest and it grows only up to 15cm in length can hide a genome of a length of 160 billion nucleobases. Moreover, it takes great deal of energy for an organism to replicate almost 100 meter of DNA every time a cell replicates. It is still very puzzling how a plant like a fern can hold such an extreme size genome and make it functional. Plants have an history of inherit extra copies of entire chromosomes or to accumulate long sections of repetitive DNA sequences. This could probably explain how ferns end it up with such a large genome. Another assumption made from plant evolutionist Liming Cai suggests that fork fern might had a repeated history of genetic bottleneck. This happens when some species undergo multiple replication and with time loose some of the genetic diversity. This is also connected to deleterious mutations that tends to accumulate and “junk” DNA could play a role in creating the large genomes. I think even though now genome as large as the one of the fern can be traced and sequenced it is important to be studied to preserve biodiversity. Through different variety of genomes we can learn way more about how the human one works by comparing and contrasting how different species had survived through centuries of evolution.
