Tmesipteris oblanceolata, a fern, has a genome five times larger than the human one. It is the largest yet observed in nature, reports Nature, and its 160 billion 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."
There's also the question of how and why an organism evolved to have so many base pairs. Generally, having more base pairs leads to higher demand for the minerals that comprise DNA and for energy to duplicate the genome with every cell division, Leitch says. But if the organism lives in a relatively stable environment with little competition, a gargantuan genome might not come with a high cost, she adds.
The marbled lungfish, Protopterus aethiopicus, has the largest animal genome—thirty billion base pairs less than this fern. Even mistletoe has more DNA than a human.
