A scanning electron micrograph of the bladder-like trap of Utricularia gibba. The plant uses vacuum pressure to suck in tiny prey at great speed. (Photo : University of Buffalo)
The carnivorous bladderwort, an insect-eating plant cultivated by humans as decorative flowers, ruthlessly gets rid of DNA non-essential to its survival, making it a more efficient killer.
"Utricularia gibba", the aquatic version of the bladderwort (scientific name: Utricularia), has a smaller genome than many well-known plants but surprisingly more genes.
The bladderwort's 80 million base pairs of DNA are six times smaller than the grape. But it's got 28,500 genes to the grape's 26,300 genes, said a new study published in Molecular Biology and Evolution.
This means only around three percent of the plant's DNA is so-called "junk DNA". In humans, over 90 percent of DNA is junk DNA, or genomic DNA that doesn't encode proteins and whose function (if it has one) isn't well understood, said The Washington Post.
The new study suggests Utricularia gibba, or the carnivorous bladderwort, might owe its super-compact genome to a long history of relentless DNA editing, said Victor Albert of the University at Buffalo.
In 2013, Albert found that Utricularia gibba lacked the junk DNA most organisms have in abundance.
He said Utricularia gibba is gaining and throwing away DNA at an unusually fast rate. Albert and his colleagues believe the plant's genome has duplicated entirely at least three times.
Instead of just adding all of those redundant genes to its DNA like human's do, the carnivorous plant keeps removing DNA it doesn't need.
Albert explained that when genes turnover at a rapid rate, only the really important ones survive from generation to generation. In the case of Utricularia gibba, the genes it's kept are those that allow the plant to consume meat fibers and help it keep its cell walls watertight, for example.
The fact genes useful to Utricularia gibba's carnivorous life prevailed indicates natural selection drove this plant's pruning its DNA.
In future studies, Albert and his colleagues hope to pinpoint the reasons behind this incredible survival mechanism.
All Utricularia are carnivorous and capture small organisms by using bladder-like traps. Terrestrial species tend to have tiny traps that feed on minute prey such as protozoa and rotifers swimming in water-saturated soil. Aquatic species have bladders that are usually larger and can feed on bigger prey such as mosquito larvae and young tadpoles. Despite their small size, the traps are extremely sophisticated.
