Utricularia gibba, commonly known as the humped bladderwort, is a carnivorous, obligate wetland plant native to most of the contiguous United States. A study recently published in the Journal of Molecular Biology and Evolution investigates the unique genome of this aquatic plant. What sets the bladderwort’s genome apart from other plants is its ratio of size to number of genes; relative to its small size this genome has an enormous number of genes.
A genome is defined as a complete set of chromosomes; all the inheritable traits of an organism. The humped bladderwort has some 80 million DNA base pairs, but with just 25, 800 genes. Compared to a species of grape plant with 26, 300 base pairs, the bladderwort’s genome is 6 times smaller.
In 2013, the main author the recently published study, Victor Albert of the University of Buffalo, found that Utricularia gibba lacked what is commonly thought of as “junk” DNA. Junk DNA are regions which don’t do any direct coding, most species have copious amounts of junk DNA. The human genome has approximately 90% non-coding DNA, however, it is now assumed that these pairs have roles that are just not known as of now.
This new study finds that the tiny, yet efficient genome may be attributed to excessive DNA editing. In short this means that the little aquatic, carnivorous plants are gaining and tossing DNA at an unusually fast rate. Albert and his team now believe that the plant has entirely duplicated its genome at least three times. But unlike the genomes of other species, the bladderwort rids itself of redundant DNA pairs. Albert explains; “It turned out that those rates of evolutionary turnover — especially the rate of loss — was incredibly high compared to other plants. The genome was subjected to some heavy-duty deletion mechanisms.”
However, genes critical to the plants survival, those which code for its carnivorousness and water-tight cells, were protected and preserved from generation to generation. This heartily reinforces that natural selection is at work in creating this creature’s unique DNA culling methodology. Unfortunately, the driving mechanism behind why the bladderwort is a serial DNA repeater and deleter. Albert and colleagues plan to continue this line of research in hopes of clearly illuminating the plant’s genome contrivances.