The tiny genome of the carnivorous bladderwort plant was found to contain a variety of "evolutionary treasures."
The study revealed the fascinating plant, dubbed Utricularia gibba, holds more genes than plants such as those that produce grapes and coffee, despite having a much smaller genome, the University of Buffalo reported. The aquatic plant boasts thread-like branches and tiny traps used to capture prey.
The extremely compact genome was believed to have been created through "rampant" DNA deletion, in which genetic material was eliminated at a shocking rate.
"The story is that we can see that throughout its history, the bladderwort has habitually gained and shed oodles of DNA," said University at Buffalo Professor of Biological Sciences Victor Albert. "With a shrunken genome we might expect to see what I would call a minimal DNA complement: a plant that has relatively few genes -- only the ones needed to make a simple plant. But that's not what we see."
A comparison with the grape genome showed U. gibba's genome holds 28,500 genes, compared to about 26,300 for the grape, which has a genome that is roughly six times larger. A number of the bladderwort's genes allow it to create enzymes similar to papain, which works to break down meat fibers. It also holds many genes associated with the biosynthesis of cell walls, which allows it to exist in aquatic environments.
"When you have the kind of rampant DNA deletion that we see in the bladderwort, genes that are less important or redundant are easily lost," Albert said. "The genes that remain -- and their functions -- are the ones that were able to withstand this deletion pressure, so the selective advantage of having these genes must be pretty high."
Much of the DNA the aquatic plant deleted over time was determined to be "junk DNA," which is noncoding and does not contain genes. The researchers found the plant had undergone three duplication events in its evolutionary history in which its entire genome was replicated, providing it with redundant copies of every gene. The new genes were quickly balanced out by a swift deletions process.
"When you look at the bladderwort's history, it's shedding genes all the time, but it's also gaining them at an appreciable enough rate, permitting it to stay alive and produce appropriate adaptations for its unique environmental niche," Albert said.
The findings were published in a recent edition of the journal Molecular Biology and Evolution.
