Chuck Bednar for redOrbit.com – @BednarChuck
A carnivorous plant known as the humped blatterwort has a genetic makeup that sounds like something out of a science-fiction novel – it has a smaller genome than many well-known types of plants, but has a greater number of genes, a team of researchers has discovered.
Writing in a recent edition of the journal Molecular Biology and Evolution, researchers from the University of Buffalo reported that the bladderwort (Utricularia gibba) has 80 million base pairs of DNA, six times fewer than the grape, but has 28,500 genes versus the grape’s 26,300. It also has a smaller genome but more genes than the coffee and papaya plant, they added.
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Previous research
According to the Washington Post, the study builds upon previous research conducted by lead author and Buffalo professor Victor Albert in 2013. In that paper, Albert revealed that the plant had far less “junk” DNA (DNA that does not directly code for proteins) that is abundant in many types of organisms. The bladderwort has just three percent of so-called junk DNA, he explained, while an estimated 90 percent of human DNA is either junk or have unknown roles.
Albert believes that the carnivorous plant only has time to maintain coding DNA, and in the new study, he suggests that its ultra-efficient genome may be due to long-term, widespread editing of DNA. Essentially, the newspaper explained, the plant is adding new and deleting old DNA at an unusually rapid pace, and it may have even duplicated its entire genome at least three times.
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“The story is that we can see that throughout its history, the bladderwort has habitually gained and shed oodles of DNA,” Albert, a biological sciences professor, said. “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.”
Rampant DNA deletion
Further research revealed that U. gibba contains an abnormally high amount of genes responsible for facilitating carnivorous behavior, specifically those which enable it to create enzymes which help break down meat fibers. The bladderwort was also found to be rich in genes associated with the biosynthesis of cell walls, which helps the aquatic plant species keep water at bay.
“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,” explained Albert. “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.”
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“Accordingly, we found a number of genetic enhancements, like the meat-dissolving enzymes, that make Utricularia distinct from other species,” he continued. The majority of the DNA that the plant deleted over time was noncoding DNA that contained no genes, Albert added.
He and his colleagues compared the bladderwort to four related plant species in order to find out how it evolved its current genetic structure. They discovered a pattern of rapid DNA alteration in which the plant was constantly shedding genes while also gaining them as a solid rate, allowing it to remain alive and produce adaptations appropriate for its environment.
However, Albert and his colleagues are still uncertain why this particular species rapidly copies and deletes its genetic material. The professor told the Washington Post that it simply might not be as good at repairing its DNA as its aquatic, carnivorous, larger-genomed relatives. The team is planning to conduct future studies hoping to uncover the reason for this unusual mechanism.
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