Carnivorous plant discards 'junk' DNA

Posted by Thomas Anderson

Genes make up about 2 percent of the human genome. The rest consists of a genetic material known as noncoding DNA, and scientists have spent years puzzling over why this material exists in such voluminous quantities.

Now, a new study offers an unexpected insight: The large majority of noncoding DNA, which is abundant in many living things, may not actually be needed for complex life, according to research set to appear in the journal Nature.

The clues lie in the genome of the carnivorous bladderwort plant, Utricularia gibba.

The U. gibba genome is the smallest ever to be sequenced from a complex, multicellular plant. The researchers who sequenced it say that 97 percent of the genome consists of genes — bits of DNA that code for proteins — and small pieces of DNA that control those genes.

It appears that the plant has been busy deleting noncoding "junk" DNA from its genetic material over many generations, the scientists say. This may explain the difference between bladderworts and junk-heavy species like corn and tobacco — and humans.

The international research team, led by the Laboratorio Nacional de Genómica para la Biodiversidad (LANGEBIO) in Mexico and the University at Buffalo, reported on its findings on May 12 in Advanced Online Publication in Nature.

The study was directed by LANGEBIO Director and Professor Luis Herrera-Estrella and UB Professor of Biological Sciences Victor Albert, with contributions from scientists in the United States, Mexico, China, Singapore, Spain and Germany.

"The big story is that only 3 percent of the bladderwort's genetic material is so-called 'junk' DNA," Albert added. "Somehow, this plant has purged most of what makes up plant genomes. What that says is that you can have a perfectly good multicellular plant with lots of different cells, organs, tissue types and flowers, and you can do it without the junk. Junk is not needed."