Thecarnivorous plant Utricularia gibba, which inhabits freshwater aquatic environments and has the smallest genome of a multicellular plant ever sequenced, has revealed thatnon-coding DNA (misnamed “junk DNA”) may not be necessary for cellular processes. According to an international study in which the Center for Genomic Regulation (CRG) has participated, 97% of the plant genome consists of genes and small DNA fragments that control them. That is, it happens just the opposite of other plants such as corn or tobacco, and even thatin the human genome, where genes encoding essential proteins account for approximately 2%, while the rest consists of non-coding or junk DNA, which does not code to generate proteins.
Utricularia has developed a complex hunting system: it pumps water from tiny chambers called vesicles, turning them into a suction pump that can suck and trap unsuspecting victims. And as it evolved, it has also eliminated junk DNA from its genetic material. “The surprising news is thatonly 3% of U. gibba’s genetic material is so-called ‘junk’ DNA“, comments Victor Albert, professor at the University of Buffalo and co-author of the work. And, therefore,”it is possible to have a perfect multicellular plant, with different types of cells, organs and tissues such as flowers, without the remnants: No need for junk DNA. “
Scientists have spent many hours unraveling what noncoding DNA does and why it exists in such quantities. A recent series of articles from ENCODE, a highly publicized international research project, noted that most noncoding DNA (8%) appears to play a role in biochemical functions, such as regulating and promoting DNA conversion. in its relative, RNA, necessary in protein synthesis.
But Herrera-Estrella and her collaborators argue thatorganisms may not need to accumulate junk DNA to benefit. Rather, they propose that some species might have a mechanistic bias, toward removing large amounts of noncoding DNA while others might be biased in just the opposite direction, toward DNA insertion and duplication. These biases do not mean that one way is better than the other, but that there are two innate ways of doing it and each organism adopts one and the other to different degrees. The organism’s place on this sliding scale depends in large part on the pressure that natural selection can exert to increase or decrease these traits.
