Research shows Utricularia gibba maintains a small genome size by resisting gene duplications.
Nature is beautiful and so are its mechanisms. The carnivorous humped bladderwort (U. gibba) 
is unique in showing a wonderful evolutionary trait which would put all of us in awe; wondering if we could, would we ever remove a part of us which we thought is never going to be of any use. The finding published online inNature overturns the notion that repetitive, non-coding DNA or “Junk DNA” is necessary for life.
While duplication of genes and mobile elements such as transposons are the basis of increasing complexity of plant genome, U. gibba; a relative of the tomato, has experienced a net gain of just 1.5% in its size, since their split 87,000 years ago. It has retained only a single copy of its genes. This means it has ejected everything it doesn’t need and therefore now has a genome only 10th the size of a tomato’s genome.
It is well known that transposons play a primary role in increasing genome size. The bladderwort is unique in having almost no retrotransposons whatsoever. Apparently, this intelligent carnivore has retained all the miRNA silencing genes. miRNA’s do not encode their own proteins, but they do bind messenger RNA, preventing their encoded proteins from being constructed and this is how they are exceptional in suppressing these retrotransposons in the bladderwort. This indicates that, despite its small genome, the general repertoire of miRNA mediated gene regulation in plants is conserved in U. gibba.
This first-of-its-kind study has again fueled the debate deciding whether junk DNA is either Trash or Treasure. The question still remains as to why the genomes have accumulated so much non-coding DNA when this carnivore could do well with bare essentials.
Source: Ibarra-Laclette, E., Lyons, E., Hernández-Guzmán, G., Pérez-Torres, C., Carretero-Paulet, L., Chang, T., Lan, T., Welch, A., Juárez, M., Simpson, J., Fernández-Cortés, A., Arteaga-Vázquez, M., Góngora-Castillo, E., Acevedo-Hernández, G., Schuster, S., Himmelbauer, H., Minoche, A., Xu, S., Lynch, M., Oropeza-Aburto, A., Cervantes-Pérez, S., de Jesús Ortega-Estrada, M., Cervantes-Luevano, J., Michael, T., Mockler, T., Bryant, D., Herrera-Estrella, A., Albert, V., & Herrera-Estrella, L. (2013). Architecture and evolution of a minute plant genome Nature DOI: 10.1038/nature12132
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