Junk-free Species: Floating bladderwort, Utricularia gibba (from Genome Digest) The floating bladderwort (Utricularia gibba) is a carnivorous plant with a highly specialized hunting technique. The plant pumps water into tiny chambers, or bladders, creating a vacuum in each one that can suck in and trap unsuspecting insect prey. Despite this complex behavior, the bladderwort’s recently sequenced genome indicates that the aquatic plant has the smallest genome–80 million base pairs–of any higher plant that has been sequenced so far. By comparison, plants like the grape and the tomato have 490 and 780 million base pairs respectively. Yet the bladderwort has roughly the same number of genes as the grape and tomato. The reason for this discrepancy lies in the bladderwort’s systematic shedding of so-called “non-coding DNA”, or DNA that does not code for proteins. The vast majority of human DNA, about 98 percent, is non-coding, or what used to be called “junk” DNA. In fact, complex organisms have a preponderance of non-coding DNA. However, the bladderwort genome is comprised of only 3 percent non-coding DNA, despite three separate incidents of genome doubling, where offspring receive two full copies of the entire genome, in its evolutionary history. The finding contradicts recent high profile projects, such as ENCODE, that suggest that non-coding DNA plays biochemical roles critical to complex life. nature/nature/journal/v498/n7452/full/nature12132.html
Posted on: Fri, 21 Jun 2013 08:14:29 +0000
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