‘Biology of Genomes’ conference is taking place this week, and we are covering unusual genomes published over the last decade.
Our today’s nomination goes to bladderwort. When this genome got published two years back, it ended all debates about functionality of junk DNA. Therefore, it definitely deserves a place among top ten unusual genomes.
When we argue against functionality of junk DNA, many others say that it is impossible to say so until someone deletes all junk DNA in a small baby and shows that he lives till old age. Nature (not the journal) may have done such an experiment in a different organism and Nature journal published the report despite telling us two weeks back that junk DNA was not understood. We wish other pressing problems of the world get solved so quickly.
The bladderwort genome is amazing in many respects. 82 Mb is rather tiny compared to 22 Gb conifer genome and even larger lily genome. Quite surprisingly, the genome went through three rounds of whole genome duplication since diverging from common ancestry with tomato and grape. Still it has only 2% of junk dna, or essentially every piece of DNA that could be removed was removed.
The original paper -
Architecture and evolution of a minute plant genome h/t: angry ?@DanGraur
It has been argued that the evolution of plant genome size is principally unidirectional and increasing owing to the varied action of whole-genome duplications (WGDs) and mobile element proliferation1. However, extreme genome size reductions have been reported in the angiosperm family tree. Here we report the sequence of the 82-megabase genome of the carnivorous bladderwort plant Utricularia gibba. Despite its tiny size, the U. gibba genome accommodates a typical number of genes for a plant, with the main difference from other plant genomes arising from a drastic reduction in non-genic DNA. Unexpectedly, we identified at least three rounds of WGD in U. gibba since common ancestry with tomato (Solanum) and grape (Vitis). The compressed architecture of the U. gibba genome indicates that a small fraction of intergenic DNA, with few or no active retrotransposons, is sufficient to regulate and integrate all the processes required for the development and reproduction of a complex organism.