Swedish scientists have mapped the gene sequence of Norway spruce (the Christmas tree) – a species with huge economic and ecological importance - and that is the largest genome to have ever been mapped. The genome is complex and seven times larger than that of humans. The results have been published in the prestigious journal Nature.
The scientists have identified about 29,000 functional genes, marginally more than humans have, but the question arises: why is the spruce genome still seven times larger than ours? According to the study an explanation is “genome obesity” caused by extensive repetitive DNA sequences, which have accumulated for several hundred million years of evolutionary history. Other plant and animal species have efficient mechanisms to eliminate such repetitive DNA, but these do not seem to operate so well in conifers.
“It is remarkable that the spruce is doing so well despite this unnecessary genetic load,” says Professor Pär Ingvarsson at UPSC. “Of course, some of this DNA has a function but it seems strange that it would be beneficial to have so very much. This appears to be something special for conifers.”
Story source: Adapted from a Umea University News Release via AlphaGalileo, 21 May 2013
Journal Reference: Björn Nystedt, et al. The Norway spruce genome sequence and conifer genome evolution. Nature, 2013; DOI: 10.1038/nature12211