Norway Spruce Genome Sequenced by Scientists: The DNA of a Christmas Tree

If you like Christmas trees, you'll be happy to know that scientists have mapped the genome of the Norway spruce--the type of tree usually decorated during the holidays. Mapping this particular genome doesn't just have benefits for the holiday season, though. The Norway spruce is a species with huge economic and ecological importance--and has a corresponding massive genome.

The Norway spruce is the fastest growing of the spruces. It can reach between 115 to 180 feet in height and is actually a native of Europe, growing from Norway in the northwest and Poland eastward. It possesses dark green needles and is an evergreen, which means that it remains green year-round. One of the most widely planted spruces, the tree is used in forestry for timber and paper production. In addition, it's also used as an ornamental tree, both in parks and in your living room during Christmas.

The recent effort to sequence the Norway spruce's genome is interesting to both science and the forest industry. It wasn't easy to do, either. The greatest challenge was to get the approximately 20 billion "letters" found in the spruce's genetic code into the correct order, rather than obtaining the actual DNA sequences.

"Imagine a library with ten thousand books as thick as the bible, written in a language with only four letters," said Stefan Jansson at UPSC in a news release. "If someone took one hundred identical copies of each of the ten thousand titles, passed them all through a document shredder and mixed all the shreds, and you then were asked to piece together an accurate copy of each title, you realize that it can be a bit problematic."

After sequencing the genome, researchers discovered that not only is it complex, but also seven times larger than that of humans. In fact, the scientists identified about 29,000 functional genes.

So why does a tree have more functional genes than a human does? The researchers believe that the explanation is "genome obesity." This is caused by extensive repetitive DNA sequences, which have accumulated for several hundred million years of evolutionary history. While other plant and animal species have efficient mechanisms to eliminate this repetitive DNA, conifers don't seem to possess such mechanisms.

"It is remarkable that the spruce is doing so well despite this unnecessary genetic load," said Pär Ingvarsson at UPSC in a news release. "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."

The findings could actually benefit the forestry industry. Forest tree breeding is currently entering a new era as science meets agriculture. Newer and more effective methods could potentially be used to ensure that trees that are planted each year are able to survive the environment they're placed in.

The findings are published in the journal Nature.