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12/24/2009

 

Danish researcher Pär Ingvarsson had his Christmas tree a long time before Christmas. As always, it is a nice spruce tree. At Christmastime, the plant geneticist simply takes his research home. Ingvarsson's goal is to map the genome of the humble Christmas tree.

A foundation has given Ingvarsson and his team €7 million to sequence the tree's genome. If they are successful, it will be the world's first decryption of a coniferous tree's genetic make-up. Up until now only one other tree has had its DNA sequenced: the balsam poplar.

"So far, nobody has ventured into conifers because their genomes are so vast," Ingvarsson explains. Coniferous trees only have 12 chromosomes, but these carry around seven times as much information as the 46 human chromosomes. The prospect of decoding such a gigantic genome has only become possible using new robotic sequencers.

Ingvarsson suspects the secrets of the conifer's evolutionary success story are hidden somewhere in the mass of data. Conifers are some of the oldest plants we have -- they have populated a large part of what is modern Europe and North America for at least 300 million years. They don't appear to have been affected very seriously by climate fluctuations or natural catastrophes.

"It's quite likely that, from the very beginning, conifers have had a very advantageous genetic make-up," he says.

So does the explanation for the tree's environmental adaptability rest somewhere within its gigantic genomes? "Maybe they have a lot of copies of the same gene and that's why they are so adaptive," Ingvarsson suggests.

Christmas Trees' Clue to Climate Change

The researchers are also hoping to find out how the trees are dealing with the climate change happening today. "It is possible that, for the first time in Earth's history, the climate is changing so quickly that the trees' genes are not able to react in the normal way," says Matthias Fladung, a botanic researcher at the Institute for Forest Genetics and Forest Tree Breeding in Grosshansdorf near Hamburg. If one knew which genetic features made plants able to adapt to climate change better, then one could choose to grow more trees with those qualities.

And that is the precise goal of the forest geneticists. With the help of molecular biology, they want to be able to predict the qualities a tree will have before a seedling is even planted. "Everywhere you can find pines and fir trees that are over a hundred years old -- which is why conventional tree breeding methods have to be ruled out. They take far too long," explains Reiner Finkeldey, a professor of forest genetics at the University of Göttingen in Lower Saxony. "If you could identify the characteristics of a seedling -- such as a fast rate of growth -- just by using a genetic test, then that would be extremely handy."

Finkeldey is another scientist who is looking for the conifer's survival strategies in its genetic code. He gathers pine needles in Ukraine, ones from trees that have managed to survive the Chernobyl disaster, where a nuclear reactor exploded in 1986. "Some of the trees dealt with the radiation better than others," Finkeldey notes. "We want to find out why."

Finding the perfect Christmas Tree

Meanwhile, researchers in Copenhagen are already well on the way to finding the genes for the perfect Christmas tree. The Danes are the leading exporters of Christmas trees, delivering around 10 million to neighboring countries each year. Germans are particularly fond of the beloved Nordmann fir produced in Denmark.

As such an important export, it comes as little surpise than an entire team at the University of Copenhagen is dedicated to Christmas tree research. In Jens Iver Find's laboratory at the Zoological Museum, Denmark's natural history museum, a whole armada of conifer clones are stored in liquid nitrogen. The biologist is trying to ascertain which ones will produce the best Christmas trees. "The most important thing is good shape," the scientist says. "But it is also important that the tree can withstand frost. It would also be good if it had fewer needles." A mere 15 percent of the trees in Denmark's Christmas tree plantations grow up to become such glorious specimens. Using his method of genetic selection, Find believes that that percentage of perfect Christmas trees could go up to 60. The first trials of his clone trees are already underway and, during the coming year, Find will plant another 15,000 small trees.

Using the genetic testing, Danish researchers will also eventually be able to work out which pine needles have a higher percentage of water in them. These plants could then be marketed as more "flame retardant" Christmas trees.

Compared to the Dane's research, the work being done by a group of British students seems like a holiday game. They are trying to develop a glowing Christmas tree by implanting it with luciferase, an enzyme for bioluminescence used by creatures like fireflies.

But Danish scientists say the methods they are using -- direct implantation into the conifer's genes -- are unlikely to work.

"We experimented with genetically modified Christmas trees for a while too," Find says. A special gene was introduced which would make the trees more resistant to pests. "But we gave up. People just don't want plants out of some laboratory standing in their living rooms," he concludes.