Scientists aim to build a better Christmas tree
PUYALLUP, Wash. — Katie Coats used to work in a crime lab in Seattle. These days, she reports to a quieter research facility about 40 miles south, in the shadow of Mt. Rainier.
Here, Coats wields a surgical blade on her subjects, slicing away small chunks of cells and delicately dropping them in vials to preserve for genetic analysis.
Coats isn’t trying to chase down rapists or serial killers. She’s using the tissue — which, on a recent day, came from a Canaan fir — to make better Christmas trees.
Or so her boss, plant pathologist Gary Chastagner, hopes.
It’s tempting to think the evergreen in your living room is a pristine piece of nature, plucked from a silent and snowy hillside.
In fact, for at least the last 30 years, the majority of American Christmas trees have come from farms, planted in methodically managed rows and tended on a rigorous schedule. They have been bred to have that crisp clean mountain smell and that fresh bluish hue. They’ve been sheared to get those thick, brushy needles and that tight conical shape.
And a small cadre of researchers such as Chastagner has been perfecting them in the lab too.
These sleuths have spent decades counting and measuring needles and branches, sometimes setting up pop-up labs near Christmas tree lots. Like champion rose growers, they nurture the beauties and weed out the “Charlie Brown trees” that are oddly shaped, or trees that grow too slowly or fall prey to pests.
Armed with a $1.3-million grant from the U.S. Department of Agriculture, Chastagner and his fellow Christmas tree scientists are adding genetic analysis to their arsenal. Their goal is to pinpoint why some trees turn out better than others.
The researchers don’t expect consumers to share their interest in tree taxonomies — what makes a spruce different from a pine, or a Douglas fir — not really a “true” fir, they note — different from a balsam, Fraser or noble fir.
“They may know, ‘I bought this tree last year, it was a noble fir, I liked the strong branches,’” Chastagner said. “Or they may know, ‘I grew up with a Douglas fir and I liked how it smells.’”
His real concern, he added, is that no matter what tree a shopper picks, it does not have any of the annoying inconveniences that make people turn to artificial trees instead of the real thing.
It may not approach the seriousness of halting climate change, but Chastagner sees his quest as a matter of survival for the U.S. Christmas tree industry, which employs about 100,000 people and brings in more than $1 billion a year.
According to the National Christmas Tree Assn., Americans bought 30.8 million farm-grown Christmas trees in 2011, spending an average of $34.87.
Those numbers haven’t changed much in the last 50 years, even as the number of U.S. households has grown and tree quality has improved, Chastagner said. In the meantime, sales of “plastic tree-shaped decorations,” as a spokesman for the National Christmas Tree Assn. calls them, have been creeping up.
So Christmas tree growers are highly motivated to address the foibles that turn off consumers. (One word: needles.)
Chastagner joined the cause shortly after coming to Washington State University’s agricultural research center here in 1978. He spends his autumns visiting tree plantations, big-box stores like Wal-Mart and corner retail lots across the country, hounding salespeople and performing spot inspections of the goods. (His two sons grew up dreading these drive-bys.)
Typically, after peppering a salesperson with questions about deliveries and maintenance, Chastagner gets permission to take a few photos with an ever-present camera and snip away small cuttings from 10 or so trees. Then he will steal away to his car or a table at a nearby fast-food joint, whip out a portable scale, weigh them “fresh” and then send the clippings back to Puyallup to test their moisture content.
Chastagner has analyzed whether using preservatives, fertilizers or chemicals to slow the evaporation of water from leaves will improve needle retention.
By and large, his data suggest, the answer is no.
What usually does work is keeping the trees amply hydrated from the moment they’re chopped down to the day they hit the curb for recycling.
As anyone who has visited a Christmas tree lot during Santa Ana winds or struggled to refill water in a too-small tree stand knows, that isn’t always so easy. And that’s what has led scientists to delve into genetics to try to find the key to breeding trees that won’t drop needles.
The first line of genetic research is decidedly low-tech. In Puyallup, 15 acres have been devoted to field trials where Chastagner and his colleagues plant different sorts of firs — noble, Nordmann, balsam, Turkish, even oddball varieties such as Korean or Nikko — to test their mettle. Trees from a single location are grown in a series of plots that vary in key ways: soil moisture, elevation, days exposed to low temperatures and so on.
Trees that thrive are declared genetic winners, and their seeds will someday supply commercial Christmas tree operations.
If a tree is a dud, it is removed from the mix.
Finding the right trees for the trials can take effort: In 2010, Chastagner went on an arduous seed-hunting trip to western Turkey, where scientists roamed mountain forests to harvest cones from Turkish and Trojan firs, which had performed well in earlier studies.
Once seeds are in hand, it takes a year or two to grow a viable seedling in the nursery, and then several more years in the replicated plots to get testable trees.
Researchers typically evaluate the trees over a number of years and screen for a variety of traits. Farmers in North Carolina and other relatively wet regions in the American East, for instance, are looking for evergreens that will resist root rot caused by Phytophthora species of water molds that propagate in moist soil.
The seeds from Turkey are now 2-year-old seedlings and haven’t yet been planted in test plots. But members of Chastagner’s team are growing and studying 28 conifer species in the series of small valleys at the Puyallup research station, a more than 100-year-old facility once devoted largely to poultry and dairy research.
Walking through muddy fields past an old white barn, through dozens of rows of neatly spaced trees, Chastagner stopped by a trial comparing Nordmann and noble firs planted in 2006. It was easy to see the dividing line between species: The majority of the noble firs were dying of root rot. The nearby Nordmanns, which are resistant to the pathogen but far less frequently planted in the Pacific Northwest, were strong and green.
Chastagner paused next to one particularly beautiful specimen.
“If I’m a farmer and I have trees like this, I’m making money,” he said.
Chastagner’s trials also evaluate trees’ growth rates, appearance and sensitivity to cold. But he is most keenly interested in whether certain seed sources produce conifers that are less likely to shed those pesky needles.
To figure out which trees have the right stuff, he has converted an old concrete cistern into a scientific testing station. The room is a no-frills affair, painted white with a couple of heaters bolted to the walls. It has a toasty evergreen smell. Rows of tables contain scores of racks, each holding up to 50 Christmas tree branches that have been left to dry. A knee-high pile of needles accumulates at one end of the room.
After nine to 11 days in the racks, Chastagner’s colleague Kathy Riley rubs each branch and gives it a shedding severity rating of 0 to 7. Some trees dry and start losing needles after just three days; others can keep their needles for weeks.
If the team identifies a tree that displays consistently great needle retention, they can graft a small branch onto the roots of another tree, to eventually plant for producing seeds.
But it will take 25 years or so for growers to be able to purchase the seed in commercial quantities. Then it will take an additional seven to 10 years or so for them to harvest the trees for mess-averse consumers.
“You can imagine, this is a long-term process,” Chastagner said.
Genetic analysis stands to reduce the time needed to figure out which trees to raise. As with efforts to study the human genome, the hope is to find precise patterns of gene variation that give an organism its unique qualities. But the project is complicated in conifers because their genomes are very large, with more than 20 billion base pairs in some cases. The human genome, by comparison, contains 3 billion base pairs.
The team that traveled to Turkey took DNA samples in addition to seeds. Chastagner is also part of a five-year project led by scientists at North Carolina State University that he called “the largest Christmas tree grant in U.S. history.” The goal is to use RNA, which builds proteins in cells, to figure out which genes are turned on or off in particular trees. That should help researchers pinpoint the tiny genetic variations that correspond with valuable traits.
The analysis may also provide a window into the cellular process that makes drying trees shed their needles in the first place. If Coats, the crime lab veteran, collects RNA from a single drying branch over the course of several days, she might capture the process in action, seeing exactly when and how stress activates the genes that make trees shed.
Chastagner concedes that new genetic insights might not change farmers’ — or buyers’ — personal tastes when it comes to growing and buying live trees.
The good news is, he doesn’t think they have to.
“People ask me, ‘What’s the perfect tree?’” he said, “and I don’t answer. For some people, the Charlie Brown tree is perfect.”
If his efforts are successful, he added, any tree should be a good one, once it’s in their home.
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