This year, for the first time in my life, I’ll be hosting my family for the holidays. And to their deep disgruntlement, we’ll be celebrating it without a Christmas tree. No, this isn’t some principled stance against the yuletide-industrial complex or a personal front in the war on Christmas. I’m just much more interested in an indoor evergreen interloper when its needles fall in someone else’s home. Now, under careful watch and watering, most firs, spruces, and pines can keep their fragrant greenery for weeks, if not months. Someone like me, who excels at neither of those things, needs a tree that can hold on to its needles – and its dignity – without an ounce of effort in upkeep.
Now, those trees are part of a massive effort to pinpoint the tiny genetic variations that determine why some trees turn out better than others. Five years ago, Chastagner and his research partners at North Carolina State University landed $1.3 million from the U.S. Department of Agriculture – the largest Christmas tree grant in U.S. history – to use RNA, which translates DNA into proteins, to figure out which genes are turned on or off in trees with valuable traits. And in a little more than a month, they’ll finally have those answers.
That’s because the conifer genome is not just enormous – 20 billion base pairs compared to your 3 billion – but also pretty weird. At some point in their deep past, spruces, pines, firs, and their relatives acquired a complete second set of genes. Scientists think this genome-wide duplication likely helped shape these species into the tallest, hardiest plants in the world. But it’s also made sequencing them an incredibly daunting challenge. And unlike corn and soybean, there hasn’t been much money available to even try. So far scientists have managed to put together partial DNA blueprints for only a handful of conifers, not including the most popular Christmas tree species.
The goal, at the end of all this, is to find a molecular biomarker for needle retention. So that Christmas tree growers can separate the strong, stoic ones from the rest of the pack much sooner. It takes a year or two to grow a viable seedling in a nursery and another six to eight before you can tell if it’s a good one – that is, if it survives the rampant root rot. With biomarkers, growers could test much earlier, only planting trees that will keep their needles post-harvest. And it could help breeders cross in resistance traits from more exotic species to more traditional American ones.