The traditional Christmas tree is a precious holiday institution in millions of homes. Periodically vacuuming up the needles that fall from Christmas trees has long been an unwelcome part of this festive custom. Megan Molteni says in a recent article that this may soon change. The article, which describes current research on Christmas tree genetics, appeared on the Wired website in December, 2017.
Despite the availability of modern research tools like genetic sequencing and computational biology in agriculture, there isn’t much information about the genetics of Christmas trees and other conifers. A group of scientists is working to expand our knowledge. The effort is about more than annoying pine needles. Christmas trees are often vulnerable to root rot caused by Phytophpora fungi. The industry loses millions of trees annually.
The research has its origins in a project that began in 1978. In that year, Dr. Gary Chastagner of Washington State University began collecting samples from the best Christmas tree specimens he could find. Chastagner initially assigned graduate students to count tree needles one by one. He has since refined the methodology. Samples are now rated on a scale of one to seven. The cuttings that show the best and worst degrees of needle retention are grafted onto root stock. They become part of a collection maintained at a 15-acre site in Puyallup, Washington. Each cutting eventually becomes a “clonal holding block.” That is, it is developed into a small stand of genetically identical Christmas trees.
The current research began five years ago as a partnership between Chastagner and scientists at North Carolina State University. The Christmas tree collection in Washington is a massive storehouse of genetic information. Funded by a grant from the United States Department of Agriculture, the project is attempting to identify the specific genes that control how well a tree retains needles. The research has gone well, and the scientists expect to start generating definitive answers early in 2018.
Chastagner and Dr. John Frampton of North Carolina State University have spent the last five years amassing the gene sequencing data from the Christmas trees. Computational biologist Dr. Jill Wegrzyn of the University of Connecticut is performing the analysis.
The task is complicated by the unusual nature of conifer genetic structure. The genome contains approximately 20 billion genes. By way of comparison, the human genome consists just three billion. Further complicating the analysis is the fact that the conifer genome contains a duplicate set of genes.
The research team has focused on cells that actually connect needles to the tree. They are looking for the genetic indicators that govern whether the needle will break off at this point. The project has also gathered data on the tree roots. The goal here is to find the genetic markers that control the degree to which a tree can resist fungal infections.
The ultimate aim of the project is not to create genetically modified Christmas trees. The complexity of the conifer genome precludes that option. Instead, researchers hope to be able to identify the best Christmas tree specimens as seedlings. Currently, growers must wait up to 10 years for trees to mature before they can be certain they have a top-quality tree.