Development of Genomic Tools in Coast Redwood
Genome science has made stunning advances in the past few decades. But until recently, no one had tried to sequence Sequoia sempervirens, the coast redwood. Part of the problem was the species’ complexity. Humans are “diploid,” meaning that for each chromosome, they have one copy inherited from their mother and one from their father. Redwoods, on the other hand, are “hexaploid,” meaning that they have three copies from each side, which triples the size of their genome.
Despite the difficulty, forest geneticist David Neale decided to begin sequencing the enigmatic redwood in 2007. “It’s an ancient species and it may be a living representation of ancestral conditions,” the University of California, Davis, professor said. “I’ve always been interested in it.” In a pilot project funded by a grant from Save the Redwoods League, Neale and colleagues Deborah Rogers and Barnaly Pande sampled 11 redwood individuals. In each tree, they examined DNA from 40 genes believed to be involved in adaptation to the environment.
“We developed better genetic tools for understanding redwoods’ response to climate change, and other factors that might be affecting populations of redwoods,” Neale said. The work suggested that redwoods might be more genetically diverse than other conifers. Because of the project’s small sample, “that’s a very preliminary conclusion” Neale said, “but it was notable to us.”
Eventually, Neale hopes to do for conifers what genomic science is doing for medicine. “If we have your DNA sequence, a physician can estimate your risk factors for disease,” Neale said. “I’m using the same technology to estimate risk factors in tree populations.” In an age when healthy forests could be part of the solution to rising carbon-dioxide levels, reaching that goal could be as important for humans as for trees.