The Redwoods Genome: Zane Moore, Ph.D.
Join Zane Moore, Ph.D., to look at the remarkable genetic marvels of redwoods.
We are especially grateful to Zane for taking the time to answer questions that we could not get to in the webinar.
Q: During the fire, were you worried or did you somehow know these trees would survive?
A: Initially, I was not worried. Then I saw some of it and thought “oh no, maybe we lost 2/3rds of them”. I became more worried a month or two after the fire than during the fire itself. But maybe 6 months to a year after the fire, I was very pleasantly surprised.
Q: How did that tree create the two sides at 250 feet up? Why aren’t there more like that?
A: That redwood tree’s top broke off (from wind or another hitting it) 550 years ago. It’s a much older tree than many of the others in that forest. The older a tree gets, the more gnarled it gets. In some areas, like near the coast, redwoods get more gnarly because of the wind breaks.
Q: Can one branch pollinate another branch on the same tree and produce a viable seed? would that be analogous to incest in its likelihood to produce genetic defects etc or would it just mean there is a less diversity in the next generation than if the branch pollinated a branch on another tree?
A: Yes, that is possible. Redwood trees do a cool thing to prevent mutations from accumulating with inbreeding. They separate out into two major cell lineages per branch—one cell lineage makes more pollen whereas the other cell lineage makes more seeds. This way, if a mutation occurs, it is unlikely to be found in both sexes. More information can be found in my dissertation, free to read online: https://escholarship.org/uc/item/6r103839
Q: Is the redwood genome the largest or are there larger genomes out there of other living species?
A: Redwoods are not the largest genomes. They are one of the largest for conifers, though some pines like white pines (sugar pine, bristlecone) have about the same genome size as redwood though they are diploid. Alerce (Fitzroya in Chile) and some junipers are tetraploid. Redwood is the only known hexaploid conifer. The largest genome is a weird fern Tmesipteris and it’s over 5x larger than coast redwood!
Q: Can the redwood species be genetically improved by breeding programs & research?
A: Yes, but it would take a long time. Typically most redwoods do not make cones for a few decades. There are some groups trying to do this and out planting coast redwoods in many other places. I think it would be worth using areas with larger clones (like Santa Cruz/Scotts Valley) to use the natural inbreeding to speed up discovery of what genes/chromosomes cause what traits.
Q: Have you used mutation rates to estimate other clone ages? What’s the range?
A: No, but I would like to! There is a curly redwood clone in Nisene Marks that might be older. It has 529 trunks and covers nearly the same area. But none of this has been “confirmed” through sequencing and would cost quite a bit to do so. It would be SO cool to do.
Q: Is the genetic variability tied to a Coast Redwood seedling that came from a seed? (vs sprouting from the base from an existing tree)
A: I’m not sure I understand the question. New genetic variation always comes from mutations (I would think mostly in the branches). A seed is simply trying new combinations of mutations in a baby seedling. The mutations may have come long ago in one tree or another tree, but the combination of different ones in an embryo is what makes sexual reproduction still necessary and so important for these trees.
Q: Do you think that the “rapid’ genetic variation will help redwoods to survive/thrive in our drier/warmer future? Are foresters trying to find better variants for forests?
A: Yes; and I think so?
Q: Are Douglas firs also hexaploidy?
A: No, they are diploid and reproduce entirely by seed.
Q: Where is the large tree that you began with? The burned-out one?
A: Between Sand Hill Overlook and West Ridge Trail Camp in Nisene Marks. You can see it from the trail if you look carefully.
Q: When did redwoods first appear on Earth?
A: 180 million years ago (first fossils in modern-day China)
Q: Can cutting of redwood forests today alter the genetic composition of the redwoods 50, 100 years in the future? Would it be for the better or worse?
A: Yes, and completely unclear whether it would be better or worse. We see that logging leaves a signature of chromosome anomalies and probably reduces the genetic diversity in the branches since the tree has to start from scratch again.
Q: Can you talk a bit about the purpose of albinos?
A: Albino redwoods are mutant branches that happen randomly but that may grow faster in certain conditions. They seem to grow better than green branches in high heavy metal conditions. It could be that they can handle heavy metal stress better than green branches because they do not have photosystems that would be damaged by heavy metals as easily. We do not know much more than this.
Q: The redwood I planted 25 years ago in my garden has thin branches that sprout from really close to its trunk – are these new trees or just branches? Those sprouts are coming out of the ground next to the trunk.
A: Both. There is no biological distinction, only a philosophical one, that separates branch from tree.
Q: Do these results have implications for fitness or longevity for Sequoia vis-a-vis diploid cypresses such as Thuja plicata or Taiwania? What sort of differences?
A: I would expect hexaploid species to be able to live longer between sexual reproductive events.
Q: Is there similar work going on with the Sierra sequoia?
A: Not on mutations in the crown. There genome was sequenced and one of the better conifer genomes that exists. Unfortunately, their population size is relatively small and extremely threatened by fire. They are DEEPLY vulnerable and need all the help they can get!
Q: Are “second growth” trees actually clones of nearby stumps of trees that were logged?
A: Oftentimes, yes. Especially in the Santa Cruz Mountains.
Q: Is there a chance that clonal root systems are actually much older than 30,000 years old? Or do entire clone systems (including the root system) die as soon as individual trees within the clone begin to die?
A: We don’t know. There is always a chance, though we have no idea on this particular question. Also, I doubt there is any organic matter in the 30,000 year old clone that is actually 30,000 years old. It’s just that it germinated as a seedling that long ago.
Q: Is there anything about the genetic structure of redwoods, or the way they propogate, that makes them more or less resilient to climate change?
A: Hexaploidy makes them more resilient, not only as individuals but also as a population. They can try out all sorts of different mutational combinations because of their genetic redundancy. Other tree species, like Douglas fir in the Santa Cruz Mountains or giant sequoia are more vulnerable.
Q: Have you seen different fungi with the giant clone clusters (compared with mature individual trees) which affect presence or success of clones?
A: Never been studied in coast redwoods. They have Arbuscular Mycorrhizae that are very small and are not known to go between trees. This is extremely understudied compared to the Ectomycorrhizae studied in Douglas fir forests in British Columbia.
Q: To what do you ascribe the amazing mutational ability of a coast redwood? Do you think it has to do with how long the species has been on the planet?
A: Evolution is an arms race between species. It is unlikely that a tree/clone with 10,000 year generation times can compete with insects or fungi with annual or sub-annual generation times. Old things must deal with change if they wish to remain old things—otherwise they will die out. I think it’s out of this necessity that redwoods do what they do. I would not be surprised if other long-lived individuals have similar mutation rates and/or ways to deal with mutational meltdown, but it has not been studied.
Q: Would a stump sprout have fewer mutations than a branch from up high? (i.e., stumps sprouts are more like the original parent tree?)
A: Potentially yes—fewer cell divisions. Potentially no—same age and close to the ground where their could be mutagens. We do not know.
Q: Is there similar research on genetics of these ancient sycamores in the santa cruz mountains?
A: No. It would be interesting to do so, though. The sycamores are amazing and Santa Cruz Mountains has the tallest ones in existence (off Eureka Canyon Road – nearly 180’ tall!!).
Q: Any hint of different mutation rates in trees growing from southern vs northern parts of the range?
A: Only one redwood tree has been studied in this regard—the one I worked on for my dissertation. It would be very interesting to know!
Q: Did you investigate the fossil burl? and if so did you find anything cool?
A: Yes, it works just like lignotubers (sprouting burls) work in redwood. There were long branch traces that branched across years that start in by where the pith is. This sprouting phenomenon has been happening since the middle of the Jurassic probably with dinosaur herbivory!
Q: Why do redwoods produce root shoots? Some produce many others none at all. Is it known what induces some redwoods to produce root shoots?
A: Redwoods do not produce shoots from their roots, usually. They almost always come from a lignotuber or burl or stem close to the ground and the base of other redwoods. This burl could extend further out. But rarely do sprouts form from roots.
It does seem to me that trunk spacing in clones has some genetically determined component. Some clones have many trunks tightly spaced, others are very loosely spaced. We have no idea why one happens vs. the other. We have no idea why some redwoods sprout and others do not.
May 2025