I once spent an enjoyable afternoon sitting outside the Department of Energy’s Joint Genome Institute in Walnut Creek listening to Jerry Tuskan, a plant geneticist who led the team that successfully sequenced the poplar genome, explaining how he would redesign a tree. By modifying how its genes expressed themselves, the tree would be altered so it didn’t “waste” all its carbon in twigs and small branches and an unnecessarily extensive root system, but instead packed all the useful stuff into the stem of the tree, a.k.a. the trunk, where it could be more productively harvested.
Tuskan is no mad scientist. He is a thoughtful, eloquent man who has thought long and hard about how to integrate energy crops into an agricultural system that is both biodiverse and sustainable. And he clearly likes trees, a lot. Yet even as we stared up at an elm tree, imagining how to rejigger its canopy, I could not help catching my breath at the sheer ambition necessary to imagine overhauling the genetic architecture of a tree from the top down. I’d trust Jerry Tuskan to do the right thing, but I’m not so confident about, say, an oil company executive looking to diversify out of petroleum.
I was reminded this week of my conversation with Tuskan by the news that Taiwanese scientists, working with researchers at North Carolina State University, have successfully genetically modified the eucalyptus tree so that it consumes three times as much carbon dioxide as an unmodified tree. As an extra benefit, the ratio of lignin to cellulose in the genetically modified eucalyptus is altered so there is less lignin (the nasty, super recalcitrant stuff in plant walls that is so hard to break down) and more of the good stuff — the cellulose.
[Taiwan Forestry Research Institute] researcher Chen Zenn-zong explained that cellulose, hemicelluloses, and lignin in trees are all created from carbon elements. “However, only cellulose can be used in commercial processes of pulp manufacturing and bio-ethanol extraction,” he added.
“The idea behind the whole project is to increase the value of genetically-modified eucalyptus to related industries, so we adjusted the ratio of cellulose and lignin, ” Chen said. “Meanwhile, we enhance the tree’s capacity in absorbing CO2 to reduce greenhouse gases, so that the more trees planted for production, the more CO2 are consumed.”
Last December, I had some fun with a recommendation by renewable energy experts in Thailand who were calling for the expansion of eucalyptus plantations because the oily gum trees would make a great biofuel feedstock. I urge all eucalyptus friends and foes to revisit that post — if only to recommend, once again, the definitive tract “The Eucalyptus of California: Seeds of Good, or Seeds of Evil?”
Suffice to say, the history of eucalyptus in California does not engender confidence in the ability of humans to “manage” that particular plant. Much as I am delighted, as any essentially optimistic believer in the potential of scientific advances would be, by the possibility that we could chomp our way out of a global warming catastrophe by designing super CO2 chowing plants, I am still a bit leery at the prospect of a new, improved, bionic eucalyptus.
I leave you once again, with the anti-eucalyptus bile of novelist Norman Douglas:
“A single eucalyptus can ruin the faire landscape. No plant on earth rustles such a horribly metalic fashion when the wind blows through these everlasting withered branches; the noise chills on the marrow; it is like the sibilant chant of ghosts. Its oil is called “medicine” only because it happens to smell rather nasty; it is worthless timber, objectionable in form and hue — objectionable above all things, in its perverse, and inhuman habits.”
But we can redesign it! We can make it better!