Even given government incentives and a price on carbon, however, ArborGen must satisfy concerns from regulators and environmental groups that its engineered trees will not, especially when gifted with the ability to resist cold, spread untrammeled through forests.
At its most basic, life is about reproduction. And the species' struggle to adapt and survive can make attempts to control the fertility of plants difficult, according to Steve Strauss, a tree geneticist at Oregon State University who has also consulted with ArborGen.
ArborGen relies on what has been the most popular system for restricting plant pollen, which uses a bacterial gene to produce a toxic enzyme called barnase that slices apart genetic material in a cell, causing death. Through genetic trickery, the enzyme is only produced in the pollen-spreading parts of the tree, destroying its ability to reproduce -- at least most of the time.
Given the number of trees that will be produced, there will likely be enough genetic instability to allow a very small number of the freeze-tolerant eucalyptuses to reproduce, Strauss said. Rather than an absolute containment system, barnase should be thought of as a mitigation strategy, he added.
"It doesn't mean there are no pollen grains produced," Strauss said. "Almost nothing in biology is 100 percent."
A tiny number of seedlings are almost assured to escape from the eucalyptus plantations, Strauss said. But since the trees, in his evaluation, are unlikely to prove invasive, there should be little cause for alarm.
"When you talk about trees, storms happen, wind blows," he said. "The containment is not absolute. There is the chance of some spread. Is it likely to become an invasive weed? Seems unlikely to me."
Until now, only two of ArborGen's experimental eucalyptus stations have been allowed to flower, and the company has reported little in the way of pollen production in the trees. It is now seeking to greatly expand the number and location of trees allowed to flower to 28 sites totaling 330 acres scattered across seven states. The Agriculture Department issued a draft approval of the expansion, subject to public comment, earlier this month.
The modified eucalyptus trees are already planted at most of these sites, and as they approach sexual maturity, ArborGen has been forced to pluck the trees' flowers or cut them down completely, causing millions of dollars in lost research, said Nancy Hood, ArborGen's public affairs director.
This test acreage is fairly small, hardly the equivalent of a full-scale commercial planting, as some environmental groups have accused. (For comparison, there are more than 32 million acres of pine plantation in the South.) However, ArborGen has confessed that it hopes USDA will deregulate the trees by the time the cohort reaches harvest age -- around seven years or so -- allowing the resulting pulp to be sold.
Many biotech researchers are supportive of the expanded experimental permit, which will allow more complete studies of the fertility containment system. While ArborGen has released little in the way of peer-reviewed research so far, it will publish barnase results this year, said Maud Hinchee, ArborGen's chief technology officer.
Such data would be a welcome change. While barnase's mechanism is well documented -- and approved for use in domesticated crops like rapeseed -- its effectiveness has barely been studied, according to an analysis written by Strauss in 2007.