- C4 fixation is a characteristic of smaller, monocot plants. Trees are slower-growing dicots. There are more pathways to these organisms than just increasing energy production efficiency. For example, have you proven that trees actually reinvest the excess glucose into growth, rather than trigger negative feedback pathways to slow glucose production?
- Also, you claim that the plant is faster growing with harder wood. Typically with trees, the speed of growth is inversely proportionate to the strength of the wood - i.e. cottonwoods and box elders grow fast but are terrible woods, while oak and maple are the inverse. Given the long lifespan of these organisms, have you any preliminary data to back up these claims that these trees are growing faster and stronger?
I used to do plant transgenics in a past life, and while skeptical, I do see projects like this as a solution for the future - though more along the lines of faster growing algae because ultimately the bottom line is the variable cost of converting sq meters of sunlight into carbon energy. It's just super easy to fall for hype and go straight to science fiction rather than focus on the science.