Trees naturally absorb CO2 through photosynthesis(光合作用), releasing oxygen, storing carbon for decades, or even centuries. Biotechnology firm Living Carbon says lab trials of its genetically changed poplars(杨树) take up more carbon and grow 1.5 times faster than unchanged trees.
Engineering the poplar's genes makes its photosynthesis more efficient. turning more carbon dioxide into sugars to create wood biomass. The team added genes from pumpkin and green algae(藻类) that allow quicker growth and better carbon storage by lowering the rate of a process called photorespiration(光呼吸)—which wastes energy and allows fixed carbon to re-enter the atmosphere as CO2.
Promising as the firm's lab results are, biologists warn that high growth rates are not guaranteed in the wild as the poplars compete for sunlight with other plants and trees. Genetically modified(GM) supertrees may also need intensive watering and fertilizer(化肥) to sustain their rapid growth.
Results are crucial given the rate of climate change and climbing CO2 levels in the atmosphere. But critics say there are risks to planting GM trees in the wild if they reproduce with other trees, or negatively affect other plant and animal species.
Living Carbon says its trees are a hybrid that can only reproduce from cuttings, so cannot cross-pollinate(授粉) with wild trees.
If the field trials are successful then it will still take time to get approval from the government. One sixth, around 135, tree species in the US may face extinction due to climate change, deforestation, foreign insect species, or disease. And even though field trials of a GM chestnut tree have shown its resistance to some foreign disease that wiped out billions of American chestnuts, it still has not been approved for planting.
If CO2 storage is the aim then there are species that already fit the bill. California's Redwood trees store more carbon than any other species. Redwoods are not suitable for every forestry plot, so creating climate adaptable trees through reproducing programmes that fit into local ecosystems is the goal. But in the rush to fix the climate crisis, increase CO2 uptake, and carbon storage, GM supertrees may be part of that solution.
