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Genetically modified tree

life science Maturity 9-11 Next article →

A genetically modified tree, often called a GM tree or transgenic tree, is a tree with its DNA altered through genetic engineering. DNA contains the biological instructions that determine how a living organism grows and functions. Scientists modify this DNA to introduce novel traits that do not occur naturally within a specific species. These modifications aim to provide benefits to industries, foresters, or the environment. Common goals include creating resistance to pests, diseases, or harsh environmental conditions. Some trees are engineered for herbicide tolerance or to change lignin levels to lower paper production costs.

Apfe-auf-Naehrboden
Apfe-auf-Naehrboden

The process of genetic engineering involves inserting specific genes into a tree's genome. For example, to increase wood volume, scientists may use a technique called Agrobacterium tumefaciens mediated recombination. In the year 2000, the company FuturaGene used this method to create a eucalyptus variety known as H421. They inserted the cel1 gene from a small plant called Arabidopsis thaliana into a hybrid eucalyptus. This gene produces an enzyme called endo-(1,4)-β-glucanase Cel1. This enzyme breaks bonds in the plant cell wall, which increases the flexibility of the cell wall matrix. This flexibility allows cells to expand and elongate more easily, resulting in greater biomass.

Researchers also work to alter lignin, a substance that binds wood fibers together. Reducing lignin can lower pulping costs by up to $15 per cubic meter. Traditionally, removing lignin requires expensive and hazardous chemicals. Some scientists tried reducing lignin levels, but this often made trees weaker against wind, snow, and disease. To solve this, researchers at the University of Columbia introduced chemically labile linkages. They inserted a gene from the plant Angelica sinensis. This allows the lignin to break down easily when treated with a mild base at 100 degrees C. This method maintains the tree's strength and growth potential.

There are several distinct types of genetic modifications currently under development. One type focuses on frost tolerance to expand where certain trees can grow. ArborGen is researching freeze-tolerant eucalyptus to allow cultivation further north than the southern tip of Florida. Another type involves insect resistance. The Bt eucalyptus variety uses three genes from the bacterium Bacillus thuringiensis. These genes produce proteins called Cry that target the intestines of certain caterpillars. This helps prevent losses of up to 40% in productivity caused by pests. Additionally, some trees are modified for herbicide tolerance. FuturaGene developed eucalyptus in Brazil that is tolerant to the herbicide glyphosate by using a gene from the bacterium Agrobacterium tumefaciens.

History shows that GM tree research has been active since 1988. While many GM crops are widely used, GM forest trees are still in early stages. In 2002, China approved GM poplar trees for commercial use. Approximately 1.4 million insect-resistant poplars were planted as part of the 'Green Wall' project to stop desertification. In Brazil, the H421 eucalyptus variety received regulatory approval in 2015. More recently, the Bt 1521K059 eucalyptus variety was approved in 2023. In the United States, a company called Living Carbon was founded in 2019. They began planting hybrid poplars in a Georgia forest in February 2023 to study carbon sequestration.

The significance of this technology is seen in its potential environmental and economic impacts. Living Carbon's modified trees showed a 53% increase in above-ground biomass in early trials. This allowed them to absorb 27% more carbon dioxide than normal trees. Such traits could help combat climate change through carbon capture. However, the scale of potential impact also brings significant environmental concerns. One major worry is the escape of transgenes into the wild through pollination. Pine pollen, for instance, can travel distances of up to 3,000 kilometers. This makes the risk of cross-breeding with wild species quite high.

Because of these risks, the Convention on Biological Diversity suggests that GM forest trees should be completely sterile before commercial use. Sterility would prevent the trees from producing pollen or seeds that could spread modified genes. Ensuring complete containment has proven difficult for scientists. While some experts predicted containment might be possible by 2020, many questions remain. This connects to broader discussions about biodiversity and the management of natural ecosystems. Scientists continue to balance the industrial benefits of faster growth and disease resistance against the need to protect native forest populations.

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