Should we apply genetic engineering techniques to try and avoid tree species from becoming extinct? In the United States, chestnut trees are said to have been made resistant to some fungal diseases by transferring genes from wheat. Currently, there is a debate in the United States about whether these genetically engineered trees (which are generated by using older genetic engineering techniques) should be released for planting without additional requirements. Many experts are warning that trees can live for a few hundred years and go through various stages of growth, flowering, seed formation and aging during this time. Consequently, effects can emerge that were not observed in the first few years. During their lifetime, the trees will also be exposed to various changes in their environment, such as climate change. The resulting stress can alter their gene regulation and biological properties. Forest trees interact with their environment in many ways, e. g. through root fungi, insects, wild animals and other plant species. In the course of their lives, trees produce huge amounts of pollen and seeds that can be transported for miles in the wind. The artificially modified genetic material can spread via pollen, seeds and, in the case of poplars, also through shoots growing in the environment. If the genetically engineered trees spread to natural populations, the consequences are very difficult to predict.
In short, the time periods that would need to be considered in risk assessment are too long and the possible interactions too complex. It is by no means unlikely that the trees or their descendants will develop characteristics in response to the different stress factors not originally observed in the first generation of the genetically engineered trees. This can weaken natural tree populations and disrupt or even destroy associated ecosystems.
Scientists in China, the USA and Sweden are all using CRISPR to genetically engineer forest trees. The first releases of gene manipulated poplars were requested in Sweden in 2016. These trees show a whole series of intended changes in their genome: flowering, growth, formation of branches, leaves and roots are all affected. The aim of the scientists was to create trees with significantly different growth patterns and appearance. Economic goals in this field include accelerated growth and altered wood quality for use in the wood and paper industry.
This example shows: The release of genetically modified trees endangers the ecosystem of forests, especially if they can spread in the environment and their modified genes reach natural populations. From the perspective of the precautionary principle, releases of genetically engineered trees that may allow them to spread without control cannot be permitted.