Japan granted approval in January 2021 for the first ‘CRISPR tomatoes’ to be used in food production. The tomatoes contain a much higher concentration of a plant compound (GABA) compared to those derived from conventional breeding. GABA (γ-Aminobutyric acid) can diminish the transmission of specific signals in the central nervous system which may, amongst others, cause lower blood pressure. Therefore, the tomatoes will be introduced as a modern ‘lifestyle’ product. At the same time, it is known that GABA has a multifunctional role in tomato plants: it influences, for instance, plant growth, resistance to plants pests and diseases as well as several other metabolic reactions.
The concentration of GABA is naturally enhanced in plants attacked by pest organisms. However, all attempts to achieve a permanent higher level of GABA in the plants through conventional breeding have failed. Due to the multifunctional role of GABA, it has to be assumed that the genetic intervention will affect plant metabolism on several levels. These changes also can cause unintended health effects at the stage of consumption. In addition, the plants can show unexpected reactions to environmental stress conditions, which can again have an impact on the safety of food products.
There have been previous reports on CRISPR tomatoes: in 2018, scientists succeeded in using CRISPR/Cas to change several genes at the same time in non-domesticated wild tomatoes. Six genes were cut with the result that small fruits growing on bushy plants were changed into tomatoes that look similar to the ones currently marketed. This was intended to show that the outcomes of years of conventional breeding are replicable within a very short period of time using new genetic technology. However, there are also greater changes in the concentration of compounds in these GE tomatoes. This kind of gene manipulation, i.e. changing several genes at the same time, is called ‘multiplexing’. Even though no additional genes were inserted, the impact was extraordinary: the number of fruits, their size, form and compounds as well as the architecture of the plants were changed in just a few working steps and within a short period of time.
This example shows how it is possible to bring about major changes in the composition of food plants without inserting additional genes. The cultivation and consumption of the tomatoes are associated with a wide range of risks. Therefore, such genetically engineered plants need to be thoroughly investigated before any conclusions can be drawn on health and environmental risks or safety.