Gene scissors found to cause chaos in the genome of tomatoes
20 June 2023 / Recent scientific findings have revealed chromothripsis-like effects after the application of CRISPR/Cas in the genome of tomatoes. Chromothripsis refers to a phenomenon in which often several hundred genetic changes occur simultaneously in a 'catastrophic' event. Many sections of the genetic material can be swapped, twisted, recombined or even lost if this occurs.
It has been known for some time that ‘CRISPRthripsis’, which is another term for the above-described phenomenon, occurs in mammalian (and human) cells. This effect has now been also demonstrated in plants after gene scissor applications. The new study was already published before the peer-review process. The findings show that gene scissor applications cause unintended genetic alterations much more frequently than previously thought, affecting large parts of the genome.
When both strands of DNA are cut, as is typically the case with the CRISPR/Cas, the ends of the chromosomes can loose contact with each other. If the repair of the break in the chromosomes fails, the severed ends can be lost, restructured or incorporated elsewhere. Chromothripsis otherwise seems to be relatively rare in plants. CRISPR/Cas applications can frequently result also in changes at genomic sites that are particularly well-protected by natural repair mechanisms. The risks cannot generally be estimated, they must be investigated thoroughly in each and every case.
The recent findings shed new light on the alleged ‘precision’ of gene scissors: although the new technology can be used to target and cut precise locations in the genome, the consequences of ‘cutting’ the genome are to some extent unpredictable and uncontrollable. Plants obtained from new genetic engineering (New GE) cannot, therefore, be regarded as safe per se, and need to be thoroughly investigated for risks.
Without exact genomic analyses, chromothripsis can be easily overlooked. It is, for example, not unlikely that it also occurred in plants obtained from New GE that were already deregulated in the US.
Attempts are currently being made in Europe to largely deregulate plants obtained from CRISPR/Cas applications. According to leaked documents, the EU Commission plans to give companies permission to release New GE plants into the environment and to market their products after only a short period of notification. Similar to the USA, the proposed criteria exempting them from mandatory risk assessment would not require any investigation of unintended genetic changes, e. g. chromothripsis. The new regulation would not only be applicable to plants used in agriculture, but also would allow the release of wild plants with no in-depth risk assessment. Testbiotech is warning that the planned deregulation and large scale releases of New GE organisms could threaten natural resources needed by future generations.
Christoph Then, email@example.com, Tel + 49 151 54638040