Kawall K (2021) → The Generic Risks and the Potential of SDN-1 Applications in Crop Plants. Plants 2021, 10, 2259. Environmental Sciences Europe 33 (1):38. doi:10.1186/s12302-021-00482-2
The publication focuses on so-called SDN-1 ‘gene scissor’ applications, such as CRISPR/Cas, that are used to make small genetic changes in the genome of target organisms. The applications can, however, lead to significant changes in plant metabolism and constituents, especially if they are made repeatedly and in combination. The publication provides an overview of complex SDN-1 applications (i.e. multiplexing and alteration of multiple gene variants) as well as single point mutations in market-oriented crops. For this purpose, the current study analysed a dataset previously published by Modrzejewski et al. 2020, and divided induced SDN-1 changes into three categories, i.e. multiplexing, the alteration of multiple gene variants and the alteration of single genes. It was found that SDN-1 applications knocked out single genes in slightly more than half of the studies examined. Among them is the ‘CRISPR tomato’ which has an increased content of an antihypertensive ingredient (i.e. GABA) and is already approved in Japan. This latter case highlights the fact that conventional breeding was not able to change the relevant genes in the same way that was possible using gene scissors. More complex SDN-1 applications were carried out in other studies, e.g. the silencing of several different genes.
In addition to describing the intended genetic changes achievable with SDN-1 applications, the publication also presents specific and sometimes novel risks associated with gene scissors that can arise from unintended effects. On the one hand, these so-called off-target effects can result from the fact that the gene scissors cut at unintended regions of the genome, and thus induce changes at these sites. On the other hand, the gene scissors can also cause unintended changes at the target sequence (also called on-target effects). Risk assessment should, therefore, also consider the additional procedures used to introduce the gene scissors into the plant cells.
It was found that case-specific risk assessment is the most appropriate way of assessing plants derived from new genetic engineering, as it takes both the properties of the end product and the process-related risks into account.
Studies from the following review were analysed in the publication:
D. Modrzejewski et al. (2020): 2. Aktualisierung der Übersicht über Nutz- und Zierpflanzen, die mittels neuer molekular-biologischer Techniken für die Bereiche Ernährung, Landwirtschaft und Gartenbau erzeugt wurden – marktorientierte Anwendungen (Version 20. März 2020)