Where are we with unintended effects in genome editing applications from DNA to phenotype: focus on plant applications

Marie-Bérengère Troadec,Jean-Christophe Pagès

doi:10.1007/s11248-019-00146-1

Abstract

Agriculture has benefited from various conventional techniques for plant breeding, including chemical- or radiation-induced mutagenesis, and to some extent from transgenesis. Genome editing techniques are likely to allow straightforward, cost-effective and efficient gene-specific modifications for identified genetic traits associated to agronomic interest. As for previous plant breeding techniques, genome editing techniques need an appraisal for unintended effects. Hence, an evaluation of potential specific risks associated with genome editing must be considered. The Scientific Committee of the High Council for biotechnology (HCB), using a broad theoretical and literature-based approach, identified three categories of points to consider in terms of hazards in health and environment, as compared to conventional breeding: (1) technical unintended effects related to effector persistence as well as risks associated with off-target modifications or other unintended genome modifications, (2) risks arising from the desired trait and its novelty in the plant, and (3) risks associated with the potential modification of plant breeding practices, owing to efficacy and technical ease-of-use of genome editing (acceleration), be it for single traits or for combined modifications (multiplex genome editing). Due to novelty, HCB also envisions the need for specific risk assessment and management.

Highlights

Agriculture has benefited from conventional plant breeding techniques
The relative efficacy and ease-of-use of genome editing may be beneficial to (1) the direct transfer of a trait of interest identified in a model variety into various other elite varieties of the same species, (2) the translational use of academic knowledge acquired from the understanding of a phenotype in a cultivated or a wild species into other, (3) the selection of variants in up-to- not modified plants, provided that techniques for genome editing tools are usable in this species and (4) multiplex gene modification of elite varieties
Having listed the possible unintended events, it appears that, at the molecular level, most question could be addressed at an early step of their development

Summary

Introduction

Agriculture has benefited from conventional plant breeding techniques. To increase genetic variability, which supports discovery of traits of agronomic interest, breeders have historically used several techniques, including chemical- or radiation-induced mutagenesis, and transgenesis. The key characteristic of genome edition is that the modification is site-directed aiming at specificity It implies that the genome of the targeted plant is at least partially known, and, in the case of SDN1/2, that the function of the targeted gene is defined, while the allele encoding the desired phenotypic trait should be characterized. Following the choice of the agronomic trait, three molecular steps support genome edition: (1) the targeting of the desired sequence, (2) the DNA-cut at the selected sequence, and (3) the induction of the DNA-repair process (Fig. 2). A selection process is needed to detect the organisms harboring small insertion or small deletion, and leading to the desired gene inactivation supporting the sought agronomic trait This repair step produces various molecular products; this process denominated SDN1.

Problematics and discussion

Conclusion

Compliance with ethical standards