ADVISORY COMMITTEE ON RELEASES TO THE ENVIRONMENT Advice on a plant breeding technique involving oligo-directed mutagenesis: RTDSTM

Advice: ACRE considers that herbicide tolerant (HT) oilseed rape plants produced by Cibus LLC have been developed using a form of mutagenesis. It considers that this technique does not involve the use of recombinant nucleic acid molecules. Consequently, the HT oilseed rape plants could be excluded from the GMO Deliberate Release legislation in accordance with Annex 1B of Directive 2001/18/EC. Introduction to oligo-directed mutagenesis Oligonucleotide-directed mutagenesis (ODM) is a technique used to correct or to introduce specific mutations at defined sites of the genome. ODM is a generic term covering several approaches and applications. It is referenced in the literature under other names such as targeted nucleotide exchange, chimeraplasty, oligonucleotide-mediated gene editing, chimeric oligonucleotide-dependent mismatch repair, oligonucleotide-mediated gene repair, triplex-forming oligonucleotide-induced recombination, oligodeoxynucleotide-directed gene modification, therapeutic nucleic acid repair approach and targeted gene repair (see e.g. All these techniques are based on the site-specific correction or directed mutation (base substitution, addition or deletion) of an episomal or chromosomal target gene after introduction of a chemically synthesized oligonucleotide with homology to that target gene (except for the nucleotide(s) to be changed). In all cases, the gene modification is induced directly and exclusively via the effect of the oligonucleotide itself, i.e. independent of any delivery vector system. The above-mentioned definitions do not cover cases where the oligonucleotide is chemically modified to incorporate a mutagen (the oligonucleotide is used as a vector to deliver the mutagenic agent in a DNA site-specific manner) (Kalish and Glazer, 2005), nor cases where the oligonucleotide is used together with zinc-finger nucleases (ZFNs) to generate double-strand breaks at specific genomic sites (Wright et al., 2005). Although the usefulness of the technique has been first demonstrated in mammalian cells, preliminary studies at the end of the 1990s demonstrated that oligonucleotide-mediated mutagenesis is applicable to plants and can induce target gene mutations (Beetham et al., gene modification has been demonstrated notably in maize, rice, tobacco and wheat, e.g. to create plants insensitive to the action of a specific herbicide (Dong et al. 2000). Altered genes have been shown to be stably maintained during mitosis (Beetham et Herbicide tolerant oilseed rape produced by RTDS™ ACRE was requested to consider a specific ODM technique-the " Rapid Trait Development System " (RTDS™) developed by Cibus LLC and used to generate oilseed rape tolerant to sulfonylurea herbicides. Organisms produced by mutagenesis can be excluded from Directive 2001/18/EC (under which the release into the environment …