New plant breeding techniques

(July 2013)

Executive Summary

Food Standards Australia New Zealand (FSANZ) convened an expert scientific panel to provide advice on a number of new plant breeding techniques that have come to the attention of regulators. Appendix 1 provides details of the membership of the panel. The techniques discussed were:

  1. Pioneer Hi-Bred International's proprietary seed production technology (SPT) - developed for use in corn to improve the efficiency of hybrid seed production. It involves using a genetically modified (GM) plant line to propagate a male-sterile plant line which is then used as one of the parents to produce hybrid seed. The genetic modification is not inherited by the hybrid plant line.
  2. Reverse breeding - a novel plant breeding technique that involves suppressing meiotic recombination in order to recreate homozygous parental lines that, once hybridised, reconstitute the composition of an elite heterozygous plant without the need for backcrossing or selection.
  3. Cisgenesis and intragenesis - involve transferring a new gene into the genome of a plant using gene technology. In both cases the gene is derived from either the same or a cross-compatible species.
  4. GM rootstock grafting - involves grafting the vegetative part of a non-GM plant (the scion) onto the rootstock of a GM plant to create a chimeric plant that shares a single vascular system.
  5. Oligo-directed mutagenesis (ODM) - involves the use of synthetic oligonucleotides to introduce small, site-specific mutations into the plant genome.
  6. Zinc-finger nuclease (ZFN) technology - involves the use of an engineered zinc finger nuclease to introduce site-specific mutations into the plant genome. Depending on the type of ZFN technology deployed, mutations can either be restricted to one or a few nucleotides or involve the insertion of a new piece of DNA.

The objectives of the workshop were to: enhance FSANZ's scientific knowledge and understanding of each of the techniques; and provide scientific advice on the nature of derived food products. It was not the role of the panel to make a legal determination as to whether the techniques or their derived food products would come within the definition of 'food produced using gene technology' in Standard 1.5.2 of the Australia New Zealand Food Standards Code. However, the expert panel were asked to provide their scientific opinion on whether derived food products should be regarded as GM food.

As a result of the panel discussion, the techniques were grouped into three categories. Category 1 comprises cisgenesis/intragenesis, targeted gene addition or replacement using ZFN technology, and GM rootstock grafting. It was the view of the panel that foods produced using these techniques should be regarded as GM food and undergo premarket safety assessment.  In the case of cisgenesis/intragenesis and targeted gene addition or replacement using ZFN technology the derived food would be similar to that produced using standard transgenic techniques. Consideration of GM rootstock grafting was more complicated because food produced by a non-GM scion grafted onto a GM rootstock would not contain any introduced DNA. However, it may contain novel RNA and/or protein as a result of the genetic modification to the rootstock. Depending on the genetic modification, the food may also have altered composition or other characteristics. The panel did however note the following:

    • in the case of cisgenesis and intragenesis, a simplified form of food safety assessment may be warranted because the transferred genes will be derived from the same or a closely related species which is likely to be commonly used as food and have a history of safe use; 
    • in the case of GM rootstock grafting, the majority of foods will not contain any novel genetic material or have altered characteristics and therefore should only require a simplified food safety assessment. 

Category 2 comprises techniques used for targeted mutagenesis, including ODM and ZFN technology. It was the view of the panel that changes introduced using such techniques would be typically small and definable and have predictable outcomes. Such techniques would therefore be similar to traditional mutagenic techniques used in conventional plant breeding and food derived from these plants should not be regarded as GM food.

Category 3 comprises techniques which involve the use of gene technology at an early stage that is separate from the final plant breeding process. The techniques in this category include SPT and reverse breeding. Although not specifically discussed, the panel noted that accelerated breeding following induction of early flowering using gene technology could also be included in this category. In the case of SPT the panel was of the view that food produced using this technique should not be regarded as GM food as a genetic separation exists between the early GM ancestor (known as the GM maintainer line) and the non-GM parents of the final food-producing line, which does not contain the genetic modification. The panel considered however that it would be useful to have more information confirming the reliability of the sorting technique for indicating the presence or absence of the introduced genes as well as general compositional analysis confirming the equivalence of an F1 hybrid produced via SPT with a standard F1 hybrid.

While there are clear parallels with SPT, the panel did not consider they could reach firm conclusions about reverse breeding because insufficient technical detail was available on how transgene-free end products are produced, as well as the reliability of the process overall.  They noted however that there did not appear to be any particular hazards associated with the GM component of the technique. The panel also considered it would be helpful to develop some criteria for distinguishing techniques such as SPT, accelerated breeding and reverse breeding from those where the final food-producing lines are clearly GM and also for ensuring that a complete barrier/genetic separation exists between the early GM breeding lines and the non-GM food-producing lines.



FSANZ greatly appreciates the enthusiastic approach of the expert panel to this task and their contribution of knowledge and expertise to this work.

Download: New Plant Breeding Techniques Workshop Report pdf (534 kb) | (word 224 kb)