Transcript Slide 1
The New Zealand Institute for Plant & Food Research Limited Intragenics/cisgenics and other emerging techniques for genetic modification Tony Conner New techniques in crop breeding Plant breeders have always been rapid adopters of new technologies: - Haploid plants & chromosome doubling - Chromosome manipulation – substitution & addition lines between species - Chemical- and radiation- induced mutations - Cell & tissue culture – wide hybrids, in vitro fertilisation, protoplast fusion, spontaneous genetic changes The New Zealand Institute for Plant & Food Research Limited Molecular biology era Two key technologies: - DNA diagnostics for marker-assisted selection - Genetic engineering, now allows the routine transfer of DNA from any source to crops Latter was a step too far for society Strict regulations throughout the world, usually embedded in legislation The New Zealand Institute for Plant & Food Research Limited Genetic modification refinements New breeding and genetic modification techniques have continued to rapidly evolve Unclear whether these new techniques result in GMOs as defined in legislation Growing interest in developing techniques that result in plants not containing any new DNA sequences In some cases the resulting changes are similar to, or identical to, those from breeding The New Zealand Institute for Plant & Food Research Limited Emerging issues Scientists are confused as to whether these techniques are, or should be, considered as producing GMOs Regulators are even more confused and are not prepared to make decisions In the modern era of public consultation, how can we expect society to debate the issues when products are ready to go, and the technology is still evolving? The New Zealand Institute for Plant & Food Research Limited Intragenics/cisgenics Genetic engineering of plants with their own DNA Assembly of vectors for gene transfer from the target species Transfer genes from the genepool to elite lines of the crop May or may not involve ‘chimeric’ genes GM crops without foreign DNA Issues around the use of term ‘cisgenics’ The New Zealand Institute for Plant & Food Research Limited Null segregants from transgenics Non-transgenic progeny segregating from plants heterozygous for transgenes These non-GM plants are still legally GM in many countries, including NZ and Europe Should these plants be considered transgenic? But what if the transgene has already been used to increase or decrease the frequency of natural recombination? Provides a valuable breeding tool to break-up or maintain ‘linkages groups’ [co-inherited genes] The New Zealand Institute for Plant & Food Research Limited Grafting onto root stocks What if non-transgenic plants are grafted onto transgenic rootstocks? - resistance to root diseases in fruit trees or grapes on which non-GM scions are grown – are the harvested fruit GM? - but what if rootstock transgenes are designed to translocate silencing micro-RNAs from the rootstock to the scion to induce changes in gene expression? The New Zealand Institute for Plant & Food Research Limited Targeted mutagenesis Allow the exact desired change to be induced in a genome ‘Oligonucleotide-directed mutagenesis’ (ODGM) for site-specific alteration Oligonucleotide molecules are not incorporated into the genome Induce a DNA repair mechanism to make the desired change(s) Will become more important with whole genome sequence knowledge More precise and targeted than ‘classical’ mutagens The New Zealand Institute for Plant & Food Research Limited Implications and issues arising No clear biological distinction between traditional plant breeding approaches and GMOs Complete continuum of technologies from traditional plant breeding to transgenics - Matter of interpretation whether new techniques fall within the scope of GMO legislation - Definitions of GMOs differ between countries - Enforcement difficult when resulting organisms are indistinguishable from conventional breeding The New Zealand Institute for Plant & Food Research Limited