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Cisgenesis: an alternative approach to GM crops
Plant breeding has at this moment two gene pools available: 1. plant breeders’ gene pool consisting of all crossable germplasm. All the genes from this source are available in classical plant breeding. Functional genes isolated from this natural source are called “cisgenes”; 2. a new gene pool consists of transgenes, which are chimeric and mostly partly or totally consisting of genes from non-crossable species, including bacteria, viruses, etc. When GM breeding started in the eighties of last century’ only transgenes belonging to the new gene pool were available. The complicated biosafety regulations, needed for this new gene pool, have been based on these so called transgenic traits but because of the transformation process accidentally they are also including cisgenes. In this way cisgenesis belongs to the expensive class of GM breeding which is only practiced by multinationals in the so called large crops such as maize, soybean and cotton.
Reconstructed logic delivers several arguments against the classification of cisgenesis into the GMO class: 1. Cisgenes are already existing in nature and belong to the breeders gene pool, 2. It does not fit the definition of a GMO, 3. It is in practice classical breeding replacing existing introgression and translocation breeding with the advantage of absence of linkage drag, 4. The EFSA recently showed that cisgenesis is as safe as classical plant breeding, 5. Another EU committee on new techniques concluded in majority that a sequence of at least 20 bp is needed to come to a new combination which has to be classified as GMO. So, cisgenic plants, mostly without insertion of borders, are not considered to be a GMO. A simple rule should be developed, including criterions, for defining true cisgenic plants.
In this presentation, the creation of cisgenic, more durable, resistance of potato against potato late blight will be discussed. This is based on working simultaneously on the genetics of both potato and Phytophthora infestance and on stacking of broad spectrum R-genes. Isolation and use of over 20 R-genes and more than seven Avr-genes will be described and the use of them to come to functional stacking of at least three R-genes. Another important issue is, because of absence of cisgenic selection markers, the setup of a marker free transformation system. Cisgenesis is the most effective way to improve in one step worldwide frequently used free potato varieties, which are highly susceptible to late blight. If needed additional broad spectrum R-genes can be added later by re-transformation.
