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Why Organic Farming Should Embrace Co-Existence with Cisgenic Late Blight–Resistant Potato

Godelieve Gheysen, René Custers
Sustainability 2017 v.9 no.2 pp. -
European Union, Solanum tuberosum, breeding, cisgenesis, cisgenic plants, crop production, disease control, disease resistance, field experimentation, fungicides, irradiation, laws and regulations, mutagenesis, mutants, organic foods, organic production, potatoes, resistance genes
The EU regulation on organic farming does not allow the use of genetically modified organisms (GMOs) which are subject to Directive 2001/18/EC. Mutagenesis using irradiation or chemicals is genetic modification, but the organisms obtained through these techniques are not subject to the provisions of the GMO directive. Such mutants can therefore be used in organic agriculture. Derived from its basic principles, organic farming can only use natural substances to control disease and crops should be resilient, which, in the case of disease resistance, means that durable (horizontal) resistance is preferred to vertical (single gene) resistance. Cisgenesis can achieve such a durable resistance by introducing multiple resistance genes in one step. These multiple-resistant plants only contain natural genes that can also be introduced by breeding. In case cisgenic plants are not subject to the provisions of the GMO legislation, they can even be legally used in organic agriculture. In case they are not exempted from the GMO regulation, the question is: why obstruct a cisgenic potato crop that can hardly be distinguished from a potato crop that is the result of conventional breeding? Among the reasons why organic agriculture does not allow the use of GMOs it is mentioned that genetic engineering is unpredictable, it causes genome disruption and it is unnatural. However, our knowledge of plant genome evolution and breeding has increased dramatically. We now know that breeding is more unpredictable and causes more genome disruption than genetic engineering. Recent field trials have shown the efficacy of cisgenic late blight–resistant potatoes carrying multiple resistance genes. Large-scale growing of such durably resistant potatoes would not only be environmentally beneficial by it would strongly reducing the need for fungicide sprays in conventional potato cultivation and it would also reduce the disease pressure in organic potato cultivation.