Agroscope, 8046 Zurich, Switzerland

GM potato plants are resistant to late blight

Late blight of potato, caused by the pathogen Phytophthora infestans, is the most significant disease in potato cultivation. Large quantities of fungicides are used to control this disease. New, resistant varieties of potato have heretofore not caught on, owing to deficiencies in agronomic traits or tuber characteristics compared to the established breeds. Agroscope studied genetically modified (GM) potatoes of the popular «Désirée» variety which were developed in public research institutes in Norwich (UK) and Wageningen (NL). Genetic engineering methods were used to transfer one or two genes mediating resistance to P. infestans from various wild potato species into these potatoes. Agroscope has now grown these plants under field-like conditions in a vegetation hall and inoculated them with two virulent Swiss P. infestans isolates. The GM plants were resistant, whilst the original «Désirée» variety and further control varieties exhibited severe late-blight symptoms. This demonstrates that the transferred resistance genes are also effective against P. infestans strains occurring in Switzerland.

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