The fourth DuRPh demo day (DuRPh = Durable Resistance against Phytophthora), held on Thursday 28 August 2014, generated some lively discussion at the professional session in the afternoon and the public session in the evening. Anyone looking at the test field was left in no doubt that the resistant ‘DuRPh potatoes’ have a lot to offer when it comes to making potato farming more sustainable and environmentally-friendly.
Around forty professionals from the public and the private sector attended the afternoon sessions. It was clear from the tenor of the discussion that the plant-breeding businesses wanted revised EU regulations on genetically modified plants. They contended that potatoes which have been modified with genes that are native to potatoes anyway and are resistant to phytophthora (cisgenic potatoes) should not have to undergo the entire EU admission procedure for genetically modified crops. The potato breeders cannot afford to market the resistant species at present because of the high costs attached to the EU legislation.
The audience at the evening session was also impressed by the plants and wondered how soon the DuRPh results could be repeated in the outside world.
During the guided tour of the test field the visitors were shown vulnerable and resistant plants. Most of the resistant plants came from the DuRPh programme. There were also two resistant species that had been developed through cross-breeding. It emerged that even if there was only one resistant gene in a plant (through GM or classical techniques) there were already phytophthora spores that could break it. Low doses of fungicide (25% of the recommended quantity) could still prevent these plants from being contaminated, and the resistant gene itself was also protected against further breakthrough. The plants in which the resistant genes were stacked did not need to be sprayed, even in this heavy phytophthora season, to be completely free of the disease.
Resistant genes from wild potatoes
This year, for the first time, potatoes were on show which have been equipped with a set of three different resistant genes from wild potatoes via genetic modification. The fungus has great difficulty penetrating the resistance of such species. It is as if the plants have been fitted with three different locks. The pathogen then has to develop three different ‘keys’, one to fit each lock at the same time, in order to launch a successful attack on the plant.
Potato growing much more environmentally-friendly
Combining the cultivation of these gentech potatoes with phytophthora monitoring will enable the resistance to be used to the full. Potato growing will be much more environmentally-friendly across the world and farmers who cannot afford costly pesticides can still get a good yield from this increasingly important crop.
During both the afternoon and the evening session questions were asked about the conditions under which Wageningen UR would make the results of DuRPh available. Wageningen UR wants as many businesses and institutes as possible to have access to the DuRPh knowledge and genes and will deal generously with licence applications.
The research findings do, however, show unequivocally that resistance genes require the utmost care in practice. The genetic composition of the phytophthora population must be meticulously monitored and the deployment of specific combinations (stacks) of resistant genes must be carefully targeted. Wageningen UR will keep a watchful eye on developments and a finger on the pulse.