e RE S EARCH The first DuRPh field trials are encouraging will not be abruptly broken down. This means that gene stacking, resistance management in place and time, and a few other preconditions are needed. In the latter case, it is quite conceivable to consider patenting the R-genes, agreeing with breeders on the use of such genes, the way in which we have to register such new “old” varieties and how to regulate their seed potato supply. A seed potato company such as Averis has already started to use R-genes in a non-food starch variety. As from today, DuRPh still has seven years to go and if the trials of the basic principles outlined above are successful, we will definitely also find answers for the preconditions. There remains the question of how the consumer and the legislator will deal with the acceptance of this form of genetic modification (cisgeneses). Is the final product only going to be judged on the process of its development, genetic modification, or will it be judged on its characteristics: only the potato. We will need to make considerable progress with DuRPh in the coming seven years on this point also. ● Anton Haverkort www.durph.nl DuRPh coordinator ctive? from a variety at different times and places in order to outsmart Phytophthora permanently. Furthermore, we develop marker-free plants, which do not contain any herbicide or antibiotics resistance at all. This is possible by making many transformants and by establishing whether they are resistant against all Phytophthora strains that we have available (that is, in fact, the “marker”). Moreover, we check in the laboratory with PCR whether the gene can, indeed, be found. gle gene resistance is quickly broken down again, so we stack 3 to 5 genes from various wild varieties to make a cassette, which is subsequently inserted into a variety. To prevent this stacking from failing to last long enough, we introduce the concept of “dynamic variety”, whereby we temporarily insert or remove sets of resistance genes in or Ten years and five subsidiary projects The DuRPh Project has a length of 10 years (2006-2015) and a budget of one million euros a year. There are five subsidiary projects. The first part involves the identification of R-genes in wild potato species. To do this, we cross with a susceptible variety and check whether the offspring roughly consists of very susceptible and very resistant genotypes. In the laboratory, the researchers “cut” this R-gene and multiply (clone) it with the E. coli bacterium. The second part involves the transfer (transformation) of the cloned genes to existing varieties. For our research, we use Première, Désirée and Aveka, three varieties with increasing lateness. In part three, we select the plants that were made in part two and have “regenerated” or grown from a single cell, because they can show individual difference – although they are genetically identical. In this part, we select plants that contain the gene, are resistant (tests) and look exactly the same as the original variety. The latter is of importance so that the variety can be made flexible at a later stage. It is at this stage that permission to plant transformed plants in the field is requested at the Ministry of Environment and implementation of the field trials takes place. Part four involves resistance management or the management of the battle between the resistance mechanism of the plant and the attack strategy of the disease. Here we check how many genes need to be stacked and which different cassettes need to be inserted and removed, and used again later. We also research how the cassettes of genes can be inserted into, or how they should be divided among fields to minimise the chance of a break down. We also look at the Phytophthora populations in the Netherlands and in Europe to know which resistant genes are likely to be the most successful. The last part of DuRPh is what we are also doing now: communicate with and inform every interested party and stakeholder, so that they can form an opinion about our method of operation. ● Potato World 2009 • number 1 25 Pagina 24

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