Research into cisgeneses continues unabated RE SEARCH Stacking of resistances is important The effect can also be reviewed in the trial fields in which the various resistance genes have been introduced into existing potato varieties with the help of cisgeneses. Bright green plants among the died-off ones are proof of this, which breeder/researcher Hutten shows us during our walk round the trial field. He points at the importance of marker technology. This technology helps find out which resistance genes actually occur in certain wild and newly-bred varieties. The wild varieties with resistances that breeding stations throughout the world use in their crossing varieties, are not always the same. And yet, they may contain the same resistance genes, as molecular research has now shown. That knowledge is important, for example, if you want to stack more resistance genes in a potato by crossing or cisgeneses. ‘Stacking is very important’, Hutten tells us, ‘because it makes it more difficult for aggressive Phytophthora strains to break through the resistance.’ Some R genes don’t work In the trial field of the DuRPh project, Hutten shows the results of both the resistance introduced by cisgeneses and by crossing. The assessments are completed and the apparently healthy plants are already ‘over the top’ as the researcher describes the condition of the crop. At any rate, it’s clear what the impact of the added Phytophthora resistance is. For example, Hutten points to a field with dead plants of the susceptible Désirée, variety with further on, a field with healthy plants of that same Désirée, but then with added resistance genes. To test the resistance, the researchers contaminate the healthy susceptible plants with known Phytophthora isolates. ‘In this way, we are able to discover which resistance and stacking of resistances work effectively. Meanwhile, it’s also been discovered that some resistance genes don’t work via genetic engineering. We haven’t found a scientific explanation for this, but we suspect what it might be. But we need many years of research to be certain of this. At all events, the DuRPh project will continue until the year 2015’, says Hutten. ● Leo Hanse ‘Stacking is very important’, Ronald Hutten tells us at the DuRPh trial field, ‘because it makes it more difficult for aggressive Phytophthora strains to break through the resistance.’ Potato World 2013 • number 1 5 Pagina 4
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