56 I EUROPEAN SEED I EUROPEAN-SEED.COM into our improved breeding populations. We did the same for Late Blight or Root Knot Nematode resistance, because little genetic variation for resistance against these diseases was available in the European potato varieties.” She says in other diseases such as Blackleg there is hardly any breeding possible because “we lack the prerequisites for breeding pro- gress: genetic variation and an efficient and reliable phenotyping system.” Resistance breeding is an important column in the Meijer breeding program says Heselmans. In areas with inten- sive cultivation, soil-born diseases like wart-disease and nematodes give huge problems, whereas late blight globally is an important threat. Besides that, for many other diseases like silverscab, common scab and virus there is a min- imum level of resistance required. “To retrieve resistance towards diseases into our commercial potato breeding program, Meijer co-operates with universities and genebanks to introgress new resistance genes from wild species. It is of huge importance that genetic diversity is main- tained. For that reason, recently a group of Dutch potato breeders decided to actively support the Dutch genebank (CGN) to maintain and release new material.” According to Smeenge, nematodes and then especially the two species Globodera rostochiensis and G. pallida are the most important pests. He draws his genetic diversity from starch-varie- ties, from the gene-bank at Wageningen University (WUR), and from his own breeding lines. “Second is late blight and we get our diversity from the Louis Bolk Institute through the ‘Bio-Impuls’ Program, and his own breeding mate- rial. And third: common scab and virus. Diversity comes from his own breeding program which is already in existence for more than 45 years.” Backx says the diseases that are most important depends partly what the variety will be used for and in which area it will grow. Late blight is a disease you find everywhere so resistance to this dis- ease is very important. However, a single resistance is quickly broken. So, you need to work on complex multiple resistances, which is not easy. “We should not forget that common scab is not for all growers in all areas an issue. Other items like nem- atode resistance are the most important. The genetic diversity for the resistances he finds in the gene-bank, but also uses other Solanum types and existing vari- eties. That is the common way to create genepools,” he says. LATE BLIGHT, CISGENESIS, AND FURTHER BREEDING According to Backx, the resistance can only be effective if it is a multiple resist- ance, based on different systems. The fungus is that quick to adapt. Through classic breeding this is hardly possible. With cisgenesis it has been realised. “Here you get to the question whether a product created through cisgenesis should be allowed on the market. It is one of the ‘new breeding technologies’ that was already reported on in previous issues of European Seed. If we could use those techniques, it would help the breed- ers and with that the farmers and envi- ronment enormously. Personally, I would be in favour to allow a proper cisgenesis product as long as you can prove there is no ‘strange DNA’ (= of completely another species) in it.” Heselmans shares that Meijer sup- ports the position of Plantum on this sub- ject which indicates that cisgenesis is a new plant breeding method that does not result in foreign DNA in the end product, so no species barriers are not crossed and should, according to the Dutch govern- ment, not be regulated as GMO Bandsma believes there are suffi- cient genes against late blight. “The only thing which is very important is we need to stack more genes of late blight into a potato variety/seed line. We think it is possible to achieve a good variety which is very strong to late blight without cis- genesis. It will take some time! We know the FOBEK has good genetic diversity for the late blight genes. We don’t like GMO, but we believe that cisgenesis could be a good addition to the potato breeding. Using genes against late blight from another Solanum family, could be a good opportunity to solve the problem. On the other hand, how quickly will the late blight fungus be able to adjust/break the resistance?” Smeenge says that his view on this is that with cisgenesis they are transplant- ing genes within the species Solanum tuberosum (potato). “In fact, this is the same as we do in making normal cross- ings. The benefit of cisgenesis is that it can lead to a new variety in a very short time! So, I think it should be released for production and special for further breed- ing. However, I am against transplanta- tion of genes between different species (e.g. potato and sugarbeet). I have an eth- ical problem: we are going to play God!” Several late blight resistant vari- eties have been commercialized lately that were bred by classical methods of recombination and selection says Prigge, “including our variety ‘Connect’. So, it is possible. These varieties stem from exten- sive research and pre-breeding efforts in both the public and the private potato sec- tors that aimed at exploiting resistance loci from unadapted Solanum species for introgression breeding programmes in potato. Whilst these pre-breeding activi- ties are very time-consuming, sustainable R gene stewardship requires stacking of several R genes, and that’s where we see the great advantage of the new breeding techniques, because with e.g. cisgenesis you can develop stable resistances more efficiently.” Editor’s Note: This article has been condensed for print. To read the full version, go to European-Seed.com Potato breeding takes 10-12 years to develop a new variety (Source HZPC)