RE SEARCH New breeding method leads surprisingly fast to new varieties WHY DOES SOLYNTA GO FOR INBREEDING? capacity to test the seed. There could be a range of pathogens in it, which is why the seed must first be placed in quarantine at the nVWA. Their capacity is 25 seeds per import, which might pose a problem if you want to import 100,000 seeds in one go. Tomato seed (near-family of the potato) has already been regulated and legalised. It’s possible, but will take time. How do you make sure that the farmers get proper planting stock? And we also want to do more for the processing industry. For example, developing varieties that don’t form accylamide during frying. Or starch potatoes with a higher amylopectine content. That’s also much easier to breed into F1 hybrid varieties. We’re talking major changes here.’ This means that inbreeding results in a gigantic, genetic leap forward. You enrich the gene material of all plants that matter,’ Pim Lindhout teaches us. ‘Suppose aa x AA provides a not very healthy plant. As long as this plant is heterozygote and the capital A is dominant, you won’t see the lower case a. Because a not very healthy plant has this type of allele, you can pick it out at diploid level. What do you do with that plant? You throw it away, and in doing so you strengthen the progeny with the capital A. At some point you can work towards individuals that are all capital AA. And you’ll never find that weak lower case a again in the progeny. This way, you can get rid of all plants with alleles that have a negative effect on plant growth. This means that inbreeding results in a gigantic genetic leap forward. You enrich the gene material of all plants that matter,’ Pim Lindhout explains. ‘By enormously narrowing down the genetic basis in hybrid cultivation, in principle, you’re keeping only those genes you want to keep’, he continuous his lesson. ‘But you also throw away genes. You can see that with the selection. Suppose you started with Phytophthora resistance and eventually got rid of the symptoms. You don’t see Phytophthora anymore. But you still have the original donor, which you use for a new crossing and you’re going to cross that one back with your inbreeding lines. When you do this a couple of times, you keep the same basis. And then you add new resistance again. So you can cross new genes, gene by gene, into a next generation. The advantage is that you know for sure that the inbreeding line has a good combination of genes. You’ll only add more good genes to them, thus improving a variety. That can be genes for tuber size, eye depth, etcetera. To make such a hybrid programme a success, all plants must have the same self-compatibility. At the trial field we’re looking at plants that flower and plants that produce berries. We only continue with the plants that produce berries, because we know that they’re self-compatible. The plants with flowers may produce fantastic tubers, but we’ll still throw them away. So, we’re not looking at tubers, but at berries. With this hybrid technique, you’re much more into genetics itself, as a result of which we can take much bigger steps genetically speaking. Much quicker than with traditional breeding.’ ‘Once you have a new variety by using our method, you can supply plenty of planting stock the following year.’ Reactions ‘The reaction varies from “Pim, you’re crazy” to “If this is true, you’ll get a Nobel Prize.’ What we now want is a lot of publicity. Not only via the media, but also via institutions like the CIP Potato Centre in Peru, which already has a lot of experience with growing seed in the True Potato Seed Project. They’ve worked on that for the past thirty years. It hasn’t been a success. They have hybrid varieties, but they haven’t bred the parents in, like we do in our method. This resutls in a mishmash of all kinds of different genes. They are heterozygote and uniform, but that’s about all. In general, the seed is so poor that the result is unacceptable for many countries. Only in countries where seed potato growing is very difficult can True Potato Seed give a slight improvement. The CIP could make real progress if they used our F1 hybrid crossings. Especially because we work with natural crossing methods. ● Leo Hanse Potato World 2012 • number 3 17 Pagina 16
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