RE SEARCH New plant breeders’ rights protocol offers scope for potato seed This spring, Bejo Zaden BV in Warmenhuizen acquired plant breeders’ rights for the True Potato Seed (TPS) Oliver variety. This raises the question of how the plant breeders’ rights protocol has been adapted for this TPS variety. Lysbeth Hof and Jan Kees Schipper of Naktuinbouw (the Netherlands Inspection Service for Horticulture) answer this question. They also look forward to a possible admission of TPS material on the National Varieties List. ‘W hen a potato breeder looks at a field with the TPS Oliver variety, he or she will come to the conclusion that there is more variation than usual’, Jan Kees Schipper, who has worked as a potato breeders’ rights researcher at Naktuinbouw for thirty years now, comes straight to the point. According to his colleague Lysbeth Hof, Researcher of Breeders’ rights in field crops, this means that you need to look differently at TPS in breeders’ rights research than we’re used to doing with vegetatively-propagated potato varieties. ‘Breeders’ rights start with the interpretation of the international UPOV (Union for the Protection of New Varieties of Plants) Convention. Seventyfour countries have put their signatures to that convention, and agreements were made about how countries are expected to deal with the protection of varieties. For example, article 8 of this convention stipulates that ‘a variety is uniform if, depending on the variation that can be expected by the special characteristics of the propagation, it is sufficiently uniform in its relevant characteristics’’, Hof quotes. On the basis of this article, Hof has unravelled whether plant Breeders’ rights also apply to a TPS variety. Lysbeth Hof (l) and Jan Kees Schipper of Naktuinbouw explain how the Plant Breeders’ Protocol has been amended for TPS varieties. Own identity Before a variety acquires plant breeders’ rights, Naktuinbouw carries out a DUS test. DUS stands for Distinctness, Uniformity and Stability. Naktuinbouw carries out this test on behalf of the Board for Plant Varieties or the European Community Plant Variety Office (CPVO). ‘DUS means that a variety needs to have its own unique identity. You need to be able to describe a variety before you can protect it. We also say that a variety needs to have its own distinctive qualities. As you need to be able to recognise a variety, it needs to be the same year in year out’. ‘In a variety that’s propagated vegetatively, the identity is perfectly stable. However, in hybrids, you have more divergence in the offspring’, Schipper knows from experience. A potato does not tolerate inbreeding, which is why it’s difficult to breed hybrids. We know that, with the tetraploid Oliver variety, Bejo is introducing a hybrid variety based on a limited number of inbred lines. The parents are then selected from those lines and propagated clonally. Crossing two slightly inbred parents resulted in the Oliver variety. The parent material is not homozygote, and that’s why the offspring is divergent. You may call Oliver a hybrid, but genetically-speaking, it’s actually a population, which is why we need to assess this type of TPS variety differently from the conventional, vegetatively-propagated varieties’, Hof explains. In addition to Bejo, Solynta, HZPC and KWS and others are also in the process of developing hybrid varieties. ‘On the Solynta company’s website – we officially don’t know anything yet about HZPC and KWS – it says that this company works with diploid parents. They can breed these parent lines because they use the S-locus inhibitor gene (Sli). An Sli gene makes inbreeding possible. A limiting factor in this is mainly the inbreeding depression. Because they inbreed at least seven times, the Solynta material is many times more homozygote than that of Bejo. It’s quite clear that varieties from these two different breeding programmes each require a different approach. And definitely different from the current varieties on the market. We expect very different levels of uniformity from the two types of hybrid potato varieties. That’s why we distinguish two types of TPS hybrids. These are the only slightly inbred SIP hybrids (Slightly Inbred Parents) and the frequently inbred HIP hybrids (Highly Inbred Parents)’, Hof explains. This is about Potato World 2017 • number 3 13 Pagina 12

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