51 GERMINATION.CA NOVEMBER 2017 if a variety can be granted Plant Breeders’ Rights (PBR) is based on the expression of the characteristics that result from a certain genetic composition. Existing Possibilities Despite this basic statement, there is a general feeling that molecular techniques are useful and may even be required to keep the quality of the DUS decision high, and at the same time, help to keep the costs of a DUS test reasonable. Therefore, UPOV has already established principles to guide the use of molecular techniques. It is possible to apply a molecular test to replace a bio test. This can be useful in a case where, for example, an expensive trial has to be organized to observe a single characteristic when the absence or presence of that characteristic can also be shown in a molecular marker test. An example is the presence of cytoplasmic male sterility in Brassica crops. To observe this in the field, a replanting of the plants in a second year is necessary, where a PCR test will give the desired result in a matter of days. Also, some disease resistance characteristics can be observed using marker techniques. The idea behind this is that if there is a ‘one-to-one’ relation between the visually observed or measured char- acteristic and the molecular result, UPOV allows the use of a molecular test. The same reasoning is used in molecular techniques used in the management of reference collections. If a clear relation can be shown between the molecular fingerprints and the morphological features, a molecu- lar test may be used to manage the reference collection; to decide on close varieties for inclusion in the growing trial or to discard varieties from common knowledge as potential comparing varieties. Examples of this approach are the maize and potato DNA databases. In these cases, molecular distances and morphological distances are com- pared and, in combination, safety thresholds are estab- lished. Is this Enough? In the Netherlands, we are of the opinion that for a strong sustainable PBR system, more is needed. Not only will breeding techniques develop and produce more new vari- eties, the set of varieties of common knowledge will grow dramatically as a result of that. Breeding activities take place worldwide and, as a result, a broad diversity of types and varieties is available. Seed companies operate on a worldwide basis so the introduction of new varieties is not confined to certain regions or countries. One of the major challenges in DUS testing is to ensure that new plant variety applications do not pres- ently exist and are clearly distinct from all other varieties of common knowledge. The quality of the DUS decision therefore depends largely on the available information on the common knowledge varieties, the subsequent man- agement of the variety collection and design of the DUS trials that contain an acceptable and workable number of comparing varieties without missing any relevant variety of common knowledge as a reference. Risks in the Current DUS System It is almost impossible to have and maintain a full over- view of common knowledge. The rapid development of new varieties due to intensive molecular assisted breed- ing and increased global character of the plant breeding industry, makes it an already hard and soon impossible task to keep track of common knowledge in living form in seeds or plants. In addition, the sending of plant material around the world for testing purposes is subject to phytosanitary requirements that sometimes make it impossible to import samples. We also need to consider that there is a relative subjec- tivity of the variety description. For several mainly quan- titative characteristics, the variety description –- which is the ID of a variety in the current system and fully based on phenotype –- is influenced by climate and other envi- ronmental factors, which vary by geographical location. So, variety descriptions received from other examina- tion offices (EO) are of limited utility and reliability. As more breeding takes place in other climate zones, the variety description (and photographs) that are provided by the breeder in the form of a Technical Questionnaire might differ from the expression at the EOs that are responsible for the DUS tests. This can result in the selec- tion of wrong comparing varieties with the potential result that trials have to be repeated in additional year(s) with relevant comparing varieties. These external environmen- tal factors hamper the usefulness of comparing variety descriptions. Solution to Overcome the Risks DNA profiles, available in well-organized databases with DNA data of varieties of common knowledge, are con- sidered as objective and are a valuable tool to guarantee the efficiency and quality of DUS tests in the near future. There are no restrictions on the number of varieties of common knowledge that can be added in such a DNA database. And there are no restrictions on phytosanitary regulations as DNA can be exchanged instead of whole plants/seeds. A further benefit is that DNA profiles are not sensitive to external environmental factors and are considered as an objective description of the genotype. Other Advantages Each individual UPOV member should keep track of all varieties of common knowledge. This is a huge task and much work is done in each member state. The availabil- ity of complete DNA databases that are accessible to all members is an important step in improving the quality of the protection. The DNA of new applications can be tested against the DNA of all varieties of common knowledge in the database. If there is a match, an immediate action can be taken. If there is no 100 per cent match, the information