Essentially Derived Varieties in Ornamentals

The concept of Essentially derived varieties (EDVs) was introduced in the UPOV 1991 act to protect the interests of the breeder of the initial variety. When a variety is considered as an EDV, authorisation for commercial exploitation is needed from the breeder of the initial variety. There is considerable debate going on about which approaches to use for determining essential derivation and also which thresholds should be used in the different plant species. For determining whether a variety should be considered essentially derived from an existing variety two conceptually different approaches can be taken. The first one is based on genetic conformity, the second is more a forensic approach. For the implementation of the EDV concept using the conformity approach it is important that similarities between unrelated varieties can clearly be separated from essentially derived varieties. In the forensic approach the high genetic similarity between original variety and mutant is taken as a starting point. The basic idea is to calculate the probability that a second, putatively derived, variety would have a profile identical to the initial variety, given an independent breeding history. Both approaches will be illustrated and ways to implement the EDV concept will be discussed. INTRODUCTION In the international convention for the protection of new varieties of plants of 1991 the concept of ‘essentially derived varieties’ (EDV) was introduced to protect the interests of the breeder of the initial variety. The International Union for the Protection of new varieties of Plants (UPOV) defines an essentially derived variety in the 1991 act. as follows: a variety shall be deemed to be essentially derived from another variety (“the initial variety”) when (i) it is predominantly derived from the initial variety, or from a variety that is itself predominantly derived from the initial variety, while retaining the expression of the essential characteristics that result from the genotype or combination of genotypes of the initial variety, (ii) it is clearly distinguishable from the initial variety, and (iii) except for the differences which result from the act of derivation, it conforms to the initial variety in the expression of the essential characteristics that result from the genotype or combination of genotypes of the initial variety (UPOV, 1991). The UPOV (1991) act gives examples of how essentially derived varieties may be obtained. These include the selection of a natural or induced mutant, or of a somaclonal variant, the selection of a variant individual from plants of the initial variety, backcrossing, or transformation by genetic engineering. Most ornamental species are outbreeders and varieties are maintained vegetatively. Crosses result in diverse plant material that can be easily distinguished, the more so when several founding fathers were used. Repeated backcrossing is not (often) used in ornamental breeding. This reduces the ways that EDVs can be made in ornamentals to somaclonal variant, induced or natural mutants, and GMOs. The latter is currently not an issue in Europe. For both somaclonal variants and mutants the genetic similarity between initial variety and derivatives will be very high (close to 1.0). The morphological differences result from just one or a very few changes in the DNA of the initial variety, which are unlikely to be detected using molecular markers. Mutants are a common phenomenon among many ornamental plant species. Usually, such mutants or ‘sports’ are discovered