Management of peach tree reference collections: ongoing research & development program relevant to the community plant variety rights protection system

Peach/nectarine is an important fruit tree crop in Europe and indeed world-wide. The registration of new cultivars, either for Plant Breeders' Rights or National Listing (PBR/NL) purposes in the European Union (EU), requires the completion of a distinctness, uniformity and stability (DUS) test in one of the EU Member States. The number of candidate cultivars and potentially required example cultivars entered for DUS testing is steadily increasing annually. Moreover, DUS testing of this type of tree crops requires the maintenance of large orchards, particularly with the aim of having a complete reference collection. In France, Hungary, Spain and Italy, peach tree breeding activity is characterized by an important number of cultivars available and a short turn-over of the cultivars. This situation will extend to new EU members states in the coming years, with the development of the European trade. However, although the diversification increases the number of segments, for each segment, new released cultivars are genetically closer and closer. The consequence is that it is now difficult in some cases to distinguish between cultivars. Clearly, developing means of "managing" reference collections is highly desirable in order to be able to compare candidate cultivars with the closest cultivars of common knowledge in the reference collections prior to planting them, and so reduce the number of cultivars that need to be grown, without eroding the strength of PBR and the relevance of DUS tests. Effective means of such a management include the definition of a standardised way to compare phenotypic data and to use molecular markers to eliminate the reference cultivars which do not need to be compared to the candidate cultivars. In peach tree, various molecular markers such as DNA microsatellites (SSR) have been developed and evaluated, but they have not yet been used for the characterization of large collections. Therefore, this project will generate a database compiling both phenotypic data, including standardised morphological descriptions and digital pictures, and a large data set of DNA profiles for 522 peach tree cultivars selected among the EU granted and listed cultivars.