Molecular characterisation of french olive cultivars using microsatellites: towards the establishment of a reference genotype d

Abstract

Olive, Olea europaea L., is a mediterranean fruit species that is cultivated mainly for oil but also for canned fruits. Because of the traditional cultivation, most orchards include several cultivars. Numerous cases of homonymy (one denomination for several genotypes) and synonymy (one genotype with several denominations) could occur in different traditional olive areas. Recently in France, a regular increase in cultivated surface is noted leading to the increase of plant multiplication by cuttings. According to the conditions on health and pomological qualities defined by European Union (Directives 93/48 and 93/79), the nursery men have to ensure the conformity of plant material based on morphological descriptors. However, because of most discriminating characters are related to olive fruit, morphological characterisation has to be completed by a molecular approach.Isozymes were the first genetic markers used in olive fingerprinting [1, 2]. However, their usefulness has been limited due to the small number of isozyme systems available, the low level of polymorphism obtained, and the influence of environmental factors. The emergence of new PCR-based molecular markers, such as RAPD, AFLP, and SSR, has created the opportunity for fine-scale genetic characterisation of germplasm collections because they are highly polymorphic and are not influenced by environmental conditions (see also review by Wunsch and Hormaza [3]). RAPD and AFLP markers have been previously used for cultivar characterisation in olive [4, 5, 6], but because of the use of arbitrary sequences these markers can not be exchanged among laboratories according to standardized protocols [7]. Because of specific loci, microsatellite markers (Simple Sequence Repeat, SSR) were reproducible and can be used by different laboratories with comparable results. Recently, SSR loci were developed on olive [8, 9, 10, 11].As a first step for exploring the usefulness of SSR loci in french olive characterisation, we analysed a set of accessions using SSR loci and the sequencer Abi 3100. Our aim was to select the most discriminating combination of SSR markers and to provide a basis for establishing a database of genotype reference for each of french olive cultivar.