Identification of an olive (Olea europaea L.) core collection with a new set of SSR markers

Simple Sequence Repeat (SSR) or microsatellite markers have become extremely useful tools in genetic identification and variability studies. To date around one hundred of these markers have been developed in the olive tree (Olea europaea L. subsp. europaea) and the majority of them are di- or tri-nucleotide. The analysis of the numerous articles recently published on plant microsatellite markers, shows however a higher relevance of markers with long core repeat motifs than those with di- or tri-nucleotide repeat motifs. This work presents a new set of highly informative and polymorphic tetra- and hexa-nucleotide SSR markers. The newly designed SSR markers have been employed to genotype the 36 olive cultivars of the core collection from Worldwide Olive Germplasm Bank of Cordoba, Spain (WOGBC). This article describes the allelic profiles of the 36 olive cultivars for a set of ten SSR markers and also a protocol for a multiplex polymerase chain reaction (PCR). The designed multiplex PCR can lead to an optimal amplification of up to five different SSR markers in the same reaction tube. Finally, the use of only four of the set of ten SSR markers employed, allows the differentiation of any cultivar of the WOGBC core collection from the remaining 35 cultivars.