DNA Sequence Analysis of Microsatellite Markers Enhances Their Efficiency for Germplasm Management in an Italian Olive Collection

Genetic diversity studies using microsatelite analysis were carried out in a set of 39 accessions of Olea europaea L., corresponding to the majority of the regional autochthon germplasm in Apulia. Samples of olive leaves were harvested from plants growing in the olive germplasm collection of the Consiglio per la Ricerca e Sperimentazione in Agricoltura (C.R.A.) - Istituto Sperimentale per l'Olivicoltura at Rende in Cosenza Italy. Herein, we evaluated the extent to which microsatellite analysis using electrophoresis was capable of identifying traditional olive cultivars. In addition, the DNA sequence of all amplicons was determined and the number of repeat units was established for each sample. Using five loci, electrophoretic analysis identified 24 genotype profiles, while DNA sequence analysis detected 28 different genotype profiles, identifying 54% of cultivars. The remaining 46% were composed of seven different accession groups containing genetically indistinguishable cultivars, which are presumably synonyms. This study demonstrates the utility of microsatellite markers for management of olive germplasm and points out the high level of polymorphisms in microsatellite repeats when coupled with DNA sequence analysis. The establishment of genetic relationships among cultivars in the Apulian germplasm collection allows for the construction of a molecular database that can be used to establish the genetic relationships between known and unknown cultivars.