High genetic diversity detected in olives from the south Mediterranean basin

Abstract

The Olive tree (Olea europaea L.) is native to the Mediterranean basin where it shows a wide range of diversity accounting for about 2,000 cultivars. The ability to discriminate olive cultivars and estimate their genetic variability is pivotal not only for their management but also for an optimal exploitation of olive genetic resources. The purpose of this study was to investigate the genetic diversity of olive genotypes from Algeria, Syria and Italy including first time analysis of four Maltese olive genotypes, including the cultivar Leucocarpa and three ancient olives. Twelve highly polymorphic Simple Sequence Repeat markers were used and proved to be very informative, with a total of 174 alleles with sizes ranging from 110 bp (DCA13) to 268 bp (DCA15), and extensive polymorphism among the genotypes. The principal coordinates analysis (PCoA) was able to group the cultivars into three distinct populations according to their geographic origin, except for the Maltese genotypes, that grouped with the Italian ones. The Analysis of the Molecular Variance revealed a high percentage of molecular variance within populations (73%), with 27% of variance at inter-population level. This study will be useful for a better understanding of the olive genetic diversity in the Mediterranean basin, as a step towards an optimal conservation of olive genetic resources.