Development and Characterization of Expressed SSRs in Olive (Olea europaea L.)

The olive (Olea europaea L.) is one of the most ancient domesticated fruit tree of the Mediterranean Basin. It is an important source of oil with confirmed beneficial effects on human health. Despite its economic and nutritional importance, the first EST transcripts from developing olive fruits were published as late as 2009. In this study we present a new set of 29 EST-SSR primer sequences in olive generated from EST transcripts. ESTs were obtained in the frame of olive transcriptome project which included construction of normalized cDNA library from developing fruits of variety ‘Istrska belica’. SSR sequences were identified in the assembled transcripts by Perl script MISA and primers were designed by Primer3 software. Novel markers were tested for genotyping on a set of eight olive varieties. Altogether 116 different alleles were amplified and the number of alleles per locus varied from 2 to 7, with an average of 4 alleles. The observed heterozygosity ranged between 0.125 and 1.0, with an average of 0.698. Polymorphic information content (PIC) was from 0.110 to 0.795 and classified 22 loci as informative markers (PIC > 0.5) and 11 loci as suitable markers for gene mapping (PIC > 0.7). Twenty-nine newly developed EST-SSRs not only provide a tool for diversity analysis; they may helpful to localize genes involved in agronomic and productive traits and therefore play a significant role in marker assisted selection and construction of genetic maps.