Linkage Mapping of Olive (Olea europaea L.) Genome through Genotyping By Sequencing (GBS)

The olive tree (Olea europaea L., 2n=2x=46) is one of the oldest and long-lived fruit species cultivated in the Mediterranean Basin with a significant economic value. Up to date, only a few hundred of the markers were be able to be mapped in the olive genome, which was contained insufficient number of markers to construct a high-density olive linkage map and to cover the genome in previously published papers. Olive linkage map was constructed based on the 92 F₁ individuals generated from a cross between two highly heterozygous olive genotypes, Memecik (female parent) and Uslu (male parent) cultivars. Using GBS and SSR markers, we were able to map a total of 3,890 SNPs and 13 SSR markers in olive and constructed the most comprehensive SNP reference linkage map. In the Memecik linkage map, a total of 2,071 polymorphic markers (2,063 SNPs and 8 SSR) mapped and generated 23 linkage groups. The total Memecik map length was 2,921.9 cM with an average distance of 1.41 cM between adjacent markers. In the Uslu linkage map, a total of 1836 markers (1,827 SNPs and 9 SSR) mapped and generated 23 linkage groups. The total Uslu map length was 2,543.2 cM with an average distance of 1.38 cM between adjacent markers. Twenty-three linkage groups for each of the parents were obtained, which corresponded to a haploid chromosome number (n=23) for olives. This map could be used for future applications of GBS in olive include the development of genomic selection, QTL analysis and positional cloning of genes controlling traits of interest.