QTL mapping for fatty acid composition in olive oil using a high-density genetic map based on SNP markers

Olive (Olea europaea L.) is an evergreen tree species that grows naturally in regions with Mediterranean climates. Its oil and fruits are commercially valuable. Olive oil contains high levels of omega-9 (oleic acid). Because the high percentage of oleic acid makes olive oil deterioration-resistant, the development of olive varieties containing high oleic acid is one of the major goals of olive breeding programs. Therefore, this study aimed to determine quantitative trait loci (QTL) affecting fatty acid composition of olive oil. Thus, early selection of olive genotypes with a high oleic acid content can be possible. For the determination of QTLs affecting the fatty acid composition of olive oil, a high-density genetic map was developed using a segregating olive F1 population with 121 progeny and single-nucleotide polymorphism (SNP) markers based on Genotyping by Sequencing (GBS). The fatty acid composition of the segregating olive F1 population was determined using gas chromatography (GC) in two different harvest years. The 2892.13 cM genetic map was composed of 3.254 SNP markers on 23 chromosomes, with an average distance of 0.9328 cM. A total of 31 QTLs were discovered in the first harvest year and 29 in the second harvest year. Common QTLs associated with fatty acid composition in both years have been found on chromosome 01, chromosome 02, and chromosome 10. For oleic acid, 11 QTLs were discovered in the first harvest year and 12 QTLs in the second harvest year. With these results, the QTLs linked to fatty acid synthesis in olive oil can be used as genetic resources for marker-assisted selection (MAS) in olive breeding studies.