Mapping of QTLs associated with frost tolerance in olive (Olea europaea L.)

The olive (Olea europaea L.) is widely distributed due to its high adaptability to different environmental conditions. However, in recent years, sudden extreme temperature decreases and frost damage have caused significant yield and quality losses in some regions. This situation has led to the development of varieties with high frost tolerance, suitable for regions where cold damage may occur. It takes many years to develop varieties using classical breeding methods in olives. Therefore, early selection should be made using biotechnological methods. Markers about any trait provide a great advantage, especially in plant species with a very long juvenile sterility period, as they allow for a selection of nonpurpose plants in the early stage of the breeding process. The elucidation of the molecular mechanism associated with frost stress is important in laying the groundwork for breeding studies. To determine the locations of genes controlling frost tolerance in olives on chromosomes, linkage Quantitative Trait Loci (QTL) and association mapping studies were performed on leaf tissues of Memecik × Uslu hybrids (104 genotypes) subjected to frost tests under controlled conditions in the laboratory. Twenty-three linkage groups (LG) exactly matching the haploid chromosome number (n = 23) of the olive were obtained for the maternal parent Memecik and 26 LG for the paternal parent Uslu. A total of 4377 markers were mapped for the Memecik cultivar and 4664 markers for Uslu. The total number of markers mapped for both parents was 9041. This study investigated candidate QTLs associated with frost tolerance in the olive.