Application of EST-SSR markers for analysis of polymorphism of lettuce varieties (Lactuca sativa L.) of domestic breeding

Purpose. Determination of molecular genetic polymorphism of lettuce cultivars of Ukrainian breeding by EST-SSR markers. Methods. Molecular genetic analysis, statistical methods. Results. The results of molecular genetic polymorphism study of 7 lettuce cultivars by 7 EST-SSR markers are presented. As a result of the analysis by studied markers, 37 alleles were detected with an average 5.29 alleles per locus. The KSL-92 marker, which identified 7 alleles, proved to be the most polymorphic (PIC – Polymorphism Information Content 0.98). The lowest PIC value (0.57) was noted for the KSL-37 marker by which 3 alleles were identified. For assessing the genetic diversity of lettuce cultivars by EST-SSR markers, genetic distances between cultivars were determined based on Jaccard’s similarity coefficient. It was determined that the most similar cultivars with genetic distances 0.17 were ‘Zorepad’ and ‘Malakhit’, ‘Malakhit’ and ‘Dublianskyi’, ‘Dublianskyi’ and ‘Smuhlianka’, ‘Krutianskyi’ and ‘Smuhlianka’. The most distant cultivar was ‘Skarb’ with a genetic distance 0.00 compared to other studied cultivars. According to the calculated genetic distances, the cultivars ‘Zorepad’ and ‘Malakhit’, ‘Malakhit’ and Dublianskyi’, which belong to the same variety Lactuca sativa L. var. secalina have a strong genetic similarity. The cultivars‘Skarb’ and ‘Pohonych’, which belong to the varieties Lactuca sativa L. var. longifolia and Lactuca sativa L. var. angustana, respectively, were genetically distant, what was confirmed by genetic distances values. It was determined that the Shannon index within the lettuce variety by 7 EST-SSR markers is 0.61, between varieties – 0.96, the average value is 1.57. Conclusions. According to the results of studies of 7 lettuce cultivars, it was found that the highest polymorphism was determined by the KSL-92 marker, the minimum of alleles number (3 alleles) was identified by KSL-37 marker. Based on calculated genetic distances, it was noticed that lettuce cultivars, genetic distances between which are 0.17, were the most similar. The most distant cultivar based on 7 EST-SSR markers was ‘Skarb’ cultivar.