Genetic diversity among Ocimum species based on ISSR, RAPD and SRAP markers

Genetic diversity among 37 basil accessions representing four species (Ocimum basilicum, O. americanum. O. gratissimum and O. tenuiflorum) was evaluated individually using different maker systems. The applied marker systems potentiallty targeted different regions of the genome and included 36 inter-simple sequence repeat (ISSR). 20 random amplified polymorphic DNA (RAPD), and ten sequence-related amplified polymorphism (SRAP) markers. Among these three marker systems, SRAP showed the highest mean value of polymorphic information content (PIC, 0.29) and resolving power (Rp, 30.19) which were much higher than those of RAPD (0.23, 5.13) and ISSR (0.19, 1.39). Basil accessions were clustered into three groups using data from SRAP or the combined data set, indicating that the genetic diversity in different target regions of the tested basil genomes was not the same. All showed very good fit of cophenetic matrices between similarity matrix and dendrogram and the results were highly correlated between marker types. In addition, the SRAP dendrogram was correlated most with the combined data set indicating that SRAP makers could be a better tool for genetic diversity analysis in basil than RAPD and ISSR markers.