Molecular diversity study within holy basil species (Ocimum tenuiflorum L.) using ISSR and RAPD markers

In the present study, molecular diversity among the 38 accessions of holy basil (Ocimum tenuiflorum) collected from four phyto-geographical regions of India was assessed using RAPD and ISSR markers. A total of 80 fragments were amplified with 19 selected RAPD primers (4.21 fragments amplified per primer), of which 66 (82.50%) were polymorphic. The resolving power (Rp) for RAPD ranged from 2.32 to 8.96 with an average of 5.48 per primer. Similarly, nine ISSR primers amplified a total of 25 scorable fragments (2.77 fragments amplified per primer) out of which 18 fragments amplified (72.00%) were polymorphic. The Rp for ISSRs ranged from 2.4 (UBC-807) to 9.95 (UBC-886). For genetic diversity and genetic relationship study, the fragments amplified by both the marker systems were pooled for analysis. Jaccard's similarity coefficient was used to estimate the genetic diversity and it varied from 0.0259 to 0.935. Cluster analysis was done using UPGMA method which grouped all 38 accessions into four clusters. Genetic relationship based on RAPD and ISSR markers show that all 38 accessions do not show any genetic isolation based on phyto-geographical regions of India. Analysis of molecular variance (AMOVA) study shows that 9% of variation was present between the phyto-geographic regions whereas, the maximum variation was observed between the accessions (91%). Principal Coordinate Analysis (PCoA) showed that large diversity existed in O. tenuiflorum collection and percentage of variation explained by the first 3 axes was 60.57%. The diversity present within O. tenuiflorum species can be exploited for breeding and diversity conservation.