Assessing the genetic diversity of tobacco (Nicotiana tabacum L.) varieties

The genetic diversity of 40 tobacco (Nicotiana tabacum L.) cultivars was analyzed using 12 ISSR primers. The cultivars were evaluated for 14 traits using a simple lattice design (7×7) with two replications. Of 149 amplified bands, 142 (95.3%) were polymorphic. Maximum and minimum bands were generated by primers UBC825 (17 bands and 94.11% polymorphic) and UBC824 (7 bands and 100% polymorphic), respectively. Of the studied primers, UBC824 showed maximum Polymorphism Information Content (PIC) (0.43) and the highest genetic diversity, and thus could be used in future genetic diversity studies. In principal coordinate analysis using a similarity matrix, the first two coordinates, which are the main coordinates, explained 41.97% of the total variance. Cluster analysis was performed to determine the genetic relationship of tobacco cultivars using the un-weighted pair-group method with arithmetic average (UPGMA) based on morphological traits and ISSR markers separately. Plant genotypes were divided into nine main groups of flue-cured tobacco cultivars, and a cophenetic correlation coefficient was calculated (r = 0.9), indicating the usefulness of the UPGMA method for clustering plant genotypes. Cluster analysis based on morphological traits divided the studied genotypes into five groups using the UPGMA method. Results of canonical discriminate function analysis using the Fisher Linear method showed that the UPGMA method separated the genotypes with 100% accuracy. Both clusters were consistent with the geographical origins of the cultivars.