Assessment of genetic diversity in Solanum trilobatum L., an important medicinal plant from South India using RAPD and ISSR markers

Solanum trilobatum L. is an Indian medicinal plant containing rich amount of steroidal glyco-alkoloids that can be used as precursor for commercial steroid production. Two efficient marker systems such as Random Amplified Polymorphic DNA (RAPD) and Inter Simple Sequence Repeats (ISSR) were used for the first time to assess the genetic diversity across 14 S. trilobatum accessions obtained from five South Indian states. Twenty out of 60 RAPD primers generated 189 distinct bands of which 160 were polymorphic with an average of 8 polymorphic bands per primer. A maximum of up to 15 fragments were amplified with an average of 9.45 bands per primer and the amplicons varied in size between 100 and 3,000 bp. The percentage of polymorphism ranged from 55.5 to 100, with an average of 84.6. ISSR profiling using 7 out of 20 primers amplified 83 bands and the number of amplified fragments varied from 2 to 16 with a size range of 200-1,800 bp. Totally 72 polymorphic bands were obtained using 7 ISSR primers at an average of 10.28 polymorphic bands per primer. Polymorphism percentage varied from 50 to 100 among the selected accessions resulting in an average percentage of polymorphism of 86.7. The PIC values ranged from 0.49 to 0.93 for RAPD and 0.16 to 0.90 for ISSR primers. The study pointed out that ISSR markers were more efficient than RAPD markers in evaluating the degree of genetic variation in S. trilobatum. The UPGMA cluster analysis grouped all Tamil Nadu accessions in one cluster and other state accessions in another cluster. The Principal component analysis also substantiates this clustering pattern. Thus the phylogenetic relationship and a high genetic variation revealed in the present study could provide a baseline data for conservation and improvement of this plant in future. Also the molecular markers identified in this study will be helpful in authentication of this species to prevent adulteration in herbal medicine.