Analysis of Genetic Variation among Populations of Withania somnifera (L.) in South India based on RAPD Markers

Abstract

Aim: The present study was carried out to analyze the genetic variations among 20 different populations of Withania somnifera (L.) Dunal collected from different habitats (locations) by RAPD analysis. Methodology: DNA was isolated from the fresh leaf samples collected from the field by Bernatsky and Tankley method. Isolated genomic DNA was purified by phenol: chloroform: isoamyl alcohol (25:24:1) extraction mixture and then amplified by MJ themal cycler. Amplified DNA products were quantified and then subjected to RAPD analysis by the method of Williams et al. Results: Randomly amplified polymorphic DNA (RAPD) was used to analyze the genetic variation and relationship among 20 populations of Withania somnifera collected from different part of South India, including the states of Tamilnadu, Puducherry, Kerala, Andhra Pradesh, Karnataka, Gujarat, Maharashtra and supplemented by two commercial varieties from Uttar Pradesh and Delhi. Out of 40 primers, 11 selected primers produced 96 consistent RAPD markers ranging in size from 0.2 kb to 4.0 kb; out of which 75 were polymorphic. Similarity indices were estimated using the Dice coefficient of similarity and cluster analyses were carried out on the similarity estimates using the unweighted pair-group method to produce a dendrogram using arithmetic average (UPGMA) in the NTSYSpc-verson 1.80 software. The similarity coefficient ranges from 0.53 to 0.98, suggesting that the pronounced genetic variations exist among populations of W. somnifera in South India. The cluster analysis indicates that the 20 populations of W. somnifera were divided into five major groups, regardless of geographical locations. Conclusion: The RAPD analysis indicates existence of genetic variations in natural populations and it may influence and produce changes in phytochemical constituents of W. somnifera populations.