RAPD and ISSR polymorphism in the medicinal plants: Ocimum sanctum, O. basilicum and O. gratissimum

Ocimum is used in a variety of food industry and herbal drug industry. It is an important constituent of various traditional medicines. Its essential oil content gives it a unique flavour. Its popular in curing various human diseases like malaria, colic, vomiting, common cold, cough and skin problems. More than 60 varieties of Ocimum with a variety of leaf colour from green, to red to violet. Its important to analyze the genetic basis of this variety. In our study, we have studied four species of Ocimum: O. sanctum, O. basilicum, O. gratissimum and O. americanum taken from different geographical regions. These species differ with each other in oil contents and secondary metabolites, like: linalool, estragole, and cineole. Very few studies have been done to study the genetic variation among these species. We report a preliminary study on estimation and analysis of genetic variation through random amplification of polymorphic DNA (RAPD) and intersimple sequence repeat polymorphism (ISSR). The RAPD results showed amplified fragments in the range of 2500 to 250 bp., 60% of them were polymorphic and the others monomorphic. We have got certain species specific bands for Ocimum sanctum which can be utilized for authentication of the species. Among the ten ISSR primers tested, we have got bands in the size range of 250 bp to 1 Kb., and the % polymorphism among the three species is found to be around 40%. Our results showed that both RAPD and ISSR techniques are sensitive, precise and efficient tool for genomic analysis in the species’ of Ocimum. Such kind of studies are very useful to put Ocimum species in appropriate taxonomic groups. DNA based markers like ISSR are more useful than the traditional morphological and biochemical markers.