Journal of Medicinal Plants Research Vol. 4(17), pp. 1822-1824, 4 September, 2010 Available online at http://www.academicjournals.org/JMPR DOI: 10.5897/JMPR10.060 ISSN 1996-0875 ©2010 Academic Journals Short Communication Detection of somaclonal variations using RAPD fingerprinting in Silybum marianum (L.) Tariq Mahmood 1 *, Nazia Nazar 1 , Bilal Haider Abbasi 2 , Mir Ajab Khan 1 , Mushtaq Ahmad 1 , Muhammad Zafar 1 1 Department of Plant Sciences, Quaid-i-Azam University, Islamabad-45320, Pakistan. 2 Department of Biotechnology, Quaid-i-Azam University, Islamabad-45320, Pakistan. Accepted 27 April, 2010 Random amplification of polymorphic DNA (RAPD) markers was used to detect somaclonal genetic variations between in vitro and in vivo grown tissues of Silybum “S. marianum”. Ten primers (OPC1- OPC10) of RAPD OPC were used. All the primers gave reproducible banding pattern except OPC3. Monomorphic bands were observed in case of all primers, whereas only OPC10 generated different banding pattern among the samples of S. marianum. OPC 10 produced ten unique bands in each sample ranging in size from 200 - 1000 bp. On the basis of the results obtained, it was observed that genetic variation is present in different samples of S. marianum and RAPD technique can be used to detect genetic similarities and dissimilarities between in vitro- and in vivo-grown tissues of S. (S.) marianum. Key words: RAPD, regeneration, Silybum, somaclonal variation, thistle. INTRODUCTION Silybum (S.) marianum (L.) Gaertn is used for oral treatment of toxic liver damage and for therapy of chronic inflammatory liver diseases and liver cirrhosis (Morazzoni and Bombardelli, 1995). This activity of S. marianum is due to a mixture of flavonolignans, known as silymarin (Kurkin et al., 2001). At present, all of the commercially available Silybum is obtained from wild. The increasing worldwide demand for Silybum is endangering the sparse populations. Thus, to fulfill the increasing demand, developing an efficient in vitro regeneration protocol of genetically similar S. marianum plants with desirable agronomic and chemical traits is needed. In this respect different studies related to the standardization of its tissue culture conditions and antioxidants activity has been reported (Abbasi et al., 2010). Nonetheless, somaclonal variation frequently occurs as a consequence of the propagation process in different plant species (Chuang et al., 2009). Somaclonal variation reduces the commercial *Corresponding author. E-mail: taariq.mahmood@yahoo.com, tmahmood@qau.edu.pk. Tel: +92-51-9064 3144. Fax: +92-51- 9064 3004. value of plants (Oropeza et al., 1995). Thus it is very important to detect somaclonal variation at earlier stage of plant growth to avoid economic loss (Chuang et al., 2009). Genetic variation analyses can be observed from morphological characters and other markers as protein or deoxyribonucleic acid (DNA)-based markers. However, the morphological characters evaluation requires the plants to grow to full maturity prior to identification. Subsequently genetic resources characterization also needed to establish development of genetic markers for valuable traits (Paterson et al., 1991). RAPD is the simplest, sensitive and useful technique for the analysis of genetic fidelity of in vitro propagated plants (Chuang et al., 2009; Williams et al., 1993). Because RAPD polymorphism results from either a nucleotide base change that alter the primer binding site, or from an insertion or deletion within amplified region. Polymorphism usually results in the presence or absence of amplification products from a single locus (Tingey and del Tufo, 1993). In this study, RAPD was employed to evaluate the genetic reliability of S. marianum plantlets regenerated by leaf organogenesis. To the best of our knowledge, this is