Genetic diversity assessment of Milk Thistle (Silybum marianum L.) ecotypes using ISSR markers

Milk Thistle (Silybum marianum L.) is one of the important ancient medicinal plants that have been used to treat liver disease, bile-related diseases and poisoned individuals by poisonous mushrooms. Assessment of genetic variation in Milk Thistle like the other important plants is a key component in breeding programs. The aim of this study was studying genetic variation of some Iranian Milk Thistle ecotypes using ISSR marker. A total of 41 repeatable polymorphic marker loci were produced by 9 ISSR primers. The average of polymorphism information content (PIC), Shannon’s information index and Nei’s gene diversity were 0.38, 0.49 and 0.33, respectively. Using cluster analysis by UPGMA algorithm and Jaccard similarity matrix, different ecotypes of Milk thistle grouped in 4 main clusters. We did not find an exact match between dendrogram grouping and geographical grouping of ecotypes. This could be due to the high diversity of this plant or relocation of ecotypes. The results indicate existence of a significant variation among Iranian Milk thistle ecotypes to start the breeding programs.