Evaluation of accession structure and genetic diversity in Iranian milk thistle (Silybum marianum L.) by ISSR markers

Abstract

The aim of this study was to investigate the genetic variations of Iranian Silybum marianum accessions using inter simple sequence repeat (ISSR) markers. Twenty-nine accessions from various Iran regions and a sample from Hungary were selected and evaluated by 19 ISSR primers. A clear banding pattern was produced by 9 primers and a total of 85 repeatable polymorphic bands were detected. ISSR7 and ISSR8 primers identified the most Polymorphic Information Content (PIC) with 100% among primers. In the tested accessions, polymorphism information content (0.45), polymorphic percentage (83 %), and Shannon?s information index (0.53) assessed a high level of genetic variation. Based on Jaccards distances, cluster analysis molecular traits with unweighted pair group method with arithmetic mean (UPGMA) method were taken into consideration, and accessions were grouped into nine clusters and confirmed by principal coordinate analysis. Four clusters were identified by a Bayesian structure analysis, and 12 individuals were maintained inside the admixed clusters. According to the findings, ISSR marker system can be considered as a powerful tool for detection of genetic diversity of accessions in S. marianum. The results indicate existence of a high variation among Iranian S. marianum accessions to start the breeding programs.