Comparative assessment of genetic diversity among twenty varieties of Brassica juncea [L.] Czern & Coss using RAPD and ISSR markers

Abstract

PCR based molecular markers such as RAPD (random amplified polymorphic DNA) and ISSR (inter simple sequence repeats) were employed for the evaluation of genetic diversity among twenty varieties of Brassica juncea. Mean polymorphism information content (PIC) value was greater for RAPD (0.4195) as compared to ISSR (0.2602). In RAPD analysis, 98.9% loci were polymorphic whereas in ISSR, 94.8 % were polymorphic. The number of loci in RAPD profile ranged from 7 to 10 with an average of 9.3 per primer whereas in ISSR, these were from 3 to 12 with an average of 6.8 loci per primer. RAPD based genetic similarity ranged from 0.224 to 0.842 whereas ISSR derived genetic similarity 0.467 to 0.880. The mental test between two Jaccard’s similarity matrices gave r = 0.89, showing good fit correlation in between ISSR†and RAPDâ€based similarities. The results obtained from the consensus tree constructed from RAPD+ISSR marker more likely support the distribution of the twenty genotypes of B. juncea based on ISSR analysis. The twenty varieties were clustered into three main clusters 1, 2, and 3 respectively. In combined dendrogram study, each cluster has 13, 3, and 4 varieties.