Genetic Diversity Analysis of Brassica Species Using PCR-Based SSR Markers

Genetic diversity is an important measure for the improvement of many crop species including Brassica. This study evaluated the genetic divergence among six Brassica species using simple sequence repeats (SSR). Ten SSR markers produced overall 21 alleles with an average of 2.1 alleles per primer. Out of 21, 18 alleles showed polymorphism (85.71%) and 3 alleles showed monomorphism (14.28%). A similarity matrix was constructed using Popgen32 software. Genetic identity ranged from 33.33 to 76.19%. B. nigra and B. campestris showed the highest identity, while the lowest identity was observed between B. campestris and B. oleracea. Sizes of amplified alleles were ranged from 70 to 290 bp. Polymorphic information content (PIC) varied from 0.37 to 0.71, with an average of 0.66 per primer. A dendrogram classified the genotypes into two main clusters. Cluster-A is further divided into cluster-C, which consists of B. carinata and B. oleracea. B. napus and B. juncea each form an independent cluster. Cluster-B consists of B. nigra and B. campestris, meaning that these two species are closely related to each other. The results indicated that these species can be isolated from each other at the molecular level by using molecular markers.