Evaluation of Genetic Diversity in Brassica juncea (L.) Using Protein Profiling and Molecular Marker (RFLP)

An understanding of the extent, distribution and patterns of genetic variation is useful for estimation of any possible loss of genetic diversity and assessment of genetic variability and its potential use in breeding programs, including establishment of heterotic groups. This study assessed patterns of genetic diversity and relationships among five accessions of Brassica juncea using sodium dodecyl sulphate and restriction fragment length polymorphism marker systems. The protein profile showed low level of polymorphism (28.57%). The RFLP marker showed a high degree of polymorphism (87.5%) among the five accessions of Brassica juncea. A total of 8 clear bands were scored in all the five accessions. Among the 8 scorable bands calculated, only one band at position 2 with 820 kb was monomorphic and the rest were polymorphic. Upon UPGMA analysis the dendrogram clustered the five accessions into two main clusters. Cluster 1 comprising three accessions IC 343120, IC 248997 and IC 426377. Cluster 2 comprising two accessions IC 426384 and IC 312514. The low polymorphism results of SDS-PAGE showed that SDS-PAGE has limited use in Brassica because of the conservative nature of seed proteins. However, RFLP markers are superior to SDS-PAGE because they provide better coverage of the genome and reveal higher level of polymorphism.