Diversity analysis of Ethiopian mustard breeding lines using RAPD markers

Abstract

Ethiopian mustard (Brassica carinata A. Braun) is an oilseed crop less known to the other parts of the world. Utilization of the available germplasm of B. carinata for different breeding purposes requires information on genetic diversity. Random amplified polymorphic DNA (RAPD) was employed to characterize the genetic diversity of 22 B. carinata inbred lines derived from accessions collected from eight different geographic areas in Ethiopia and one from Sweden. Forty-three primers were used for amplification. The resulting RAPD pattern was analysed with respect to size and distribution of fragments, reproducibility, genetic diversity and informativeness of the marker for genotype specific amplification. In total, 371 bands were amplified of which 239 (65%) were polymorphic. Band size ranged from 300 to 4000 kb. The number of bands generated by each primer varied from 3 to 15 with an average of 8.6, while number of polymorphic bands varied from 1 to 12 with an average of 5.6. RAPD patterns were reliably reproducible between replicates. Genetic similarity (GS) calculated from the marker data using Jaccard`s similarity coefficient (JCS) ranged from 0.34 to 0.84. Using cluster analysis based on unweighted pair-group method with arithmetic average (UPGMA) and principal coordinate analysis (PCoA), the 21 Ethiopian inbred lines were grouped into three subgroups and the single genotype introduced from Sweden formed a separate group. The clustering pattern failed to show a clear correspondence between geographic and molecular diversities within the Ethiopian gene pool. Generally, RAPD differentiation was higher for the exotic genotype, thus formation of a gene pool distinct from the Ethiopian gene pool could be possible through introduction. Based on the genetic relatedness, selective parental combinations were earmarked as potential parents for the future breeding work. The RAPD assay generated genotype-specific products in 14 of the genotypes studied which could be used as DNA fingerprint for variety identification.