SSR marker variations in Brassica species provide insight into the origin and evolution of amphidiploids.

BACKGROUND

Oilseed Brassica represents an important group of oilseed crops with a long history of evolution and cultivation. To understand the origin and evolution of Brassica amphidiploids, simple sequence repeat (SSR) markers were used to unravel genetic variations in three diploids and three amphidiploid Brassica species of U's triangle along with as an outlier.

RESULTS

Of 124 Brassica-derived SSR loci assayed, 100% cross-transferability was obtained for and three subspecies of , while lowest cross-transferability (91.93%) was obtained for . The average % age of cross-transferability across all the seven species was 98.15%. The number of alleles detected at each locus ranged from one to six with an average of 3.41 alleles per primer pair. Neighbor-Joining-based dendrogram divided all the 40 accessions into two main groups composed of / and . C-genome of oilseed remained relatively more conserved than A- and B-genome. A- genome present in and seems distinct from each other and hence provides great opportunity for generating diversity through synthesizing amphidiploids from different sources of A- genome. had least intra-specific distance indicating narrow genetic base. appears to be more primitive species from which other two diploid species might have evolved.

CONCLUSION

The SSR marker set developed in this study will assist in DNA fingerprinting of various Brassica species cultivars, evaluating the genetic diversity in Brassica germplasm, genome mapping and construction of linkage maps, gene tagging and various other genomics-related studies in Brassica species. Further, the evolutionary relationship established among various Brassica species would assist in formulating suitable breeding strategies for widening the genetic base of Brassica amphidiploids by exploiting the genetic diversity present in diploid progenitor gene pools.