Relationship and genetic diversity analysis of Brassica juncea and U tringle species using intron polymorphic markers

Abstract

Intron Polymorphism (IP) markers were used to unravel the genetic variation and relationship among 26 genotypes representing six cultivated Brassica species described in the classical U triangle. One hundred and twenty-five Arabidopsis thaliana-derived IP markers were assayed and 90 to 100% cross-transferability was observed in the six Brassica species suggesting that IP markers were highly conserved during the evolution of different Brassica species. The number of alleles observed in species at each locus ranged from one to ten with an average of 2.89 alleles per primer pair and there was no consensus between the number of alleles amplified in diploid and tetraploid species. The size range of amplified alleles was 120-1250bp, which reflects enormous deletions/insertions in different alleles. In B. juncea, 100% cross-transferability had been obtained and 121 IP markers resulted in polymorphic amplicons with PIC value of 0.04 to 0.48. The dendrogram divided all the 26 genotypes into two groups composed of B. napus/B. rapa/B. oleracea and B. carinata/B. nigra/B. juncea. A-genome present in B. juncea and B. napus/B. rapa seems distinct from each other and hence provides a great opportunity for generating diversity through resynthesizing amphidiploids from different available sources of Agenome. The A and B genomes are more similar in comparison to C genome in tetra-diploid species.The evolutionary relationship established between various Brassica species would support in formulating suitable breeding approaches for widening the genetic base of Brassica amphidiploids by exploiting the genetic diversity found in diploid progenitor gene pools.