THE ASSESSMENT OF GENETIC DIVERSITY BETWEEN AND WITHIN BRASSICA SPECIES AND THEIR WILD RELATIVE (ERUCA SATIVA) USING SSR MARKERS

Abstract

Microsatellites markers were tested for their ability to distinguish genomic distribution of the Brassica species of the U Triangle and E. sativa. The objectives of the present study were to investigate the genetic diversity of six Brassica species from U-Triangle (representing three genomes, A, B, C) and one from genus Eruca and to identify promising sources of genetic variation for breeding purposes. A total of 54 SSR markers were analyzed in order to detect variation between and within the selected genomes. Three primer pairs depicted the greatest genetic diversity showing 97% polymorphism between Brassica and Eruca genomes (2.55 alleles per locus). Polymorphic Information Content (PIC) values ranged from 0.40 (SSR primer Na14-DO7) to 0.79 (NA10-G09). For comparison within Brassica genomes and Eruca, all the genomes were grouped in three modules i.e., ABE, ACE and BCE (Fig. 1). The tetraploid originating from their parental diploids alongwith Eruca was considered in the same module. For the estimation of relatedness within and among genomes, dice coefficients were computed as a measure of genetic similarity matrix. On the basis of genetic distances, dendrogram was constructed through cluster analysis. Two major clusters at coefficient of similarity level (0.47) were observed. One cluster comprised of all Brassica genomes and their accessions, while another consisting of all accessions of Eruca genome. The cluster containing Brassica genomes was further subdivided into four sub-groups that contained diploid and tetraploid species in a way that tetraploid species were grouped in between their diploid parental species with varying genetic distances. Present findings confirmed the validity of SSR markers in genomic studies.