Genetic diversity in leafy mustard ( Brassica juncea var. rugosa ) as revealed by agro-morphological traits and SSR markers

Leafy mustard ( B. juncea var. rugosa ) constitutes an important group of vegetable mustard crops in India and is mainly cultivated in home-backyard and hilly regions of Uttarakhand and some North-eastern states. In the present study, various agro-morphological traits, physiological and biochemical traits along with SSR markers were used for genetic diversity evaluation in a germplasm collection of leafy mustard. This study revealed a significant variation among 59 accessions of leafy mustard in both qualitative and quantitative agro-morphological traits indicating the accessions’ promising potential for consumption purpose and for use in breeding programs. Maximum variability was recorded for leaf area elongation rate (CV = 53.12%), followed by total plant weight (TPW) (CV = 50.63%) and seed yield per plant (CV = 44.33%). In molecular analysis, 155 SSRs evaluated resulted in 482 alleles and the number of alleles varied form 1 to 8 with an average of 3.11 alleles per marker. A total of 122 (78.70%) SSRs resulted into polymorphic amplicons. PIC value varied from 0.32 to 0.77 with an average value of 0.44 per SSR locus. The unweighted neighbour-joining-based dendrogram analysis divided all the 59 accessions into two major groups on the basis of both agro-morphological traits and SSR markers, whereas, three subpopulations/subgroups were predicted by population STRUCTURE analysis. AMOVA indicated the presence of more variability within population than among population. Overall, agro-morphologically better performing and genetically diverse genotypes have been identified which could be further used as donors for leafy mustard improvement programs.