Genetic characterization of Indian mustard lines using SSR markers

Abstract

Genetic diversity is the cornerstone of crop improvement, as the identification and effective utilization of variation within germplasm determine the success of breeding programs. Indian mustard (Brassica juncea L.), a major oilseed crop of India, possesses a relatively narrow genetic base, highlighting the need for systematic molecular diversity analysis. In the present investigation, 40 promising breeding lines developed through the pedigree method at BAU, Sabour, along with four check varieties, were evaluated for genetic diversity using simple sequence repeat (SSR) markers. Out of 22 SSR markers screened, six markers (gi258659503gbGT070143.1, BRMS-018F, gi407345453gbJK615950.1, cnu_m612aF, cnu_m606aF and PBCESSRJU9) were polymorphic and used for diversity analysis. Cluster analysis based on SSR polymorphism grouped the genotypes into distinct clusters, revealing substantial molecular variability and heterogeneous divergence within clusters. Based on dendrogram topology and branch length, genotypes R.Suflam, BRBJ55, BRBJ45, BRBJ42 and BRBJ46 from Cluster I and BRBJ02, BRBJ03, BRBJ07, BRBJ101, BRBJ106 and BRBJ53 from Cluster II were identified as genetically most divergent. Inter-cluster crosses such as R × BRBJ02, BRBJ55 × BRBJ03, BRBJ45 × BRBJ07, BRBJ42 × BRBJ101 and BRBJ46 × BRBJ106 were suggested to exploit maximum genetic diversity. The identified diverse genotypes and proposed crosses provide a strong molecular basis for parent selection and can be effectively utilized for broadening the genetic base and enhancing genetic gain in Indian mustard breeding programs.