Abstract

he assessment of genetic variability is of utmost importance in crop improvement and the conservation of genetic resources. In the current study, two high-yielding sesame cultivars, namely SI 10 and SI 04, were subjected to treatment with ethyl methane sulphonate (EMS) mutagens. Four different concentrations of EMS (0.5%, 1.0%, 1.5%, and 2.0%) were applied to both cultivars. In this study we aimed to evaluate the genetic variability in a mutant population of sesame (Sesamum indicum L.) by employing morphological characters and Simple Sequence Repeat (SSR) markers. The morphological data collected were analyzed using R 4.2.2 software. Analysis of variance revealed significant differences (P=0.05) among most of the morphological traits. Notably, the mutant lines C1P18 SI 10, C3P06 SI 10, C4P10 SI 04, C4P13 SI 04, C1P10 SI 04, C1P18 SI 10, and C2P02 SI 10 exhibited the highest production of capsules per plant and seeds per capsule, indirectly indicating their potential as superior yielders. Furthermore, molecular genetic variation was assessed using twenty-eight SSR markers that were widely distributed across the sesame genome to characterize the mutants. Seventeen out of the 28 primers exhibited polymorphism. Cluster analyses, employing the Euclidean similarity test and a complete link clustering method, were performed to construct a dendrogram based on the morphological data. The mutants were clustered into two major groups and two minor groups. In contrast, the SSR marker-based dendrogram clustering resulted in the discovery of two major clusters, A and B, with a similarity index of 79%. The mutants from both genotypes displayed a diversity range of 10-20% based on the SSR markers, whereas morphological characterization revealed a diversity range of 10 to 51.2%. This study concluded that SSR markers provided a more accurate representation of the true variability in the mutants compared to morphological characterization. Moreover, the use of a lower concentration of EMS (0.5%), which does not cause chromosomal damage, appeared to be more effective in increasing variability in sesame. In summary, this study highlighted the importance of assessing genetic variability in sesame mutants using both morphological and molecular approaches. The findings shed light on the potential for improving sesame crops through the selection of promising mutants and the utilization of SSR markers for accurate characterization of genetic diversity