Optimization of Chemical Mutagenesis Conditions with Ethyl Methanesulfonate and Screening of Mutants in Sesame (Sesamum indicum L.)

Abstract

Background: Sesame is a globally important oilseed crop rich in antioxidants, widely valued for food, medicine, and industrial uses. EMS-induced mutagenesis is used to create genetic variation in sesame, with LD50-guided dosing helping determine effective mutation levels for research. Aims: to assess the chemical toxicity of ethyl methanesulfonate (EMS) mutagen and to induce additional genetic variation from two sesame varieties. Study Design: Randomized Complete Block design with 3 replications. Eight treatments resulting from the combination of two factors: Treatment duration at two levels and EMS dose at four levels. Place and Duration of Study: The Department of Biology laboratory, Faculty of Science, from January 9th to 17th, 2024, and the Experimental station of the Faculty of Agronomy and Environmental Sciences, Dan Dicko Dankoulodo University of Maradi, from May 2024 to December 2025. Methodology: In a first step, EMS was applied to seeds of the sesame variety SN303 at three doses of 0.5%, 1%, and 1.5% over two incubation periods to determine the lethal dose (LD50). The treated seeds and the control were germinated in Petri dishes at room temperature in the laboratory, and germination was assessed every 2 days for up to 7 days. In a second step, the determined LD50 of EMS was used to mutagenize seeds of the variety SN303 and the exotic line PI599446. M1 generation was conducted in controlled conditions in the greenhouse, while subsequent generations were conducted in the field. Results: Germination was strongly affected by the mutagenic treatment and decreased as EMS dose increased. The LD50 was determined to be 0.6% for 6 h incubation period and 0.5% for 12 h. A wide range of phenotypic variability was observed in the M2 generation for both SN303 and PI599446 derived populations. The highest mutation frequencies, 53 x 10-4 and 21 x10-4 were obtained with chlorophyll mutants for PI599446 and SN303, respectively. Agronomically interesting genotypes, namely those with aspects of shattering limitation and those with determinate growth were also obtained. Conclusion: In this study, lower concentrations of EMS (0.5-0.6%) were more effective in inducing useful genetic variation in sesame.